The document discusses several methods for growing single crystal materials, including Czochralski, Bridgman, Stockbarger, zone melting, and Verneuil techniques. The Czochralski method involves pulling a crystal seed from a melt of the material using precise temperature control. The Bridgman and Stockbarger methods use controlled solidification of a melt in a temperature gradient. Zone melting and hydrothermal crystal growth allow for purification or synthesis of crystals. These growth methods are important for producing large, high-quality single crystals for applications in electronics, optics, and other devices.
The document discusses several techniques for growing single crystals, which are important for measuring anisotropic properties and fabricating devices. The Czochralski technique involves pulling a crystal seed from a melt held just above its melting point to form a single crystal. The Bridgman and Stockbarger techniques use controlled solidification of a melt within a temperature gradient furnace. Zone melting involves melting a small region of a sample to purify it as impurities concentrate in the liquid. The Verneuil technique grows crystals by melting and solidifying powder precursors in an oxygen-hydrogen flame.
Zone melting is a key technique for single crystal growth fabrication. Zone melting is a group of techniques used to purify an element or compound and control its composition. This presentation will discuss the basics of the zone melting technique and with help of 2-3 research papers, the examples of zone melting would be explained. Single crystal growth is a quite useful technique used in various applications in the field of metallurgy as well as nanomaterials synthesis. The technique is used for the removal of unwanted impurities from the material, control the discontinuities in impurity distribution, and also maintaining uniform doping of the impurity in the material.
The document discusses various methods for casting and solidifying materials, including single crystal casting techniques. Single crystal casting of turbine blades involves directional solidification where a single crystal grows longitudinally through a ceramic mold for increased strength. For microelectronics, the Czochralski method pulls a seed crystal from molten material to form long single crystal ingots. Rapid solidification involves cooling molten material at over 106 K/s to form non-crystalline metallic glasses without grain growth. Roll casting is a common rapid solidification technique where molten material is spun against a chilled roll to rapidly solidify into amorphous ribbons or sheets.
This document discusses gravimetric analysis methods. It defines gravimetric analysis as isolating and weighing an element or compound in pure form to determine the quantity present. The main types discussed are precipitation gravimetry, electrogravimetry, and volatilization gravimetry. Precipitation gravimetry, the formation of an insoluble precipitate, is explained in detail including factors that influence successful precipitation and purity of the precipitate. Advantages include high precision and accuracy, while disadvantages include being time-consuming and requiring clean glassware and accurate weighing. An example of barium chloride estimation by precipitating and weighing barium sulfate is also provided.
The document discusses various methods for crystal growth, including growth from melt, solution, and vapor phase. It describes the Czochralski method, Bridgman process, zone melting, and floating zone techniques for melt growth. Convection effects are discussed, and models like Burton-Prim-Slichter are presented to understand solute transport and segregation during crystal growth. Microscopic inhomogeneity caused by unsteady conditions is also mentioned.
Nanoscience and nanotechnology involve working at the nanoscale level of 1 to 100 nanometers. The document discusses various methods for producing and characterizing nanoparticles and nanofluids. Top-down methods break down bulk materials into nanoparticles using techniques like ball milling, while bottom-up methods build nanoparticles from smaller units using approaches such as sol-gel synthesis and laser ablation. Characterization techniques discussed include UV-Vis spectroscopy, dynamic light scattering, transmission electron microscopy, and atomic force microscopy.
The document discusses several techniques for growing single crystals, which are important for measuring anisotropic properties and fabricating devices. The Czochralski technique involves pulling a crystal seed from a melt held just above its melting point to form a single crystal. The Bridgman and Stockbarger techniques use controlled solidification of a melt within a temperature gradient furnace. Zone melting involves melting a small region of a sample to purify it as impurities concentrate in the liquid. The Verneuil technique grows crystals by melting and solidifying powder precursors in an oxygen-hydrogen flame.
Zone melting is a key technique for single crystal growth fabrication. Zone melting is a group of techniques used to purify an element or compound and control its composition. This presentation will discuss the basics of the zone melting technique and with help of 2-3 research papers, the examples of zone melting would be explained. Single crystal growth is a quite useful technique used in various applications in the field of metallurgy as well as nanomaterials synthesis. The technique is used for the removal of unwanted impurities from the material, control the discontinuities in impurity distribution, and also maintaining uniform doping of the impurity in the material.
The document discusses various methods for casting and solidifying materials, including single crystal casting techniques. Single crystal casting of turbine blades involves directional solidification where a single crystal grows longitudinally through a ceramic mold for increased strength. For microelectronics, the Czochralski method pulls a seed crystal from molten material to form long single crystal ingots. Rapid solidification involves cooling molten material at over 106 K/s to form non-crystalline metallic glasses without grain growth. Roll casting is a common rapid solidification technique where molten material is spun against a chilled roll to rapidly solidify into amorphous ribbons or sheets.
This document discusses gravimetric analysis methods. It defines gravimetric analysis as isolating and weighing an element or compound in pure form to determine the quantity present. The main types discussed are precipitation gravimetry, electrogravimetry, and volatilization gravimetry. Precipitation gravimetry, the formation of an insoluble precipitate, is explained in detail including factors that influence successful precipitation and purity of the precipitate. Advantages include high precision and accuracy, while disadvantages include being time-consuming and requiring clean glassware and accurate weighing. An example of barium chloride estimation by precipitating and weighing barium sulfate is also provided.
The document discusses various methods for crystal growth, including growth from melt, solution, and vapor phase. It describes the Czochralski method, Bridgman process, zone melting, and floating zone techniques for melt growth. Convection effects are discussed, and models like Burton-Prim-Slichter are presented to understand solute transport and segregation during crystal growth. Microscopic inhomogeneity caused by unsteady conditions is also mentioned.
Nanoscience and nanotechnology involve working at the nanoscale level of 1 to 100 nanometers. The document discusses various methods for producing and characterizing nanoparticles and nanofluids. Top-down methods break down bulk materials into nanoparticles using techniques like ball milling, while bottom-up methods build nanoparticles from smaller units using approaches such as sol-gel synthesis and laser ablation. Characterization techniques discussed include UV-Vis spectroscopy, dynamic light scattering, transmission electron microscopy, and atomic force microscopy.
This document provides an overview of principles of extractive metallurgy. It outlines the course objectives which are to understand extractive metallurgy processes, identify extraction types, learn thermodynamics of extraction, and understand various metal production flow sheets. The syllabus covers topics like extraction processes, pyrometallurgy versus hydrometallurgy, calcination, roasting, smelting, thermodynamics principles, and electrometallurgy. Key extraction concepts like comminution, classification, separation methods, and kinetics are also mentioned.
This document discusses key production variables that affect ceramic membranes, including raw materials, fabrication methods, sintering temperature, and coating techniques. Raw materials like kaolin clay and fly ash can lower costs, while additives like zeolites and apatite suit different applications. Fabrication by slip casting, extrusion or pressing yields different strengths. Higher sintering temperatures increase properties but must be below melting points. Coating methods like sol-gel, CVD and ALD can precisely control layer thickness but require specialized equipment. Process variables must be optimized to produce high-performance ceramic membranes.
VAC uses rapid solidification technology to cast thin metallic ribbons from molten metal with extremely high cooling rates of 106 K/s, high casting speeds of 100 km/h, and automatic reel changing during winding. This allows the production of amorphous or nanocrystalline soft magnetic alloys with superior properties for applications such as magnetic cores and inductive components. Various single crystal growth methods are used to eliminate grain boundaries, including floating zone, Czochralski crystal pulling, and hydrothermal synthesis using water as a mineralizing agent. Twin-roll and twin-belt casting are continuous casting methods that produce thin strips with fine grain structure and high casting rates.
This document discusses different approaches for nanofabrication including top-down and bottom-up. It describes various synthesis methods for nanoparticles including solid, liquid, and gas phase techniques. Specific solid phase methods like agitated ball milling and specific liquid phase techniques like sol-gel synthesis and solvothermal synthesis are explained. Gas phase methods like chemical vapor deposition, laser ablation, and references for further reading are also summarized.
Introduction to thin film growth and molecular beam epitaxyOleg Maksimov
This document provides an introduction to thin film growth techniques focusing on molecular beam epitaxy (MBE). It describes various physical vapor deposition and chemical vapor deposition methods. MBE is explained in detail, including the advantages of growth in an ultra-high vacuum environment with independent material sources and in-situ monitoring via RHEED. Different growth modes such as Frank-van der Merwe, Volmer-Weber, and Stranski-Krastanov are also summarized.
This document discusses various methods for crystal growth, including growing crystals from solution and vapor phase. It describes how crystallization occurs as atoms or molecules arrange in a repeating pattern. There are multiple techniques for obtaining crystals depending on the material, such as growing from molten solid, solution, or vapor phase. A common method is growing from solution, which involves precipitating crystals from a saturated solution by techniques like cooling or evaporation to reduce solubility in a controlled manner. Proper conditions like solvent choice, temperature control, and supersaturation levels are important for successful crystal growth.
Solvothermal method mithibai college msc part 1 pradeep jaiswalPradeep Jaiswal
This document discusses the solvothermal method for preparing nanomaterials. The solvothermal method involves conducting chemical reactions in a closed vessel (autoclave) where the solvent is heated above its boiling point. This allows reactions to occur under high temperature and pressure. An example given is the preparation of chromium dioxide nanoparticles by oxidizing chromium oxide in an autoclave with water and chromium trioxide. Advantages of the solvothermal method include precise control over the size, shape and properties of the synthesized nanoparticles. Disadvantages include the need for expensive autoclave equipment and safety issues during high pressure/temperature reactions.
There are two main methods for growing silicon crystals for solar cells - Czochralski (CZ) and float zone (FZ). In CZ growth, a silicon seed crystal is dipped into molten silicon and slowly pulled to form a cylindrical ingot. FZ growth uses a floating molten zone to recrystallize a silicon rod. FZ crystals have higher purity, lifetime and efficiency but require higher quality feedstock. CZ is more commonly used due to lower costs. Improvements aim to increase growth rate, reduce energy use, and cut more wafers from each ingot to lower costs.
The process of transformation of a substance from liquid to solid state in which the crystal lattice forms and crystals appear.
•Volume shrinkage or volume contraction
The Czochralski method is used to grow large single crystal boules of semiconductors like silicon that are then cut into wafers for manufacturing integrated circuits. In the process, a seed crystal is dipped into a melt of the material held at a temperature slightly above its melting point. The seed is slowly extracted while being rotated, allowing the melted material to solidify on the seed in a crystalline structure to form a cylindrical ingot. This ingot is then cut and polished into wafers for semiconductor device fabrication. The Czochralski method is well-suited for silicon crystal growth and is the predominant industrial process for producing silicon wafers.
Crystallization is a separation process very commonly used in the industry of many different materials, from commercially very common chemicals to very specific ones. It also plays an important role in the pharmaceutical industry, as more than 90% of active pharmaceutical ingredients (API) are synthesized as a crystalline product. Crystallization may have a significant direct and indirect influence on the quality of a product; therefore, it is one of the most important purification and separation methods in the production of APIs.
This document discusses powder bed fusion processes, specifically selective laser sintering (SLS). It describes the SLS process which uses a laser to fuse powdered material into a solid 3D part by sintering it layer by layer. Key parameters that influence the SLS process are discussed such as laser power, scan speed, powder size and distribution, and temperature maintenance. Common materials used include polymers, metals and ceramics. Applications of SLS include prototypes, tools, and low volume production.
Investment materials are used to form molds for dental casting. They are composed of refractory materials like quartz or cristobalite, a binder like gypsum or phosphate, and other chemicals. Gypsum-bonded investments are commonly used for gold alloy casting while phosphate-bonded investments can withstand higher temperatures for casting alloys like cobalt-chromium. Ethyl silicate investments are used for high-fusing base metal alloys. The investments require properties like stability at high temperatures, sufficient expansion to compensate for metal shrinkage, and ease of removal after casting.
Crystalline, Glassy Solids and Liquid CrystalRakesh Sheoran
This document discusses solid state physics and different types of solids. It defines solid state physics as studying the properties of solid materials, especially periodicity properties of crystals. The main types of solids discussed are crystalline solids, which have long-range atomic order, amorphous solids which lack long-range order, and quasi-crystalline solids. Liquid crystals are also introduced, which have properties between solids and liquids, such as fluidity but also some atomic ordering. The main types of liquid crystals - nematic, smectic and cholesteric - are defined along with their structural properties. Finally, some applications of liquid crystals are mentioned such as in LCD displays, thermometers, and medical imaging
This document discusses dental casting investment materials. It begins by defining investment materials as those suitable for forming molds for molten metals. Investments contain refractory materials, binders, and other chemicals. The main types are gypsum-bonded for gold alloys, phosphate-bonded for metal-ceramics and cobalt-chromium, and ethyl silica-bonded for base metal alloys. Properties required include strength, expansion to compensate for shrinkage, and porosity. The components, properties, manipulation and types of each major investment material are described in detail.
Crystallization is the process of obtaining crystals of a pure substance from its hot, saturated solution. It involves a physical change as no new substances are formed - only a change from liquid to solid state. Crystallization is used to purify naturally occurring impure substances and obtain them in pure crystalline form. There are three main steps: supersaturation of the solution, nucleation where crystal seeds form, and crystal growth. Common applications include purification of drugs, seawater, and in separating substances like alum in industries. Types of crystallization include evaporative, cooling, and reactive crystallization.
Routine histopathology techniques and staining [Autosaved].pptxchandreshmishra13
The document provides information about routine histopathology techniques and staining. It discusses fixation of histology samples, ideal fixatives, changes after fixation, types of fixatives, and the mechanisms of fixation. It also covers tissue processing techniques including dehydration, clearing, infiltration, embedding, and sectioning of tissue blocks using a microtome. Key steps in processing like fixation, dehydration, clearing and infiltration are described in detail. Common fixatives, dehydrating agents, and clearing agents used are also listed.
Routine histopathology techniques and staining [Autosaved].pptxchandreshmishra13
This document provides an overview of routine histopathology techniques and staining. It discusses fixation of histology samples using an ideal fixative like formaldehyde. It describes the changes that occur in tissue after fixation, including shrinkage and hardening. Different types of fixatives and their mechanisms of action are explained. The document also covers tissue processing techniques including dehydration, clearing, infiltration and embedding in paraffin wax. Key steps and factors influencing tissue processing are summarized. Staining, troubleshooting, decalcification and special techniques like tissue marking and orientation are briefly outlined.
impulse(GreensFn), Principle of SuperpositionSc Pattar
Impulse superposition
Green’s function for underdamped oscillator
Exponential driving force
Green’s function for an undamped oscillator
Solution for constant force
Step function method
Research project proposal and Publishing pdfSc Pattar
This document outlines the key components of a research proposal, including objectives, introduction/background, methodology, timeline, personnel, facilities, and budget. It discusses the importance of clearly stating the research problem and objectives. The methodology section should provide details on data collection, analysis, and statistical tests. A timeline in the form of a Gantt chart or flow chart can help show sequencing and relationships between tasks. The proposal should also specify the personnel, facilities, equipment, and funding required to complete the study.
This document provides an overview of principles of extractive metallurgy. It outlines the course objectives which are to understand extractive metallurgy processes, identify extraction types, learn thermodynamics of extraction, and understand various metal production flow sheets. The syllabus covers topics like extraction processes, pyrometallurgy versus hydrometallurgy, calcination, roasting, smelting, thermodynamics principles, and electrometallurgy. Key extraction concepts like comminution, classification, separation methods, and kinetics are also mentioned.
This document discusses key production variables that affect ceramic membranes, including raw materials, fabrication methods, sintering temperature, and coating techniques. Raw materials like kaolin clay and fly ash can lower costs, while additives like zeolites and apatite suit different applications. Fabrication by slip casting, extrusion or pressing yields different strengths. Higher sintering temperatures increase properties but must be below melting points. Coating methods like sol-gel, CVD and ALD can precisely control layer thickness but require specialized equipment. Process variables must be optimized to produce high-performance ceramic membranes.
VAC uses rapid solidification technology to cast thin metallic ribbons from molten metal with extremely high cooling rates of 106 K/s, high casting speeds of 100 km/h, and automatic reel changing during winding. This allows the production of amorphous or nanocrystalline soft magnetic alloys with superior properties for applications such as magnetic cores and inductive components. Various single crystal growth methods are used to eliminate grain boundaries, including floating zone, Czochralski crystal pulling, and hydrothermal synthesis using water as a mineralizing agent. Twin-roll and twin-belt casting are continuous casting methods that produce thin strips with fine grain structure and high casting rates.
This document discusses different approaches for nanofabrication including top-down and bottom-up. It describes various synthesis methods for nanoparticles including solid, liquid, and gas phase techniques. Specific solid phase methods like agitated ball milling and specific liquid phase techniques like sol-gel synthesis and solvothermal synthesis are explained. Gas phase methods like chemical vapor deposition, laser ablation, and references for further reading are also summarized.
Introduction to thin film growth and molecular beam epitaxyOleg Maksimov
This document provides an introduction to thin film growth techniques focusing on molecular beam epitaxy (MBE). It describes various physical vapor deposition and chemical vapor deposition methods. MBE is explained in detail, including the advantages of growth in an ultra-high vacuum environment with independent material sources and in-situ monitoring via RHEED. Different growth modes such as Frank-van der Merwe, Volmer-Weber, and Stranski-Krastanov are also summarized.
This document discusses various methods for crystal growth, including growing crystals from solution and vapor phase. It describes how crystallization occurs as atoms or molecules arrange in a repeating pattern. There are multiple techniques for obtaining crystals depending on the material, such as growing from molten solid, solution, or vapor phase. A common method is growing from solution, which involves precipitating crystals from a saturated solution by techniques like cooling or evaporation to reduce solubility in a controlled manner. Proper conditions like solvent choice, temperature control, and supersaturation levels are important for successful crystal growth.
Solvothermal method mithibai college msc part 1 pradeep jaiswalPradeep Jaiswal
This document discusses the solvothermal method for preparing nanomaterials. The solvothermal method involves conducting chemical reactions in a closed vessel (autoclave) where the solvent is heated above its boiling point. This allows reactions to occur under high temperature and pressure. An example given is the preparation of chromium dioxide nanoparticles by oxidizing chromium oxide in an autoclave with water and chromium trioxide. Advantages of the solvothermal method include precise control over the size, shape and properties of the synthesized nanoparticles. Disadvantages include the need for expensive autoclave equipment and safety issues during high pressure/temperature reactions.
There are two main methods for growing silicon crystals for solar cells - Czochralski (CZ) and float zone (FZ). In CZ growth, a silicon seed crystal is dipped into molten silicon and slowly pulled to form a cylindrical ingot. FZ growth uses a floating molten zone to recrystallize a silicon rod. FZ crystals have higher purity, lifetime and efficiency but require higher quality feedstock. CZ is more commonly used due to lower costs. Improvements aim to increase growth rate, reduce energy use, and cut more wafers from each ingot to lower costs.
The process of transformation of a substance from liquid to solid state in which the crystal lattice forms and crystals appear.
•Volume shrinkage or volume contraction
The Czochralski method is used to grow large single crystal boules of semiconductors like silicon that are then cut into wafers for manufacturing integrated circuits. In the process, a seed crystal is dipped into a melt of the material held at a temperature slightly above its melting point. The seed is slowly extracted while being rotated, allowing the melted material to solidify on the seed in a crystalline structure to form a cylindrical ingot. This ingot is then cut and polished into wafers for semiconductor device fabrication. The Czochralski method is well-suited for silicon crystal growth and is the predominant industrial process for producing silicon wafers.
Crystallization is a separation process very commonly used in the industry of many different materials, from commercially very common chemicals to very specific ones. It also plays an important role in the pharmaceutical industry, as more than 90% of active pharmaceutical ingredients (API) are synthesized as a crystalline product. Crystallization may have a significant direct and indirect influence on the quality of a product; therefore, it is one of the most important purification and separation methods in the production of APIs.
This document discusses powder bed fusion processes, specifically selective laser sintering (SLS). It describes the SLS process which uses a laser to fuse powdered material into a solid 3D part by sintering it layer by layer. Key parameters that influence the SLS process are discussed such as laser power, scan speed, powder size and distribution, and temperature maintenance. Common materials used include polymers, metals and ceramics. Applications of SLS include prototypes, tools, and low volume production.
Investment materials are used to form molds for dental casting. They are composed of refractory materials like quartz or cristobalite, a binder like gypsum or phosphate, and other chemicals. Gypsum-bonded investments are commonly used for gold alloy casting while phosphate-bonded investments can withstand higher temperatures for casting alloys like cobalt-chromium. Ethyl silicate investments are used for high-fusing base metal alloys. The investments require properties like stability at high temperatures, sufficient expansion to compensate for metal shrinkage, and ease of removal after casting.
Crystalline, Glassy Solids and Liquid CrystalRakesh Sheoran
This document discusses solid state physics and different types of solids. It defines solid state physics as studying the properties of solid materials, especially periodicity properties of crystals. The main types of solids discussed are crystalline solids, which have long-range atomic order, amorphous solids which lack long-range order, and quasi-crystalline solids. Liquid crystals are also introduced, which have properties between solids and liquids, such as fluidity but also some atomic ordering. The main types of liquid crystals - nematic, smectic and cholesteric - are defined along with their structural properties. Finally, some applications of liquid crystals are mentioned such as in LCD displays, thermometers, and medical imaging
This document discusses dental casting investment materials. It begins by defining investment materials as those suitable for forming molds for molten metals. Investments contain refractory materials, binders, and other chemicals. The main types are gypsum-bonded for gold alloys, phosphate-bonded for metal-ceramics and cobalt-chromium, and ethyl silica-bonded for base metal alloys. Properties required include strength, expansion to compensate for shrinkage, and porosity. The components, properties, manipulation and types of each major investment material are described in detail.
Crystallization is the process of obtaining crystals of a pure substance from its hot, saturated solution. It involves a physical change as no new substances are formed - only a change from liquid to solid state. Crystallization is used to purify naturally occurring impure substances and obtain them in pure crystalline form. There are three main steps: supersaturation of the solution, nucleation where crystal seeds form, and crystal growth. Common applications include purification of drugs, seawater, and in separating substances like alum in industries. Types of crystallization include evaporative, cooling, and reactive crystallization.
Routine histopathology techniques and staining [Autosaved].pptxchandreshmishra13
The document provides information about routine histopathology techniques and staining. It discusses fixation of histology samples, ideal fixatives, changes after fixation, types of fixatives, and the mechanisms of fixation. It also covers tissue processing techniques including dehydration, clearing, infiltration, embedding, and sectioning of tissue blocks using a microtome. Key steps in processing like fixation, dehydration, clearing and infiltration are described in detail. Common fixatives, dehydrating agents, and clearing agents used are also listed.
Routine histopathology techniques and staining [Autosaved].pptxchandreshmishra13
This document provides an overview of routine histopathology techniques and staining. It discusses fixation of histology samples using an ideal fixative like formaldehyde. It describes the changes that occur in tissue after fixation, including shrinkage and hardening. Different types of fixatives and their mechanisms of action are explained. The document also covers tissue processing techniques including dehydration, clearing, infiltration and embedding in paraffin wax. Key steps and factors influencing tissue processing are summarized. Staining, troubleshooting, decalcification and special techniques like tissue marking and orientation are briefly outlined.
impulse(GreensFn), Principle of SuperpositionSc Pattar
Impulse superposition
Green’s function for underdamped oscillator
Exponential driving force
Green’s function for an undamped oscillator
Solution for constant force
Step function method
Research project proposal and Publishing pdfSc Pattar
This document outlines the key components of a research proposal, including objectives, introduction/background, methodology, timeline, personnel, facilities, and budget. It discusses the importance of clearly stating the research problem and objectives. The methodology section should provide details on data collection, analysis, and statistical tests. A timeline in the form of a Gantt chart or flow chart can help show sequencing and relationships between tasks. The proposal should also specify the personnel, facilities, equipment, and funding required to complete the study.
This document discusses Fourier series and their properties. Fourier series can be used to represent periodic functions as the sum of sinusoids. The coefficients in the Fourier series depend on integrals of the function over one period. Fourier series are useful for analyzing signals that repeat over time.
This document introduces partial differential equations (PDEs) and discusses three main classes of PDEs - parabolic, hyperbolic, and elliptic equations. It provides examples of common PDEs like the heat equation and wave equation. The document outlines the topics that will be covered in a course on PDEs, including methods for finding exact and numerical solutions to PDEs like separation of variables, Fourier series, and characteristics. It presents the tentative schedule covering derivation and solving techniques for common PDEs over several weeks.
This document contains lecture notes on the topic of quantum tunneling. Key points include:
- Quantum particles can tunnel through barriers that would be classically forbidden due to the probabilistic nature of quantum mechanics. The probability of tunneling decreases exponentially with the barrier width and height.
- Tunneling explains several phenomena including alpha decay, fusion in the sun's core, and scanning tunneling microscopy. It allows particles to penetrate barriers they could not classically overcome.
- Exponential decay in radioactive processes occurs because the probability of the particle remaining inside the nucleus decreases over time as it tunnels through the barrier and escapes.
The document discusses various length scales that are important in physics, chemistry, and biology. It provides examples of fundamental length scales in quantum physics where quantum effects become prominent below 7 nanometers. In electric phenomena, the charging energy of a single electron becomes comparable to thermal energy below 9 nanometers. For magnetic structures, the energy barrier for flipping the spin of a magnetic particle must be larger than thermal energy, which requires a size above 3 nanometers. The document also discusses important length scales for polymers, electrolytes, and self-organization driven by competing short-range attraction and long-range repulsion forces between different blocks or particles.
The document discusses the effective mass approximation in quantum mechanics. It begins by defining the effective mass as inversely proportional to the curvature of energy bands. Having a effective mass allows electrons in crystals to be treated similarly to classical particles, with the crystal forces and quantum properties accounted for in the mass. The effective mass can be a tensor and depends on the crystal direction. It then discusses measuring the effective mass using cyclotron resonance and how it varies by crystallographic direction. In general, the effective mass incorporates the quantum mechanical behavior of electrons in crystals to allow a classical particle treatment.
A view of SardarVallabhabhai Patell scp 31/10/2014Sc Pattar
Sardar Vallabhbhai Patel was an Indian independence leader who served as the first Home Minister and Deputy Prime Minister of India. He was born in 1875 in Gujarat and played a leading role in the country's struggle for independence. As Home Minister, Patel integrated the princely states into the Indian union after independence, earning him the title "Iron Man of India". He helped organize farmers' movements against the British and later promoted non-violent civil disobedience. Patel passed away in 1950 due to health issues. He is remembered for unifying India and establishing a strong foundation for the new republic.
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
JAMES WEBB STUDY THE MASSIVE BLACK HOLE SEEDSSérgio Sacani
The pathway(s) to seeding the massive black holes (MBHs) that exist at the heart of galaxies in the present and distant Universe remains an unsolved problem. Here we categorise, describe and quantitatively discuss the formation pathways of both light and heavy seeds. We emphasise that the most recent computational models suggest that rather than a bimodal-like mass spectrum between light and heavy seeds with light at one end and heavy at the other that instead a continuum exists. Light seeds being more ubiquitous and the heavier seeds becoming less and less abundant due the rarer environmental conditions required for their formation. We therefore examine the different mechanisms that give rise to different seed mass spectrums. We show how and why the mechanisms that produce the heaviest seeds are also among the rarest events in the Universe and are hence extremely unlikely to be the seeds for the vast majority of the MBH population. We quantify, within the limits of the current large uncertainties in the seeding processes, the expected number densities of the seed mass spectrum. We argue that light seeds must be at least 103 to 105 times more numerous than heavy seeds to explain the MBH population as a whole. Based on our current understanding of the seed population this makes heavy seeds (Mseed > 103 M⊙) a significantly more likely pathway given that heavy seeds have an abundance pattern than is close to and likely in excess of 10−4 compared to light seeds. Finally, we examine the current state-of-the-art in numerical calculations and recent observations and plot a path forward for near-future advances in both domains.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
Travis Hills of MN is Making Clean Water Accessible to All Through High Flux ...Travis Hills MN
By harnessing the power of High Flux Vacuum Membrane Distillation, Travis Hills from MN envisions a future where clean and safe drinking water is accessible to all, regardless of geographical location or economic status.
Microbial interaction
Microorganisms interacts with each other and can be physically associated with another organisms in a variety of ways.
One organism can be located on the surface of another organism as an ectobiont or located within another organism as endobiont.
Microbial interaction may be positive such as mutualism, proto-cooperation, commensalism or may be negative such as parasitism, predation or competition
Types of microbial interaction
Positive interaction: mutualism, proto-cooperation, commensalism
Negative interaction: Ammensalism (antagonism), parasitism, predation, competition
I. Mutualism:
It is defined as the relationship in which each organism in interaction gets benefits from association. It is an obligatory relationship in which mutualist and host are metabolically dependent on each other.
Mutualistic relationship is very specific where one member of association cannot be replaced by another species.
Mutualism require close physical contact between interacting organisms.
Relationship of mutualism allows organisms to exist in habitat that could not occupied by either species alone.
Mutualistic relationship between organisms allows them to act as a single organism.
Examples of mutualism:
i. Lichens:
Lichens are excellent example of mutualism.
They are the association of specific fungi and certain genus of algae. In lichen, fungal partner is called mycobiont and algal partner is called
II. Syntrophism:
It is an association in which the growth of one organism either depends on or improved by the substrate provided by another organism.
In syntrophism both organism in association gets benefits.
Compound A
Utilized by population 1
Compound B
Utilized by population 2
Compound C
utilized by both Population 1+2
Products
In this theoretical example of syntrophism, population 1 is able to utilize and metabolize compound A, forming compound B but cannot metabolize beyond compound B without co-operation of population 2. Population 2is unable to utilize compound A but it can metabolize compound B forming compound C. Then both population 1 and 2 are able to carry out metabolic reaction which leads to formation of end product that neither population could produce alone.
Examples of syntrophism:
i. Methanogenic ecosystem in sludge digester
Methane produced by methanogenic bacteria depends upon interspecies hydrogen transfer by other fermentative bacteria.
Anaerobic fermentative bacteria generate CO2 and H2 utilizing carbohydrates which is then utilized by methanogenic bacteria (Methanobacter) to produce methane.
ii. Lactobacillus arobinosus and Enterococcus faecalis:
In the minimal media, Lactobacillus arobinosus and Enterococcus faecalis are able to grow together but not alone.
The synergistic relationship between E. faecalis and L. arobinosus occurs in which E. faecalis require folic acid
MICROBIAL INTERACTION PPT/ MICROBIAL INTERACTION AND THEIR TYPES // PLANT MIC...
Crystal_growth.pptx
1. GROWTH OF SINGLE CRYSTALS
MICRONS TO METERS
• Vapor, liquid, solid phase crystallization techniques
• Single crystals - meaningful materials property measurements
• Single crystals allow measurement of anisotropic phenomena
in crystals with symmetry lower than cubic (isotropic)
• Single crystals important for fabrication of devices, like silicon
chips, yttrium aluminum garnet solid state lasers, beta-beryllium
borate for doubling and tripling the frequency of CW or pulsed
laser light, lithium niobate optoelectronic switch for guiding
light in miniature optical circuits, quartz crystal oscillators for
ultra-sensitive nanogram mass monitors
2. LET'S GROW CRYSTALS
• Key point to remember when learning how to be a
crystal grower (incidentally, an exceptionally rare
profession and extraordinarily well paid)
• Many different techniques exist, hence one must think
very carefully as to which method is the most
appropriate for the material under consideration
• Think also about size of crystal desired, stability in air,
morphology or crystal habit required, orientation,
doping, defects, impurities
• So let's proceed to look at some case histories.
3. Pulling direction of
seed on rod
Heater
CZOCHRALSKI
Crucible
Inert atmosphere under
pressure prevents
material loss and
unwanted reactions
Layer of molten oxide
like B2O3 prevents
preferential
volatilization of one
component - precise
stoichiometry control
Melt just above mp
High viscosity low
vapor pressure
Growing crystal
Crystal seed
Counterclockwise
rotation of melt and
crystal being pulled
from melt, helps
maintain uniform T,
composition and
homogeneity of crystal
growth
4. CZOCHRALSKI METHOD
• Interesting crystal pulling technique (but can you
pronounce and spell the name!)
• Single crystal growth from the melt precursor(s)
• Crystal seed of material to be grown placed in contact with
surface of melt
• Temperature of melt held just above melting point, highest
viscosity, lowest vapor pressure favors crystal growth
• Seed gradually pulled out of the melt (not with your hands
of course, special crystal pulling equipment is used)
5. CZOCHRALSKI METHOD
• Seed gradually pulled out of the melt (not with your
hands of course, special crystal pulling equipment is used)
• Melt solidifies on surface of seed
• Melt and seed usually rotated counterclockwise with
respect to each other to maintain constant temperature
and to facilitate uniformity of the melt during crystal
growth, produces higher quality crystals, less defects
• Inert atmosphere, often under pressure around growing
crystal and melt to prevent any materials loss and
undesirable reactions like oxidation, nitridation etc
6. GROWING BIMETALLIC SINGLE CRYSTALS
LIKE GaAs REQUIRES A MODIFICATION OF
THE CZOCHRALSKI METHOD
• Layer of molten inert oxide like B2O3 spread on top of the molten
feed material to prevent preferential volatilization of the more
volatile component of the bimetal melt
• Critical for maintaining precise stoichiometry, e.g., Ga1+xAs and
GaAs1+x when made rich in Ga and As, become p- and n-doped!!!
• The Czochralski crystal pulling technique is invaluable for
growing many large single crystals as a rod, to be cut into wafers
and polished for various applications like silicon, germanium,
lithium niobate
• Utility of some single crystals made by Czochralski listed below
7. EXAMPLES OF CZOCHRALSKI GROWN SCs
SOLIDIFICATION OF STOICHIOMETRIC MELT
• LiNbO3 - NLO material - Perovskite - temperature dependent
tetragonal-cubic-ferroelectric-paraelectric phase transition at Curie T –
electrical control of refractive index – use electrooptical switch
• SrTiO3 - Perovskite substrate – used for epitaxial growth of high Tc
defect Perovskite - YBa2Cu3O7 superconducting films - SQUIDS
• GaAlInP - quaternary alloy semiconductor - near IR diode lasers
• GaAs wafers – red laser diodes - photonic crystal devices
• NdxY3-xAl5O12 – neodynium YAG - NIR solid state lasers - 1.06 microns
• Si - microelectronic chips, Ge - semiconductor higher electron mobility
faster electronics than Si
8. BRIDGMAN AND STOCKBARGER METHODS
Controlled Crystallization of a Stoichiometric Melt
STOCKBARGER fixed temperature
gradient - moving crystal
BRIDGEMAN changing
temperature gradient - static crystal
T
T
Distance
Distance
Crystallization of melt on seed as
crucible gradually displaced through
temperature gradient from hotter to
cooler end
melt crystal
Furnace gradually cooled and
crystallization begins on seed at
cooler end of crucible
Tm
Tm
T1
T2
T3
Temperature gradient
9. BRIDGMAN AND STOCKBARGER METHODS
• Stockbarger method is based on a crystal growing from the
melt, involves the relative displacement of melt and a
temperature gradient furnace, fixed gradient and a moving
melt/crystal
• Bridgman method is again based on crystal growth from a
melt, but now a temperature gradient furnace is gradually
lowered and crystallization begins at the cooler end, fixed
crystal and changing temperature gradient
• Both methods are founded on the controlled solidification
of a stoichiometric melt of the material to be crystallized in
a temperature gradient
10. BRIDGMAN AND STOCKBARGER METHODS
• Stockbarger and Bridgman methods both involve
controlled solidification of a stoichiometric melt of the
material to be crystallized in a temperature gradient
• Enables oriented solidification
• Melt passes through a temperature gradient
• Crystallization occurs at the cooler end
• Both methods benefit from seed crystals, predetermined
orientation and controlled atmospheres
11. T
Distance
Crystal or powder
Localized melt region - impurities
concentrated in melt – energetic benefit
Crystal growing from seed
Temperature profile furnce
Pulling direction
Tm
ZONE MELTING CRYSTAL GROWTH AND
PURIFICATION OF SOLIDS
12. ZONE MELTING CRYSTAL GROWTH AND
PURIFICATION OF SOLIDS
• Method related to the Stockbarger technique - thermal
profile furnace employed - material contained in a boat
• Only a small region of the charge is melted at any one
time - initially part of the melt is in contact with the seed
• Boat containing sample pulled at a controlled velocity
through the thermal profile furnace
• Zone of material melted, hence the name of the method -
oriented solidification of crystal occurs on the seed -
simultaneously more of the charge melts
13. ZONE MELTING CRYSTAL GROWTH AND
PURIFICATION OF SOLIDS
• Partitioning of impurities occurs between melt and crystal
• Basis of the zone refining methods for purifying solids
• Impurities concentrate in melt more than the solid phase
where structure-energy constraints of crystal sites more
severe than melt - impurities swept out of crystal by
moving the liquid zone
• Used for purifying materials like W, Si, Ge, Au, Pt to ppb
level of impurities, often required for device applications
14. O2 + powdered precursor(s)
O2 + H2
Fusion flame
Liquid drops of molten precursor(s)
Growing crystal
Support for growing crystal
VERNEUIL FUSION FLAME METHOD
15. VERNEUIL FUSION FLAME METHOD
• 1904 first recorded use of the method, useful for
growing crystals of extremely high melting and refractory
metal oxides, examples include:
• Ruby red from Cr3+/Al2O3 powder, sapphire blue from
Cr2
6+/Al2O3 powder, luminescent host CaO powder
• Starting material fine powder form, passed through
O2/H2 flame or plasma torch
• Melting of the powder occurs in the flame, molten
microdroplets fall onto the surface of a seed or growing
crystal, leads to controlled crystal growth
16. CRYSTAL GROWING METHODS
CZOCHRALSKI, BRIDGMAN, STOCKBARGER, ZONE MELTING, VERNEUIL
• All methods have the advantage of rapid growth rates of large crystals
required for many advanced device applications
• BUT the CRYSTAL QUALITY obtained by all of these techniques
must be checked for inhomogeneities in surface and bulk composition
and structure, gradients, domains, impurities, point-line-planar
defects, twins, grain boundaries
• THINK how you might go about checking this if you were
confronted with a 12"x12"x12" crystal - useful methods for small
crystals include: confocal optical microscope, polarization optical
microscope birefringence, Raman microscope, spatially resolved OM,
XRD, TEM, ED, EDX, AFM – what does one use for large ones?
18. HYDROTHERMAL SYNTHESIS AND
GROWTH OF SINGLE CRYSTALS
• Basic methodology, water medium and high
temperature growth, above normal boiling point
• Water functions as solublizing phase, pressure
transmitting agent, often mineralizing agent added to
enhance dissolution, transport of reactants and crystal
growth, speeds up chemical reactions between solids
• Useful technique for the synthesis and crystal growth of
phases that are unstable in a high temperature
preparation in the absence of water
20. HYDROTHERMAL SYNTHESIS AND GROWTH OF
SINGLE CRYSTALS
• Temperature gradient reactor - dissolution of reactants at
one end - with help of mineralizer transport to seed at the
other end - crystallization at seeded end
• Because some materials have negative solubility
coefficients, nutrients dissolve at cooler end and crystals
grow at the hotter end in a temperature gradient
hydrothermal reactor, counterintuitive!!!
• Good example is a-AlPO4 known as Berlinite, isoelectronic
and isostructural with Quartz, important for its high
piezoelectric coefficient - application of pressure to a crystal
of Quartz or Berlinite creates a distortion of structure,
electrical polarization of the lattice and associated voltage
21. HYDROTHERMAL SYNTHESIS AND GROWTH OF
SINGLE CRYSTALS
• Ability of certain non-centrosymmetric crystals like quartz
to generate a voltage in response to applied mechanical
stress - Greek piezein - squeeze or press
• Effect reversible - piezoelectric crystals, subject to an
externally applied voltage, change shape by a small amount
• Compressive stress along [100] disturbs crystal symmetry
distorting SiO4 tetrahedra along 3-fold axis (not for [001] 2-
fold axis) creating charge asymmetry and electrical charges
across opposite crystal faces that generates a V
• Berlinite alpha-AlPO4 more polar Al-O larger than alpha-
quartz Si-O with which it is isoelectronic and isostructural -
use as a high frequency oscillator and mass monitor
22. HYDROTHERMAL GROWTH OF
QUARTZ SINGLE CRYSTALS
• Water medium - Nutrients 400oC - Seed 360oC
• Pressure 1.7 Kbar - Mineralizer 1M NaOH dissolves
silica
• Uses of single crystal quartz: radar, sonar, piezoelectric
transducers, mass monitors
• Annual global production hundreds of tons of quartz
crystals, amazing
24. QUARTZ CRYSTALS GROW IN
HYDROTHERMALAUTOCLAVE
400°C T2
360°C T1
SiO2 powder nutrient dissolving region
Baffle allows passage of minerlized
species to quartz seed crystal
NaOH/H2O mineralizer
SiO2 seed
25. ROLE OF THE MINERALIZER IN HYDROTHERMAL
SYNTHESIS AND CRYSTAL GROWTH
• Consider growth of quartz crystals - control of crystal
growth rate, through mineralizer, temperature pressure
• Solubility of quartz in water is important
• SiO2 + 2H2O Si(OH)4
• Solubility about 0.3 wt% even at supercritical
temperatures >374oC
• A mineralizer is a complexing agent (not too stable) for
the reactants/precursors, which have to be solublized
(dissolved not too quickly) and transported to the growing
crystal
26. ROLE OF THE MINERALIZER IN HYDROTHERMAL
SYNTHESIS AND CRYSTAL GROWTH
• NaOH mineralizer, dissolving reaction, 1.3-2.0 KBar
• 3SiO2 + 6OH- Si3O9
6- + 3H2O
• Na2CO3 mineralizer, dissolving reaction, 0.7-1.3 KBar
• CO3
2- + H2O HCO3
- + OH-
• SiO2 + 2OH- SiO3
2- + H2O
• NaOH creates growth rates about 2x greater than with
Na2CO3 because of different concentrations of
hydroxide mineralizer
27. EXAMPLES OF HYDROTHERMAL CRYSTAL
GROWTH AND MINERALIZERS
• Berlinite alpha-AlPO4 - larger piezoelectric coefficient
than quartz – polarity effect Al-O > Si-O
• Powdered AlPO4 cool end of reactor, negative solubility
coefficient T2 > T1 - try to explain this effect
• H3PO4/H2O mineralizer
• AlPO4 seed crystal at hot end
T1
T2
a-AllPO4 powder
Baffle
H3PO4/H2O
mineralizer
a-AlPO4 seed
28. EMERALD CRYSTALS GROW IN
HYDROTHERMALAUTOCLAVE
T2
T1
T2
SiO2 powder nutrient at hot end
Al2O3/Cr2O3/BeO powder nutrients at hot end
Emerald - Cr(3+) doped beryl seed
crystal at cool center of hydrothermal
synthesis - crystal growth autoclave
NH4Cl or HCl mineralizer
29. EXAMPLES OF HYDROTHERMAL CRYSTAL
GROWTH AND MINERALIZERS
• Emeralds Be3Al(Cr)2Si6O18 Beryl contains Si6O18
12- six rings
• SiO2 powder at hot end 600oC
• NH4Cl or HCl/H2O mineralizer, 0.7-1.4 Kbar
• Cool central region for seed, 500oC
• Al2O3/BeO/Cr3+ dopant powder mix at other hot end 600oC
• 6SiO2 + Al(Cr)2O3 + 3BeO Be3Al(Cr)2Si6O18
30. EXAMPLES OF HYDROTHERMAL CRYSTAL
GROWTH AND MINERALIZERS
• Metal crystals - metal powder at hot end 500oC
• Mineralizer 10M HI/I2 - metal seed at cool end 480oC
• Dissolving reaction transports Au to the seed crystal:
• Au + 3/2I2 + I- AuI4
-
• Metal crystals grown include
• Au, Ag, Pt, Co, Ni, Tl, As at 480-500oC
T2
T1
Metal Powder
Baffle
10MHI/I2
mineralizer
Metal seed