La_(0.7)Ca_(0.3)MnO_3纳米颗粒的聚丙烯酰胺凝胶法制备及性能  

Polyacrylamide Gel Preparation and Properties of La_(0.7)Ca_(0.3)MnO_3 Nanoparticles

作　　者：朱彦虎[1,2] 杨华[1,2] 县涛[1,2] 魏智强[2] 马金元[2] 冯旺军[2] 

机构地区：[1]兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室,兰州730050 [2]兰州理工大学理学院,兰州730050

出　　处：《硅酸盐学报》2011年第12期1892-1897,共6页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(50962009);教育部重点(209130);甘肃省自然科学基金(1010RJZA041);兰州理工大学优秀青年资助计划(Q200902)资助项目

摘　　要：采用聚丙烯酰胺凝胶法制备La0.7Ca0.3MnO3纳米颗粒。通过X射线衍射和扫描电镜研究不同pH值和不同络合剂对制备La0.7Ca0.3MnO3纳米颗粒形貌及性能的影响。结果表明:合成La0.7Ca0.3MnO3钙钛矿相的最佳pH=2;分别以醋酸、草酸、柠檬酸和乙二胺四乙酸为络合剂,在600℃煅烧温度制备的高纯La0.7Ca0.3MnO3纳米颗粒的形貌规整、呈类球形,尺寸分布较窄,平均粒径分别为30、37、45、50nm;以酒石酸为络合剂,在900℃煅烧制备的单相La0.7Ca0.3MnO3颗粒的形貌不甚规整,颗粒间出现明显的煅烧粘连现象,颗粒尺寸较大,平均粒径为170nm。磁滞回线测量结果表明:制得的La0.7Ca0.3MnO3颗粒在室温均表现为顺磁性,其顺磁磁化率随样品颗粒尺寸的减小而减小。A polyacrylamide gel route was used to fabricate La0.7Ca0.3MnO3 nanoparticles. Influence of pH values and chelating agents on particle morphology and properties of the prepared La0.7Ca0.3MnO3 nanoparticles were investigated by X-ray diffraction and scanning electron microscopy. The optimal pH value for synthesis of perovskite La0.7Ca0.3MnO3 was obtained to be 2. Using acetic acid, oxalic acid, citric acid, and ethylenediamine-tetraacetic acid as chelating agents, single-phase La0.7Ca0.3MnO3 nanoparticles were prepared at a calcination temperature of 600 ℃. The particles prepared using the four chelating agents are uniform and regu- larly-shaped spheres, and have an average size of 30, 37, 45 nm, and 50 nm, respectively. When using tartaric acid as the chelating agent, a much higher calcination temperature at 900 ℃ was required to produce single-phase La0.7Ca0.3MnO3 particles. The obtained particles exhibit an irregular morphology and an obvious adhesive behavior, and have a relatively large average size of 170 nm. Mag- netic hysteresis loop measurements indicate that the prepared La0.7Ca0.3MnO3 samples exhibit paramagnetism at room temperature, but their paramagnetic susceptibilities exhibit a decreasing trend with the decrease of sample particle size.

关 键 词：钙钛矿锰氧化物 纳米颗粒 聚丙烯酰胺凝胶法 PH值 络合剂 

分 类 号：O469[理学—凝聚态物理]