Investigation into the Crystal Structure of the Perovskite Lead Hafnate, PbHfO₃

Abstract

The room‐temperature crystal structure of the perovskite lead hafnate PbHfO3 is investigated using both low‐temperature single crystal X‐ray diffraction (Mo Kα radiation, λ = 0.71069 Å) and polycrystalline neutron diffraction (D1A instrument, ILL, λ = 1.90788 Å). Single crystal X‐ray data at 100 K: space group Pbam, a = 5.856 (1), b = 11.729 (3), c = 8.212 (2) Å, V = 564.04 Å3 with Z = 8, μ = 97.2 mm−1, F(000) = 1424, final R = 0.038, wR = 0.045 over 439 reflections with F >1.4σ(F). Polycrystalline neutron data at 383 K: a = 5.8582 (3), b = 11.7224 (5), c = 8.2246 (3) Å, V = 564.80 Å3 with χ2 = 1.62. Although lead hafnate has been thought to be isostructural with lead zirconate, no complete structure determination has been reported, as crystal structure analysis in both these materials is not straightforward. One of the main difficulties encountered is the determination of the oxygen positions, as necessary information lies in extremely weak l = 2n + 1 X‐ray reflections. To maximize the intensity of these reflections the X‐ray data are collected at 100 K with unusually long scans, a procedure which had previously been found successful with lead zirconate. In order to establish that no phase transitions exist between room temperature and 100 K, and hence that the collected X‐ray data are relevant to the room‐temperature structure, birefringence measurements for both PbZrO3 and PbHfO3 are also reported.

Structural transformations in Pb1 − xBi4 + xTi4 − xMnxO15(x = 0.2 and 0.4): a Raman scattering study

“…(2008). Similar relations have been found in the perovskite‐type compounds PbZrO 3 and PbHfO 3 . This fact also shows that the amount of A ‐site Pb affects the octahedral structure.…”

Tetragonal-to-monoclinic phase transition in a ferroelectric perovskite: The structure ofPbZr0.52Ti0.48Noheda1, Gonzalo2, Cross3 et al. 2000Phys. Rev. B

“…Selected bond distances for the two models are shown in Table II (Table II). The tendency of Pb +2 , which has a lone sp electron pair, to form short covalent bonds with a few neighboring oxygens is well documented in the literature 23,[39][40][41] .…”

Temperature-dependent neutron powder diffraction evidence for splitting of the cationic sites in ferroelectric PbHf0.4Ti0.6O3

“…55), Z = 8 (Shirane & Pepinsky, 1953;Jankowska-Sumara et al, 1995;Corker et al, 1998). 55), Z = 8 (Shirane & Pepinsky, 1953;Jankowska-Sumara et al, 1995;Corker et al, 1998).…”