Microscopic structure at the morphotropic phase boundary in lead-barium meta-niobat
Abstract
Lead-barium niobate Pb1−xBaxNb2O6 is a tetragonal tungsten-bronze ferroelectric that exhibits enhanced functional properties near a morphotropic phase boundary separating orthorhombic and tetragonal phases. Using first-principles electronic-structure calculations combined with ab initio molecular dynamics, we investigate how Ba substitution modifies cation-site occupancy, local distortions, and polarization behavior across the solid solution. By explicitly accounting for vacancy ordering and the inequivalent A-site cages intrinsic to the tungsten-bronze framework, we identify the structural origin of the orthorhombic-to-tetragonal transition. Increasing Ba content progressively weakens the cooperative in-plane off-centering of Pb ions in the pentagonal channels and promotes out-of-plane displacements of Nb and A-site cations, leading to a rotation of the spontaneous polarization from [110] to [001]. The transition occurs near x ≈ 0.6, in quantitative agreement with experimental phase diagrams. These results provide a microscopic interpretation of the morphotropic phase boundary in Pb1−xBaxNb2O6 and establish a clear structure-polarization relationship for tungsten-bronze ferroelectrics.
Related
- Fine-structure Raman interferometry with metastable barium for magnetically resilient inertial sensing
- Microscopic Nonreciprocity-Governed Topological Boundary Flows in Active Matter
- Microscopic Origin of the Shannon-Rényi Boundary Phase in the Critical Ising Chain
- Beyond the ETH envelope: exact two-resolvent fluctuation structure, projected microscopic closure, and rigid versus nonperturbative sectors
- Helium Atom Scattering from Cold Salty Water: Impact of Microscopic and Mesoscopic Surface Structure
BibTeX
@misc{fornari2026microscopic,
title = {{Microscopic structure at the morphotropic phase boundary in lead-barium meta-niobat}},
author = {Marco Fornari and Virginia Carnevali},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.41601},
eprint = {2610.41601},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.41601},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Microscopic structure at the morphotropic phase boundary in lead-barium meta-niobat
AU - Marco Fornari
AU - Virginia Carnevali
PY - 2026
DA - 2026/10/30
PB - arXiv
DO - 10.48550/arxiv.2610.41601
UR - https://arxiv.org/abs/2610.41601
AB - Lead-barium niobate Pb_1−xBa_xNb_2O_6 is a tetragonal tungsten-bronze ferroelectric that exhibits enhanced functional properties near a morphotropic phase boundary separating orthorhombic and tetragonal phases. Using first-principles electronic-structure calculations combined with ab initio molecular dynamics, we investigate how Ba substitution modifies cation-site occupancy, local distortions, and polarization behavior across the solid solution. By explicitly accounting for vacancy ordering and the inequivalent A-site cages intrinsic to the tungsten-bronze framework, we identify the structural origin of the orthorhombic-to-tetragonal transition. Increasing Ba content progressively weakens the cooperative in-plane off-centering of Pb ions in the pentagonal channels and promotes out-of-plane displacements of Nb and A-site cations, leading to a rotation of the spontaneous polarization from [110] to [001]. The transition occurs near x ≈ 0.6, in quantitative agreement with experimental phase diagrams. These results provide a microscopic interpretation of the morphotropic phase boundary in Pb_1−xBa_xNb_2O_6 and establish a clear structure-polarization relationship for tungsten-bronze ferroelectrics.
ER -