M3鈭?i>x(NH4)xCrO8 (M = Na, K, Rb, Cs): A New Family of Cr5+-Based Magnetic Ferroelectrics

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• 作者：Raghabendra Samantaray ; Ronald J. Clark ; Eun S. Choi ; Haidong Zhou ; Naresh S. Dalal
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：March 23, 2011
• 年：2011
• 卷：133
• 期：11
• 页码：3792-3795
• 全文大小：792K
• 年卷期：v.133,no.11(March 23, 2011)
• ISSN：1520-5126

文摘

Upon consideration of the hydrogen-bonding properties of the NH₄⁺ cation, we synthesized a new class of compounds, M_3鈭?i>x(NH₄)_xCrO₈ (M = Na, K, Rb, Cs). These magnetic compounds with the simple 3d¹ ground state become ferroelectric. X-ray studies confirmed that the phase transition involves a symmetry change from I4̅2m to Cmc2₁ to P1. The transition temperature depends linearly on the composition variable x. The transitions are of the order鈭抎isorder type, with N鈭扝路路路O bonding playing the central role in the mechanism. Extension of this idea to the introduction of ferroelectricity in several other classes of materials is suggested.