The crystal structure and bonding environment of K_{2}Ca(CO_{3})_{2}bütschliite were probed under isothermal compression via Raman spectroscopy to 95 GPa and single crystal and powder Xray diffraction to 12 and 68 GPa, respectively. A second order BirchMurnaghan equation of state fit to the Xray data yields a bulk modulus,
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Perovskite oxides (ternary chemical formula ABO_{3}) are a diverse class of materials with applications including heterogeneous catalysis, solidoxide fuel cells, thermochemical conversion, and oxygen transport membranes. However, their multicomponent (chemical formula
 Award ID(s):
 2016225
 NSFPAR ID:
 10491218
 Publisher / Repository:
 Nature Publishing Group
 Date Published:
 Journal Name:
 Scientific Data
 Volume:
 10
 Issue:
 1
 ISSN:
 20524463
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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Abstract GPa with an imposed value of$${K}_{0}=46.9$$ ${K}_{0}=46.9$ for the ambient pressure phase. Compression of bütschliite is highly anisotropic, with contraction along the$${K}_{0}^{\prime}= 4$$ ${K}_{0}^{\prime}=4$c axis accounting for most of the volume change. Bütschliite undergoes a phase transition to a monoclinicC 2/m structure at around 6 GPa, mirroring polymorphism within isostructural borates. A fit to the compression data of the monoclinic phase yields Å^{3}$${V}_{0}=322.2$$ ${V}_{0}=322.2$$$,$$ $,$ GPa and$${K}_{0}=24.8$$ ${K}_{0}=24.8$ using a third order fit; the ability to access different compression mechanisms gives rise to a more compressible material than the lowpressure phase. In particular, compression of the$${K}_{0}^{\prime}=4.0$$ ${K}_{0}^{\prime}=4.0$C 2/m phase involves interlayer displacement and twisting of the [CO_{3}] units, and an increase in coordination number of the K^{+}ion. Three more phase transitions, at ~ 28, 34, and 37 GPa occur based on the Raman spectra and powder diffraction data: these give rise to new [CO_{3}] bonding environments within the structure. 
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