• Boulova, Marina
• Lucazeau, Guy
• Bouvier, Pierre
• Crichton, Wilson

Abstract

The high-pressure behaviour of microcrystalline tungsten oxide (WO<SUB>3</SUB>) has been investigated with angle-dispersive synchrotron x-ray powder diffraction in a diamond anvil cell up to 40 GPa at room temperature. Up to 21 GPa, the pressure dependence of the volume of the monoclinic high-pressure (<I>P</I>2<SUB>1</SUB>/<I>c</I>) phase is described by a third-order Birch–Murnaghan equation of state with parameters <I>V</I><SUB>0</SUB> = 210.9(7)Å<SUP>3</SUP>, <I>K</I><SUB><I>T</I></SUB> = 27(2)<I>GP</I> <I>a</I> and <I>K</I>' = 9.4(5). At 24 GPa, a first-order phase transition occurs with an approximate Δ<I>V</I> of 7.4% to a monoclinic <I>P</I>2<SUB>1</SUB>/<I>a</I> unit cell with <I>a</I> = 6.1669(8)Å, <I>b</I> = 4.5758(6)Å, <I>c</I> = 5.3159(6)Å, β = 101.440(9)<SUP>ˆ</SUP>. A second transition is observed at pressures higher than 31 GPa with an approximate Δ<I>V</I> of 12% to a phase described by a third monoclinic unit cell, with <I>a</I> = 10.3633(22)Å, <I>b</I> = 3.9065(8)Å, <I>c</I> = 9.3459(18)Å and β = 98.539(14)ˆ

Topics

• impedance spectroscopy
• phase
• x-ray diffraction
• phase transition
• tungsten