Temperature Dependence of Lattice Parameters and Anisotropic Thermal Expansion of Bismuth Oxide

Abstract

Temperature dependence of lattice parameters of bismuth sesquioxide (Bi2O3) has been obtained between 26° and 778°C by the Rietveld method using neutron powder diffraction data. Lattice parameters and unit‐cell volume of α and δ phases increased, while the β angle of α phase decreased with an increase of temperature. Here the denotes the lattice parameter a of the α phase on the basis of pseudo‐fluorite lattice. The thermal expansion coefficients of α phase were 26.7, 6.6, and 9.0 (× 10−6°C−1) for and axes, respectively, indicating a large anisotropy. The α‐ to ‐δ phase transition of Bi2O3 was confirmed between 721° and 760°C on heating. At the α–δ transition point, the lattice parameters and unit‐cell volume discontinuously changed, indicating that the transition is of the first order.

Correlation of Electrical Response and Structural Phase Transitions in Bi2O3 Nanowires

“…Moreover, lattice parameters and angles of each phase at the temperature of interest are required, which in turn requires knowledge of its temperature dependence. Such data have been scarcely reported for Bi 2 O 3 . Despite these difficulties, the assignments of the observed diffraction maxima to the phases detailed for each sample and temperature are unambiguous and nicely support the ionic transport data, as will be explained in the following.…”

Fast oxygen diffusion in bismuth oxide probed by quasielastic neutron scattering

“…The nearest-neighbor distance between the partially oxygen-occupied tetrahedral sites in Bi 2 O 3 is ca. 2.83 Å, based on the δ-phase lattice parameter of 5.66 Å [39]. The fits for the 0.5 Å -1 ≤ Q ≤ 1.7 Å -1 range described in Table 1 yield the L values consistently close to the expected value of 2.83 Å, irrespective of whether the background spectra were subtracted from the Bi 2 O 3 data, or not.…”

Empirical Evidence for A‐Site Order in Perovskites

“…Li (1−3 x )/2 La (1+ x )/2 TiO 3 order parameter and r A correction (Å) where both are functions of x . Ordering from reported site‐occupancy numbers . Inset shows the order parameter as a function of r A correction (Å) and can be thought of as an empirical model for ordering (0 = disorder, 1 = fully ordered).…”