Line-focus-beam acoustic microscopy detection of variations of growing conditions of LiTaO3 crystals

Line:focus-beam (LFB) acoustic microscopy is applied to evaluate the homoge neities of optical-grade LiTaO3 single crystals, pulled along the crystallo graphic Y axis. Z-cut substrates prepared from three kinds of single crysta ls with different chemical compositions of 48.0, 48.5, and 49.0 Li2O-mol% a s the starting materials, and one commercially available optical-grade cong ruent LiTaO3 single crystal, are examined by measuring the leaky surface ac oustic wave (LSAW) velocities along the Y axis. Using the relationship betw een the LSAW velocities and chemical compositions obtained from the three c rystals, some significant and characteristic velocity variations of 0.54 m/ s along the pulling-axis direction and of at most 0.38 m/s along the diamet er direction were observed on the congruent specimen surface, corresponding to the chemical composition changes of 0.017 and 0.012 Li2O-mol%, respecti vely This is the first evidence to signify that the variations are in essen ce due to changes of the crystal growing conditions during the growth proce ss.