钙钛矿锰氧化物La_(0.87)Dy_(0.13)Mn_(1-x)Fe_(x)O_(3)(x=0.1,0.2)的磁热效应

Magnetothermal Effect of Perovskite Manganese Oxide La_(0.87)Dy_(0.13)Mn_(1-x)Fe_(x)O_(3)(x=0.1,0.2)

采用高温固相反应法制备了La_(0.87)Dy_(0.13)Mn_(1-x)Fe_(x)O_(3)(x=0.1,0.2)多晶样品,并通过对XRD图谱、M-T曲线、M-H曲线等数据进行研究。结果表明:该组样品呈现出良好的单相性,属于正交结构,空间群为Pbnm;两组样品的居里温度TC分别在130、100 K左右,Tθ<T<TG区间为类Griffiths相温区;当T<130 K时样品处于铁磁态,当130 K<T<240 K,样品处于顺磁-铁磁共存态,当T>240 K时,样品处于顺磁态;当外加磁场为5570.46 kA·m时,两个样品的磁熵变最大值均出现在TC附近,分别为S_(M_((x=0.1)))≈2.654 J/(kg·K)、S_(M_((x=0.2)))≈1.909 J/(kg·K),RCP值分别为RCP_(x=0.1)=302.579 J/kg,RCP_(x=0.2)=236.319 J/kg。结合最大磁熵变值和RCP值可知,相较于La_(0.87)Dy_(0.13)Mn_(0.8)Fe_(0.2)O_(3),La_(0.87)Dy_(0.13)Mn_(0.9)Fe_(0.1)O_(3)更具有作磁制冷材料的潜能。

The La_(0.87)Dy_(0.13)Mn_(1-x)Fe_(x)O_(3)(x=0.1,0.2)polycrystalline sample was prepared via high-temperature solid-phase reaction method,and researched by XRD spectrum,M-T curves,M-H curves data.The results show that the samples have good single-phase,belong to the orthogonal structure,space group Pbnm;The Curie temperature TC of the two groups of samples was around 130 K and 100 K respectively,and the interval of Tθ<T<TG was the phase temperature region of Griffiths.When T<130 K,the sample is in the ferromagnetic state;when 130 K<T<240 K,the samples are in the paramagnetic state;when T>240 K,the samples are in the paramagnetic state.When coupled with the magnetic field of 5570.46 kA·m,maximum magnetic entropy change of these two samples are near the TC,respectively S_(M_((x=0.1)))≈2.654 J/(kg·K),S_(M_((x=0.2)))≈1.909 J/(kg·K).The RCP values are RCP_(x=0.1)=302.579 J/kg,RCP_(x=0.2)=236.319 J/kg.Combining the maximum magnetic entropy change value and RCP value,it can be seen that La_(0.87)Dy_(0.13)Mn_(0.9)Fe_(0.1)O_(3) has more potential as a magnetic refrigeration material than La_(0.87)Dy_(0.13)Mn_(0.8)Fe_(0.2)O_(3).