Реферат: Holmium polysulfide crystals were grown from the solution in KI melt at variable PS –T conditions in the range of 690-750 °C and (10, 15.8, 16.8)·105 Pa. The crystals of every batch showed a diversity of forms. Two crystals of different habitus were selected from one batch and characterized using single-crystal X-ray diffraction as HoS1.885(5), P4/nmm, a=3.820(1), c=7.840(3) Å, d=6.542 g/cm3 (I), and HoS1.863(8), P21/m, a=10.961(2), b=11.465(2), c=10.984(2) Å, beta=91.27(3)°, d=6.486 g/cm3 (II). Raman spectra of crystals I and II demonstrated the same local symmetry, P21/m, but the difference of the characteristic band forms explained the distinction in total crystal structures. Five crystals of different habiti were found to be isostructural to the crystal II and had composition HoS1.837(3). The influence of growth conditions on crystal shape was shown. The data of gross chemical analysis together with density measurements of individual crystals allowed to estimate maximum content of the tetragonal phase in crystals of all batches as 40 mass.%. Powders of holmium polysulfide were prepared at different PS –T conditions in the range of 600-820 °C and (2.1, 6.5, 16.8)·105 Pa. The content of this phase, less than 10 mass.% was established by use of powder diffraction method for crystals from every batch as well as for powder samples. The study of the phase equilibrium in the system HoS1.5 – HoS2 showed the presence of only one stable phase of composition HoS1.84. The nature of the tetragonal phase HoS1.885 is discussed. HoS1.84 crystals are transparent in the 0.65 to 25 mcm spectral range, the bands within the range are related to electronic transitions in Ho+3. The optical Eg values estimated for 20 mcm plate from the absorbance spectra are 2.2 eV (80 K) and 2.1 eV (300 K). Magnetic susceptibility measurement at temperatures from 0 to 300 K showed HoS1.84 to be paramagnetic with antiferromagnetic interaction between metal ions below 50 K, with C=13.05 K, Theta = - 4.5 K and mueff = 10.22 muB at mucalc = 10.5 muB.

Библиографическая ссылка: Belaya S.V. , Vasilyeva I.G.
HOLMIUM POLYSULFIDES: CRYSTAL GROWTH, CRYSTAL STRUCTURE, COMPOSITION, PROPERTIES AND APPLICATION PERSPECTIVE
В сборнике Advances in Chemistry Research. – Nova Science Publishers, Inc.., 2011. – Т.6. – C.155-184. – ISBN 978-1-61728-982-8.

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