Heat capacity is a fundamental thermodynamic parameter closely related to the state of matter and energy properties. By measuring heat capacity, one can obtain thermodynamic functions such as entropy, enthalpy, and Gibbs free energy. It can also explore scientific phenomena of theoretical and applied value in areas such as lattice dynamics, superconductivity, magnetism, and phase transitions in the liquid helium temperature regime, providing guidance for related thermodynamic research questions.
Recently, a team led by Dr. Shiquan from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, has made a new breakthrough in the development of low-temperature calorimetry instruments. They have developed a Gifford-MacMahon (G-M) type refrigeration adiabatic calorimeter, realizing precise measurements of heat capacity of condensed matter in the temperature range of 4-100K without the need for liquid helium. Their findings have been published in the Journal of Scientific Instruments.
Adiabatic calorimetry without liquid helium. Image provided by DICP.
Adiabatic calorimetry is the most accurate and reliable method for measuring the heat capacity of condensed matter. Previously, our team had established a series of precise adiabatic calorimeters in the temperature range of 4.2-600K. However, these instruments required the use of liquid nitrogen or liquid helium to achieve low-temperature measurement environments, which resulted in high experimental costs and cumbersome operations, thus becoming one of the bottlenecks restricting the development of adiabatic calorimetry technology and research on low-temperature heat capacity.
To address these issues, in this work, we utilized a liquid-helium-free closed-cycle G-M cryocooler to achieve liquid-helium temperatures and developed an adiabatic calorimeter for low-temperature heat capacity measurements without the need for liquid helium. This innovation enabled precise measurements of the heat capacity of condensed matter in the liquid-helium temperature range without the use of liquid helium. Through validation with standard material heat capacity measurements, the calorimeter demonstrated an accuracy of ±0.8% and a precision of ±1.5% in heat capacity measurements in the temperature range of 4-100K. This provides an economical, convenient, and reliable means for conducting heat capacity experiments in the liquid-helium temperature range and investigating related thermodynamic issues.
Related paper information: https://doi.org/10.1063/5.0159807
