The infrared absorption spectra of LaBO3, InBO3, and ScBO3have been observed as crystalline powders in the wavelength range from 7 to 20 microns. The borates had a B10/B11ratio varying from the natural abundance (18/82) up to about 96/4. The four fundamental frequencies for B10fell within the ranges, ohgr;1= 939, ohgr;2= 740ndash;790, ohgr;3= 1265ndash;1330, ohgr;4= 606ndash;675, all in cmmdash;1. The totally symmetric frequency, ohgr;1is observed only in LaBO3, which has less than threefold site symmetry, unlike the other two salts.The GVF force constants have been calculated and are compared with those of BF3. A very strong specific coupling of the outhyphen;ofhyphen;plane bending mode (ohgr;2) is observed in LaBO3, but the fine structure is not well resolved, and only a rough estimate of the coupling constant and dipole derivative can be made.
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