Antiferroelectric Tetragonal Tungsten Bronzes

Recently the presence of two phase transitions on heating in K2(La0.75Pr0.25)Nb5O15 has been observed and have been assigned to successive ferro- (FE) to antiferro- (AFE) to para-electric (PE) transformations. This composition is of particular interest as the room temperature AFE phase results in a high and voltage stable permittivity (and hence capacitance) under large applied electric fields. As a result these materials can be utilised in high capacitance, high voltage multi-layer capacitors (MLCs). We aim to determine the underlying crystallographic changes associated with the FE-AFE transition, and also an in-situ study of MLCs fabricated from this material under an applied electric field. These studies will give us an atom-scale insight into the origin of the properties of this materials allowing development of further materials for application as high voltage capacitors.

近期，研究人员在加热K2(La0.75Pr0.25)Nb5O15时观察到两个相变过程，它们被归因于连续的铁电（FE）→反铁电（AFE）→顺电（PE）转变。该成分具有特殊研究价值，因其室温反铁电相在强外加电场下可产生高且电压稳定的介电常数（进而获得稳定电容）。因此，这类材料可应用于高电容、高压多层电容器（MLCs）。我们旨在明确与铁电-反铁电转变相关的潜在晶体学变化，并对由该材料制备的MLCs在施加电场下进行原位研究。这些研究将使我们从原子尺度深入理解该材料性能的起源，从而为开发更多用于高压电容器的材料提供支持。