Dy$_2$CoCrO$_6$ 纳米材料中自旋重取向转变的磁有序及光学性质研究
Investigation of magnetic ordering with spin reorientation transition and optical properties in Dy$_2$CoCrO$_6$ nanomaterials
AI总结：
本研究合成了多晶Dy$_2$CoCrO$_6$纳米颗粒，发现其具有正交结构、混合价态，在119 K发生反铁磁转变并在31 K发生自旋重取向，且1.97 eV的带隙使其在可见光催化领域具应用前景。
摘要：
本研究报告了多晶 Dy$_2$CoCrO$_6$ (DCCO) 纳米颗粒的合成与物理性质。使用 Rietveld 精修分析粉末 X 射线衍射 (XRD) 图谱表明，该化合物结晶于空间群为 Pbnm 的正交晶系结构。通过场发射扫描电子显微镜和透射电子显微镜的显微图像证实，其颗粒尺寸约为 57 nm。X 射线光电子能谱 (XPS) 研究确定了 Co 和 Cr 阳离子的混合价态。磁化率数据表明，在 140-340 K 温度范围内呈现 Curie-Weiss 行为，并在 119 K 的 Neel 温度下出现反铁磁相互作用。在 31 K 时，DCCO 表现出从 $Γ_4$(G$_x$A$_y$F$_z$) 到 $Γ_2$(F$_x$C$_y$G$_z$) 的自旋重取向转变。此外，室温磁化测量证明了其反铁磁行为及低温下的弱铁磁相互作用。另外，DCCO 表现出带直接光学带隙为 1.97 eV 的半导体特性，显示出在可见光驱动能量收集和催化应用中的前景。
英文摘要：
This study reports the synthesis and physical properties of polycrystalline Dy$_2$CoCrO$_6$ (DCCO) nanoparticles. Analysis of the powder X-ray diffraction (XRD) pattern using Rietveld refinement showed that the compound crystallizes in an orthorhombic crystal structure with a space group Pbnm. The particle size of approximately 57 nm was confirmed through micrographs obtained from field emission scanning electron microscopy and transmission electron microscopy. The X-ray photoelectron spectroscopy (XPS) investigations identified a mixed-valence state of Co and Cr cations. Magnetic susceptibility data indicated Curie-Weiss behavior in the temperature range 140-340 K and the onset of antiferromagnetic interactions with a Neel temperature of 119 K. At 31 K, DCCO shows spin reorientation transition from $Γ_4$(G$_x$A$_y$F$_z$) to $Γ_2$(F$_x$C$_y$G$_z$). Furthermore, room-temperature magnetization measurements demonstrated the antiferromagnetic behavior with weak ferromagnetic interactions at low temperatures. Additionally, DCCO exhibited semiconducting behavior with a direct optical bandgap of 1.97 eV, indicating promise for visible-light-driven energy harvesting and catalytic applications.
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