钙钛矿型[C(NH2)3]CuxCd1-x(HCOO)3 金属有机框架中多极和轨道有序的控制。
Control of Multipolar and Orbital Order in Perovskite-like [C(NH2)3]CuxCd1-x(HCOO)3 Metal-Organic Frameworks.
机构信息
Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QR, U.K.
Laboratory of Crystallography, University of Bayreuth , D-95440 Bayreuth, Germany.
出版信息
J Am Chem Soc. 2016 Aug 3;138(30):9393-6. doi: 10.1021/jacs.6b05208. Epub 2016 Jul 22.
We study the compositional dependence of molecular orientation (multipolar) and orbital (quadrupolar) order in the perovskite-like metal-organic frameworks [C(NH2)3]CuxCd1-x(HCOO)3. Upon increasing the fraction x of Jahn-Teller-active Cu(2+), we observe an orbital disorder/order transition and a multipolar reorientation transition, each occurring at distinct critical compositions xo = 0.45(5) and xm = 0.55(5). We attribute these transitions to a combination of size, charge distribution, and percolation effects. Our results establish the accessibility in formate perovskites of novel structural degrees of freedom beyond the familiar dipolar terms responsible for (anti)ferroelectric order. We discuss the implications of cooperative quadrupolar and multipolar states for the design of relaxor-like hybrid perovskites.
我们研究了钙钛矿型金属-有机骨架[C(NH2)3]CuxCd1-x(HCOO)3中分子取向（多极）和轨道（四极）有序的组成依赖性。随着 Jahn-Teller 活性 Cu(2+)分数 x 的增加，我们观察到轨道无序/有序转变和多极重取向转变，每个转变都发生在不同的临界组成 xo = 0.45(5) 和 xm = 0.55(5)。我们将这些转变归因于大小、电荷分布和渗流效应的组合。我们的结果表明，在甲酸盐钙钛矿中，除了负责（反）铁电有序的熟悉偶极子项之外，还存在新的结构自由度。我们讨论了协同四极和多极态对设计弛豫体类似的混合钙钛矿的影响。
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