arXiv subjects

V. V. Vengerovsky

Publications and source records attributed to V. V. Vengerovsky.

2 recordsLinked to original sources

arXiv2020

Negative Thermal Expansion in Solid Deuteromethane

The thermal expansion at constant pressure of solid CD$_4$ III is calculated for the low temperature region where only the rotational tunneling modes are essential and the effect of phonons and librons can be neglected. It is found that in mK region there is a giant peak of the negative thermal expansion. The height of this peak is comparable or even exceeds the thermal expansion of solid N$_2$, CO, O$_2$ or CH$_4$ in their triple points. It is shown that like in the case of light methane, the effect of pressure is quite unusual: as evidenced from the pressure dependence of the thermodynamic Grüneisen parameter (which is negative and large in the absolute value), solid CD$_4$ becomes increasingly quantum with rising pressure.

cond-mat.mtrl-sci↗

arXiv2019

The Effect of Pressure on the Negative Thermal Expansion of Solid Methane

The effect of pressure on the thermal expansion of solid CH$_4$ is calculated for the low temperature region where the contributions from phonons and librons can be neglected and only the rotational tunnelling modes are essential. The effect of pressure is shown to increase the magnitude of the peaks of the negative thermal expansion and shifts the positions of the peaks to the low-temperature region, which goes asymptotically to zero temperature with increasing pressure. The Gruneisen thermodynamical parameter for the rotational tunnelling modes is calculated. It is large, negative, and increases in magnitude with rising pressure.

cond-mat.mtrl-sci↗