Debye Temperature and Static Displacements in LuH/sub X/ Single Crystals from Energy Dispersive X-Ray Diffraction

摘要

Integrated Bragg intensities of LuH/sub x/ along the hexagonal c-direction have been measured by energy-dispersive x-ray diffraction as a function of temperature and hydrogen concentration x less than or equal to 0.133 H/Lu. From the temperature-dependent measurements we show the Debye temperature THETA/sub D/ to increase linearly with the hydrogen content delta THETA/sub D// delta x = 0.75K/% H/Lu. For pure Lu we find THETA/sub D/ = 157K +- 1K. From static Debye-Waller factor measurements (at T = 17K) we determined the displacements of the Lu atoms close to hydrogen on tetrahedral sites (u/sub 1st shell/ = 0.09 +- 0.002 A and u/sub 2nd shell/ = 0.03 +- 0.002 A. We demonstrate that the static Debye-Waller factor is not very sensitive to pair formation of hydrogen atoms. Therefore the measurements gave no indication of hydrogen pairs on adjacent tetrahedral sites. (ERA citation 10:025839)