In this study, strontium titanate (SrTiO) nanoparticles were obtained utilizing a one-step supercritical continuous solvothermal synthesis process involving acetylacetonate precursors for both strontium and titanium cations instead of the historical alkoxide ones. These precursors are expensive, difficult to access (especially for strontium isopropoxyde) and inadequately stable, forcing the use of a glove box and controlled atmospheres, which is not the case for acetylacetonates. Pure SrTiO nanoparticles with a crystallite size of roughly 20 nm were successfully synthesized. In addition to the cubic structure of SrTiO, FTIR revealed surface functions that are typical of "wet" processes, while Raman spectroscopy showed the activation of non-centrosymmetric modes brought on by non-linear contributions. The nanoparticles show a faceted shape and are stable at elevated temperatures (up to 800 °C), according to high temperature XRD measurements. However, due to a chemical deficiency in strontium, titanium dioxide (TiO) phases are formed at higher temperatures. high temperature HRTEM investigations showed the existence of two populations of particles, with a better stability for the bigger-sized particles after thermal treatment as well as the sintering and restructuring of the smallest ones. Also, the microscopy results suggest the possibility of a chemical inhomogeneity within the crystallites. Overall, this study offers important new knowledge on the physicochemical characteristics of the synthesized SrTiO nanoparticles and their thermal stability using a novel supercritical continuous solvothermal approach based on the use of acetylacetonate precursors.

中文翻译：

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基于水/乙醇混合物中乙酰丙酮前体的新型溶剂热流合成钛酸锶纳米粒子


在这项研究中，钛酸锶（SrTiO）纳米颗粒是利用一步超临界连续溶剂热合成工艺获得的，该工艺涉及锶和钛阳离子的乙酰丙酮前体，而不是历史上的醇盐前体。这些前体价格昂贵，难以获得（尤其是异丙氧基锶）并且稳定性不够，迫使使用手套箱和受控气氛，而乙酰丙酮化物则不然。成功合成了晶粒尺寸约为 20 nm 的纯 SrTiO 纳米粒子。除了 SrTiO 的立方结构之外，FTIR 还揭示了“湿”过程典型的表面功能，而拉曼光谱则显示了非线性贡献带来的非中心对称模式的激活。根据高温 XRD 测量，纳米颗粒呈现多面形状，并且在高温（高达 800 °C）下保持稳定。然而，由于锶的化学缺陷，二氧化钛（TiO）相在较高温度下形成。高温HRTEM研究表明存在两种颗粒群，较大尺寸的颗粒在热处理后具有更好的稳定性，而最小颗粒的烧结和重组也具有更好的稳定性。此外，显微镜结果表明微晶内可能存在化学不均匀性。总的来说，这项研究使用基于乙酰丙酮前体的新型超临界连续溶剂热方法，为合成的 SrTiO 纳米粒子的物理化学特性及其热稳定性提供了重要的新知识。