Crystal structures of (a) cubic C-Sm2O3; (b) monoclinic B-Sm2O3; and (c) hexagonal A-Sm2O3.
Representative angle dispersive x-ray diffraction patterns (λ = 0.6199 Å) of Sm2O3 under selected pressures: (a) compression, (b) decompression. The diffraction peaks marked with ♥ and ● are contributed by C and A phases, respectively.
Typical Le Bail refinement of the XRD pattern of Sm2O3. (a) Mixture phases of C and B at pressure of 0.1 MPa, (b) mixture phases of C, B, and A at 4.2 GPa, (c) A phase at 13.5 GPa. Solid line, symbols, and solid line at the bottom represent observed and calculated patterns and their differences, respectively. The rows of vertical bars indicate the diffraction positions.
The lattice parameters for cubic and hexagonal phases of Sm2O3 with increasing pressures. Solid symbols: This experiment. Empty symbols: Guo's experiment. The limited data points for monoclinic phase are not included.
Experimental pressure-volume data for Sm2O3. Solid symbols: This experiment. Empty symbols: Guo's experiment. The solid line is the fitting with Birch-Murnaghan equation of state for the P-V data. The estimated error bars lie within the size of the symbols.
Raman spectra of Sm2O3 under increasing pressure and after fully release of pressure. The Raman peaks marked with *, ♦, and ♥ are contributed by C, B, and A phases, respectively.
Shift in Raman frequencies of Sm2O3 plotted as a function of pressure. Solid symbols: This experiment. Empty symbols: Hongo's experiment.
Refined lattice parameters of the different structures of Sm2O3 at various pressures.
Experimental and theoretical bulk moduli, unit-cell volumes, and volume change at phase transitions for Sm2O3.
Mode frequencies, pressure coefficients, and Grüneisen parameters for phonon modes in cubic, monoclinic, and hexagonal phases of Sm2O3. The Raman mode of cubic phase is marked with *.
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