BiMnO 3的高温高压合成及其结构和磁性研究

High pressure high temperature synthesis of BiMnOP_3 and its structure and magnetic properties

利用国产六面顶液压机,以 Bi2 O 3、MnO 2和Mn 粉末为原料（n （Bi2 O 3）/n （MnO 2）/n （Mn ）＝2∶3∶1）,在高温高压条件下（3～5 GPa,600～800℃）,制备了钙钛矿结构 BiMnO 3烧结体.利用 X 射线衍射仪（XRD）、扫描电子显微镜（SEM）、振动样品磁强计（VSM）对烧结样品进行了测试分析,考察了烧结温度、压力对样品结构、组织形貌及磁性的影响.实验结果表明,当烧结温度为600℃时,钙钛矿结构BiMnO 3晶粒开始形成,随着温度的升高,其相对含量增加,比饱和磁化强度逐渐增大,而比饱和磁化强度随着压力增大,先增大后减小；样品矫顽力随晶粒尺寸减小而减小.合成钙钛矿结构 BiMnO 3单相最佳实验条件为4 GPa,800℃,1 h,其居里温度为99 K,在90 K的测试温度条件下,最大的比饱和磁化强度为35 A·m2/kg,最小的矫顽力为37．6×79．6 A/m.

The BiMnO 3 sintered body with perovskite structure was prepared,using Bi2 O 3 ,MnO 2 and Mn pow-ders as starting materials (n (Bi2 O 3 )/n (MnO 2 )/n (Mn)=2∶3∶1),under high temperature and high pressure (HPHT,3-5 GPa,600-800 ℃)conditions in a China CS-IV type cubic-anvil high pressure apparatus (CHPA). The sintered samples were tested and analyzed by using X-ray diffraction (XRD),scanning electron microscopy (SEM)and vibrating sample magnetometer (VSM),and the effects of sintering temperature and pressure on the sample structure,morphology and magnetic properties were studied.The experimental results show that:when the sintering temperature was 600 ℃,the grains of perovskite BiMnO 3 begin to form;with the increase of temperature,the relative content of BiMnO 3 increases and the saturation magnetization increases gradually. While the saturation magnetization increases first and then decreases with the pressure increases;the coercivity decreases with decreasing of grain size.The optimum experimental synthesis conditions of BiMnO 3 single-phase with perovskite structure are 4 GPa,800 ℃,1 h,and its Curie temperature was 99 K.Under the test-tempera-ture of 90 K, the maximum saturation magnetization and minimum coercivity were 35 A ?? m2/kg and 37.6×79.6 A/m respectively.