No abstract

The X-ray luminescence spectra of doped lithium tetraborate have been analyzed on the basis of accounting the set of spectral transitions for different atomic charge states. It has been shown that the X-ray luminescence peculiarities are to a great extent due to the transitions between the energy levels of dopant atoms and ions, as well as to the levels, which form the lithium tetraborate matrix.

No abstract

Li 2 B 4 O 7 (LTB) single crystals are grown from stoichiometric and B 2 O 3 -enriched (1.6 and 2.4 mol %) melts. At large B 2 O 3 excesses, the thermoluminescence intensity in the crystals is markedly higher, attesting to an increased density of structural defects. LTB crystals grown from B 2 O 3 -enriched melts may contain zones enriched in two types of defects. Defects of one type result from the breaking of bonds involving bridging oxygens, without significant changes in the position of neighboring atoms. Defects of the other type appear at large B 2 O 3 excesses in the melt, which enable more significant changes in the structure of the boronoxygen framework, leading to the formation of nanoscale regions differing in composition from LTB. The present results may be helpful in assessing the quality of LTB single crystals and in optimizing the crystal growth of LTB.