GRÜNEISEN PARAMETER AND DEBYE TEMPERATURE UNDER THE COMBINED INFLUENCE OF SIZE AND PRESSURE

Abstract

A theoretical investigation has been conducted to examine the impact of size and pressure on the Debye temperature, utilizing a size-dependent Grüneisen parameter. The Grüneisen parameter, a dimensionless and crucial parameter, serves as a representation of the thermodynamic and thermoelastic characteristics of solids, offering insights into lattice anharmonicity. The Debye temperature signifies the point at which collective vibrations transition to independent thermal vibrations. While there exists an abundance of theoretical and experimental research on the pressure dependence of Debye temperature in bulk materials, measuring it at the nanoscale presents challenges. In recent years, numerous studies have explored the size-dependent variations in the Debye temperature. However, the investigation into the combined effects of size and pressure on the Debye temperature has remained unexplored until now. In this study, the research conducted by Kumari and Dass has been utilized to examine the combined impact of size and pressure on the Debye temperature for nanoparticles. The findings reveal a reduction in the Grüneisen parameter under pressure at the nanoscale. Furthermore, the Debye temperature exhibits enhancement for a specific particle size due to variations in the unit cell parameter under pressure, particularly up to 1 GPa. These outcomes align consistently with data extracted from experimental studies on the melting temperature, which is dependent on both size and pressure. Understanding the pressure dependence of the Debye temperature is essential for observing the recoilless fraction of γ-ray emission or absorption in the Mӧssbauer effect.