Raman investigation of lattice vibration modes and thermal conductivity of Nd-doped zircon-type laser crystals

The Raman spectra of neodymium-doped yttrium orthovanadate Nd:YVO4 (NYV) and neodymium-doped gadolinium orthovanadate Nd:GdVO4 (NGV) have been measured at room temperature with different geometrical configurations. On the basis of the group theory and lattice dynamics theory, all the Raman peaks are assigned, and a correlation between the thermal conductivity and the Raman scattering strength is presented. The thermal conductivity of Nd:GdVO4 and Nd:YVO4 crystals along [1 1 0] and [1 0 1] directions are calculated and a good agreement with experimental results is obtained. The higher thermal conductivity of NGV crystal is mainly attributed to the fact that the effective radius of Gd3+ ion in NGV crystal is close to that of Nd3+ ion, which in return, enhances the crystal field strength of the laser crystal.