High-pressure modifications of the rare earth oxide fluorides REOF (RE = Pr, Nd, Sm – Gd) were successfully synthesized under conditions of 11 GPa and 1200 °C applying the multianvil high-pressure/high-temperature technique. Single crystals of HP-REOF (RE = Nd, Sm, Eu) were obtained making it possible to analyze the products by means of single-crystal X-ray diffraction. The compounds HP-REOF (RE = Nd, Sm, Eu) crystallize in the orthorhombic α-PbCl2-type structure (space group Pnma, No. 62, Z = 4) with the parameters a = 632.45(3), b = 381.87(2), c = 699.21(3) pm, V = 0.16887(2) nm3, R1 = 0.0156, and wR2 = 0.0382 for HP-NdOF, a = 624.38(3), b = 376.87(2), c = 689.53(4) pm, V = 0.16225(2) nm3, R1 = 0.0141, and wR2 = 0.0323 for HP-SmOF, and a = 620.02(4), b = 374.24(3), c = 686.82(5) pm, V = 0.15937(2) nm3, R1 = 0.0177, and wR2 = 0.0288 for HP-EuOF. Calculations of the bond valence sums clearly showed that the oxygen atoms occupy the tetrahedrally coordinated position, whereas the fluorine atoms are fivefold coordinated in form of distorted square-pyramids. The crystal structures and properties of HP-REOF (RE = Nd, Sm, Eu) are discussed and compared to the isostructural phases and the normal-pressure modifications of REOF (RE = Nd, Sm, Eu). Furthermore, results of investigations by EDX and Raman measurements including quantum mechanical calculations are presented.

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rare earth oxide raman singlecrystal xray multianvil bond valence sums mechanical normalpressure

Michael Schauperl,Matthias Glätzle, Martina Tribus, Klaus R. Liedl, Hubert Huppertz, Clivia Hejny,.Orthorhombic HP-REOF (RE = Pr, Nd, Sm – Gd) – High-Pressure Syntheses and Single-Crystal Structures (RE = Nd, Sm, Eu). 2016 (20),1142-1134.

Michael Schauperl, et al."Orthorhombic HP-REOF (RE = Pr, Nd, Sm – Gd) – High-Pressure Syntheses and Single-Crystal Structures (RE = Nd, Sm, Eu)" 2016

Michael Schauperl,Matthias Glätzle, Martina Tribus, Klaus R. Liedl, Hubert Huppertz, Clivia Hejny,"Orthorhombic HP-REOF (RE = Pr, Nd, Sm – Gd) – High-Pressure Syntheses and Single-Crystal Structures (RE = Nd, Sm, Eu)"