论文标题
Perovskite SM $ _ {1-x} $ sr $ _x $ nio $ _3 $（x = 0，0.2）和infinite-layer sm $ _ {0.8} $ _ {0.8} $ sr $ _ {0.2}
Synthesis and physical properties of perovskite Sm$_{1-x}$Sr$_x$NiO$_3$ (x = 0, 0.2) and infinite-layer Sm$_{0.8}$Sr$_{0.2}$NiO$_2$ nickelates
论文作者
论文摘要
最近，在nd $ _ {1-x} $ _x $ _x $ nio $ _2 $ infinite-layer薄膜中发现了大约9-15k的超导性，这激发了人们对相关稀有稀有镍盐的巨大兴趣。通常，合成这一112阶段的第一步是制造RNIO $ _3 $相位，但是，据报道，由于形成了不寻常的Ni $^{3+} $氧化状态，因此很难成功合成113期。随着稀土元件的离子半径减少，制备的难度得到了增强。在这项工作中，我们报告了对多晶Perovskites的多种物理特性的综合和调查电影。通过X射线衍射和能量分散X射线谱进行的结构和组成分析表明，样品主要包含Sm $ _ {1-X} $ SR $ _X $ _X $ _X $ nio $ _3 $的钙钛矿相和少量NIO Inio Inlurities。磁化和电阻率测量表明，在全局绝缘背景下，母体相位$ _3 $在约224K处经历顺磁性 - 抗磁力磁性过渡。相比之下，SR掺杂的样本SM $ _ {0.8} $ sr $ _ {0.2} $ nio $ _3 $显示出金属行为从300k到约12k，而低于12k的电阻率显示出轻微的对数增长。同时，从磁化曲线中，我们可以看到，可能的旋转玻璃状态出现在SM $ _ {0.8} $ sr $ _ {0.2} $ nio $ $ _3 $中的12k以下。使用软化学减少方法，我们还获得了无限层相位SM $ _ {0.8} $ sr $ _ {0.2} $ nio $ _2 $，带有Square Nio $ _2 $ planes。该化合物显示出一种绝缘行为，可以通过三维可变范围模型来描述。在polycrystalline SM $ _ {0.8} $ sr $ _ {0.2} $ nio $ _2 $中，超导性仍然不存在。
Recently, superconductivity at about 9-15K was discovered in Nd$_{1-x}$Sr$_x$NiO$_2$ infinite-layer thin films, which has stimulated enormous interests in related rare-earth nickelates. Usually, the first step to synthesize this 112 phase is to fabricate the RNiO$_3$ phase, however, it was reported that the 113 phase is very difficult to be synthesized successfully due to the formation of unusual Ni$^{3+}$ oxidation state. And the difficulty of preparation is enhanced as the ionic radius of rare-earth element decreases. In this work, we report the synthesis and investigation on multiple physical properties of polycrystalline perovskites Sm$_{1-x}$Sr$_x$NiO$_3$ (x = 0, 0.2) in which the ionic radius of Sm$^{3+}$ is smaller than that of Pr$^{3+}$ and Nd$^{3+}$ in related superconducting thin films. The structural and compositional analyses conducted by X-ray diffraction and energy dispersive X-ray spectrum reveal that the samples mainly contain the perovskite phase of Sm$_{1-x}$Sr$_x$NiO$_3$ with small amount of NiO impurities. Magnetization and resistivity measurements indicate that the parent phase SmNiO$_3$ undergoes a paramagnetic-antiferromagnetic transition at about 224K on a global insulating background. In contrast, the Sr-doped sample Sm$_{0.8}$Sr$_{0.2}$NiO$_3$ shows a metallic behavior from 300K down to about 12K, while below 12K the resistivity exhibits a slight logarithmic increase. Meanwhile, from the magnetization curves, we can see that a possible spin-glass state occurs below 12K in Sm$_{0.8}$Sr$_{0.2}$NiO$_3$. Using a soft chemical reduction method, we also obtain the infinite-layer phase Sm$_{0.8}$Sr$_{0.2}$NiO$_2$ with square NiO$_2$ planes. The compound shows an insulating behavior which can be described by the three-dimensional variable-range-hopping model. And superconductivity is still absent in the polycrystalline Sm$_{0.8}$Sr$_{0.2}$NiO$_2$.
