Аннотация:Crystals of rare-earth aluminum borates RAl3(BO3)4 (RAB, R = Y or lanthanide) belong to the structural type of carbonate mineral huntite CaMg3(CO3)4, and they are the subjects of extensive studies due to their promising nonlinear optical and laser properties. Their ten representatives with R = Y, Nd, Eu, Gd-Er, Yb were discovered by A. Ballman a half of century ago. RAB single crystals characterize by good chemical, mechanical, thermal properties, and wide isomorphic substitutions in R-positions of their crystal structure. Among them, LuAl3(BO3)4 (LuAB) crystals were also considered as a host matrix with Yb3+ and Er3+ dopants.
LuAB and (Er,Yb):LuAB single crystals were grown by solution growth on dipped seeds (SGDS) method using 250 ml platinum crucibles. For saturation temperature testing, mainly two types of LuAl3(BO3)4 seeds were used: 1) small "point" seeds, measuring 0.2x0.2x0.4 mm to 0.5x0.5x1.5 mm, and 2) "bulk" ones (2-3 mm in diameter). The crystals obtained were investigated using an Xcalibur SCCD single crystal diffractometer. Quantitative electron microprobe analysis (EMPA) of polishing LuAB and (Er,Yb):LuAB crystals was performed within an accuracy of 0.01-0.1 wt.% at Kα-Lα-Mα lines by means a Cameca Camebax SX-50 analyzer.
It was found that LuAB phase crystallizes from molybdate complex system in the temperature range of 1130-900oC when its concentration varies from 20 to 45 wt.% in the initial LuAl3(BO3)4-(K2Mo3O10-Al2O3-B2O3) mixture. The data obtained were presented graphically as their projection onto the cross-section at 900°C of a temperature-composition diagram. As a result, and (Er,Yb):LuAB single crystals with size up to 10x10x10 mm were grown by SGDS method and characterized by EMPA, DTA and XRD techniques. The growth of these crystals with sufficient sizes remains a comparatively long-duration procedure so far