反铁电钛矿CaTiSiO5中共存的位移和有序无序晶格不稳定性。

IF 4.7 2区化学 Q1 CHEMISTRY, INORGANIC & NUCLEAR

Inorganic Chemistry Pub Date : 2025-10-02 DOI:10.1021/acs.inorgchem.5c02798

Akitoshi Nakano,Toshiya Uohashi,Ayako Taguchi,Hiroki Moriwake,Hiroki Taniguchi

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引用次数: 0

摘要

我们利用密度泛函理论（DFT）和温度相关同步加速器x射线衍射（XRD）相结合的方法研究了钛矿型化合物CaTiSiO5的相变机制。声子计算在布里渊区Γ和Y点处都发现了软模式，表明该系统接近铁电和AFE不稳定性。各向异性扩散散射揭示了沿c轴原子位移的强一维相关性。Ti和Ca的各向异性原子位移参数（ADPs）表现出不同的温度演化特征：Ti表现出与位移转变一致的发散行为，而Ca表现出有序-无序转变的阶梯变化特征。这些发现强调了CaTiSiO5中位移不稳定性和无序不稳定性的共存，并通过钛矿型化合物的晶格模式工程为功能反铁电体的设计提供了新的见解。

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Coexisting Displacive and Order-Disorder Lattice Instabilities in the Antiferroelectric Titanite CaTiSiO5.

We investigate the phase transition mechanism in the titanite-type compound CaTiSiO5, a promising antiferroelectric (AFE) candidate, using a combination of density functional theory (DFT) and temperature-dependent synchrotron X-ray diffraction (XRD). Phonon calculations identify soft-modes at both the Γ and Y points of the Brillouin zone, indicating that the system is close to both ferroelectric and AFE instabilities. Anisotropic diffuse scattering reveals strong one-dimensional (1D) correlation of atomic displacement along the c-axis. Anisotropic atomic displacement parameters (ADPs) of Ti and Ca exhibit contrasting temperature evolutions: Ti shows divergent behavior consistent with a displacive transition, whereas Ca exhibits step-like changes characteristic of an order-disorder transition. These findings highlight the coexistence of displacive and disorder-type instabilities in CaTiSiO5 and offer new insight into the design of functional antiferroelectrics via lattice-mode engineering in titanite-type compounds.

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来源期刊

Inorganic Chemistry 化学-无机化学与核化学

CiteScore

7.60

自引率

13.00%

发文量

1960

审稿时长

1.9 months

期刊介绍： Inorganic Chemistry publishes fundamental studies in all phases of inorganic chemistry. Coverage includes experimental and theoretical reports on quantitative studies of structure and thermodynamics, kinetics, mechanisms of inorganic reactions, bioinorganic chemistry, and relevant aspects of organometallic chemistry, solid-state phenomena, and chemical bonding theory. Emphasis is placed on the synthesis, structure, thermodynamics, reactivity, spectroscopy, and bonding properties of significant new and known compounds.