The inhomogeneity in a congruent LiTaO3 crystal has been observed by transmission synchrotron topography. Many extraordinary regions exist in congruent LiTaO3 crystal and they often show diffraction intensity different from that of ordinary regions in synchrotron topographs. Differential thermal analysis indicates that the Curie temperature of the extraordinary region is lower than that of ordinary region, and the extraordinary region is really a high defect density region. The diffraction contrast of the extraordinary region in synchrotron topographs is explained qualitatively by a calculation at the selected wavelength.

Studies of photochromic damage induced in KTiOPO4 single crystals by 514.5nm laser irradiation is reported. A dependence of photochromic damage on polarization was observed. Along the same propagation direction (y901j23:31), the gray-track susceptibility for 8z polarization irradiation is one order magnitude lower than that for >z polarization irradiation for KTP crystal. The results clearly show that in KTiOPO4, a correlation exists between the gray-track susceptibility and the ionic electrical conductivity. Due to a high ionic electrical conductivity along the polar z-axis, the optical absorption centers will be annihilated with 8z polarization irradiation as soon as they are produced. This results in a lower gray-track susceptibility for 8z polarization irradiation.

The growth defects in Nd: YCa4O (BO3) 3 (Nd:YCOB) crystals were investigated by transmission synchrotron topography. It was found that growth striations were the primary defects in Nd: YCOB crystals. Grown-in dislocations, mosaic blocks and inclusions were also observed in the crystals. The effect of temperature field on the formation of growth defects in the crystals was discussed.

Large GdCa4O (BO3) 3 crystal has been grown by the Czochralski method. The quality of GdCa4O (BO3) 3 crystal was assessed by white-beam synchrotron radiation topography. It has been found that there is a sub-grain boundary in the GdCa4O (BO3) 3 crystal. The boundary divides the large GdCa4O (BO3) 3 crystal into two individuals. Due to the misorientation between the two individuals, the image shifts can be observed in the synchrotron topographs. Based on the misorientation determined by high resolution X-ray diffractometer, the image shifts were calculated for several reflections. The calculations are in agreement with the measurements from the topographs very well. In addition, the formation mechanism of sub-grain boundary is discussed.

A Raman scattering study of the vibrational modes in K2Al2B2O7 crystals has been performed at room temperature. The vibrational modes are classified by the nuclear site group analysis method and the internal vibrational modes are assigned to vibrations of the BO3 triangle and AlO4 tetrahedron.