Temperature EPR study of LiY 1-xYb xF 4(Gd 3+) single crystals

Abstract

The EPR investigation has been carried out on Gd 3+-doped LiY 1- x Yb x F 4 single crystals in the temperature range 4.2 to 428 K. The experimental data were fitted to both Debye and Einstein models and results are discussed. The average effective Debye temperatures (and velocities of sound) were determined to be 860 K (6.58 × 10 5 cm s −1) for LiY 1- x Yb x F 4 and 405 K (3.11 × 10 5 cm s −1) for LiYF 4, whereas the average value of hv/ k originate in the Einstein approximation (and velocities of sound) to be 570 K (4.36 × 10 5 cm s -1) and 286 K (2.20 × 10 5 cm s −1) respectively. It has to be compared with the local velocities of sound calculated using the local Debye temperature ( θ SLR = 180 K) to be 1.37 × 10 5 and 1.38 × 10 5 cm s −1 for LiYbF 4 and LiYF 4 crystals, respectively.