Lattice Vibrations and Thermal Properties of Stoichiometric KYb(WO4)2 Crystal

Single crystal KYb(WO4)(2) (KYbW) has been grown by the top-seeded solution growth (TSSG) method. Polarized Raman and infrared spectra have been recorded at room temperature. The lattice vibration modes were calculated, and the strongest peaks appear at 760 and 908 cm(-1) with a line-width Delta omega(R) of 14.2 and 10 cm(-1), corresponding to relaxation times of 0.747 and 1.061 ps, respectively. This makes KYbW attractive for stimulated Raman scattering (SRS) applications and for use in the picosecond regime. Differential thermal analysis and thermal gravimetric analysis curves, high-temperature X-ray diffraction patterns, specific heat, thermal expansion and thermal conductivity have been studied. The thermal expansion anisotropy of KYbW is weaker than that of KGd(WO4)(2) (KGW), but stronger than that of KLu(WO4)(2) (KLuW). The thermal diffusivity along the c-axis is large (lambda(c) > lambda(a) > lambda(b)). The results are consistent with the anisotropic structure of crystalline KYbW.