Pressure-induced decomposition of Bi14WO24

TL;DR

This study investigates the high-pressure behavior of Bi14WO24, revealing its irreversible decomposition at 2.85 GPa and providing detailed measurements of its compressibility and equation of state.

Contribution

It is the first to report the pressure-induced decomposition of Bi14WO24 and to quantify its compressibility and structural changes under high pressure.

Findings

Bi14WO24 decomposes irreversibly into Bi2O3 and WO3 at 2.85 GPa

The bulk modulus of Bi14WO24 is 49.8 GPa

Linear compressibility along axes a and c are 6.94×10^-3 GPa^-1 and 3.73×10^-3 GPa^-1

Abstract

We present a study of the high-pressure behaviour Bi14WO24, a high oxide ion conductor member of the Bi2O3-WO3 binary system. The tetragonal polymorph of Bi14WO24 was studied under high-pressure conditions using synchrotron powder X-ray diffraction. It was found that in contrast to isostructural Bi14CrO24 and Bi14MoO24 which experience a phase transition around 5 GPa, in our study Bi14WO24 undergoes an irreversible chemical decomposition into Bi2O3 and WO3 at 2.85(5) GPa. The pressure dependence of the unit-cell parameters of Bi14WO24 was also determined, and hence the linear compressibility along different axes and room-temperature pressure-volume equation of state were derived. Bulk modulus of tetragonal Bi14WO24 was found to be 49.8(2.6) GPa, and the linear compressibility of the two crystallographic axes, \k{appa}a and \k{appa}c were 6.94(2) 10-3 GPa-1 and = 3.73(1) 10-3 GPa-1, respectively. The pressure induced decomposition can be attributed to the favourable increasing density of the system to accommodate the pressure induced stress.