Qualitative AC calorimetry under high pressure using piston-cylinder apparatus without adiabatic approximation

Area of Science:

• Materials Science
• Thermodynamics
• Physical Chemistry

Background:

• Accurate measurement of thermal properties like heat capacity and thermal conductivity is crucial for understanding material behavior.
• Conventional AC calorimetry methods face challenges in measuring these properties in liquid samples, especially under high pressures and low temperatures.

Purpose of the Study:

• To develop and validate a new alternating current (AC) calorimetry method capable of measuring heat capacity and thermal conductivity.
• To extend the application of AC calorimetry to liquid samples under high-pressure (up to 2.1 GPa) and low-temperature (down to ~40 K) conditions.

Main Methods:

• Development of an AC calorimetry technique utilizing a piston-cylinder apparatus.
• Implementation of a planar one-dimensional heat conduction model with a pair of platinum resistors.
• Application of the developed method to various substances including NH4Cl, cyclohexene, methylcyclohexane, and ice.

Main Results:

• Successful measurement of heat capacity and thermal conductivity under high pressures (up to 2.1 GPa) and low temperatures (~40 K).
• Demonstrated capability to measure thermal properties of liquid samples, a significant advancement over traditional AC calorimetry.
• Validated the method's effectiveness through experimental application to diverse materials.

Conclusions:

• The new AC calorimetry method provides a robust approach for determining thermal properties of materials, including liquids, under extreme conditions.
• This technique expands the scope of AC calorimetry, enabling new avenues for research in condensed matter physics and materials science.