Revised Bismuth Chloroselenite System: Evidence of a Noncentrosymmmetric Structure with a Giant Unit Cell

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• 作者：Almaz Aliev ; V. M. Kovrugin ; Marie Colmont ; Christine Terryn ; Marielle Huv茅 ; O. I. Siidra ; S. V. Krivovichev ; Olivier Mentr茅
• 刊名：Crystal Growth & Design
• 出版年：2014
• 出版时间：June 4, 2014
• 年：2014
• 卷：14
• 期：6
• 页码：3026-3034
• 全文大小：688K
• 年卷期：v.14,no.6(June 4, 2014)
• ISSN：1528-7505

文摘

The reactions between PbO, Bi₂O₃ (or BiOCl), and SeO₂ by the chemical vapor transport method using HCl as a transporting agent afforded three novel bismuth/lead chloroselenites, namely, 尾-BiSeO₃Cl (1), Bi₆(SeO₃)₄Cl₁₀ (2), and PbBi₁₀(SeO₃)₁₂Cl₈ (3). Compound 1 is noncentrosymmetric (space group Cc, SHG active) and has a giant unit cell (V = 19792(2) 脜³). In the context of the complex BiSeO₃Cl phase diagram reported by Oppermann et al., it was assigned to the undescribed 尾-form on the basis of its IR spectra and powder X-ray diffraction pattern. The comparison between the 伪-, 尾-, and 纬-forms suggests their formation via the condensation of volatile Bi(SeO₃)Cl molecules. Analysis of the structures of the 伪-, 尾-, and 纬-forms indicates that the 伪 鈫?尾 鈫?纬 phase transitions are associated with a dramatic fluctuation of structural complexity together with the transitional character of the 尾 phase. Compounds 1 and 3 are layered compounds with identical ([M₈Cl₁₆]⁸⁺ and [M₁₄(SeO₃)₂₄]^{6鈭?/sup>) layers, where M stands for Bi in 1 and Pb/Bi in 3. There are additional [Bi₁₂Cl₃₂]4+ layered subunits in 1. The crystal structure of 2 consists of the [Bi₆(SeO₃)₄Cl₁₀] building blocks forming an open framework with six-membered-ring channels. These three compounds complete the poorly known bismuth selenium oxochloride panorama.}