Jianhua Jiang

Growth, defects, and properties of GdCa4O(BO3)3 and Nd:GdCa4O(BO3)3 crystals

Pure and neodymium-doped gadolinium calcium oxoborate crystals of high quality were grown by the Czochralski method. The orientation of crystal was precisely determined, and the samples for measurements were prepared. Through synchrotron x-ray topography and high-resolution x-ray diffractometry, the twin structure was discovered. Some properties such as the figure of merit value, and dielectric, piezoelectric, and elastic constants were measured along with a discussion of the anisotropy of the laser properties.

The growth defects in self-frequency-doubling laser crystal NdxY1 − xAl3(BO3)4

The growth defects in flux-grown NdxY1 − xAl3(BO3)4 (NYAB) single crystals have been investigated by means of chemical etching and synchrotron radiation techniques. The band-shaped and polysynthetic twins were detected by optical microscopy due to the difference in etching rates between the host crystal and the twin. In the meantime, the orientation and symmetry of the twins were analyzed from their etching patterns. A large number of etch pits with regular shapes were also found on the surface, and these etch pits correspond to outcrops of the dislocations originating from the seed crystal or inclusions.

The formation mechanisms of dislocations and negative crystals in LiB3O5 single crystals

Dislocations and negative crystals in LiB3O5(LBO) single crystals were investigated by white-beam synchrotron radiation topography (WBSRT) and birefringence image. The WBSRT revealed that the grown-in dislocations are mainly pure screw or edge types with the Burgers vectors in the low index directions on the (010) lattice plane. Based on the structure analysis, the cause of the formation of dislocations can be interpreted in terms of the loose packing of B-O rings on the (010) lattice plane. In addition, the negative crystals, which were observed by the birefringence image, tend to present at regular shapes which are similar to that of the host crystal, It is proposed that the negative crystals result from the formation of liquid parent inclusions and the following inward growth.

Characterization of Growth Defects in Nd:YCa4O(BO3)3 Crystals by Transmission Synchrotron Topography

The growth defects in Nd: YCa 4 O(BO 3 ) 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.

Growth defects in Nb:KTP crystals observed by synchrotron radiation topography

Abstract The growth striations, growth sector boundaries and grown-in dislocations in flux-grown Nb-doped KTiOPO 4 crystals have been investigated by white-beam synchrotron radiation topography. The distribution of growth sectors, which mainly consists of {011} and {201} sectors, is clearly shown and characterized, and the effects of growth striations on the non-critical phase matching along the [100] direction are discussed.

Growth and defects in YbxY1−xAl3(BO3)4 crystals

YbxY1-xAl3(BO3)(4) (x = 0.1, 0.07 and 0) crystals have been grown by the flux method. The growth defects of YbxY1-xAl3(BO3)(4) crystals were detected by X-ray topography. It is found that the perfection of YbYAB crystal with low Yb dopant is better than that with high Yb dopant. In Yb0.1Y0.9Al3(BO3)(4) crystal, growth bands, growth boundaries, grown-in dislocations and inclusions were observed. However, the densities of growth defects for Yb0.07Y0.93Al3(BO3)(4) and YAl3(BO3)(4) are low and no obvious inclusions are observed in these crystals. In addition, growth twins were detected in YbxY1-xAl3(BO3)(4) crystal by using the chemical etching method. It is found that the growth twins occur frequently in Yb0.1Y0.9Al3(BO3)(4) crystal whereas no growth twin appears in YAl3(BO3)(4) crystal. Based on the experimental observations, the formation mechanism of growth twins is discussed. In the meantime, the effective measures for reducing the growth twins and defects are proposed

Growth defects in flux grown RbTiOAsO4 crystals observed with white-beam synchrotron radiation topography

Abstract The growth defects in flux grown RbTiOAsO 4 crystal have been investigated by white-beam synchrotron radiation topography. It is found that growth sector boundaries are the primary growth defects and they show strong X-ray kinematical contrast in the topograph. All the dislocations are growth induced and appear only in the near capping region. The area away from the capping region is nearly dislocation free. Growth bands show weak contrast in the X-ray topograph, which implies that the impurity contents are relatively low in various growth sectors and each growth sector is uniform in composition.

Investigation of Optical Inhomogeneities and Growth Defects in Flux‐Grown Nb:KTP Crystals

Optical inhomogeneities and growth defects in flux-grown Nb-doped potassium titanyl phosphate crystals have been investigated. The growth striations, growth sector boundaries and dislocations are revealed by white-beam synchrotron radiation topography. All of the observed dislocations are growth induced and no ferroelectric domains are found in the crystals. It is believed that the main reason for causing the instability of the 90° non-critical phase matching along the 2-direction is related to the growth striations, especially of {011} sectors.

Growth Twinning in Self-Frequency-Doubling Laser Crystal NdxGd1—xAl3(BO3)4 Observed with White-Beam Synchrotron Radiation Topography

The growth twinning in self-frequency-doubling laser crystal NdxGd1-xAl3(BO3)(4) (NGAB) has been observed with white-beam synchrotron radiation topography (WBSRT). It is shown that the growth twinning in flux-grown NGAB crystal is the 180 degrees rotation twin in which the twofold symmetric operation axis is parallel to the [0001] direction and this kind of twinning often shows the black-and-white contrast in X-ray topography. It is believed that the growth twinning in NGAB was induced by growth bands formed during crystal growth.