Pressure induced Structure Change and Anomalies in Thermodynamic Quantities and Transport Properties in Liquid Lithium Hydride

Abstract

Understand the nature of liquid structure and its evolution under different conditions is a major challenge in condensed physics and materials science. Here, we report a pressure-induced structure change spanning a wide pressure range in liquid-state lithium hydride (LiH) by first-principles molecular dynamic simulations. This behavior can be described as a continuous crossover from low pressure liquid with Li${}^{+}$-H${}^{-}$ duality symmetry to high pressure one with broken of duality symmetry. The thermodynamic quantities such as heat capacity and ionic transport properties such as diffusivity are also saliently impacted. It is important to stress that such behavior is firstly predicted for this category of materials, which is ubiquitous in universe as well as in industry applications. Lastly, a comprehensive high-pressure high-temperature phase diagram of LiH is constructed, which embodies rich physics in this previously-thought-simple ionic compound.

23 pages, 4 figures, with Supplementary Information

References in corpus (6)

• Tetrahedral clustering in molten lithium under pressure
• Thermodynamic anomalies and three distinct liquid-liquid transitions in warm dense liquid hydrogen
• Lattice stability and high pressure melting mechanism of dense hydrogen up to 1.5 TPa
• Interplay of anionic quasi-atom and interstitial point defects in electrides: abnormal interstice occupation and colossal charge state of point defects in dense FCC-lithium
• Prediction of anomalous LA-TA splitting in electrides
• Compression and phase diagram of lithium hydrides at elevated pressures and temperatures by first-principles calculations