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我们用温和水热法合成了系列的焦绿石结构氧化物R2Ru2O7(R=Pr3+,Sm3+～Ho3+).找到了最佳的反应条件,得到纯的产物,所有的样品是八面体的形貌.对样品进行了粉末X射线衍射、扫描电镜、X射线能谱等测试,讨论了水热条件下影响晶化的因素.我们发现,产物的纯度与投料的选择以及碱的浓度有着密切的关系.此外,我们也研究了产物的磁性,其中Sm2Ru2O7和Eu2Ru2O7分别在96K和80K发生ZFC和FC曲线分叉,说明在该温度下发生了由顺磁到反铁磁转变.水热法得到的样品的反铁磁转变温度比用高温固相法得到的样品的转变温度低.磁转变温度上的这种改变可能来源于水热合成的样品的独特的局域结构和含丰富氧的表面,这是水热反应得到的样品的一个重要特征.
We synthesized a series of pyrochlore structural oxides R2Ru2O7 (R = Pr3 +, Sm3 + ~ Ho3 +) by mild hydrothermal method. The optimal reaction conditions were found to give pure products, all of which were octahedrons. X-ray powder diffraction, scanning electron microscopy, X-ray spectroscopy and other tests were carried out to discuss the factors affecting the crystallization under hydrothermal conditions.We found that the purity of the product is closely related to the choice of feedstock and alkali concentration.In addition, We also studied the magnetic properties of the product, in which Sm2Ru2O7 and Eu2Ru2O7 occurred at 96K and 80K, respectively, and the ZFC and FC curve bifurcation, indicating the paramagnetism to antiferromagnetic transition occurred at this temperature. The magnetic transition temperature is lower than the transition temperature of the sample obtained by the high temperature solid phase method.This change in the magnetic transition temperature may be derived from the unique local structure of the hydrothermally synthesized sample and the surface rich in oxygen, An important feature of the sample obtained from the reaction.