摘要
采用传统的高温固相反应法制备了La_(0.8)Sr_(0.2)Mn_(1-x)Co_xO_3(x=0, 0.1, 0.3)多晶样品。系统研究了Co掺杂量对La_(0.8)Sr_(0.2)MnO_3(LSMO)多晶样品的类Griffiths相、磁熵变、临界行为和电输运性质的影响。研究结果表明:制备的多晶样品均具有菱形对称结构;三样品在低温磁转变温度(T_(C2))以上均存在类Griffiths相; La0.8Sr0.2Mn_(1-x)Co_xO_3(x=0,0.1, 0.3)样品外加磁场为7 T的最大磁熵变ΔS_(max)分别为-2.28、-2.05和-2.75 J/(kg·K), Co元素的掺杂使得ΔS_(max)先减小后增大;母相的临界行为与平均场模型拟合得最好,掺杂后样品的临界行为和3D海森伯模型拟合最好;母相为半导体材料, Co元素掺杂量达到0.1时在低温磁转变温度(TC2)附近出现金属绝缘体转变;高温区三样品的导电方式均满足小极化子模型。
La（0.8）Sr（0.2）Mn（1-x）CoxO3（x=0,0.1,0.3）samples were prepared via the conventional high-temperature solid-state reaction method.The effects of Co doping on Griffiths phase,magnetic entropy change,critical behavior,and electrical transport properties of La（0.8）Sr（0.2）MnO3（LSMO）polycrystalline samples were systematically investigated.Results show that the prepared polycrystalline samples all have rhombohedral symmetry structures with Griffiths phase above the low temperature magnetic transition temperature（T（C2））.When magnetic field is applied tothe La（0.8）Sr（0.2）Mn（1–x）CoxO3（x=0,0.1,0.3）samples,the maximum magnetic entropy changeΔS（max） for 7 T is -2.88,-2.05,and -2.75 J/（kg·K）,respectively.Doping of Co element makesΔS（max ）decrease first and then increase.The critical behavior of the parent phase fits best with the mean field model,and that of the sample after doping fits best with the 3D Heisenberg model.The mother phase is a semiconductor material,and the metal insulator transition appears near the low temperature magnetic transition temperature（T（C2））when the Co element doping amount reaches 0.1.The conductivity of the three samples in high temperature region satisfies the small polaron model.
作者
刘娇
王文清
吴鸿业
田野
曹凤泽
赵建军
LIU Jiao;WANG Wen-Qing;WU Hong-Ye;TIAN Ye;CAO Feng-Ze;ZHAO Jian-Jun(Department of Physics,Baotou Normal University,Baotou 014030,China;Inner Mongolia Key Laboratory of Magnetism and Magnetic Materials,Baotou Normal University,Baotou 014030,China)
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2018年第11期1237-1247,共11页
Journal of Inorganic Materials
基金
国家自然科学基金(11164019
51562032
61565013)
内蒙古自治区科学基金(2015MS0109
NJZZ11166
NJZY12202
NJZY16237)
包头市科学技术局产学研合作项目(2014X1014-01
2015Z2011)
内蒙古自治区研究生科研创新项目(S201710127(S01))~~
关键词
钙钛矿锰氧化物
类Griffiths相
临界指数
电性
perovskite manganese oxide
Griffiths-like phase
critical exponent
electrical （electrical property）
