Key Role of Bismuth in the Magnetoelastic Transitions of Ba3BiIr2O9 and Ba3BiRu2O9 As Revealed by Chemical Doping

详细信息    查看全文

• 作者：Peter E. R. Blanchard ; Zixin Huang ; Brendan J. Kennedy ; Samuel Liu ; Wojciech Miiller ; Emily Reynolds ; Qingdi Zhou ; Maxim Avdeev ; Zhaoming Zhang ; Jade B. Aitken ; Bruce C. C. Cowie ; Ling-Yun Jang ; Thiam Teck Tan ; Sean Li ; Chris D. Ling
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：January 21, 2014
• 年：2014
• 卷：53
• 期：2
• 页码：952-960
• 全文大小：570K
• ISSN：1520-510X

文摘

The key role played by bismuth in an average intermediate oxidation state in the magnetoelastic spin-gap compounds Ba₃BiRu₂O₉ and Ba₃BiIr₂O₉ has been confirmed by systematically replacing bismuth with La³⁺ and Ce⁴⁺. Through a combination of powder diffraction (neutron and synchrotron), X-ray absorption spectroscopy, and magnetic properties measurements, we show that Ru/Ir cations in Ba₃BiRu₂O₉ and Ba₃BiIr₂O₉ have oxidation states between +4 and +4.5, suggesting that Bi cations exist in an unusual average oxidation state intermediate between the conventional +3 and +5 states (which is confirmed by the Bi L₃-edge spectrum of Ba₃BiRu₂O₉). Precise measurements of lattice parameters from synchrotron diffraction are consistent with the presence of intermediate oxidation state bismuth cations throughout the doping ranges. We find that relatively small amounts of doping (10 at%) on the bismuth site suppress and then completely eliminate the sharp structural and magnetic transitions observed in pure Ba₃BiRu₂O₉ and Ba₃BiIr₂O₉, strongly suggesting that the unstable electronic state of bismuth plays a critical role in the behavior of these materials.