Genetic Analysis of the Accompanying of (Lu,Y)_3Al_5O_(12):Ce in Lu_xY_(1-x)AlO_3:Ce Single Crystals

Lu_xY_(1-x)AlO_3:Ce single crystal samples were prepared by the Czochralski method.Based on X-ray diffraction (XRD) and composition analyses,and analysis of phase diagram of Lu_2O_3-Al_2O_3 and the structural stability of Lu_xY_(1-x)AlO_3:Ce,it is supposed that as the content of Lu increase,the melt delamination is exacerbated,and the crystallization interval of Lu_xY_(1-x)AlO_3:Ce in the phase di- agram may shift towards the interval rich in Lu,resulting in the accompaniment of (Lu,Y)_3Al_5O_(12):Ce on the top of Lu_xY_(1-x)AlO_3:Ce single crystals.With the increase of the content of Lu,the thermal stability of Lu_xY_(1-x)AlO_3:Ce single crystals decreases,the oxygen vacancy in those crystals furthers the decrease,so the seed surface tends to decompose into (Lu,Y)_3Al_5O_(12):Ce and (Lu,Y)_4Al_2O_9:Ce while seeding,and the former decomposition product provides the crystal nucleus to induce crys- tallization of (Lu,Y)_3Al_5O_(12):Ce,resulting in the accompaniment of (Lu,Y)_3Al_5O_(12):Ce on the coat of Lu_xY_(1-x)AlO_3:Ce single crystals.An adjustment of the melt composition to make the tool ratio n((Lu,Y)_2O_3):n(Al_2O_3) equal to 1.17-1.00,and a greater temperature gradient inside the melt and at the solid liquid interface to improve melt convection,restrain melt delamination and the decomposition on the seed surface may contribute to the acquisition of Lu_xY_(1-x)AlO_3:Ce with high Lu content.