Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
Nanotechnology. 2012 Jan 20;23(2):025702. doi: 10.1088/0957-4484/23/2/025702.
Defect mediated high temperature ferromagnetism in oxide nanocrystallites is the central feature of this work. Here, we report the development of room temperature ferromagnetism in nanosized Co-doped barium titanate particles with a size of around 14 nm, synthesized by a solvothermal drying method. A combination of x-ray diffraction with state-of-the-art electron microscopy techniques confirms the intrinsic doping of Co into BaTiO3. The development of the room temperature ferromagnetism was tracked down to the different donor defects, namely hydroxyl groups at the oxygen site (OH·(O) and oxygen vacancies (V··(O), and their relative concentrations at the surface and the core of the nanocrystal, which could be controlled by post-synthesis drying and thermal treatments.
缺陷介导的氧化物纳米晶高温铁磁性是这项工作的核心特征。在这里，我们报告了通过溶剂热干燥法合成的粒径约为 14nm 的 Co 掺杂钛酸钡纳米颗粒在室温下铁磁性的发展。X 射线衍射与最先进的电子显微镜技术相结合，证实了 Co 对 BaTiO3 的本征掺杂。室温铁磁性的发展可以追溯到不同的施主缺陷，即氧位上的羟基（OH·（O）和氧空位（V··（O），以及它们在纳米晶表面和核心的相对浓度，这可以通过后合成干燥和热处理来控制。
