PDF《D02.多铁性材料》

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多铁性材料 分会主席:董帅、殷月伟、马静、张金星、刘俊明 D02-01 六角铁氧体多铁性材料新体系探索 陈湘明,刘娟,孙土来,刘小强,田鹤,高庭庭 浙江大学 与六角稀土锰酸盐类似,六角稀土铁氧体 h-RFeO3 的铁电性起源于其结构基元-FeO5 双金字塔的畸变,而这种畸变必然 导致 Fe-O-Fe 超交换作用的变化,最终导致本征的电控磁性.同时,稀土铁氧体的磁转变温度一般高于稀土锰酸盐,因而有 望成为诱人的室温多铁性新体系.然而,稀土铁氧体的室温稳定结构为正交钙钛矿结构,h-RFeO3 通常为亚稳定相.本工作 通过 In 部分置换 LuFeO3 中的 Lu、引入化学压,从而在宽成分范围内获得了稳定的 h- Lu1-xInxFeO3 固溶体陶瓷.自x=0.4 起可获得六角单相结构,x=0.4~0.6 的范围内为 P63cm 结构,x=0.75 时转变为 P63/mmc 结构.随着 In 置换量增加,从P63/ mmc 到P63cm 的相变点 TC 从>

1000K 单调降低至室温以下.虽因其电导率过高,未能测得饱和的电滞回线.根据 X 射线衍 射数据可计算离子偏离中心对称结构的位移,从而计算出(Lu1-xInx)FeO3 对应于 x=0.4, 0.5 与0.6 的自发极化值:1.98, 2.94 与1.93mC/cm2 .通过球差矫正电子显微镜直接观察到了其铁电离子位移与 幸运花瓣 铁电畴结构.该材料为反铁磁体,表现 出明显的室温弱铁磁性,而随着温度进一步下降会转变成铁磁体.室温铁电与弱铁磁性的确定,显示出 h-(Lu1-xInx)FeO3 作 为室温多铁性材料新体系的巨大潜力. D02-02 Stacking Fault in Polar Magnet Zn2FeNbO6 李满荣

1 ,韩艺丰

1 ,吴枚霞

1 ,David Walker2 ,Martha Greenblatt3 1.中山大学化学学院 2.Lamont Doherty Earth Observatory, Columbia University,

61 Route 9W, PO Box

1000 Palisades, New York

10964 United States 3.Department of Chemistry and Chemical Biology, Rutgers, the State University of New Jersey,

610 Taylor Road, Piscataway, New Jersey 08854, United States The coexistence of spontaneous polarization (PS) and magnetic ordering in polar magnet makes it promising for multiferroic and magnetoelectric applications in spintronics. A good example is the LiNbO3-type Zn2FeTaO6, which demonstrates PS of ~

51 μ C/cm2 and antiferromagnetic ordering below ~

25 K. A weak switchable component is also observed around

2 K. Here we present the study on the parent polar magnet Zn2FeNbO6. Attempts to make Zn2FeNbO6 at similar high-pressure condition were successful but original crystal structure analysis was frustrated. Although synchrotron X-ray diffraction techniques clearly indicate isostructural LiNbO3-type symmetry of Zn2FeNbO6, routine Rietvled refinements never converge to an acceptable fitting. Detailed electron diffraction and crystallographic simulation revealed stacking fault in the honeycomb layers in ab-plane, which well explained the diffraction data using updated structural model. Given the similar ionic size and electron configuration between Nb5+ and Ta5+ , the reason that the stacking fault is absent in Zn2FeTaO6 but appears in Zn2FeNbO6 is unclear and thus needs further investigation. D02-03 DyCrO4 高压相大线性磁电耦合效应及场诱导的铁磁铁电 龙有文 中国科学院物理研究所 DyCrO4 是一种罕见的具有 Cr5+ 电荷态的化合物,常压下结晶为锆石型晶体结构(空间群 I41/amd) .该相对外加压力非 常敏感,高压下会发生一级不可逆结构相变,转变成白钨矿型晶体结构(空间群 I41/a) .经过一定压力与温度处理,我们得 到了白钨矿型 DyCrO4 高压相,并通过不同温度与磁场下磁化率、磁化强度、比热、介电常数、热释电、中子衍射等系列测 试,详细研究了材料的磁电性能.白钨矿型 DyCrO4 具有共线非极化反铁磁基态,在±3T 磁场范围内,展示了线性磁电耦 合与逆磁电耦合效应,并且线性磁电耦合系数高达