常熟理工学院学报
常熟理工學院學報
상숙리공학원학보
JOURNAL OF CHANGSHU INSTITUTE OF TECHNOLOGY
2014年
4期
17-21
,共5页
杨小之%邵强%吕群%韩志达
楊小之%邵彊%呂群%韓誌達
양소지%소강%려군%한지체
钙钛矿%尺寸效应%磁熵变%磁制冷
鈣鈦礦%呎吋效應%磁熵變%磁製冷
개태광%척촌효응%자적변%자제랭
perovskite%size effect%magnetic entropy change%magnetic refrigeration
采用溶胶-凝胶法制备不同粒径的La缺位La0.9MnO3钙钛矿氧化物.用X射线衍射、扫描电子显微镜、振动样品磁强计对材料的晶体结构、微结构、磁性和磁热效应进行了研究.结果表明,不同温度下退火(700 oC~1100 oC)的样品均具有菱形钙钛矿结构.退火温度从700 oC增加到1100 oC,样品的平均晶粒大小从25 nm增加到1000 nm.随着晶粒大小的增加,材料在低温的饱和磁化强度逐渐增强,铁磁到顺磁的相变变得陡峭,从而使材料的磁熵变逐渐增加.当材料的晶粒尺寸大于500 nm时,材料的磁熵变趋于稳定(-2.7 J/kg·K).
採用溶膠-凝膠法製備不同粒徑的La缺位La0.9MnO3鈣鈦礦氧化物.用X射線衍射、掃描電子顯微鏡、振動樣品磁彊計對材料的晶體結構、微結構、磁性和磁熱效應進行瞭研究.結果錶明,不同溫度下退火(700 oC~1100 oC)的樣品均具有蔆形鈣鈦礦結構.退火溫度從700 oC增加到1100 oC,樣品的平均晶粒大小從25 nm增加到1000 nm.隨著晶粒大小的增加,材料在低溫的飽和磁化彊度逐漸增彊,鐵磁到順磁的相變變得陡峭,從而使材料的磁熵變逐漸增加.噹材料的晶粒呎吋大于500 nm時,材料的磁熵變趨于穩定(-2.7 J/kg·K).
채용용효-응효법제비불동립경적La결위La0.9MnO3개태광양화물.용X사선연사、소묘전자현미경、진동양품자강계대재료적정체결구、미결구、자성화자열효응진행료연구.결과표명,불동온도하퇴화(700 oC~1100 oC)적양품균구유릉형개태광결구.퇴화온도종700 oC증가도1100 oC,양품적평균정립대소종25 nm증가도1000 nm.수착정립대소적증가,재료재저온적포화자화강도축점증강,철자도순자적상변변득두초,종이사재료적자적변축점증가.당재료적정립척촌대우500 nm시,재료적자적변추우은정(-2.7 J/kg·K).
La-deficient La0.9MnO3 perovskite nanoparticles with different grain size were prepared by sol-gel method. The crystal structure, microstructure, magnetic properties, and magnetocaloric effect in La0.9MnO3 nanoparticles were studied using x-ray diffraction, scanning electron microscopy and vibrating sample magnetom-eter. All samples that annealed at different temperatures (700 ℃~1100 ℃) have rhombohedral structure. With the increase of annealing temperatures from 700 ℃ to 1100 ℃, the average crystal size increases gradually from 25 nm to 1000 nm. The magnetization and magnetic entropy change (ΔSM) increase with the increase of crystal size. The value of ΔSM becomes stable when the crystal size is larger than 500 nm.