Crystal Structure of La4Si2O7N2 Analyzed by the Rietveld Method Using the Time-of-Flight Neutron Powder Diffraction Data

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• 作者：Junichi Takahashi ; Hisanori Yamane ; Naoto Hirosaki ; Yoshinobu Yamamoto ; Takayuki Suehiro ; Takashi Kamiyama ; and Masahiko Shimada
• 刊名：Chemistry of Materials
• 出版年：2003
• 出版时间：March 11, 2003
• 年：2003
• 卷：15
• 期：5
• 页码：1099 - 1104
• 全文大小：179K
• 年卷期：v.15,no.5(March 11, 2003)
• ISSN：1520-5002

文摘

The polycrystalline single-phase sample of La₄Si₂O₇N₂ was prepared at 1773 and 1873 Kby the gas-pressured sintering method. The structure refinement was carried out by theRietveld method using time-of-flight neutron powder diffraction data measured at 297 K.La₄Si₂O₇N₂ is isostructural with the Y₄Al₂O₉ high-temperature phase and crystallizes in amonoclinic cell, P2₁/c (No. 14-1), Z = 4. The lattice parameters refined for the sample preparedat 1773 K were a = 8.0375(2) Å, b = 10.9900(2) Å, c = 11.1115(2) Å, and = 110.9214(14).Nitrogen atoms statistically occupy the bridging site and the terminal sites of Si₂O₅N₂ditetrahedra in the La₄Si₂O₇N₂ structure. The nonmetal sites surrounded by La atoms onlyare fully occupied by oxygen atoms.