纳米晶Sr-Cr水合石榴石的水热合成与磁性研究

Hydrothermal Synthesis and Magnetic Property of Nanocrystalline Sr-Cr Hydrogarnet

在相对温和的水热体系里合成出纳米品Sr－Cr水合石榴石，采用XRD、IR和XPS光谱图对产物进行了表征．结果表明，高溶解性的初始物和高浓度的矿化剂大大降低其晶化温度，并提高其结晶度．随温度升高，出现Sr十二面体最近邻的OH-断裂与分解过程，在空气或氧气中，还出现了Cr（Ⅲ）到Cr（Ⅳ）氧化过程．骨架离子Cr（Ⅲ）的价态变化直接决定着水合石榴石的分解过程及其产物的结构类型,低温磁化率测量表明Sr3Cr2（OH）12是顺磁性的；在该结构中出现了轨道角动量的完全猝灭．该结构中存在较高对称性的Cr－OH八面体．

Nanocrystalline Sr-Cr hydrogarnet was synthesized from a relatively mild hydrothermal system. High solubility of the initial of species and highly concentrated mineralizer lowered the crystallization temperature and enhanced the crystalinity. With increasing temperature, OH bondingsto the Sr dodecahecra were broken, and in air or O2, oxidation from Cr(III) to Cr(VI) occurred.Valence variation of the framwork Cr ions determined the decomposition process and the structuraltypes of the decomposition products. Nanocrystalline Sr-Cr hydrogarnet is paramagnetic, and thecomplete quenching of the orbitle monument was observed. Highly symmetric Cr-OH octahedrawere revealed.