Simple decoration of inclusion cavities within isostructural two-component organic salts

Abstract

Page s 253SHELXL97 program. Samples had significantly different colors, depending on the growth atmosphere (Ar+O 2 : yellow or orange) and post-grown treatment (Ar and vacuum: almost colorless; air: bright orange). The analysis of the color and crystal composition of La 3 (Ga x Ta 1-x ) Ga 5 O y allowed to divide their into four groups: colorless (y~14), orange (y~13.95-13.97), yellow (y~13.92-13.93), and colorless (y~13.90). These results are agreed with transmission spectroscopy («Specord-M40», wave range 11000-50000 cm -1 ): the yellow crystals with the oxygen vacancies () have the band 28500 cm -1 . The low-grade band 20800 cm -1 is present at colored crystals and absent at colorless ones (the like result has been wrote in [1]). At that the study of their chromaticity diagrams showed the different shade for the samples of the like visual color. The orange and colorless (the last group) Y54°-crystals, Y54° cut and the orange, yellow and colorless (the first group) Z-crystals, Z cut have the microhardness value ~13.8, ~12.2 GPa and ~12.6, ~10.4 and ~9.7Gpa, respectively. It was found that the temperature maximum of the yellow plate (Z-crystal, Z-cut) dielectric loss tangent has an effusive relaxation maximum in the temperature range 300-550 о С. The topography by Shultz method (reflection 50.0) of the yellow plate (Z-crystal, Z-cut) with the refined composition La 3 (Ga 0.58 Ta 0.42 )Ga 5 (O 13.92 0.08 ) shown absence of blocks. According to the rocking curves (the scheme of a doublecrystal X-ray diffractometer: Si (400) monochromator, (n, -n)) of the same sample, the half-width of the Bragg 50.0 and 40.0 peaks (value β exp ) are ~22′′ in contrast to the Z-crystalLGT, Y cut [2], in which β exp~6 ′′. So, a series of properties of LGT can be associated with the atmosphere of growth and post-grown treatment (the composition of crystals and their color), the growth and cut directions (the microhardness and structural perfection). Moreover langatate crystals are more appropriate for the high temperature applications compared with langasite ones. [1] O.A.Buzanov et al., Crystallography Reports, 52(4) 2007,691-696. [2] D.V.Roshchupkin et al.