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Register a new userCharacterization of the pressure coefficient of manganin and temperature evolution of pressure in piston-cylinder cells
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We report measurements of the temperature- and pressure-dependent resistance, $R(T,p)$, of a manganin manometer in a $^4$He-gas pressure setup from room temperature down to the solidification temperature of $^4$He ($T_textrm {solid}sim$ 50 K at 0.8 GPa) for pressures, $p$, between 0 GPa and $sim$0.8 GPa. The same manganin wire manometer was also measured in a piston-cylinder cell from 300 K down to 1.8 K and for pressures between 0 GPa to $sim$2 GPa. From these data, we infer the temperature and pressure dependence of the pressure coefficient of manganin, $alpha(T,p)$, defined by the equation $R_p = (1+alpha p) R_0$ where $R_0$ and $R_p$ are the resistance of manganin at ambient pressure and finite pressure, respectively. Our results indicate that upon cooling $alpha$ first decreases, then goes through a broad minimum at $sim$120 K and increases again towards lower temperatures. In addition, we find that $alpha$ is almost pressure-independent for $Tgtrsim$60 K up to $psim$2 GPa, but shows a pronounced $p$ dependence for $Tlesssim$60K. Using this manganin manometer, we demonstrate that $p$ overall decreases with decreasing temperature in the piston-cylinder cell for the full pressure range and that the size of the pressure difference between room temperature and low temperatures ($T=1.8$ K), $Delta p$, decreases with increasing pressure. We also compare the pressure values inferred from the magnanin manometer with the low-temperature pressure, determined from the superconducting transition temperature of elemental lead (Pb). As a result of these data and analysis we propose a practical algorithm to infer the evolution of pressure with temperature in a piston-cylinder cell.
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Pressure calibration for most diamond-anvil cell (DAC) experiments is mainly based on the ruby scale, which is key to implement this powerful tool for high-pressure study. However, the ruby scale can often hardly be used for programmably-controlled DAC devices, especially the piezoelectric-driving cells, where a continuous pressure calibration is required. In this work, we present an effective pressure gauge for DACs made of manganin metal, based on the four-probe resistivity measurements. Pressure dependence of its resistivity is well established and shows excellent linear relations in the 0 - 30 GPa pressure range with a slope of 23.4 (9) GPa for the first-cycle compression, in contrast to that of multiple-cycle compression and decompression having a nearly identical slope of 33.7 (4) GPa likely due to the strain effect. In addition, such-established manganin scale can be used for continuously monitoring the cell pressure of piezoelectric-driving DACs, and the reliability of this method is also verified by the fixed-point method with a Bi pressure standard. Realization of continuous pressure calibration for programmably-controlled DACs would offer many opportunities for study of dynamics, kinetics, and critical behaviors of pressure-induced phase transitions.
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