论文部分内容阅读
通过传统的固相反应法制备了多层钙钛矿锰氧化物Ba_(6-x)Sr_xMn_5O_(16)(x=0,0.5,1.0,1.5)系列单相样品,比较详细地分析了样品的结构和磁性变化规律。通过室温X射线衍射(XRD)测试,样品为纯的单相n=5的Ruddlesden-Popper型钙钛矿结构,具有四方结构的Cmca(No.64)空间群。采用超导量子磁强计(SQUID)对该系列样品的磁性进行了研究。通过采用超导量子磁强计(SQUID)测量样品Ba6Mn5O16的磁化强度随温度变化曲线得出:由于低温强的三维反铁磁耦合,当温度低于75 K时,零场冷却(ZFC)和带场冷却(FC)曲线几乎重合。当温度达到奈尔温度TN(≈150 K)时,三维的反铁磁耦合完全被破坏,曲线的特征有一个明显的大鼓包。在温度低于50 K时,观察到居里尾(Curie tail)。随着Sr离子替代Ba离子量的增加,TN逐渐降低。样品在TN附近有很宽的转化峰,很可能存在三维反铁磁耦合到二维反铁磁耦合再到顺磁的连续变化过程。
A series of single-phase samples of Ba_ (6-x) Sr_xMn_5O_ (16) (x = 0,0.5,1.0,1.5) series with perovskite oxides were prepared by the conventional solid-state reaction method. Structure and magnetic changes. The samples were pure Ruddlesden-Popper-type perovskite structures with n = 5 and Cmca (No.64) space groups with tetragonal structure by X-ray diffraction (XRD) at room temperature. The magnetic properties of this series of samples were investigated using a superconducting quantum magnetometer (SQUID). The magnetization of Ba6Mn5O16 sample with the SQUID measurement shows that due to the strong three-dimensional antiferromagnetic coupling at low temperature, when the temperature is lower than 75 K, the zero field cooling (ZFC) and band Field cooling (FC) curves almost coincide. When the temperature reached Nel temperature TN (≈150 K), the three-dimensional anti-ferromagnetic coupling was completely destroyed, and the curve was characterized by an obvious bulge. At temperatures below 50 K Curie tail was observed. TN gradually decreases with the increase of Sr ions instead of Ba ions. The sample has a wide range of transformation peaks near TN. It is possible that there is a continuous three-dimensional antiferromagnetic coupling to two-dimensional antiferromagnetic coupling and subsequent paramagnetic changes.