Pressure-Induced Amorphization and Phase Transformations in -LiAlSiO4

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• 作者：Jianzhong Zhang ; Yusheng Zhao ; Hongwu Xu ; Matthew V. Zelinskas ; Liping Wang ; Yanbin Wang ; and Takeyuki Uchida
• 刊名：Chemistry of Materials
• 出版年：2005
• 出版时间：May 31, 2005
• 年：2005
• 卷：17
• 期：11
• 页码：2817 - 2824
• 全文大小：208K
• 年卷期：v.17,no.11(May 31, 2005)
• ISSN：1520-5002

文摘

his work presents a comprehensive study on pressure-induced amorphization (PIA) in -eucryptite(LiAlSiO₄) and on the equilibrium states of so-formed amorphous phase at elevated temperatures. Ourresults revealed that at 300 K -LiAlSiO₄ underwent progressive amorphization at pressures above 4.5GPa and became completely amorphous above 17.0 GPa. After release of pressure, -LiAlSiO₄ that waspartially amorphized at 7.5, 14.0, and 16.0 GPa reverted back to its original crystalline state. Whensubjected to a complete loss of long-range structural order, the system was recovered as an amorphousstate and did not retain the so-called structural memory. Upon heating at high pressures, the partially orcompletely amorphous -LiAlSiO₄ transformed into various crystalline phases at temperatures above973 K: between 6.9 and 10.7 GPa it was decomposed into a mixture of LiAlSi₂O₆ and LiAlO₂; at 15.3GPa the two phases recombined to form a new phase with a spinel structure; and at 22 GPa the spinelphase of LiAlSiO₄ was decomposed into its constituent oxides. The observed transformations are all ofa reconstructive type and also involve profound changes in atomic coordination environments. A largeactivation energy barrier associated with coordination changes and a hindrance of atomic mobility atkinetically low temperatures are the primary factors that trigger the PIA.