在Gd 1– x Dy x CrO 3中，将A处的两个磁离子的影响与电子，磁性和催化性质相关联,ACS Omega

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在Gd _{1– x} Dy _x CrO _3中，将A处的两个磁离子的影响与电子，磁性和催化性质相关联
ACS Omega ( IF 3.7 ) Pub Date : 2017-06-14 00:00:00 , DOI: 10.1021/acsomega.7b00480
Vikash Kumar Tripathi ₁ , Rajamani Nagarajan ₁

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考虑到没有关于钙钛矿结构的正铬铁矿的报道，该钙钛矿结构的正铬铁矿包含两个A-位磁性稀土离子，GdCrO ₃和Gd _1–_x Dy _x CrO ₃系列的逐渐被Dy ³⁺取代的样品已使用环氧化物介导的溶胶-凝胶法合成。使用高分辨率粉末X射线衍射，热分析，傅立叶变换红外光谱，拉曼光谱和紫外可见光谱，扫描电子显微镜（SEM）和透射电子显微镜（TEM）测量对样品进行了广泛表征。通过煅烧稀土硝酸盐，氯化铬（III）和环氧丙烷在800°C下反应2小时形成的干凝胶，可以得到具有正交晶钙钛矿结构的单相样品。在样品的场发射SEM（FE-SEM）和TEM图像中均观察到蠕虫状形态的均匀存在。使用低至4 K的SQUID磁力计进行的零场和场冷磁场测量表明，Neel温度为Gd _0.5 Dy_0.5 CrO ₃为155 K，大约介于GdCrO ₃（169 K）和DyCrO ₃（146 K）的中间值。对于Gd _0.5 Dy _0.5 CrO ₃样品，在外加电场下测量时，在〜38 K处观察到自旋重取向。由于这些亚铬酸盐的色带通过Kubelka-Munk函数确定，其光学带隙约为3 eV，因此证明了它们作为若丹明-6G染料水溶液光降解的催化剂的应用，其中占总染料的百分比为降解的降解随A位离子的平均离子半径而变化。即使存在H _2时，XO染料的催化氧化也观察到类似的系统趋势。O ₂，其中DyCrO ₃对反应的影响更大，其次是Gd _0.5 Dy _0.5 CrO ₃和GdCrO ₃。光催化和催化反应均遵循伪一级动力学。

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Correlating the Influence of Two Magnetic Ions at the A-Site with the Electronic, Magnetic, and Catalytic Properties in Gd1–xDyxCrO3

Considering the absence of reports dealing with the perovskite-structured orthochromites containing two A-site magnetic rare-earth ions, GdCrO₃ and progressively Dy³⁺-substituted samples of the series Gd_1–xDy_xCrO₃ have been synthesized employing the epoxide-mediated sol–gel procedure. The samples were characterized extensively using high-resolution powder X-ray diffraction, thermal analysis, Fourier transform infrared, Raman, and UV–visible spectroscopies, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) measurements. Monophasic samples possessing an orthorhombic perovskite structure emerged by calcining the xerogels formed by the reaction of rare-earth nitrates, chromium(III)chloride, and propylene oxide at 800 °C for 2 h. Uniform presence of wormlike morphology was observed in both the field emission SEM (FE-SEM) and TEM images of the samples. Zero-field and field-cooled magnetic measurements using a SQUID magnetometer down to 4 K showed that the Neel temperature of Gd_0.5Dy_0.5CrO₃ was 155 K, more or less midway between the values observed for GdCrO₃(169 K) and DyCrO₃ (146 K). For the Gd_0.5Dy_0.5CrO₃ sample, a spin reorientation was observed at ∼38 K when measured under an applied field. Because the optical band gap, determined by Kubelka–Munk function, of these chromites was around 3 eV, their application as a catalyst for the photodegradation of the aqueous rhodamine-6G dye solution was demonstrated, in which the percentage of the total dye that was degraded varied with the average ionic radius of A-site ions. A similar systematic trend was observed even for the catalytic oxidation of the XO dye in the presence of H₂O₂, with DyCrO₃ influencing the reaction to a greater extent followed by Gd_0.5Dy_0.5CrO₃ and GdCrO₃. Both the photocatalytic and catalytic reactions followed pseudo-first-order kinetics.

更新日期：2017-06-26

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