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News and Announcements
Physics Lab

 

List of Instruments : 

1. Differential scanning calorimetry (DSC)

2. Magneto dielectric set-up

3. ME set-up - PE loop tracer

4. Four Probe set-up (Pro-4 Lucas Signatone QuadPro Resistivity System)

 

1. Differential scanning calorimetry (Model: DSC131 evo) :

Differential scanning calorimetry or DSC is a  thermoanalytical technique in which the

difference in the amount of  heat required to increase the temperature of a sample and reference is

measured as a function of temperature. Both the sample and reference are maintained at nearly the

same temperature throughout the experiment. Generally, the temperature program for a DSC analysis

is designed such that the sample holder temperature increases linearly as a function of time. The

reference sample should have a well-defined heat capacity over the range of temperatures to be

scanned.

 

Applications:

With its wide temperature range (-170 °C to 700 °C) of applications, especially when dealing with

polymers and plastics (characterization, quality control) as well as with organic and pharmaceutical

compounds (polymorphism, purity, thermal stability), with inorganic substances (dehydratation,

transition, decomposition), with metals (transition)... from the raw to pharmaceutical compounds

(polymorphism, purity, thermal stability), with inorganic transformed materials. As a teaching tool

the DSC131 evo offers a unique blend of performance, ease of use and robustness to allow the

training of students in the thermodynamic principles of phase change(fusion, crystallization,

evaporation), transition (glass transition, order-disorder transition), reaction kinetics (polymerization,

decomposition), or heat capacity.

 

 

 

Specifications:

Temperature range

Ambient to 700 °C

With cooling accessories

-170 °C to 500 °C (Liquid Nitrogen Accessory)

-70 °C to 400 °C (Cryothermostat)

Programmable temperature scanning rate(heating and cooling)

0.01 to 100 °C.min-1

Cooling time

12 min (500 °C to 100 °C) Air

5 min (100 °C to 0 °C) Cryothermostat

6 min (200 °C to 25 °C) Liquid Nitrogen Accessory

12 min (25 °C to -100 °C) Liquid Nitrogen Accessory

RMS Noise (200°C)

1.5 µW

Resolution

0.8 µW

Time constant

3 s

Gases

included gas switch from gas A to gas B

Crucibles

30 µl, 100 µl

aluminum, alumina, incoloy, etc.

Pressure (non controlled)

High pressure crucible

(up to 500 bars / 7255 psi at 600 °C)

Weight

37.4 kg (82.5 lbs)

Dimensions (Height / Width / Depth)

40 / 53 / 58 cm (15.7 / 20.9 / 22.8 in)

Power requirements

230 V - 50/60 Hz.

 

 

2. Magneto dielectric set-up:

The sample is placed at the center of the electromagnet and an LCR meter calculates the dielectric / capacitance / electrical property of the sample. The current of the electromagnet is varied which changes the magnetic field applied to the sample. The LCR meter measures the electrical properties at different valuesof magnetic field. Frequency dependent measurement (20Hz to 120 MHz) can also be carried out.

Component:

Electromagnet, Magnetic Power Supply & LCR Meter

 

 

 

 

 

 

 

 

 

 

 

 

Magnetic Power supply Electro-Magnet (upto 9000Oe)

 

LCR Meter (Wayne kerr 6500P):

Measurement parameters:

  1. Capacitance (C)

  2. Inductance (L)

  3. Resistance (R)

  4. Reactance (X)

  5. Conductance (G)

  6. Susceptance (B)

  7. Dissipation Factor (D)

  8. Quality Factor (Q)

  9. Impedance (Z)

  10. Admittance (Y)

  11. Phase Angle (Ø)

 

 


 

3. ME set-up (P-E loop tracer):

In Some materials, the Center of Positive and negative charges is displaced by the application

of electric field and the material exhibits a net polarization corresponding to the electric field. With

increasing electric field the behaviour of polarization vs electric field and saturation polarization are

characteristics of a particular material.

In some materials there is magneto-electric coupling that is application of magnetic field may induce polarization and hence the P-E loop for such materials exhibit different behaviour when carried out in the presence of magnetic field. The nature of this dependence of P-E loop on magnetic field shows magneto-electric coupling. The stronger the dependence, the stronger is the magneto-electric coupling or magneto-electric coefficient.



 

 


 

Pro-4 Four Point Resistivity Systems(Lucas Signatone QuadPro Resistivity System)

Principle:

Four probe method for measuring resistance is also known as Four-terminal sensing or 4T sensing. It is a technique to measure electrical impedance. It uses separate pairs for current carrying and voltage sensing electrodes. This method is capable of making more accurate measurements than two terminal sensing. In this method, current is supplied via a pair of current leads. The voltage drop across the impedance is measured by a separate pair of leads. Thus, the voltage drop in the current carrying wires is prevented from being added to the actual value.

Measuring resistance :

Ohm’s law If physical condition (like temperature, mechanical stress) remains unchanged, the potential difference across two ends of a conductor is proportional to current flowing through a conductor.

V α I or V = I R

R is the resistance of conductor.

Resistivity: At a constant temperature, the resistance R, of a conductor is proportional to its length and inversely proportional to its area of cross-section

R α L/A or R= ρL/A

ρ is the resistivity of material.