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首页> 外文期刊>Acta Crystallographica, Section B. Structural Science >A re-investigation of the crystal structure of the perovskite PbZrO3 by X-ray and neutron diffraction
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A re-investigation of the crystal structure of the perovskite PbZrO3 by X-ray and neutron diffraction

机译：X射线和中子衍射对钙钛矿PbZrO3晶体结构的重新研究

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摘要

The crystal structure of the perovskite lead zirconate PbZrO3 has been redetermined using single-crystal X-ray diffraction (MoK alpha radiation, lambda = 0.71069 Angstrom). Single-crystal data at 100 K: space group Pbam, a = 5.884 (1), b = 11.787 (3), c = 8.231 (2) Angstrom, V = 570.85 Angstrom(3) With Z = 8, mu = 612.6 cm(-1), D-x = 8.06 Mg m(-3), F(000) = 1168, final R = 0.033, wR = 0.061 over 555 reflections with I > 2 sigma(I). An investigation is made into previous contradicting reports of a possible disorder in the oxygens and their origin by examining the crystal pseudo-symmetry. Information distinguishing an ordered and disordered oxygen substructure is shown to reside in weak l odd reflections. Because of their extremely low intensities these reflections have not contributed sufficiently in previous X-ray structure investigations and hence, to date, conclusive evidence differentiating between ordered and disordered models has not been possible. By collecting single-crystal X-ray data at low temperature and by using exceptionally long scans on selected hkl, I odd, reflections, a new accurate structure determination is presented and discussed, showing the true ordered oxygen positions. Because of the large difference in scattering factors between lead and oxygen when using X-rays, a neutron diffraction Rietveld refinement using polycrystalline samples (D1A instrument, ILL, lambda = 1.90788 Angstrom) is also reported as further evidence to support the true ordered oxygen structure revealed by the low-temperature X-ray analysis.
机译：钙钛矿锆酸铅锆PbZrO3的晶体结构已通过单晶X射线衍射（MoKα射线，λ= 0.71069埃）重新确定。 100 K时的单晶数据：空间群Pbam，a = 5.884（1），b = 11.787（3），c = 8.231（2）埃，V = 570.85埃（3）Z = 8时，mu = 612.6 cm （-1），Dx = 8.06 Mg m（-3），F（000）= 1168，最终R = 0.033，在I> 2 sigma（I）的555次反射中wR = 0.061。通过检查晶体的伪对称性，对以前相互矛盾的关于氧及其来源可能无序的报道进行了调查。区分有序和无序的氧亚结构的信息显示为存在弱的奇数反射。由于它们的强度极低，因此这些反射在以前的X射线结构研究中没有做出足够的贡献，因此，迄今为止，尚不可能区分有序和无序模型的确凿证据。通过收集低温下的单晶X射线数据并通过对选定的hkl（奇数）反射进行异常长的扫描，提出并讨论了一种新的准确的结构确定方法，显示了真正的有序氧位置。由于使用X射线时铅和氧之间的散射因子差异很大，因此还报道了使用多晶样品（D1A仪器，ILL，λ= 1.90788埃）进行中子衍射Rietveld精炼，作为支持真正有序氧结构的证据通过低温X射线分析发现。

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