Line-Focus-Beam Acoustic Microscopy Detection of Variations of Growing Conditions of LiTaO_3 Crystals

概要

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Line-focus-beam (LFB) acoustic microscopy is applied to evaluate the homogeneities of optical-grade LiTaO_3 single crystals, pulled along the crystallographic Y axis. Z-cut substrates prepared from three kinds of single crystals with different chemical compositions of 48.0, 48.5, and 49.0 Li_2O-mol% as the starting materials, and one commercially available optical-grade congruent LiTaO_3 single crystal, are examined by measuring the leaky surface acoustic wave (LSAW) velocities along the Y axis. Using the relationship between the LSAW velocities and chemical compositions obtained from the three crystals, 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 diameter direction were observed on the congruent specimen surface, corresponding to the chemical composition changes of 0.017 and 0.012 Li_2O-mol%, respectively. This is the first evidence to signify that the variations are in essence due to changes of the crystal growing conditions during the growth process.
社団法人応用物理学会の論文
1999-08-15