The crystal growth of ortho- and pyrosilicates from W and Mo crucibles

Abstract

The expensive Ir-consuming growth technology is the main obstacle at widening the area of ortho- and pyrosilicate crystal applications. Possibilities for growing silicate single crystals from melt using Mo or W crucibles in crystallizers with graphite heaters are evaluated. Such feasibility is shown in the examples of Y₂SiO₅:Ce (YSO:Ce) and La_2−xGd_xSi₂O₇:Ce (LaGPS:Ce) scintillation crystals. Application of the edge-defined film-fed growth (EFG) method for silicate growth is limited owing to non-stoichiometry because of the interaction of the CO-containing atmosphere with the melt and crystals. The bulk YSO:Ce and LaGPS:Ce crystals are grown by the Bridgman and Czochralski methods for the first time using much cheaper (compared to Iridium) molybdenum (Mo) or tungsten (W) crucibles. The optical and scintillation parameters of the obtained crystals are determined and compared to the counterparts grown by the conventional Czochralski process in Ir crucibles. The ways for further optimization of technological processes are discussed.