Kunpeng Wang

Anisotropic thermal properties of monoclinic Yb:KLu(WO4)2 crystals

Yb:KLu(WO4)2 (KLuW) crystals with large size and good optical quality have been grown by the top-seeded solution growth (TSSG) method. The melting point and specific heat, anisotropic thermal expansion and thermal conductivity have been measured. The Jackson factor α of a series of observed faces (hkl) on Yb:KLuW crystals have been calculated. In addition, the microhardness has also been measured. We find that the thermal expansion anisotropy of Yb:KLuW is weaker than KGd(WO4)2 (KGW) and KYb(WO4)2 (KYbW) and the thermal conductivity is up to 4.4Wm−1k−1 along [205] directions at 25°C, which is the greatest in their family.

Growth defects and infrared spectra analysis of CePO4 single crystals

High-quality CePO 4 single crystals (monazite) were grown by the flux TSSG (top-seeded-solution growth) slow-cooling method. The X-ray powder diffraction pattern shows good crystalline quality of the crystals and the various peaks were assigned. The unit-cell parameters were calculated using the DICVOL90 and TEROR computer programs. The concentrations of all elements in the crystals were measured by electron probe microanalysis. Growth habits were deduced by the Bravais-Friedel Donnay-Harker (BFDH) method and macro-defects in the crystals are discussed. An infrared spectrum of the crystal was recorded in the frequency range of 300 to 1600 cm -1 and all vibration frequency peaks were assigned.

Periodic transition of microcrystals on the host (110) face of KLu(WO4)2 crystals

The interesting morphology of the (110) face of laser-active potassium lutetium tungstate, KLu(WO 4 ) 2 (KLuW), crystals has been investigated with an Opton polarizing microscope. Three microcrystals with regular shapes are formed on the edge of the host (110) surface; furthermore, their shapes have a 180° rotation relationship with each other. It is suggested that the three microcrystals may be the representatives of different growth stages, indicating that a periodic transition occurs during the process of crystal growth. In addition, the morphologies of the steps spreading from the three microcrystals and the inner growth sources are very different. The shape of the observed microcrystal is predicted and the formation mechanisms are carefully analyzed. The observed periodic transition morphologies are thought to imply some profound physical background. Unfortunately, until now no universally accepted theory has been able to elucidate the periodic transition phenomena.

Rubidium gadolinium bis(tungstate).

The structure of rubidium gadolinium bis(tungstate), RbGd(WO4)2, has been determined. The crystal is built up from corner- and edge-sharing WO6 octahedral and GdO8 polyhedral groups, giving rise to a Gd-WO4 polyhedral backbone surrounding structural cavities filled with Rb+ cations. The Gd and Rb atoms lie on twofold axes.