Novel laser crystals in Ca9Y(VO4)7-x(PO4)x mixed system
| Autor: | Dmitry A. Spassky, S. Yu. Stefanovich, A. V. Mosunov, M. B. Kosmyna, B. P. Nazarenko, P.V. Mateychenko, Sergey M. Aksenov, A.N. Shekhovtsov |
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| Rok vydání: | 2017 |
| Předmět: |
Phase transition
Materials science Mechanical Engineering Metals and Alloys 02 engineering and technology Dielectric Crystal structure 010402 general chemistry 021001 nanoscience & nanotechnology Laser 01 natural sciences Ferroelectricity 0104 chemical sciences law.invention Crystallography Mixed systems Fracture toughness Mechanics of Materials law Materials Chemistry 0210 nano-technology Solid solution |
| Zdroj: | Journal of Alloys and Compounds. 708:285-293 |
| ISSN: | 0925-8388 |
| Popis: | The Ca 9 Y(VO 4 ) 7-x (PO 4 ) x (x = 0, 1, 3, 4) solid solution whitlockite-like single crystals have been grown by the Czochralski method from mixtures of single phase Ca 9 Y(VO 4 ) 7 and Ca 9 Y(PO 4 ) 7 starting materials produced by solid-state synthesis. Real compositions of solid solution crystals has been determined and analyzed. It is found that crystals with x = 0, 1, 4 exist with polar structure at room temperature, space group R 3 c . At least one of them, Ca 9 Y(VO 4 ) 7 , demonstrates ferroelectric behaviour with phase transition at 942 °C. Unlike the others, Ca 9 Y(VO 4 ) 3 (PO 4 ) 4 crystallizes in centrosymmetric whitlockite-like structure with space group R 3 ¯ c confirmed by single-crystal X-ray structure analysis. Similar to other whitlockite-family phosphates and vanadates, its crystal structure is described as a disordered structural version of usual whitlockites, corresponding to their high-temperature paraelectric phases. The transmission and luminescence spectra of solid solution crystals are reported, the hardness H v and fracture toughness K 1c of solid solution single crystals are also determined. |
| Databáze: | OpenAIRE |
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