Aamlid Solveig S, Selbach Sverre M, Grande Tor
Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
Materials (Basel). 2019 Apr 10;12(7):1156. doi: 10.3390/ma12071156.
The versatile crystal structure of tetragonal tungsten bronzes (A1₂A2₄C₄BO) can accommodate complex stoichiometries including cations in different valence states and vacant cation sites. Here, we report on the effect of thermally induced cation-vacancy disorder in the tetragonal tungsten bronze SrBaNb₂O₆ (SBNX). SBNX (x = 0.25, 0.33, 0.50, 0.61) ceramics, prepared by conventional solid-state synthesis, were annealed at varying temperatures and subsequently quenched to room temperature. The Curie temperature of all the SBNX materials increased with higher quenching temperatures, accompanied with ferroelectric hardening. The variation in thermal history also caused structural changes, specifically a contraction of the lattice parameter and a minor elongation of the parameter. These effects are discussed in relation to recent first principles calculations of the energy landscape of the cation-vacancy configurations and experimental evidence of thermally induced cation-vacancy disordering.
四方钨青铜（A1₂A2₄C₄BO）的通用晶体结构能够容纳复杂的化学计量比，包括不同价态的阳离子和阳离子空位。在此，我们报道了四方钨青铜SrBaNb₂O₆（SBNX）中热致阳离子空位无序的影响。通过传统固态合成法制备的SBNX（x = 0.25、0.33、0.50、0.61）陶瓷在不同温度下退火，随后淬火至室温。所有SBNX材料的居里温度随淬火温度升高而增加，并伴有铁电硬化。热历史的变化也导致了结构变化，具体表现为晶格参数a收缩以及c参数略有伸长。结合最近关于阳离子空位构型能量景观的第一性原理计算和热致阳离子空位无序的实验证据，对这些效应进行了讨论。
