Crystal chemical characteristics of α-CaSi2O5, a new high pressure calcium silicate with five-coordinated silicon synthesized at 1500°C and 10 GPa

Y. Kudoh, M. Kanzaki

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The crystal structure of αCaSi2O5 synthesized at conditions of 1500°C and 10 GPa, has been solved and refined in centrosymmetric space group P1, using single crystal X-ray diffraction data. The composition (Z = 4) and unit cell are Ca1.02Si1.99O5 by EPMA analysis and a = 7.243(2) A, b = 7.546(4) A, c = 6.501(4) a, α = 81.43(5)°, β = 84.82(4)°, γ = 69.60(3)°, V = 329.5(3) A3, yielding the density value, 3.55 g/cm3. The structures the square-pyramid five-fold coordination of silicon by oxygen. The ionic radius for five-coordinated Si calculated from the bond distances is 0.33 A. The substantial deviation of valence sume for Ca indicates the existence of local strain and the instability of α-CaSi2O5 at room temperature.

Original languageEnglish
Pages (from-to)429-433
Number of pages5
JournalPhysics and Chemistry of Minerals
Issue number6
Publication statusPublished - Jun 1 1998


ASJC Scopus subject areas

  • Materials Science(all)
  • Geochemistry and Petrology

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