Structural, magnetic, and oxygen storage properties of hexagonal Dy1-xYxMnO3+δ
Structural, magnetic, and oxygen storage properties of hexagonal Dy1-xYxMnO3+δ
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DOI：
10.1016/j.jssc.2014.05.017
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发表时间：
2014-09-01
影响因子：
3.3
通讯作者：
Chmaissem, O.
中科院分区：
文献类型：
--
作者：
Abughayada, C.;Dabrowski, B.;Chmaissem, O.
单相多晶样品的六方Dy 1-xYxMnO 3 + δ在整个溶解度范围内还原氧分压条件下合成。使用中子粉末衍射数据（NPD）的Rietveld精修证实了所有化学计量（δ =0）样品的母体六方P（63）cm（空间群#185）结构的持久性。由NPD数据得到的（Mn-O）键长与三角双锥配位的Mn+3高自旋态e“2 e”2相一致。详细的热重测量显示在空气或氧气气氛中在200-400 ℃的异常低温下具有大的可逆氧储存/释放能力（在氧含量3.0-3.3的范围内）。对于氧负载的富Dy样品（x < 0.5），观察到向新的六方相（Hexl）的相变发生在约5-0.29。使用Rietveld精化的X射线和中子衍射数据的分析表明，超结构是通过将原始P63 cm晶胞的c轴增加三倍而形成的。对Hexl超结构的建模收敛到与非中心对称空间群R3 c（#161）一致的结构对称性。在磁化强度测量中，在低于8 K下观察到DyMn 03.0的亚铁磁有序。Dy的磁性被稀土钇稀释，导致转变温度和有效顺磁矩都降低。(C)2014爱思唯尔公司All rights reserved.
Single-phase polycrystalline samples of hexagonal Dy1-xYxMnO3+delta were synthesized over the full solubility range under reducing oxygen partial pressure conditions. Rietveld refinements using neutron powder diffraction data (NPD) confirmed the persistence of the parent hexagonal P(63)cm (Space group #185) structure for all the stoichiometric (delta=0) samples. The (Mn-O) bond lengths derived from NPD data were found to be consistent with non-degenerate Mn+3 high-spin state e"2 e'2 in trigonalbipyramidal coordination. Detailed thermogravimetric measurements show large reversible oxygen storage/release capabilities (within the range of oxygen content 3.0-3.3) at unusually low temperatures of 200-400 degrees C in air or oxygen atmospheres. A phase transition to a new hexagonal phase (Hexl) was observed to take place around 5-0.29 for the oxygen-loaded Dy-rich samples (x < 0.5). Analysis of x-ray and neutron diffraction data using Rietveld refinements demonstrate that the superstructure is formed by tripling the c-axis of the original P63cm unit cell. Modeling of the Hexl superstructure converged to a structural symmetry consistent with the noncentrosymmetric space group R3c (#161). In magnetization measurements, a ferrimagnetic order for DyMn03.0 was observed below 8 K. The dilution of Dy magnetism with nonmagnetic yttrium results in reducing both the transition temperature and the effective paramagnetic moment. (C) 2014 Elsevier Inc. All rights reserved.