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Title: High-pressure structural study of the scheelite tungstates CaWO{sub 4} and SrWO{sub 4}

Abstract

Angle-dispersive x-ray-diffraction and x-ray-absorption near-edge structure measurements have been performed on CaWO{sub 4} and SrWO{sub 4} up to pressures of approximately 20 GPa. Both materials display similar behavior in the range of pressures investigated in our experiments. As in the previously reported case of CaWO{sub 4}, under hydrostatic conditions SrWO{sub 4} undergoes a pressure-induced scheelite-to-fergusonite transition around 10 GPa. Our experimental results are compared to those found in the literature and are further supported by ab initio total-energy calculations, from which we also predict the instability at larger pressures of the fergusonite phases against an orthorhombic structure with space group Cmca. Finally, a linear relationship between the charge density in the AO{sub 8} polyhedra of ABO{sub 4} scheelite-related structures and their bulk modulus is discussed and used to predict the bulk modulus of other materials, like hafnon.

Authors:
; ; ;  [1];  [2]; ;  [3]; ; ; ; ;  [4];  [5]
  1. Departamento de Fisica Aplicada-ICMUV, Universitat de Valencia, Edificio de Investigacion, c/Dr. Moliner 50, 46100 Burjassot, Valencia (Spain)
  2. Departamento de Fisica Aplicada, Universitat Politecnica de Valencia, Cno. de Vera s/n, 46022 Valencia (Spain)
  3. High Pressure Science and Engineering Center, Department of Physics, University of Nevada, 4505 Maryland Parkway, Las Vegas, Nevada 89154-4002 (United States)
  4. Departamento de Fisica Fundamental II, Universidad de La Laguna, La Laguna 38205, Tenerife (Spain)
  5. European Synchrotron Radiation Facility, BP 220, Grenoble, F-38043 (France)
Publication Date:
OSTI Identifier:
20719777
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 72; Journal Issue: 17; Other Information: DOI: 10.1103/PhysRevB.72.174106; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION SPECTROSCOPY; CALCIUM TUNGSTATES; CHARGE DENSITY; ORTHORHOMBIC LATTICES; PHASE TRANSFORMATIONS; PRESSURE DEPENDENCE; PRESSURE RANGE GIGA PA; SPACE GROUPS; STRONTIUM COMPOUNDS; X RADIATION; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY

Citation Formats

Errandonea, D., Pellicer-Porres, J., Segura, A., Ferrer-Roca, Ch., Manjon, F.J., Kumar, R.S., Tschauner, O., Rodriguez-Hernandez, P., Lopez-Solano, J., Radescu, S., Mujica, A., Munoz, A., and Aquilanti, G.. High-pressure structural study of the scheelite tungstates CaWO{sub 4} and SrWO{sub 4}. United States: N. p., 2005. Web. doi:10.1103/PhysRevB.72.174106.
Errandonea, D., Pellicer-Porres, J., Segura, A., Ferrer-Roca, Ch., Manjon, F.J., Kumar, R.S., Tschauner, O., Rodriguez-Hernandez, P., Lopez-Solano, J., Radescu, S., Mujica, A., Munoz, A., & Aquilanti, G.. High-pressure structural study of the scheelite tungstates CaWO{sub 4} and SrWO{sub 4}. United States. doi:10.1103/PhysRevB.72.174106.
Errandonea, D., Pellicer-Porres, J., Segura, A., Ferrer-Roca, Ch., Manjon, F.J., Kumar, R.S., Tschauner, O., Rodriguez-Hernandez, P., Lopez-Solano, J., Radescu, S., Mujica, A., Munoz, A., and Aquilanti, G.. Tue . "High-pressure structural study of the scheelite tungstates CaWO{sub 4} and SrWO{sub 4}". United States. doi:10.1103/PhysRevB.72.174106.
@article{osti_20719777,
title = {High-pressure structural study of the scheelite tungstates CaWO{sub 4} and SrWO{sub 4}},
author = {Errandonea, D. and Pellicer-Porres, J. and Segura, A. and Ferrer-Roca, Ch. and Manjon, F.J. and Kumar, R.S. and Tschauner, O. and Rodriguez-Hernandez, P. and Lopez-Solano, J. and Radescu, S. and Mujica, A. and Munoz, A. and Aquilanti, G.},
abstractNote = {Angle-dispersive x-ray-diffraction and x-ray-absorption near-edge structure measurements have been performed on CaWO{sub 4} and SrWO{sub 4} up to pressures of approximately 20 GPa. Both materials display similar behavior in the range of pressures investigated in our experiments. As in the previously reported case of CaWO{sub 4}, under hydrostatic conditions SrWO{sub 4} undergoes a pressure-induced scheelite-to-fergusonite transition around 10 GPa. Our experimental results are compared to those found in the literature and are further supported by ab initio total-energy calculations, from which we also predict the instability at larger pressures of the fergusonite phases against an orthorhombic structure with space group Cmca. Finally, a linear relationship between the charge density in the AO{sub 8} polyhedra of ABO{sub 4} scheelite-related structures and their bulk modulus is discussed and used to predict the bulk modulus of other materials, like hafnon.},
doi = {10.1103/PhysRevB.72.174106},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 17,
volume = 72,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 2005},
month = {Tue Nov 01 00:00:00 EST 2005}
}
  • CaWO{sub 4} and SrWO{sub 4} nanostructures have been synthesized via a simple microemulsion-mediated route. With careful control of the fundamental experimental parameters including the concentration of reactants, the reaction time and the temperature, the products with different morphologies of dumbbell, coral, rod and dendrite have been obtained, respectively. The possible formation mechanism of these unique morphologies has been proposed based on surfactant self-assembly under different experimental conditions. The as-synthesized CaWO{sub 4} samples with various morphologies exhibit different photoluminescence properties. X-ray powder diffraction, transmission electron microscopy, field-emission scanning electron microscopy, and luminescence spectroscopy were used to characterize these products.
  • The scheelite-type polymorph of GdCrO{sub 4} has been obtained from the corresponding zircon-type compound under high pressure and temperature conditions, namely 4 GPa and 803 K. The crystal structure has been determined by X-ray powder diffraction. This GdCrO{sub 4} scheelite crystallizes in a tetragonal symmetry with space group I4{sub 1}/a (No. 88, Z=4), a=5.0501(1) A, c=11.4533(2) A and V=292.099(7) A{sup 3}. The thermal decomposition leads to the formation of the zircon-polymorph as intermediate phase at 773 K to end in the corresponding GdCrO{sub 3} distorted perovskite-structure at higher temperatures. Magnetic susceptibility and magnetization measurements suggest the existence of long-range antiferromagneticmore » interactions which have been also confirmed from specific heat measurements. Neutron powder diffraction data reveal the simultaneous antiferromagnetic Gd{sup 3+} and Cr{sup 5+} ordering in the scheelite-type GdCrO{sub 4} with a T{sub N}{approx}20 K. The magnetic propagation vector was found to be k=(0 0 0). Combined with group theory analysis, the best neutron powder diffraction fit was obtained with a collinear antiferromagnetic coupling in which the m{sub Cr{sup 5}{sup +}} and m{sub Gd{sup 3}{sup +}} magnetic moments are confined in the tetragonal basal plane according to the mixed representation {Gamma}{sub 6} Circled-Plus {Gamma}{sub 8}. Thermal decomposition of the GdCrO{sub 4} high pressure polymorph, from the scheelite-type through the zircon-type structure as intermediate to end in the GdCrO{sub 3} perovskite. Highlights: Black-Right-Pointing-Pointer New high pressure GdCrO{sub 4} polymorph crystallizing in the scheelite type structure. Black-Right-Pointing-Pointer It is an antiferromagnet with a metamagnetic transition at low magnetic fields. Black-Right-Pointing-Pointer We have determined its magnetic structure from powder neutron diffraction data. Black-Right-Pointing-Pointer Otherwise, the room pressure zircon-polymorph is a ferromagnet. Black-Right-Pointing-Pointer The paper will be a great contribution in the study of 3d-4f magnetic interactions.« less