X-Ray Topographic Studies of Defect Structure in YVO₄Crystals

Abstract

The perfection of YVO4 crystals, which are predicted to replace formerly used YAG garnets due to higher quantum efficiency and lower excitation level, was studied. The investigations of Czochralski grown undoped YVO 4 single crystals were performed mainly by means of X-ray topographic methods. Both synchrotron and conventional X-ray sources were used. The study revealed relatively high density of weak point-like contrasts which can be most probably interpreted as dislocation outcrops. In regions of the crystal close to its boundary we observed glide bands. It was also found that in some regions the dislocations form local subgrain boundaries. The white beam back reflection and monochromatic beam topography allowed to evaluate a local misorientation which not exceeded several angular minutes. No segregation fringes were observed proving a good homogeneity of chemical composition.

Defect Structure Formed at Different Stages οf Growth Process in Erbium, Calcium and Holmium Doped YVO4Crystals

“…Comparing the results with the ones obtained for YVO 4 undoped crystals, presented by Wieteska et al [8] we can see that block structure is more distinct in doped crystals than in undoped ones.…”

“…[1][2][3][4][5][6][7][8]. The main difficulty in the applications is obtaining of the crystals with low concentration of defects.…”

“…The main difficulty in the applications is obtaining of the crystals with low concentration of defects. Several defects, such as dislocations, low-angle grain boundaries, are usually generated even in the undoped material during crystal growth process [3,8]. The defects can significantly decrease the efficiency of the laser elements.…”

Conventional and Synchrotron X-Ray Topography of Defects in the Core Region of SrLaGaO4

“…1a). The same result was observed for another samples studied earlier [8][9][10][11][12][13][14][15]. In the outer part of these crystals a lot of linear black diffraction contrasts and volume defects contrasts of irregular shapes were observed.…”

“…The results of our previous studies concerning SLG crystals were shown in Refs. [8][9][10][11][12][13][14][15].…”