Glasses and their crystallization in the (1 − х)KNbOb>3b>·хSiOb>2b> system at low glass-forming oxide contents, 0  х  0.35

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• 作者：V.N. Sigaev ; V.S. Ryzhenkov ; S.V. Lotarev ; N.V. Golubev ; S. Yu. Stefanovich ; Akira Okada
• 关键词：Glass formation ; Glass transition ; Oxide glasses ; Alkali silicates ; Special glasses and materials ; Molten salts
• 刊名：Journal of Non-Crystalline Solids
• 出版年：2010
• 出版时间：1 May 2010
• 年：2010
• 卷：356
• 期：20-22
• 页码：958-965
• 全文大小：803 K

文摘

Glasses based on the Kb>2b>O–Nbb>2b>Ob>5b>–SiOb>2b> system have been a subject of numerous studies thanks to promising electro-optical and non-linear optical properties. Most of the studies of Nb-containing glasses deal with compositions including not less than 40 mol % of SiOb>2b> or Bb>2b>Ob>3b>. In the present work, we studied glass-forming and crystallization properties of (1 − х)KNbOb>3b>·xSiOb>2b> glasses with x varying from 0 to 35 mol % by melt quenching between steel plates or by exposure to air or nitrogen flow. Thin transparent glassy plates can be obtained by quenching via pressing between metal plates for glasses with x  0.12, and transparent glass-ceramics allowing a remarkable second harmonic generation (SHG) response can be formed by heat-treatment near the first exothermic differential thermal analysis (DTA) peak over a wide range of glass compositions. It is shown that in these glasses, the crystalline Kb>4b>Nbb>6b>Ob>17b> phase and a small amount of ferroelectric KNbOb>3b>, along with ceolite-like, cristobalite and b1;-quartz SiOb>2b> phases precipitate at low temperatures in the range between the glass transition point, Tb>gb>, and the first exothermic peak on DTA curve, whereas ferroelectric KNbOb>3b> precipitates at temperatures above 800 °C. Ferroelectric crystals which precipitate in the glass bulk are shown to produce high SHG activity.