[Study on crystal growth and vibrational spectra of Yb(x) : KY(1-x) (WO4)2]

Yb(x) : KY(1-x)W (x = 0.05)and KYbW crystals were grown by TSSG method. Both of the structure and spectral properties were compared. The condition for the crystal growth is: the rotation rate 10-15 r x min(-1), the pulling speed 1-2 d(-1), the growing period 10-15 d, cooling growing speed 0.05-0.1 degrees C x h(-1), and the cooling speed 20 degrees C x h(-1). X-ray powder diffraction analysis was performed for the crystal powder. They belong to beta-KYW structure with low thermal phase. The cell parameters of the two crystals were calculated, and they are respectively a1 = 1.063 nm, b1 = 1.034 nm, c1 = 0.755 nm, beta1 = 130.75 degrees, Z1 = 4 and a2 = 1.061 nm, b2 = 1.029 nm, c2 = 0.749 nm, beta2 = 130.65 degrees and Z2 = 4. The infrared spectrum and Raman spectrum of crystal were measured. The sample of Yb(x) : KY(1-x) W (x = 0.05) had stronger infrared absorption peaks at 925, 891, 840, 777 and 749 cm(-1), which were caused by stretching vibration. The sample of KYW had stronger infrared absorption peaks at 484 and 437 cm(-1) caused by bending vibration. The vibration modes were analysed and vibrational frequencies of vibratory activity was assigned. The two crystals had strong Raman activity. The vibration of WOOW and WOW exists from 200 to 1000 cm(-1).