Oxynitride Perovskites: Synthesis and Structures of LaZrO2N, NdTiO2N, and LaTiO2N and Comparison with Oxide Perovskites
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- 作者：Simon J. Clarke ; Benjamin P. Guinot ; Charles W. Michie ; Mathieu J. C. Calmont ; and Matthew J. Rosseinsky
- 刊名：Chemistry of Materials
- 出版年：2002
- 出版时间：January 2002
- 年：2002
- 卷：14
- 期：1
- 页码：288 - 294
- 全文大小：122K
- 年卷期：v.14,no.1(January 2002)
- ISSN：1520-5002
文摘
A new oxynitride, LaZrO2N, has been synthesized by the reaction of a highly reactiveX-ray amorphous La2Zr2O7 precursor with flowing ammonia at between 900 and 1000 
C.The white insulating material crystallizes in the GdFeO3 distorted perovskite structure typewith orthorhombic space group Pnma and with a = 5.875 25(5) Å, b = 8.250 31(7) Å, c =5.810 08(5) Å, and Z = 4, as determined by neutron powder diffraction. A detailed structuralanalysis of the isostructural NdTiO2N is also reported: Pnma, a = 5.5492(1) Å, b = 7.8017(1) Å, c = 5.529 01(9) Å, and Z = 4. LaTiO2N crystallizes in a different distorted perovskitestructure, which is triclinic, and consequently has two distinct Ti(O4N2) octahedra(LaTiO2N: I
, a = 5.6097(1) Å, b = 7.8719(2) Å, c = 5.5752(1) Å, 
= 90.199(2), 
= 90.154(3), 
= 89.988(8), Z = 4). Oxide and nitride ions are completely disordered in all threephases. The M(O,N)6 octahedra (M = Ti, Zr) in these phases and a number of perovskitetitanates and zirconates become more regular as the tilting distortion of the octahedralframework becomes more pronounced, as a result of quenching of the second-order Jahn-Teller distortion of the octahedra.
C.The white insulating material crystallizes in the GdFeO3 distorted perovskite structure typewith orthorhombic space group Pnma and with a = 5.875 25(5) Å, b = 8.250 31(7) Å, c =5.810 08(5) Å, and Z = 4, as determined by neutron powder diffraction. A detailed structuralanalysis of the isostructural NdTiO2N is also reported: Pnma, a = 5.5492(1) Å, b = 7.8017(1) Å, c = 5.529 01(9) Å, and Z = 4. LaTiO2N crystallizes in a different distorted perovskitestructure, which is triclinic, and consequently has two distinct Ti(O4N2) octahedra(LaTiO2N: I, a = 5.6097(1) Å, b = 7.8719(2) Å, c = 5.5752(1) Å, = 90.199(2), = 90.154(3), = 89.988(8), Z = 4). Oxide and nitride ions are completely disordered in all threephases. The M(O,N)6 octahedra (M = Ti, Zr) in these phases and a number of perovskitetitanates and zirconates become more regular as the tilting distortion of the octahedralframework becomes more pronounced, as a result of quenching of the second-order Jahn-Teller distortion of the octahedra.