Thermal Properties of Magnesium Hydroxide Using First-Principles Method

Abstract

The thermal properties of the magnesium hydroxide crystalline powder samples, which were prepared by us, were investigated by first-principles method. The calculated results show that the forbidden band of phonon appears in both 14～19 THz and 33～102 THz. There are 3 acoustic lattice wave branches and 12 optical ones, where two horizontal acoustic branches are degeneracy and two horizontal optical ones are degeneracyhe. Moreover, The constant-volume specific heat quickly increases at low temperature; but it tends to be flat at high temperature. Besides, the Debye temperature quickly increases to 483K from temperature 0K to 10K; but from temperature 100K to 1000K, it is linear with temperature approximately, whose increasing rate is about 1.333; at temperature of 1000K, the Debye temperature is 1930K, reaching its maximum.