Heamanite-(Ce), (K0.5Ce0.5)TiO3, a new perovskite supergroup mineral found in diamond from Gahcho Kué, Canada

Anzolini, Chiara; Siva-Jothy, William K.; Locock, Andrew J.; Nestola, Fabrizio; Balić-Žunić, Tonči; Alvaro, Matteo; Chinn, I.L.; Stachel, Thomas; Pearson, D. Graham

doi:10.2138/am-2022-8098

Cited by 1 publication

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“…In nature, this Si-Cr-bearing cubic perovskite is the first example of such a vacancy-bearing structure. A similar (yet different) quadruple splitting of the oxygen position was described in isolueshite, cubic NaNbO 3 (Krivovichev et al 2000;Zaitsev et al 2017), and heamanite-(Ce), (K 0.5 Ce 0.5 )TiO 3 (Anzolini et al 2022), but these structures have no oxygen deficiency. Note that that the common mechanism of heterovalent substitution in ABO 3 perovskites implies cross-compensation of charge balance between the A and B site, e.g.…”

Section: Oxygen Vacancies: a Gateway To Compositional Flexibility Of Cubic Perovskitesupporting

confidence: 55%

Natural cubic perovskite, Ca(Ti,Si,Cr)O3–δ, a versatile potential host for rock-forming and less-common elements up to Earth’s mantle pressure

Britvin

Vlasenko

Aslandukov

et al. 2022

American Mineralogist

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Perovskite, CaTiO 3 , originally described as a cubic mineral, is known to have a distorted (orthorhombic) crystal structure. We herein report on the discovery of natural cubic perovskite. This was identified in gehlenite rocks occurring in a pyrometamorphic complex of the Hatrurim Formation (the Mottled Zone), in the vicinity of the Dead Sea, Negev Desert, Israel. The mineral is associated with native α-(Fe,Ni) metal, schreibersite (Fe 3 P) and Si-rich fluorapatite. The crystals of this perovskite reach 50 μm in size and contain many micron sized inclusions of melilite glass. The mineral contains significant amounts of Si substituting for Ti (up to 9.6 wt.% SiO 2 ) corresponding to 21 mol.% of the davemaoite component (cubic perovskite-type CaSiO 3 ), in addition to up to 6.6 wt.% Cr 2 O 3 .Incorporation of trivalent elements results in the occurrence of oxygen vacancies in the crystal structure; this being the first example of natural oxygen-vacant ABO 3 perovskite with the chemical formula Ca(Ti,Si,Cr)O 3-δ (δ ~ 0.1). Stabilization of cubic symmetry (space group Pm ͞ 3m) is achieved via the mechanism not reported so far for CaTiO 3 , namely displacement of an oxygen atom from its ideal structural position (site splitting). The mineral is stable at atmospheric pressure to 1250±50 °C; above this temperature its crystals fuse with the embedded melilite glass, yielding a mixture of titanite and anorthite upon melt solidification. The mineral is stable upon compression to at least 50 GPa. The a lattice parameter exhibits continuous contraction from 3.808(1) Å at atmospheric pressure to 3.551(6) Å at 50 GPa. The second-order truncation of the Birch-Murnaghan equation of state gives the initial volume V 0 equal to 55.5(2) Å 3 and room temperature isothermal bulk modulus K 0 of 153(11) GPa. The discovery of oxygen-deficient single perovskite suggests previously unaccounted ways for incorporation of almost any element into the perovskite framework up to pressures corresponding to those of the Earth's mantle.

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Section: Oxygen Vacancies: a Gateway To Compositional Flexibility Of Cubic Perovskitesupporting

confidence: 55%

Natural cubic perovskite, Ca(Ti,Si,Cr)O3–δ, a versatile potential host for rock-forming and less-common elements up to Earth’s mantle pressure

Britvin

Vlasenko

Aslandukov

et al. 2022

American Mineralogist

Self Cite

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Heamanite-(Ce), (K0.5Ce0.5)TiO3, a new perovskite supergroup mineral found in diamond from Gahcho Kué, Canada

Abstract: This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

Cited by 1 publication

References 57 publications

Natural cubic perovskite, Ca(Ti,Si,Cr)O3–δ, a versatile potential host for rock-forming and less-common elements up to Earth’s mantle pressure

Natural cubic perovskite, Ca(Ti,Si,Cr)O3–δ, a versatile potential host for rock-forming and less-common elements up to Earth’s mantle pressure

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