Polarized Raman spectra of single crystal Bi2ZnOB2O6 have been recorded in the spectral range 101600 cm-1 at room temperature. Factor group analysis was used to obtain the normal modes of vibration of the crystal. The Raman peaks under 300 cm-1 are assigned to external modes, which are related to the rotational and transitional movement of the [BiO6], [ZnO4], [BO4] and [BO3] groups. Compared with the vibrational spectra of the compounds referred, the satisfactory assignment of most of the high-energy modes to vibrations of Bi-O, B-O and Zn-O bonds can be achieved. In particular, the Raman high-frequency peak located at 1407 cm-1 is attributed to the B-O vibration in the [BO3] triangle.

In this paper, the lattice vibrational modes of the nonlinear optical crystal BaBPO5 are studied using polarized Raman spectrum and the first-principles calculation. The polarized Raman spectra are obtained in different configurations and recorded in a range of 100-1600 cm-1. Combining the experimental data of the FT-IR spectrum, the lattice vibrational modes of the internal and external vibrations are analyzed by the factor group analysis method. The results indicate that the primary Raman peaks of the BaBPO5 crystal are ascribed to the internal vibrations of the PO4 and BO4 tetrahedrons, and the vibrations of the PO4 tetrahedron show strong Raman- and IR-activity. On the other hand, the first-principles calculation indicates the correlation of the vibrational modes with the atomic activities. Especially, the Raman peak located at 672 cm-1 is ascribed to the vibration of the B-O-P bond, which is the connector between the PO4 and BO4 tetrahedron. These results obtained in this work are important for understanding the micro-structures of the BaBPO5 crystal, and the further study on the crystal growth mechanism.

Since LuTaO4 is a scintillator host with the highest density, it is important to investigate the structure and phase transition for its single crystal preparation. The polycrystalline formed by the mixture of Lu2O3:Ta2O5 with the molar ratio 1:1 is prepared by solid state reaction method at different temperatures. The phase transitions and structures of the polycrystalline powders are investigated by X-ray diffraction and Rietveld refinement. The results show that the polycrystalline has a single phase M'-LuTaO4 when sample is prepared at 1740 ℃, it presents a mixture phase of M'-LuTaO4 and M-LuTaO4 at 1800 ℃, and it displays a single phase M-LuTaO4 at 1840 ℃. The sample is melted when the calcined temperature is 2058 ℃, the melt is quenched and the polycrystalline is the mixture of M-LuTaO4, Lu3TaO7 and Ta2O5, whose structural parameters, including the lattice parameters, atomic fraction coordinates, etc. are obtained by Rietveld refinement to their X-ray diffraction pattern, and the results show their weight ratios are 78.1%, 18.9% and 3.0%, respectively. These results are valuable for the single crystal growth of the heavy scintillators with the host LuTaO4.

The laser-micro-Raman spectra of near-stoichiometric LiNbO3 crystals were measured and analyzed. The crystals were grown by flux pulling method. Compared with the congruent LiNbO3 crystal, the number and frequency of Raman spectral lines of A1(TO) and E(TO) modes have no change. It was validated that the LiNbO3 crystal is substitutional solid solution. The relative intensity of 738cm-1 Raman peak(A1(LO)) exhibited obvious change when the Li2O contents increase in pure LiNbO3 crystal, the 738cm-1 Raman peak disappeared in the Mg-doped and Zn-doped LiNbO3 crystals. These Raman peaks were discussed and explained from the occupied site and structure according to the Li vacancy model. The full width at half maximum (FWHM) of the 152 and 872cm-1 Raman peaks narrows with increasing the Li/Nb in the crystals. Their relationships were fitted linearlly, using the fitting equation, and the Li/Nb ratio can be calculated according to the FWHM of Raman peaks.

High temperature Raman spectroscopy has been used to probe the growth units existing in PbMoO4 melt. According to the Raman spectra of PbMoO4 crystal at various temperatures and the melt just above the crystal melting point, we found that Pb2+ cations and ［MoO4］2－ groups acting as the growth units exist in the melt. Further, we have studied the interaction between the growth units and various low-index planes of PbMoO4 crystal. The crystal growth habit and the cause of dendrite growth are explained. Finally, we point out that the best seed orientations for the crystal growth are parallel to its {101} planes.