Polymorphism of Li2Zn3.

IF 1.9 3区化学

Acta Crystallographica Section B-structural Science Pub Date : 2012-02-01 Epub Date: 2012-01-18 DOI:10.1107/S0108768111053493

Volodymyr Pavlyuk, Ihor Chumak, Helmut Ehrenberg

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引用次数: 10

Abstract

Crystal structures of low- and high-temperature modifications of the binary phase Li(2)Zn(3) were determined by single-crystal X-ray diffraction techniques. The low-temperature modification is a disordered variant of Li(5)Sn(2), space group R\bar 3m (No. 166). The high-temperature modification crystallizes as an anti-type to Li(5)Ga(4), space group P\bar 3m1 (No. 164). Two polymorphs can be described as derivative structures to binary Li(5)Ga(4), Li(5)Sn(2), Li(13)Sn(5), Li(8)Pb(3), CeCd(2) and CdI(2) phases which belong to class 2 with the parent W-type in Krypyakevich's classification. All atoms in both polymorphs are coordinated by rhombic dodecahedra (coordination number CN = 14) like atoms in related structures. The Li(2)Zn(2.76) (for the low-temperature phase) and Li(2)Zn(2.82) (for the high-temperature phase) compositions were obtained after structure refinements. According to electronic structure calculations using the tight-binding-linear muffin-tin orbital-atomic spheres approximations (TB-LMTO-ASA) method, strong covalent Sn-Sn and Ga-Ga interactions were established in Li(5)Sn(2) and Li(5)Ga(4), but no similar Zn-Zn interactions were observed in Li(2)Zn(3).

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Li2Zn3的多态性。

采用单晶x射线衍射技术测定了Li(2)Zn(3)二元相低温和高温改性后的晶体结构。低温改性是空间群R\bar 3m (No. 166) Li(5)Sn(2)的无序变体。高温改性结晶为Li(5)Ga(4)的反型，空间群P\bar 3m1 (No. 164)。在Krypyakevich分类中，这两种晶型可以描述为二元Li(5)Ga(4)、Li(5)Sn(2)、Li(13)Sn(5)、Li(8)Pb(3)、CeCd(2)和CdI(2)相的衍生物结构，属于2类，母相为w型。两种多晶态的所有原子均由相关结构中的菱形十二面体(配位数CN = 14)类原子配位。经过结构细化，得到低温相Li(2)Zn(2.76)和高温相Li(2)Zn(2.82)成分。利用紧密结合-线性松松-锡轨道-原子球近似(TB-LMTO-ASA)方法进行电子结构计算，发现Li(5)Sn(2)和Li(5)Ga(4)中存在较强的共价Sn-Sn和Ga-Ga相互作用，而Li(2)Zn(3)中没有发现类似的Zn-Zn相互作用。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Acta Crystallographica Section B-structural Science 化学-晶体学

自引率

5.30%

发文量

审稿时长

6-12 weeks

期刊介绍： Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials publishes scientific articles related to the structural science of compounds and materials in the widest sense. Knowledge of the arrangements of atoms, including their temporal variations and dependencies on temperature and pressure, is often the key to understanding physical and chemical phenomena and is crucial for the design of new materials and supramolecular devices. Acta Crystallographica B is the forum for the publication of such contributions. Scientific developments based on experimental studies as well as those based on theoretical approaches, including crystal-structure prediction, structure-property relations and the use of databases of crystal structures, are published.