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A-site-ordered quadruple perovskite manganite CeMn7O12 with trivalent cations
Journal of Solid State Chemistry ( IF 3.2 ) Pub Date : 2019-12-30 , DOI: 10.1016/j.jssc.2019.121161
Alexei A. Belik , Lei Zhang , Noriki Terada , Yoshio Katsuya , Masahiko Tanaka , Yoshitaka Matsushita , Kazunari Yamaura

A-site-ordered quadruple perovskite CeMn7O12 – the first ternary oxide in the Ce–Mn–O system – was synthesized at high pressure of 6 GPa and high temperature of about 1670 K, and its structural, magnetic, and dielectric properties were investigated. CeMn7O12 crystallizes in space group Im-3 above 649 K, and in space group I2/m below 649 K. No other structural phase transitions were found down to 10 K. Crystal structures were investigated using synchrotron X-ray powder diffraction (a = 7.50069 Å, b = 7.36836 Å, c = 7.49086 Å, β = 91.2125° at 295 K and a = 7.47367 Å at 700 K), and the structural parameters (Ce–O bond lengths) suggest the Ce3+ oxidation state giving the charge distribution as Ce3+Mn3+7O12. CeMn7O12 shows one long-range-ordered ferrimagnetic transition at TN = 78 K accompanied by very weak kink-like dielectric anomalies. Strong dielectric relaxation due to extrinsic processes was observed near 18–35 K.



中文翻译:

具有三价阳离子的A阶有序四钙钛矿锰锰矿CeMn 7 O 12

在6 GPa的高压和大约1670 K的高温下合成了A-位有序四重钙钛矿CeMn 7 O 12 -Ce-Mn-O系统中的第一个三元氧化物,其结构,磁性和介电性能被调查了。CeMn 7 O 12在高于649 K的空间群Im -3和低于649 K的空间群I 2 / m中结晶。在低至10 K时未发现其他结构相变。使用同步加速器X射线粉末衍射研究了晶体结构( 在295 K时a  = 7.50069Å,b  = 7.36836Å,c  = 7.49086Å,β = 91.2125° 在700 K时a = 7.47367Å),结构参数(Ce–O键长)表明Ce 3+的氧化态,电荷分布为Ce 3+ Mn 3+ 7 O 12。CeMn 7 O 12T N  = 78 K处显示出一个长范围的亚铁磁跃迁,伴随着非常弱的扭结状介电异常。在18–35 K附近观察到由于外在过程而引起的强介电弛豫。

更新日期:2019-12-31
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