The accurate determination of the pressure value at given temperature, P(T), is of particular importance for the creation of P-T phase diagrams, e.g. for studies of any material that has multiple phase transitions at different temperatures or a transition that has a significant shift under pressure. A decrease of pressure in a piston-cylinder cell on cooling, due to a complex interplay of different thermal expansion coefficients of the pressure medium and the materials used in construction of the cell is well appreciated in the literature. Commonly, the room temperature pressure values are obtained using manganin as a pressure gauge whereas the low temperature (2 - 7 K) values are obtained from the shifts of superconducting transitions of several elements (In, Sn, Pb). Intermediate temperatures P(T) variations were studied more than three decades ago [1] using manganin gauge with assumed temperature-independent pressure coefficient of resistance.

In this work we present simultaneous measurements of several potential wide temperature pressure gauges: manganin wire, n-InSb (SPG-10, Unipress, Poland) and in-house prepared CuMn7Sn alloy (comparable to Zeranin®) in 2.5 GPa Cu-Be/NiCrAl piston-cylinder cell using 40:60 light mineral oil – n-pentane pressure media and discuss suggestions for their use.

This work was supported by US DOE, BES, under Contract No. DE-AC02-07CH11358, Gordon and Betty Moore Foundation’s EPiQS Initiative Grant No. GBMF4411, and the W. M. Keck Foundation.

[1] J. D. Thompson, Rev. Sci. Instr. 55, 213 (1984)