A STUDY ON MAGNESIUM DIFFUSION INTO LINBO3 SINGLE-CRYSTAL BY X-RAY-DIFFRACTION, DIFFERENTIAL THERMAL-ANALYSIS, AND SCANNING ELECTRON-MICROSCOPY

The diffusion of magnesium into lithium niobate single crystal under d ifferent diffusion conditions has been studied by x-ray diffraction, g lancing-incidence x-ray diffraction, differential thermal analysis, an d scanning electron microscopy in an attempt to determine the diffusio n mechanism and evaluate the crystallinity of the diffused layer, It i s found that the magnesium diffused layer exhibits the crystal structu re of an unknown compound from the Mg-Li-Nb-O ternary system and MgNb2 O6, The MgNb2O6 is in the surface layer of the magnesium diffused laye r, while the unknown compound is in the subsurface layer beneath the M gNb2O6. It is proposed that this unknown compound and MgNb2O6 which fo rm during a solid state reaction between a thin layer of MgO and a lit hium niobate crystal in a Li2O-rich atmosphere are the real sources fo r Mg ion indiffusion into lithium niobate crystal, The changes in Curi e temperature with diffusion parameters are noted, Reasons of lattice distortion and mechanisms of Mg ion indiffusion are discussed and anal yzed.