A Pressure‐Induced Inverse Order–Disorder Transition in Double Perovskites

Deng, Zheng; Kang, Chang‐Jong; Croft, Mark; Li, Wenmin; Shen, Xi; Zhao, Jianfa; Yu, Rici; Chen, Jin; Kotliar, G.; Liu, Sizhan; Tyson, Trevor; Tappero, Ryan; Greenblatt, Martha

doi:10.1002/ange.202001922

Cited by 4 publications

(2 citation statements)

References 45 publications

(117 reference statements)

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“…High pressure experiments were performed with the cubic anvil type high pressure apparatus 34,35 . After the pressure was gradually increased to 6 GPa, the sample was heated to 1273 K and maintained for 30 min.…”

Section: Discussionmentioning

confidence: 99%

A Combinatory Ferroelectric Compound Bridging Simple ABO3 and A-site-Ordered Qudruple Perovskite

Zhao

Gao²,

et al. 2020

Preprint

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The simple ABO3 and A-site-ordered AA′3B4O12 perovskites represent two types of the most classical perovskite-based functional materials. While there are well-known simple perovskites with ferroelectric properties, so far there is no report of ferrolectricity due to symmetry breaking transition in A-site-ordered quadruple perovskites, AA′3B4O12. Here we report the synthesis at high pressure and temperature of a new A-site-ordered perovskite, PbHg3Ti4O12. Remarkably, PbHg3Ti4O12 is the only known quadruple perovskite that transforms from a high-temperature centrosymmetric (Im-3), paraelectric phase to a low-temperature, non-centrosymmetric (Imm2) ferroelectric phase. Moreover, the average ionic radius of A-site cations for PbHg3Ti4O12 is large~ 1.1 Å and the tolerance factor t is about 0.88. Surprisingly the coordination chemistry of Hg2+ is changed from the usual square planar as in typical A-site-ordered quadruple perovskite to a rare stereo type with 8 ligands in PbHg3Ti4O12 driven via pressures. Thus PbHg3Ti4O12 appears to be a combinatory link from simple ATiO3 perovskite to AA′3B4O12 type A-site-ordered perovskites, sharing both displacive ferroelectricity with the former and the structure coordination with the latter. This is the first example of ferroelectricity due to a symmetry breaking phase transition in AA′3B4O12-type A-site-ordered perovskite, and opens a new direction to search for ferroelectric materials in combinatory perovskites.

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Section: Discussionmentioning

confidence: 99%

A Combinatory Ferroelectric Compound Bridging Simple ABO3 and A-site-Ordered Qudruple Perovskite

Zhao

Gao²,

et al. 2020

Preprint

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“…Hazen and Navrotsky (1996) analysed the influence of pressure upon order–disorder reactions and showed that, in the majority of cases, increasing pressure is associated with decreasing positional disorder, though there are exceptions to this rule (Deng et al , 2020). The ordering reactions mean that structural complexity is increasing.…”

Section: Further Directionsmentioning

confidence: 99%

Structural and chemical complexity of minerals: an update

Krivovichev

Кривовичев

Hazen

et al. 2022

MinMag

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The complexities of chemical composition and crystal structure are fundamental characteristics of minerals that have high relevance to the understanding of their stability, occurrence and evolution. This review summarises recent developments in the field of mineral complexity and outlines possible directions for its future elaboration. The database of structural and chemical complexity parameters of minerals is updated by H-correction of structures with unknown H positions and the inclusion of new data. The revised average complexity values (arithmetic means) for all minerals are 3.54(2) bits/atom and 345(10) bits/cell (based upon 4443 structure reports). The distributions of atomic information amounts, chemIG and strIG, versus the number of mineral species fit the normal modes, whereas the distributions of total complexities, chemIG,total and strIG,total, along with numbers of atoms per formula and per unit cell are log normal. The three most complex mineral species known today are ewingite, morrisonite and ilmajokite, all either discovered or structurally characterised within the last five years. The most important complexity-generating mechanisms in minerals are: (1) the presence of isolated large clusters; (2) the presence of large clusters linked together to form three-dimensional frameworks; (3) formation of complex three-dimensional modular frameworks; (4) formation of complex modular layers; (5) high hydration state in salts with complex heteropolyhedral units; and (6) formation of ordered superstructures of relatively simple structure types. The relations between symmetry and complexity are considered. The analysis of temporal dynamics of mineralogical discoveries since 1875 with the step of 25 years show the increasing chemical and structural complexities of human knowledge of the mineral kingdom in the history of mineralogy. In the Earth's history, both diversity and complexity of minerals experience dramatic increases associated with the formation of Earth's continental crust, initiation of plate tectonics and the Great Oxidation event.

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