Abstract The development of lead-free ferroelectric ceramics exhibiting a high Curie point is regarded as a key aspect of improving the overall performance of high temperature sensing devices. Two-layer Dion-Jacobson phases have great potential for these applications, but the dielectric properties of many of these compounds have not been investigated and several are still erroneously considered to be non-polar. RbPrNb2O7, a two-layer Dion-Jacobson phase, has previously been identified as being non-polar at room temperature, with an orthorhombic crystal structure in space group Imma. Here, the structure of RbPrNb2O7 is re-examined and its ferroelectric (FE) character confirmed through ferroelectric, dielectric and piezoelectric measurements, using dense bulk ceramics. In addition, the microstructure and phase evolution of the compound were analysed by transmission electron microscopy, variable temperature X-ray powder diffraction and differential scanning calorimetry. RbPrNb2O7 is a ferroelectric at room temperature, exhibiting orthorhombic symmetry in space group I2cm. It undergoes a reversible FE ↔ FE phase transition at around 260 °C, with evidence for a diffuse apolar transition between 800 and 900 °C. Details of the subtle structural changes occurring at these transitions are discussed. RbPrNb2O7 possesses a high Curie point of ~1090 °C, making it a potential candidate for use in high temperature piezoelectric sensing.

中文翻译：

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RbPrNb2O7 中的相变，一种具有高居里点的层状结构铁电体

摘要 开发具有高居里点的无铅铁电陶瓷被认为是提高高温传感器件整体性能的关键方面。两层 Dion-Jacobson 相在这些应用中具有巨大的潜力，但许多这些化合物的介电特性尚未得到研究，其中一些仍被错误地认为是非极性的。RbPrNb2O7 是一种两层 Dion-Jacobson 相，先前已被确定为在室温下是非极性的，在空间群 Imma 中具有正交晶体结构。在这里，重新检查了 RbPrNb2O7 的结构，并使用致密的块状陶瓷通过铁电、介电和压电测量确认了其铁电 (FE) 特性。此外，通过透射电子显微镜、变温X射线粉末衍射和差示扫描量热法分析了该化合物的微观结构和相演变。RbPrNb2O7 在室温下是铁电体，在空间群 I2cm 中表现出正交对称性。它在 260 °C 左右经历了可逆的 FE ↔ FE 相变，有证据表明在 800 到 900 °C 之间发生了扩散非极性转变。讨论了在这些转变中发生的细微结构变化的细节。RbPrNb2O7 具有约 1090 °C 的高居里点，使其成为用于高温压电传感的潜在候选者。在空间群 I2cm 中表现出正交对称性。它在 260 °C 左右经历了可逆的 FE ↔ FE 相变，有证据表明在 800 到 900 °C 之间发生了扩散非极性转变。讨论了在这些转变中发生的细微结构变化的细节。RbPrNb2O7 具有约 1090 °C 的高居里点，使其成为用于高温压电传感的潜在候选者。在空间群 I2cm 中表现出正交对称性。它在 260 °C 左右经历了可逆的 FE ↔ FE 相变，有证据表明在 800 到 900 °C 之间发生了扩散非极性转变。讨论了在这些转变中发生的细微结构变化的细节。RbPrNb2O7 具有约 1090 °C 的高居里点，使其成为用于高温压电传感的潜在候选者。