التفاصيل البيبلوغرافية
| العنوان: |
Phase Transformations upon Formation of Transparent Lithium Alumosilicate Glass-Ceramics Nucleated by Yttrium Niobates. |
| المؤلفون: |
Dymshits, Olga, Bachina, Anastasia, Alekseeva, Irina, Golubkov, Valery, Tsenter, Marina, Zapalova, Svetlana, Bogdanov, Kirill, Danilovich, Dmitry, Zhilin, Alexander |
| المصدر: |
Ceramics (2571-6131); Sep2023, Vol. 6 Issue 3, p1490-1507, 18p |
| مصطلحات موضوعية: |
GLASS-ceramics, LITHIUM silicates, PHASE transitions, YTTRIUM, NIOBATES, NIOBIUM oxide, LITHIUM |
| مستخلص: |
Phase transformations in the lithium aluminosilicate glass nucleated by a mixture of yttrium and niobium oxides and doped with cobalt ions were studied for the development of multifunctional transparent glass-ceramics. Initial glass and glass-ceramics obtained by isothermal heat-treatments at 700–900 °C contain YNbO4 nanocrystals with the distorted tetragonal structure. In samples heated at 1000 °C and above, the monoclinic features are observed. High-temperature X-ray diffraction technique clarifies the mechanism of the monoclinic yttrium orthoniobate formation, which occurs not upon high-temperature heat-treatments above 900 °C but at cooling the glass-ceramics after such heat-treatments, when YNbO4 nanocrystals with tetragonal structure undergo the second-order transformation at ~550 °C. Lithium aluminosilicate solid solutions (ss) with β-quartz structure are the main crystalline phase of glass-ceramics prepared in the temperature range of 800–1000 °C. These structural transformations are confirmed by Raman spectroscopy and illustrated by SEM study. The absorption spectrum of the material changes only with crystallization of the β-quartz ss due to entering the Co2+ ions into this phase mainly in octahedral coordination, substituting for Li+ ions. At the crystallization temperature of 1000 °C, the Co2+ coordination in the β-quartz solid solutions changes to tetrahedral one. Transparent glass-ceramics have a thermal expansion coefficient of about 10 × 10−7 K−1. [ABSTRACT FROM AUTHOR] |
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| قاعدة البيانات: |
Complementary Index |