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Structure and magnetism of non-perovskite sodium ruthenates and the effect of rare earth doping on calcium ruthenate.

机译：非钙钛矿型钌酸钠的结构和磁性，以及稀土掺杂对钌酸钙的影响。

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摘要

The synthesis and characterization of several ternary alkali and alkaline earth ruthenates are reported. Primary characterization techniques included x-ray and neutron diffraction, magnetic susceptibility, magnetization vs. applied magnetic field measurements and specific heat measurements.; The crystal structure of Na3RuO4, determined by powder neutron diffraction, is reported. The structure consists of isolated tetramers of edge sharing RuO6 octahedra in the ab plane, creating isolated 4-member plaquettes of Ru atoms comprised of two equilateral triangles sharing an edge. Magnetic susceptibility measurements reveal an antiferromagnetic-like transition at ∼29 K, with theta w = -141 K. Neutron diffraction data indicate the onset of three-dimensional magnetic ordering at 29 K.; The structures of NaRu2O4 and Na2.7Ru 4O9 are refined using neutron diffraction. NaRu2O 4 is a stoichiometric compound consisting of double chains of edge sharing RuO6 octahedra. Na2.7Ru4O9 is a non-stoichiometric compound with partial occupancy of the Na sublattice. The structure is a mixture of single, double and triple chains of edge-shared RuO6 octahedra. NaRu2O4 displays temperature independent paramagnetism with chio=1.23*10-4 emu/molRuOe. Na2.7Ru4O9 is paramagnetic, chi o=2.0*10-4 emu/molOe with thetaw= -11.8 K and a Curie constant of 0.0119 emu/molOeK. Specific heat measurements reveal a small upturn at low temperatures, similar to the upturn previously observed in La4Ru6O19. The electronic contribution to the specific heat (gamma) for Na2.7Ru4O 9 was determined to be 15 mJ/moleRuK2.; The synthesis and primary magnetic characterization of the Ca1-x RExRuO3 (RE=Nd, Pr; x=0.1, 0.2, 0.3, 0.4, 0.5) are reported. The structure of the parent compound, CaRuO3, is maintained for the series, and refined cell parameters show a steady increase, attributed to reduction of Ru+4 to the larger Ru+3 with RE incorporation. Magnetic susceptibility data show an increase in susceptibility with increasing rare-earth concentration. The localized magnetic moments of the rare earth atoms are postulated to be responsible for this observed increase. After correcting for the rare-earth magnetic contribution, the Nd-doped compounds appear to remain paramagnetic, where the Pr-doped deviate from normal paramagnetic behavior at low temperature. No magnetic hysteresis is observed, indicating the doped compounds are not ferromagnetic.
机译：报道了几种三元碱金属和碱土金属钌酸盐的合成和表征。主要表征技术包括X射线和中子衍射，磁化率，磁化与施加的磁场测量以及比热测量。报道了通过粉末中子衍射测定的Na 3 RuO 4的晶体结构。该结构由在ab平面中共享RuO6八面体的边的孤立四聚体组成，创建了由两个共享边的等边三角形组成的Ru原子的孤立4元斑块。磁化率测量结果表明，在〜29 K处出现了类似反铁磁的转变，θw = -141K。中子衍射数据表明在29 K处出现了三维磁序。 NaRu2O4和Na2.7Ru 4O9的结构使用中子衍射法精制。 NaRu 2 O 4是化学计量的化合物，由共享边的RuO6八面体的双链组成。 Na2.7Ru4O9是一种非化学计量的化合物，部分占据了Na亚晶格。该结构是边缘共享的RuO6八面体的单链，双链和三链的混合物。 NaRu 2 O 4显示出与温度无关的顺磁性，chio ＝ 1.23×10-4 emu / molRuOe。 Na2.7Ru4O9是顺磁性的，chi o = 2.0 * 10-4 emu / molOe，taw = -11.8 K，居里常数为0.0119 emu / molOeK。比热测量显示在低温下有一个小上升，类似于先前在La4Ru6O19中观察到的上升。测定Na2.7Ru4O 9对比热（γ）的电子贡献为15 mJ / moleRuK2。报道了Ca1-x RExRuO3（RE = Nd，Pr; x = 0.1，0.2，0.3，0.4，0.5）的合成和一次磁特性。该系列保留了母体化合物CaRuO3的结构，精制的电池参数显示出稳定的增加，这归因于Ru + 4还原为较大的Ru + 3（掺入RE）。磁化率数据显示，随着稀土浓度的增加，磁化率会增加。假定稀土原子的局部磁矩是造成这种观察到的增加的原因。校正稀土磁贡献后，掺钕的化合物似乎保持顺磁性，而掺where的化合物在低温下偏离正常的顺磁行为。没有观察到磁滞现象，表明掺杂的化合物不是铁磁性的。

著录项

  • 作者

    Regan, Kimberly Ann.;

  • 作者单位

    Princeton University.;

  • 授予单位 Princeton University.;
  • 学科 Chemistry Inorganic.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 141 p.
  • 总页数 141
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 无机化学;
  • 关键词

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