Structural Distortions and Uniaxial Negative Thermal Expansion in the Polar Dion-Jacobson Oxide RbNdTa₂O₇.

ABSTRACT: We provide deeper insight into the crystal structures, sequential structural phase transitions (I2cm → Cmce → I4/mcm → P4/mmm), thermal expansion, and electronic properties of the n = 2 Dion-Jacobson polar oxide RbNdTa₂O₇, through X-ray powder diffraction, neutron powder diffraction, Raman studies, and density functional theory calculations. We observed a uniaxial negative thermal expansion (NTE) across the first-order transition, I2cm → Cmce, where the unit cell contracts along the c-axis, which is driven by a contraction of the NdTa₂O₆ layer. This NTE occurs within the temperature range of the first-order phase transition and contrasts with the corkscrew mechanism typically o

SUBMITTER: Neenu Lekshmi P 

PROVIDER: S-EPMC12821136 | biostudies-literature | 2025 Aug

REPOSITORIES: biostudies-literature