Chalcogenide glasses are prepared using a melt quench technique involving melting chalcogen elements and quickly quenching to form a glass. Their properties, such as dielectric loss and dielectric constant, can be measured using low temperature dielectric experiments by applying an electric field and measuring capacitance and dissipation factor. Hardness is also characterized using techniques like Vickers and Brinell testing that involve indenting the material. Raman spectroscopy, UV-Vis spectroscopy, EDX, DSC, and XRD are additional characterization techniques described.

1. Chalcogenide glass
preparation &
characterization

2. Slide 2
What is chalcogen?
It’s a combo of two Greek words Halkos and Genes Halkos means Ore and Genes means formation of
something. That means chalcoges are the Ore forming elements.
These are group 16 elements in Periodic table

3. Material preparation
• Chalcogenide glasses are a type of glass made from elements in the chalcogen group, such
as sulfur, selenium, and tellurium. The melt quench technique is a common method for
preparing chalcogenide glasses, and involves melting the glass-forming elements and
quickly quenching the melt to form a glassy solid. The following is a step-by-step procedure
for preparing chalcogenide glass via melt quench technique:
1.Select the appropriate chalcogenide elements for the glass composition. The composition
can vary depending on the desired properties of the glass.
2.Weigh the appropriate amounts of each element and place them into a crucible. The crucible
should be made of a material that can withstand high temperatures, such as graphite or
ceramic.
3.Heat the crucible in a furnace to melt the chalcogenide elements. The temperature and
duration of the melting process can vary depending on the composition of the glass and the
melting point of the individual elements.
4.Once the melt has formed, quickly quench it by pouring it onto a cold metal surface. The
metal surface should be pre-cooled with liquid nitrogen or another coolant to ensure rapid
quenching.
5.Allow the glass to cool to room temperature. The glass will solidify into a vitreous (non-
crystalline) state.
6.If desired, anneal the glass by heating it to a lower temperature and then cooling it slowly.
Annealing can improve the mechanical and thermal properties of the glass.
7.Cut and polish the glass into the desired shape for further analysis or use.

4. Dielectric loss and dielectric coefficient
Low temperature dielectric experiments can be used to measure the
dielectric loss and dielectric constant of a material pellet. The
dielectric loss is a measure of the energy dissipated in the material
when an electric field is applied, while the dielectric constant is a
measure of the material's ability to store electric charge.
• Step-by-step procedure for measuring dielectric loss and dielectric
constant using low temperature dielectric experiments:
1.Prepare the material pellet by pressing the material into a pellet
shape. The pellet should be uniform in size and shape, and free of
any defects or impurities that could affect the dielectric properties.
2.Place the material pellet into a cryostat, which is a device used to
control the temperature of the sample.
3.Connect the cryostat to a precision LCR meter, which is an
instrument used to measure the electrical properties of the sample.

5.  Apply an AC electric field to the material pellet using the LCR meter. The
frequency of the AC field should be in the range of 10 Hz to 1 MHz.
 Measure the capacitance and dissipation factor of the material pellet as a
function of temperature. The capacitance is a measure of the material's ability to
store charge, while the dissipation factor is a measure of the energy dissipated in
the material when an electric field is applied.
 Slowly lower the temperature of the sample to the desired low temperature,
typically in the range of 4 K to 300 K. The cryostat should be carefully controlled
to ensure that the temperature is stable and uniform throughout the sample.
 Measure the capacitance and dissipation factor of the material pellet as a
function of temperature at the low temperature. The low temperature
measurement can provide information on the intrinsic dielectric properties of the
material, as well as any changes in dielectric properties that occur at low
temperatures.
 Calculate the dielectric loss and dielectric constant of the material pellet from the
capacitance and dissipation factor data. The dielectric loss is the ratio of the
energy dissipated in the material to the energy stored in the material, while the
dielectric constant is the ratio of the capacitance of the material to the
capacitance of a vacuum.

6. Hardness tests
• Hardness tests are commonly used to measure the resistance of a material to
permanent deformation or indentation. There are various types of hardness tests
available, including the Vickers hardness test, Brinell hardness test, Rockwell hardness
test, and Knoop hardness test.
• The Vickers hardness test is a microhardness test that involves pressing a diamond
indenter with a square base into the surface of the material. The indentation size is
measured, and the Vickers hardness number is calculated based on the indentation
size and the applied load. This test is useful for measuring the hardness of thin
coatings or surface layers.
• The Brinell hardness test involves pressing a tungsten carbide ball indenter into the
surface of the material under a known load. The diameter of the indentation is
measured, and the Brinell hardness number is calculated based on the applied load
and the diameter of the indentation. This test is useful for measuring the hardness of
metals and alloys.
• The Rockwell hardness test involves pressing an indenter into the surface of the
material under a known load, and then measuring the depth of the resulting
indentation. The hardness number is calculated based on the depth of the indentation
and the applied load. This test is commonly used to measure the hardness of metals
and plastics.
• The Knoop hardness test is similar to the Vickers hardness test, but uses a rhombic-
based diamond indenter instead of a square-based one. This test is useful for
measuring the hardness of thin coatings or surface layers.
• In general, hardness tests are useful for measuring the strength and durability of
materials. They are often used in quality control and material selection processes in

7. • The choice of hardness test depends on the type of material being tested and the
specific requirements of the testing application. Here are some general guidelines
for selecting the appropriate hardness test for different materials:
1.Metals and Alloys: For metals and alloys, the Brinell hardness test is often
preferred as it provides a measure of the average hardness of the material. The
Rockwell hardness test is also commonly used for metals, as it provides a rapid
and accurate measurement of the hardness of the material. Vickers hardness test
is suitable for thin coatings and surface layers on metals.
2.Ceramics and Glasses: Ceramics and glasses are typically hard and brittle
materials, and are often tested using the Vickers or Knoop hardness tests, which
can provide accurate measurements of the microhardness of the material.
3.Polymers and Plastics: Polymers and plastics are relatively soft materials, and
are often tested using the Rockwell or Shore hardness tests, which are designed
to measure the hardness of these types of materials.
4.Composites: Composites are a combination of different materials, and the
appropriate hardness test will depend on the composition of the composite.
Generally, a combination of different hardness tests may be needed to accurately
measure the hardness of a composite material.
• In summary, the selection of the appropriate hardness test for a given material
depends on the material type, the required accuracy, and the specific
requirements of the testing application.

8. Raman Spectroscopy
• Raman spectroscopy is a powerful analytical technique that can be used to
determine the chemical composition of a material. It works by measuring the way
that light interacts with the molecular vibrations in a sample.
• When a sample is irradiated with a laser, some of the photons in the laser beam
will be scattered in different directions. Most of the scattered photons will have
the same energy as the incident photons (i.e., they will be elastically scattered),
but a small fraction will have a slightly different energy. This difference in energy
is related to the vibrational energy of the molecules in the sample.
• By analyzing the scattered light, it is possible to determine which vibrations are
present in the sample and how they are coupled to each other. This information
can be used to identify the chemical bonds and functional groups present in the
sample, as well as to measure properties such as the crystal structure, stress,
and strain.
• Raman spectroscopy is particularly useful for the analysis of materials that are
difficult to analyze using other techniques, such as those that are opaque, highly
scattering, or have a complex structure. It is also non-destructive, meaning that it
does not damage the sample being analyzed.

9. UV & NIR photo-
spectrometer
• UV (ultraviolet) and NIR (near-infrared) spectrophotometers are analytical instruments
that can be used to measure the absorption spectra of thin films. These instruments work
by measuring the amount of light that is absorbed by the thin film at different wavelengths.
• In a typical experiment, a beam of light is directed onto the surface of the thin film, and the
light that is transmitted through the film is detected by a detector. The intensity of the
transmitted light is then measured as a function of wavelength, typically over a range of
200 to 1100 nano- meters (nm) for UV-Vis spectroscopy and 800 to 2500 nm for NIR
spectroscopy.
• As the light passes through the thin film, it interacts with the molecular vibrations and
electronic transitions in the material, resulting in the absorption of some wavelengths of
light and the transmission of others. The wavelengths of light that are absorbed by the
thin film correspond to specific electronic transitions or vibrational modes in the material.
• The absorption spectrum of the thin film is then plotted as a graph of the intensity of the
transmitted light versus wavelength. The peaks in the absorption spectrum correspond to
the wavelengths of light that are absorbed by the thin film, and the positions and shapes
of these peaks can provide information about the electronic and vibrational properties of
the material.
• In summary, UV and NIR spectrophotometers measure the absorption spectra of thin films
by directing a beam of light onto the surface of the film and measuring the intensity of the
transmitted light as a function of wavelength. The resulting absorption spectrum can
provide information about the electronic and vibrational properties of the material.

10. EDX spectroscopy
• Energy Dispersive X-ray Spectroscopy (EDX) is a technique used to
determine the elemental composition and homogeneity of a sample. It
works by analyzing the X-rays emitted when a sample is bombarded with
high-energy electrons.
• When the electrons hit the sample, they knock electrons in the inner shell
of the atoms out of their orbits. This creates a hole in the inner shell, which
is then filled by an electron from an outer shell. As the electron moves to fill
the hole, it releases energy in the form of an X-ray. The energy of the X-
ray is specific to the element that it comes from, so by detecting the X-rays
emitted by the sample, it is possible to determine the elemental
composition of the sample.
• EDX spectroscopy can also be used to determine the homogeneity of a
sample. By mapping the distribution of different elements in a sample, it is
possible to determine if the sample is uniform or if it contains regions with
different elemental compositions. This is useful for identifying impurities,
defects, or other structural features of the sample.

11. • To perform EDX spectroscopy, a sample is first prepared by coating
it with a conductive material, such as carbon or gold. This helps to
prevent the sample from being damaged by the high-energy
electrons used in the analysis. The sample is then placed in the
electron microscope and exposed to the electron beam. As the X-
rays are emitted from the sample, they are detected and analyzed by
the EDX detector
• The data collected by the EDX detector can be used to create an
elemental map of the sample, which shows the distribution of
different elements in the sample. By analyzing the elemental map, it
is possible to determine the elemental composition and homogeneity
of the sample.
• In summary, EDX spectroscopy is a technique used to determine the
elemental composition and homogeneity of a sample by analyzing
the X-rays emitted when a sample is bombarded with high-energy
electrons. The technique is useful for identifying impurities, defects,
or other structural features of the sample.

12. DSC
• Differential Scanning Calorimetry (DSC) is a thermal analysis technique
that measures the heat flow associated with the temperature changes in a
sample material. DSC can be used to determine specific heat, glass
transition temperature, crystallization temperature, and melting
temperature of a sample material. The following is a step-by-step
procedure for using DSC to determine these properties:
1.Prepare the sample material by weighing a small amount (typically a few
milligrams) into a sample pan. The sample pan is usually made of a non-
reactive material such as aluminum or platinum.
2.Fill a reference pan with an inert material such as empty sample pan or
alumina. This will serve as a reference for the thermal analysis.
3.Place both the sample and reference pans into the DSC instrument.
4.Heat the sample from room temperature to a high temperature and then
cool it back to room temperature. This is called a "heat-cool-heat" cycle
and is used to eliminate any thermal history effects in the sample.

13. 5. Repeat the heating and cooling process, but this time measure the heat flow (in Watts)
as a function of temperature using the DSC instrument. The DSC instrument records
the heat flow as a function of temperature, which provides information on the thermal
behaviour of the sample.
6. Analyze the DSC data to determine the specific heat of the sample material. The
specific heat is calculated by dividing the heat flow by the temperature difference for
unit mass between the sample and reference pans.
7. Identify the glass transition temperature, which is the temperature at which the sample
undergoes a glass transition from a rigid solid to a rubbery state. The glass transition is
characterized by a change in the slope of the DSC curve.
8. Identify the crystallization temperature, which is the temperature at which the sample
begins to crystallize from the amorphous state. The crystallization temperature is
characterized by a sharp exothermic peak in the DSC curve.
9. Identify the melting temperature, which is the temperature at which the sample begins
to melt from the crystalline state. The melting temperature is characterized by an
endothermic peak in the DSC curve.
In summary, Differential Scanning Calorimetry (DSC) is a thermal analysis technique that
measures the heat flow associated with the temperature changes in a sample material.
DSC can be used to determine specific heat, glass transition temperature, crystallization
temperature, and melting temperature of a sample material. The properties are identified by
analyzing the DSC curve as a function of temperature.

14. XRD
• X-ray diffraction (XRD) is a technique commonly used to determine the crystal
structure of materials. However, it can also be used to sense short-range order
in amorphous materials.
• In amorphous materials, the atoms are arranged in a disordered manner.
However, short-range order may still exist in the form of local atomic
arrangements that are repeated over a small distance. These local
arrangements can cause peaks to appear in the XRD pattern, indicating the
presence of short-range order.
• In order to sense short-range order in amorphous materials, a technique called
X-ray Pair Distribution Function (PDF) analysis is used. In this technique, the
XRD pattern is converted into a PDF plot, which shows the probability of
finding pairs of atoms at a certain distance from each other.
• The PDF plot can reveal the presence of short-range order in amorphous
materials by showing peaks at specific distances, which correspond to the
average distance between pairs of atoms in the local atomic arrangements. By
analyzing the position and intensity of these peaks, information about the local
atomic structure of the material can be obtained.
• In summary, XRD can be used to sense short-range order in amorphous
materials by converting the XRD pattern into a PDF plot and analyzing the
position and intensity of the peaks in the plot. This technique can provide
valuable insights into the local atomic structure of amorphous materials.