Method for the determination of the specific heat of metals at low temperatures under high pressures

Abstract

Efforts are made to determine the absolute specific heat of metals as a function of pressure with an accuracy, which, for the first time, will permit a direct evaluation of the pressure variation of the electronic and phonon parameters gamma and vartheta(D'), respectively. This is achieved by employing the ac method of Sullivan and Seidel, and choosing a suitable sample configuration within a piston-cylinder pressure cell. Essential is the use of diamond powder as a pressure transmitting medium, which because of its low heat capacity and high thermal resistance, couples the sample loosely to the temperature bath, represented by the pressure cylinder. Thus, the thermal requirements of the ac method are met, and corrections--if necessary--are fully tractable. High sensitivity even at the lowest temperatures is obtained by the use of thin slices, prepared from standard carbon resistors, for thermometers. Although delicate, these sensors withstand pressures of more than 20 kbars and remain sensitive. A thorough comparison of results on indium with the literature data at zero pressure is undertaken. It shows that the accuracy of the present results is comparable with that from literature data. Preliminary results at pressures up to 8 kbar are shown; they will be discussed in a separate paper.

Breakdown of three-dimensional Dirac semimetal state in pressurizedCd3As2

“…The high-pressure heat capacity (C ac ) of Cd 3 As 2 was derived from ac calorimetry. 35,36 High pressure X-ray diffraction (XRD) experiments were performed at beam line 15U at the Shanghai Synchrotron Radiation Facility and at beam line 4W2 at the Beijing Synchrotron Radiation Facility, respectively. Diamonds with low birefringence were selected for the experiments.…”

Calorimetric investigation of CeRu2Ge2 up to 8 GPa

“…Indeed, this technique is known to be well suited to the high pressure environment [4,5] since it does not require adiabatic conditions, and allows high resolution, even on very small samples. However, absolute accuracy is generally difficult to obtain.…”

Calorimetric and transport investigations ofCePd2+xGe2−xWilhelm1, Jaccard2 2002Phys. Rev. B

“…For an anvil-type of high pressure cell a much smaller sample volume is required, which makes an adiabatic measurement a hopeless venture. Among the non-adiabatic (or dynamic) methods, ac-calorimetry [12,13] is a suitable technique to be used at high pressures. Very high sensitivity can be achieved, whereas the absolute accuracy is less than for adiabatic techniques.…”