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Optical band gap measurement by diffuse reflectance spectroscopy (drs)Sajjad Ullah
Introduction to Optical band gap measurement
by electronic spectroscopy and diffuse reflectance spectroscopy (DRS) with comparison of the results obtained suing different equation and measurement techniques.
The role of scattering in extinction of light as it passes through media is briefly discussed.
Hello, I am Subhajit Pramanick. I and my classmate, Anannya Sahaw, both presented this ppt in seminar of our Institute, Indian Institute of Technology, Kharagpur. The topic of this presentation is on exchange interaction and their consequences. It includes the basic of exchange interaction, the origin of it, classification of it and their discussions etc. We hope you will all enjoy by reading this presentation. Thank you.
Optical band gap measurement by diffuse reflectance spectroscopy (drs)Sajjad Ullah
Introduction to Optical band gap measurement
by electronic spectroscopy and diffuse reflectance spectroscopy (DRS) with comparison of the results obtained suing different equation and measurement techniques.
The role of scattering in extinction of light as it passes through media is briefly discussed.
Hello, I am Subhajit Pramanick. I and my classmate, Anannya Sahaw, both presented this ppt in seminar of our Institute, Indian Institute of Technology, Kharagpur. The topic of this presentation is on exchange interaction and their consequences. It includes the basic of exchange interaction, the origin of it, classification of it and their discussions etc. We hope you will all enjoy by reading this presentation. Thank you.
Classification of magnetic materials on the basis of magnetic momentVikshit Ganjoo
I made this presentation for my own college assignment and i had referred contents from websites and other presentations and made it presentable and reasonable hope you will like it!!!
The present article gives the fundamental properties magnetism, different materials, properties of different magnetic materials like, dia,para and ferro magnetic materials. The notes also explain how magnetism appear in materials, type of magnets and brief applications of magnetic materials. The materials is best for undergraduate science and engineering students and any other people of interest in magnetism
SOME BASIC PRINCIPLES OF MAGNETISM (Autosaved).docxZocelynManingo1
Electric Current and Magnetism
The Nature of Magnetism: Electricity’s Silent Partner
Magnetism is a property of a material that enables to attract or repel other materials. The presence and strength of the material’s magnetic properties can be observed by the effect of the forces of attraction and repulsion on other materials.
What makes magnets?
Magnets are actually created by tiny spinning electrons in an atom. The electrons move about the nucleus and spin like a top, creating a tiny magnetic field.
If electrons are spinning in the same direction there is more magnetism, while electrons spinning in opposite directions cancel out each others’ magnetic fields. Magnetic fields are invisible, we can only see the effects of the magnetic force.
Magnetic Field: The space around a magnet in which a magnetic force is exerted
— The shape of a magnetic field is revealed by magnetic field lines
Directed away from north poles and toward south poles
Magnets have two ends or poles, called north and south poles. At the poles of a magnet, the magnetic field lines are closer together.
The magnetic field lines around horse-shoe and disk magnets are closest together at the magnets’ poles. Unlike poles of magnets attract each other and like poles of magnets repel. Magnetic Poles: A region on a magnet which produces magnetic forces
The poles of a suspended magnet will align themselves to the poles of the Earth
Fundamental Rule: Like poles repel; opposite poles attract
If a force of attraction only is possible between an object and a magnet, then the object interacting with the magnet contains a ferromagnetic substance and is considered naturally magnetic.
If a force of repulsion is only between an object and a magnet, then the object interacting with the magnet may also be a permanent magnet or a temporarily magnetized ferromagnetic material.
Materials which are attracted by a magnet are known as magnetic materials. Iron, cobalt, nickel and many alloys of these metals like steel and alnico are magnetic.
Magnetic materials can be used to make permanent or temporary magnets unlike the non-magnetic materials which cannot.
INDUCED MAGNETISM
The process by which the screws become magnets is called Electric/Magnetic Induction. This same process is the reason why magnets attract non-magnetized magnetic substances such as the screw. The screw becomes an induced magnet with the end nearer the magnet having an opposite polarity to that of the permanent magnet. Hence attraction happens after magnetic induction occurs. The quicker way to know the polarity of a permanent or induced magnet is by the use of a magnetic compass. Compass needle is a small magnet that is free to pivot in a horizontal plane about an axis and that the end of the magnet that points to geographic north is called the north (N) pole. Likewise, the opposite end of the magnet is the south (S) pole.What are magnetic domains?
Magnetic substances like iron, cobalt and nickel
Thermal conductivity can be defined as the rate at which heat is transferred by conduction through a unit cross-section area of a material, when a temperature gradient exits perpendicular to the area.
A theory of the specific heat capacity of solids put forward by Peter Debye in 1912, in which it was assumed that the specific heat is a consequence of the vibrations of the atoms of the lattice of the solid.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
The Art Pastor's Guide to Sabbath | Steve Thomason
FERROMAGNETIC AND ANTIFERROMAGNETIC MATERIALS.pptx
1.
2.
3. Ferromagnetic Materials
Ferromagnetism
• Ferromagnetism comes from the term ‘ferrous’ meaning iron, the first type of metal discovered to exhibit
attraction to magnetic fields.
• Ferromagnetism is the basic method in which a compound forms a permanent magnet or is attracted to a
magnetic field.
• ferromagnetism, physical phenomenon in which certain electrically uncharged materials strongly attract
others.
• Two materials found in nature, lodestone (or magnetite, an oxide of iron, Fe3O4) and iron, have the ability to
acquire such attractive powers, and they are often called natural ferromagnets.
• They were discovered more than 2,000 years ago, and all early scientific studies of magnetism were
conducted on these materials.
• Ferromagnetic materials have large, positive susceptibility to an external magnetic field.
• Ferromagnetic materials exhibit parallel alignment of moments resulting in large net magnetization even in
the absence of a magnetic field.
• In ferromagnetic materials, when a magnetizing force is applied, the magnetic domains become aligned to
produce a strong magnetic field within the material.
• Example: iron, nickel, cobalt etc.
• Ferromagnetism is the basic mechanism by which certain materials form permanent magnets or they are
attracted towards the magnets.
• Today, ferromagnetic materials are used in a wide variety of devices essential to everyday life—e.g.,
Transformers, Electromagnets, Magnetic tape recording, Hard drives, Generators, Telephones,
Loudspeakers, Electric motors, Hard disk and Magnetic Storage.
4.
5. Continue…
Two distinct characteristics of ferromagnetic materials are their
(1) Spontaneous magnetization
(2) Existence of magnetic ordering temperature
• Spontaneous magnetization :-
The spontaneous magnetization is the net magnetization that exists inside a uniformly magnetized
microscopic volume in the absence of a field. The magnitude of this magnetization, at 0 K, is dependent on
the spin magnetic moments of electrons.
A related term is the saturation magnetization which we can measure in the laboratory. The saturation
magnetization is the maximum induced magnetic moment that can be obtained in a magnetic field (Hsat);
beyond this field no further increase in magnetization occurs.
6. • Existence of magnetic ordering temperature:-
Magnetic Ordering Temperature or Neel Temperature is the temperature
above which an Anti-Ferro-magnetic or Ferri-magnetic material becomes
Para-magnetic. Thermal Ferrites are materials that exhibit this
phenomenon.
7. Ferromagnetic Ordering
Magnetic moments originate on an atomic scale from the orbital and spin motion of
electrons. These effects are also influenced by the electronic configuration of the
elements.
Electrons in matter have two properties- Spin and Orbit.
In materials, their magnetic properties are observed due to the spins of electrons rather
than their orbital moments.
The orbital moment contribution is negligible in comparison to the spin of the electrons.
Ferromagnetic ordering of magnetic moments means they are aligned parallel to one
another which is accomplished by a ferromagnetic exchange interaction.
The characteristic temperature of ferromagnets is the curie temperature at which the
susceptibility diverges.
Ferromagnetism in magnetic material is a special case of paramagnetism in which the
individual spin magnetic moment interacts I.e. the moments are coupled.
In crystals of a ferromagnetic materials the net magnetic moment observed due to the
coupling of spins in a preferred orientation .
quantum mechanical in nature.
Ferromagnetic materials have strong ,positive magnetic susceptibility unlike paramagnets.
When the applied field is removed, ferromagnetic material retains a component of
magnetization in the direction of the applied field- they are permanently magnetized and
they have hysteresis property
8. ELECTROAGNETS
Hysteresis loop:
1)Retentivity: When applied magnetized field is removed the magnetism B or I that remains in material is
called retentivity or remenant magnetism.
2)Coercivity: or Coercive force: The Magnetism force or H applied in negative direction to make
retentivity zero is called coercivity.
Electromagnetic magnetics are made from materials with high retentivity and low coercivity.
If the energy required to make that material is low (low hysteresis loop Area) then it is good
electromagnet.
Materials like alnico, Al, Fe, Ni, Co and carbon steel are used for making electromagnets.
Soft Magnet/Temporary Magnet: Materials which show magnetic properties only in presence of external
magnet.
Hard Magnetic: Permanent Magnet.
9. EXCHANGE FIELD
If a paramagnet consisting of N ions of spin S.
Suppose, there is some local interaction which produces a magnetic field
I.e., the exchange field or Weiss field-B.
According to mean-field approximation B=(lambda)*M M:
Magnetization
10. Anti-Ferromagnetic Materials
• Antiferromagnetic structures were first shown through neutron diffraction of transition metal oxides such as
nickel, iron, and manganese oxides. The experiments, performed by Clifford Shull, gave the first results
showing that magnetic dipoles could be oriented in an antiferromagnetic structure.
• Antiferromagnetic materials occur commonly among transition metal compounds, especially oxides.
Examples include hematite, metals such as chromium, alloys such as iron manganese (FeMn), and oxides
such as nickel oxide (NiO).
• There are also numerous examples among high nuclearity metal clusters.
• Organic molecules can also exhibit antiferromagnetic coupling under rare circumstances, as seen in radicals
such as 5-dehydro-m-xylylene.
• Antiferromagnets can couple to ferromagnets, for instance, through a mechanism known as exchange bias,
in which the ferromagnetic film is either grown upon the antiferromagnet or annealed in an aligning
magnetic field, causing the surface atoms of the ferromagnet to align with the surface atoms of the
antiferromagnet.
• This provides the ability to "pin" the orientation of a ferromagnetic film, which provides one of the main
uses in so-called spin valves, which are the basis of magnetic sensors including modern hard disk drive read
heads.
• The temperature at or above which an antiferromagnetic layer loses its ability to "pin" the magnetization
direction of an adjacent ferromagnetic layer is called the blocking temperature of that layer and is usually
lower than the Néel temperature.
11. Anti Ferromagnetic Ordering
In materials that exhibit antiferromagnetism, the magnetic
moments of atoms or molecules, usually related to the
spins of electrons, align in a regular pattern with
neighboring spins (on different sublattices) pointing in
opposite directions. This is, like ferromagnetism and
ferrimagnetism, a manifestation of ordered magnetism.
Generally, antiferromagnetic order may exist at
sufficiently low temperatures, but vanishes at and above
the Néel temperature – named after Louis Néel, who had
first identified this type of magnetic ordering. Above the
Néel temperature, the material is typically paramagnetic.