Effects of pressure on the structure and lattice dynamics of TmPO ₄: Experiments and calculations

TY - JOUR

T1 - Effects of pressure on the structure and lattice dynamics of TmPO 4

T2 - Experiments and calculations

AU - Stavrou, E.

AU - Tatsi, A.

AU - Raptis, C.

AU - Efthimiopoulos, I.

AU - Syassen, K.

AU - Muñoz, A.

AU - Rodríguez-Hernández, P.

AU - López-Solano, J.

AU - Hanfland, M.

PY - 2012/1/23

Y1 - 2012/1/23

N2 - Thulium phosphate (TmPO 4) with the tetragonal zircon-type structure has been studied using angle-dispersive powder x-ray diffraction and Raman spectroscopy in a diamond anvil cell up to 55 GPa (at room temperature). The results from both experimental methods reveal a pressure-induced structural phase transition from zircon to a scheelite-type structure at 20 GPa. At the same pressure, a second phase with the monazite structure is also formed at a low concentration, which decreases and eventually vanishes with increasing pressure. Our ab initio total-energy and lattice-dynamics calculations are in good agreement with experimental findings. The calculations indicate that the main transition to the scheelite structure is related with the softening of a silent B 1u mode. Upon decompression, TmPO 4 reverses back to the original zircon structure showing significant hysteresis. The results are discussed in relation to the observed general structural systematics and phase transition sequences in zircon-type APO 4 orthophosphates under pressure.

AB - Thulium phosphate (TmPO 4) with the tetragonal zircon-type structure has been studied using angle-dispersive powder x-ray diffraction and Raman spectroscopy in a diamond anvil cell up to 55 GPa (at room temperature). The results from both experimental methods reveal a pressure-induced structural phase transition from zircon to a scheelite-type structure at 20 GPa. At the same pressure, a second phase with the monazite structure is also formed at a low concentration, which decreases and eventually vanishes with increasing pressure. Our ab initio total-energy and lattice-dynamics calculations are in good agreement with experimental findings. The calculations indicate that the main transition to the scheelite structure is related with the softening of a silent B 1u mode. Upon decompression, TmPO 4 reverses back to the original zircon structure showing significant hysteresis. The results are discussed in relation to the observed general structural systematics and phase transition sequences in zircon-type APO 4 orthophosphates under pressure.

UR - http://www.scopus.com/inward/record.url?scp=84856501331&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.85.024117

DO - 10.1103/PhysRevB.85.024117

M3 - 文章

AN - SCOPUS:84856501331

VL - 85

JO - Physical Review B

JF - Physical Review B

SN - 2469-9950

IS - 2

M1 - 024117

ER -