Non-Stoichiometry & Solid Solution
The document discusses various types of point defects that can occur in non-stoichiometric compounds including Schottky defects, Frenkel defects, and anti-site defects. It provides examples of intrinsic point defects in metal-deficient, metal-excess, oxygen-deficient, and oxygen-excess metal oxides. Solid solutions are formed when one or more minor components dissolve uniformly within the crystal lattice of a major component. Types of solid solutions include interstitial, substitutional, ordered, and disordered solutions. Experimental techniques like X-ray diffraction and density measurements can be used to study properties of non-stoichiometric compounds and solid solutions.
BASIC DISCUSSION ABOUT THE CROWN ETHER AND CRYPTAND. INCLUDING THEIR BACKGROUND,STRUCTURE,NOMENCLATURE,CAVITY SIZE, SELECTIVITY, SYNTHESIS AND APPLICATIONS.
BASIC DISCUSSION ABOUT THE CROWN ETHER AND CRYPTAND. INCLUDING THEIR BACKGROUND,STRUCTURE,NOMENCLATURE,CAVITY SIZE, SELECTIVITY, SYNTHESIS AND APPLICATIONS.
Contains information about various crystal types in solid state chemistry like Rock Salt, Wurtzite, Nickel Arsenide, Zinc Blende etc. It also gives a brief description of lattice energy and Born Haber cycle.
Theories of coordination compounds, CFSE, Bonding in octahedral and tetrahedral complex, color of transition metal complex, magnetic properties, selection rules, Nephelxeuatic effect, angular overlap model
Introductory PPT on Metal Carbonyls having its' classification,structure and applications.This is a basic level PPT specially prepared for UG/PG Chemistry students.
Contains information about various crystal types in solid state chemistry like Rock Salt, Wurtzite, Nickel Arsenide, Zinc Blende etc. It also gives a brief description of lattice energy and Born Haber cycle.
Theories of coordination compounds, CFSE, Bonding in octahedral and tetrahedral complex, color of transition metal complex, magnetic properties, selection rules, Nephelxeuatic effect, angular overlap model
Introductory PPT on Metal Carbonyls having its' classification,structure and applications.This is a basic level PPT specially prepared for UG/PG Chemistry students.
Isotopes are two atoms of the same element that have the same number of protons but different numbers of neutrons. Isotopes are specified by the mass number.
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The attractive force which holds various constituents (atom, ions, etc.) together and stabilizes them by the overall loss of energy is known as chemical bonding. Therefore, it can be understood that chemical compounds are reliant on the strength of the chemical bonds between its constituents; The stronger the bonding between the constituents, the more stable the resulting compound would be.
Similar to Solid solution and non stoichiometry (20)
Electrochemical CO2 reduction reaction (eCO2RR) is performed on two
intermetallic compounds formed by copper and gallium metals (CuGa2
and Cu9Ga4). Among them, CuGa2 selectively converts CO2 to methanol
with remarkable Faradaic efficiency of 77.26% at an extremely low potential of −0.3 V vs RHE. The high performance of CuGa2 compared to
Cu9Ga4 is driven by its unique 2D structure, which retains surface and
subsurface oxide species (Ga2O3) even in the reduction atmosphere. The
Ga2O3 species is mapped by X-ray photoelectron spectroscopy (XPS) and
X-ray absorption fine structure (XAFS) techniques and electrochemical
measurements. The eCO2RR selectivity to methanol are decreased at
higher potential due to the lattice expansion caused by the reduction of
the Ga2O3, which is probed by in situ XAFS, quasi in situ powder X-ray
diffraction, and ex situ XPS measurements. The mechanism of the formation of methanol is visualized by in situ infrared (IR) spectroscopy and the
source of the carbon of methanol at the molecular level is confirmed from
the isotope-labeling experiments in presence of 13CO2. Finally, to minimize
the mass transport limitations and improve the overall eCO2RR performance, a poly(tetrafluoroethylene)-based gas diffusion electrode is used in
the flow cell configuration.
Lattice anchoring between colloidal crystal and perovskite semiconductor stabilizes can be a useful strategy for a stable semiconductor interface for solar cell application
Ni-doping can substantially increase the p[erformance of electrochemical water splitting in the case of WC or MoC lattice. In situ XAFS shows the charge transfer between Ni and W/Mo which is the origin of better HER/OER performance in the wide pH range of electrolytes.
By creating a hydrophobic electrode surface, the competing hydrogen evolution reaction can be drastically reduced, which can dramatically enhance the performance of the electrochemical CO2 reduction.
Electrochemical CO2 reduction in acidic media is advantageous as the loss of carbonate formation (in alkaline media) is less and the current density is also high. The main goal is to suppress the competing hydrogen evolution reaction by careful optimization of electrode-electrolyte interface design.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
2. Schottky defects
• Cation and anion vacancies
Anti-Schottky defects
• Cation and anion interstitials
• (not common)
Frenkel defects
• Cation vacancies and interstitials
Anti- or anion-Frenkel defects
• Anion vacancies and interstitials
Anti-site defects
• Cation and anion swap
• (not common)
Stoichiometric compounds: intrinsic point defect
3. • Examples for oxides:
• Metal deficient oxides, e.g. M1-xO
• Metal vacancies are majority point defects, compensated by electron holes
• Examples: Co1-xO, Ni1-xO, and Fe1-xO
• Metal excess oxides, e.g. M1+xO
• Metal interstitials are majority point defects, compensated by defect electrons
• Example: Cd1+xO
• Oxygen deficient oxides, e.g. MO2-y
• Oxygen vacancies are majority point defects, compensated by defect electrons
• Examples: ZrO2-y, CeO2-y
• Oxygen excess oxides, e.g. MO2+y
• Oxygen interstitials are majority point defects, compensated by electron holes
• Example: UO2+y
Non-stoichiometric compounds have formulae that do not have simple integer ratios of atoms
they exhibit a range of composition and can be made by introducing impurities into a system,
Non-stoichiometric compounds
9. Non-Stoichiometry in Wustite (FeO)
Ferrous oxide is known as wustite it has the NaCl (rock salt) crystal
structure.
Chemical analysis proved that it is non-stoichiometric and deficient in
iron
Below 570°C, wustite disproportionate to α-iron and Fe3O4.
Fe deficiency can be happened in two ways:
1. Fe vacancy (leads to Fe1-xO), or
2. Excess of oxygen in interstitial positions (giving FeO1+x).
10. Cation Vacancy or Interstitial Anion
Experimental Observations
a = 430.1 pm
d =5.728 kg m-3
Fe/O = 0.945
V = (430.1 pm)3 = 7.956 x 10-29 m3
4 formula units of FeO in a perfect unit cell (rock salt structure)
1 mole of FeO weighs (55.85 + 16.00) g = 0.07185 kg
4 mole weigh = 4 x 0.07185 kg
4 formula units weigh = 4 x 0.07185 kg / NA = 4.733 x 10-25 kg
11. Cation Vacancy
Experimental Observations
a = 430.1 pm
Fe/O = 0.945
V = (430.1 pm)3 = 7.956 x 10-29 m3
If Fe0.945O1
1 mole of Fe0.945O1 weighs ((55.85x0.945) + 16.00) g = 0.06877 kg
4 mole is 3.78Fe + 4 O weigh = 4 x 0.06877 kg
4 formula units weigh = 4 x 0. 06877 kg / NA = 4.567 x 10-25 kg
dcv= 4.567x10-25 /7.956x10-29 kg m-3 = 5.742 x 103 kg m-3
12. Interstitial Anion
Experimental Observations
a = 430.1 pm
Fe/O = 0.945 O/Fe = 1/0.945 = 1.058
V = (430.1 pm)3 = 7.956 x 10-29 m3
If Fe1O1.058
1 mole of Fe1O1.058 weighs (55.85 + (16.00x1.058)) g = 0.07277 kg
4 mole is 4Fe + 4.232O weigh = 4 x 0.07277 kg
4 formula units weigh = 4 x 0.07277 kg / NA = 4.832x 10-25 kg
dia= 4.832x10-25 /7.956x10-29 kg m-3 = 6.076 x 103 kg m-3
13. Cation Vacancy or Interstitial Anion
Experimental density d =5.728 kg m-3
If Fe0.945O1 dcv = 5.742 x 103 kg m-3
If Fe1O1.058 dia= 6.076 x 103 kg m-3
Thus, FeO has cation vacancy
Non-stoichiometric compounds are found to exist over a range of composition. It is possible to
determine whether the non-stoichiometry is accommodated by vacancy or interstitial defects using
density measurements.
15. Koch-Cohen Cluster
• NaCl type structure with 4 interstitial
Fe3+ ions in tetrahedral voids, 13
immediately surrounding octahedral Fe2+
sites must be vacant.
• This is referred to as sueperstructure or
superlattice
Fe2+ Oh site vacant
Fe3+ Td
interstitial
17. Vegard's law
For most of the non-stoichiometric compounds, their unit cell size varies
smoothly with composition but the symmetry is unchanged. This is known as
Vegard’s Law.
Experimental and theoretical densities (103 kg m-3) for FeO
18. This law simply states that when you combine elements to form an alloy, the lattice
constant will follow a linear trend with the element concentrations, provided that there
is no phase change and lattice parameters do not differ by more than 5%.
Vegard's law continued…
Mathematical expression for Vegard’s law for a binary system A-B is:
where X is the mole fraction of component B and a = lattice parameters of pure
components
19. Application of Vegard's law
Lattice constant increases with increase in Cr substitution for Al in CuAlO2.
20. Application of Non-stoichiometric compound
Oxidation catalysis: Reactions of hydrocarbon with oxygen, a conversion that is catalysed by metal oxides.
Here transfer of "lattice" oxygen to the hydrocarbon substrate, a step that temporarily generates a vacancy (or
defect). Such catalysts rely on the ability of the metal oxide to form phases that are not stoichiometric
Ion conduction: The defect sites provide pathways for
atoms and ions to migrate through the otherwise dense
ensemble of atoms that form the crystals.
Oxygen sensors and solid state batteries are two
applications that rely on oxide vacancies.
Superconductivity: Many superconductors are non-stoichiometric. YxBa2Cu3O7−x. arguably
the most notable high temperature superconductor, is a non-stoichiometric solid with the
formula YxBa2Cu3O7−x. The critical temperature of the superconductor depends on the exact
value of x.
21. Solid Solution
Solid Solution is a solid mixture containing one or more minor components (solute)
uniformly distributed within the crystal lattice (matrix) of the major component (solvent).
Such a mixture is considered a solution rather than a compound when the crystal structure of the solvent
remains unchanged by addition of the solutes, and when the mixture remains in a single homogeneous phase.
Figure: This binary phase diagram shows
two solid solutions.
Solid solution formation usually causes increase of electrical resistance and mechanical
strength and decrease of plasticity of the alloy.
23. Solute atoms are much smaller than solvent atoms (size of the solute is less than
40% that of solvent), so they occupy interstitial position in solvent lattice.
Carbon ,nitrogen ,hydrogen ,oxygen, lithium, sodium and boron are the element
which commonly form interstitial solid solution. Steel : C atoms solute in Fe.
Solvent Atoms
Solute Atoms
Interstitial Solid Solution
24. Substitutional Solid Solution
Solute atoms sizes are roughly similar to solvent atoms.
Due to similar size solute atoms occupy vacant site in solvent atoms.
Cu and Zn, Cu and Ni, are the example of substitutional solid solution.
Solvent Atoms
Solute Atoms
25. Hume Rothery studied a number of alloy systems and
formulated condition that favour extensive substitutional
solid solubility.
Conditions of Hume Rothery’s rule
1) The size difference between solute and solvent atoms must be less
than 15%.
2) The solubility of a metal with higher valence in a solvent of
lower valence is more compared to the reverse situation e.g.
Zn is much more soluble in Cu than Cu in Zn.
3) The crystal structures of metals must be same.
4) The electronegativity difference between the metals must be small.
Hume Rothery’s Rule
26. Ordered Substitutional Solid Solution
If the atoms of the solute occupy certain
preferred sites in the lattice of the solvent,
an ordered solid solution is formed. It may
occur only at certain fixed ratios of the
solute and solvent atoms.
In Cu – Au system, Cu atoms occupying
the face-centred sites and Au atoms
occupying the corner sites of the FCC unit
cell.
Solvent Atoms
Solute Atoms
27. If the atoms of the solute are present
randomly in the lattice of the solute, it is
known as disordered solid solution.
Most of the solid solutions are disordered
solid solutions
Disordered Substitutional Solid Solution
Solute Atoms
Solvent Atoms
28. X-ray powder diffraction, XRD :
1. Fingerprint method: Determination of the crystalline phases that are present (the detection limit of phases in a
mixture is usually of the order of 2–3 wt%)
2. Measure the XRD pattern of solid solutions accurately and obtain their unit cell dimensions, which may undergo
a small contraction or expansion as composition varies. The calibration graph of unit cell dimensions against composition can be
used to determine the composition of solid solutions in a particular sample.
Usually, a unit cell expands if a small ion is replaced by a larger ion and vice versa, contracts if a smaller ion is substituted into
the structure. From Bragg’s law and the d-spacing formulae, the whole pattern shifts to lower values of 2q with increasing unit
cell parameters..
According to Vegard’s law, unit cell parameters should change linearly with solid solution composition.
3. Third, using Rietveld refinement of the powder XRD patterns of solid solutions, and in particular the intensities of the XRD
reflections, it is possible to gain detailed crystallographic information such as the sites occupied by atoms and the location of
vacancies and interstitials.
Experimental methods for studying solid solutions
29. The mechanism of solid solution formation may be inferred by a combination of density and
unit cell volume measurements for a range of compositions.
The key parameter is the mass of the average unit cell contents and whether it increases or
decreases on solid solution formation.
Density data for cubic CaO-stabilised zirconia solid solutions for samples quenched from 1600 ◦C
Density measurements
30. Many materials undergo abrupt changes in structure or property on heating and, if the
material forms a solid solution, the temperature of the change usually varies with
composition.
The changes can often be studied by differential thermal analysis/differential scanning
calorimetry (DTA/DSC) since most phase transitions have an appreciable enthalpy of
transition.
Effect of dopants on the ferroelectric Curie temperature of
BaTiO3 showing the effect of isovalent substitution of Sr,
Ca and Pb for Ba, isovalent substitution of Zr for Ti and
aliovalent substitution of Ca for Ti.
Changes in other properties – thermal activity and DTA/DSC
31. Solid solution strengthening is a type of alloying that can be used to improve the strength
of a pure metal.
Why strengthening of metal is required?
As pure metal are inherently weak due to presence of dislocation.
So, We can enhance the mechanical properties by eliminating dislocation.
So, by introducing some mechanism that prohibits the mobility of dislocations, that are
called Strengthening mechanism.
Methods For Strengthening
Of Metal
Strain hardening
Grain boundary
strengthening
Precipitation
hardening
Solid solution
strengthening
Solid solution strengthening
32. Factors affecting Solid Solution Strengthening
Difference in size between
solute and solvent atoms
Amount of solute
added
Nature of distortion
produced by solute atoms
size difference increases
the intensity of stress field
around solute atom
resistance to dislocation
is increases
strength of metal
increases.
A large concentration means more
frequent obstacles to dislocation.
The strength increases in
proportion of C ½
Spherical distortion produced
by Substitutional solute atoms
Non spherical distortion produced
by interstitial solute atoms.
33. Why is Steel so strong?
Smaller carbon atoms fill some of the small spaces available
between the iron atoms and form Interstitial Solid Solution.
Usually materials deform by the movement of dislocations. The carbon interstitials make steel stronger by fully
or partially blocking the movement of dislocations.
Fe
C
Application of Solid Solution