Crystal Structure And Properties Of Compounds And Phase Relations In The Li₂O-In₂O₃-MO_x（M=Ca, B） Systems

In order to search for new optical-functional materials or Li ion battery materials, the system of Li2O-In2O3-MOx (M=Ca, B) have been investigated by solid state reaction, structure determination and the testing of physical properties.Phase equilibrium of the Li2O-In2O3-B2O3pseudo-ternary system at700℃has been determined using powder X-ray diffraction (XRD) method. Li3In1-xEuxB2O6, Li3In1-xTbxB2O6and Li3Sc1-xEuxB2O6(x=0.02,0.04,0.06,0.08,0.10,0.12,0.14) phosphors were synthesized through conventional solid-state reaction. Their luminescence properties were studied for the first time. The present work suggests that the novel Li3InB2O6: Eu3+/Tb3+and Li3ScB2O6:Eu3+are potential red and green phosphors for white light-emitting diodes. It is exciting that the undoped LSBO is the first red-emitting intrinsic-scintillating material up to now.Phase equilibrium of the Li2O-CaO-In2O3pseudo-ternary system at1000℃has been determined using powder X-ray diffraction (XRD) method. xCaO(1-x)/2Li1+yIn1-y028(0<x<1,0<y<0.2) forms a solid solution area with three distinct structures (S.G. I41/m, R3m and Fm3m). As Ca2+ions substituted into the Li+or In3+sites, phase transformation occurred. Increasing Ca contents (x) led to a change in the crystal structure from tetragonal (x=0) to cubic (0.06) to trigonal (x=0.1) and finally to cubic (x=0.45). The boundaries were determined by several different methods such as phase disappearing, the lever rule, and the Vigard’s law.The results indicated that the trigonal solid solution S2is isostructural to LiMO2(M=Co, Ni, Mn) which have been extensively used as cathode materials for lithium ion batteries. Therefore, S2may be a promising electrode material for Li ion batteries. According to the extent of cationic disorder obtained from the value of I(003]/I(104), it will be suitable to synthesize the S2in the region of Li-rich for the application of Li ion battery.