کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1330843 978978 2011 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Synthesis and structural analysis of Bi2−ySryIr2O7, a new pyrochlore solid solution
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی معدنی
پیش نمایش صفحه اول مقاله
Synthesis and structural analysis of Bi2−ySryIr2O7, a new pyrochlore solid solution
چکیده انگلیسی

This paper presents a study of the synthesis and structural properties of the new pyrochlore-type Bi2−ySryIr2O7 series. Ten compositions with 0.0≤y≤0.9 were prepared by solid-state reaction with thermal treatments at 873, 1073 and 1323 K under atmospheric pressure conditions. Structural refinements from X-ray powder diffraction data by the Rietveld method show that all compounds of the Bi2−ySryIr2O7 solid solution crystallize in a α-pyrochlore structure. The main structural difference when bismuth is substituted by strontium concerns the x position of the O1 (x, ⅛, ⅛). This substitution significantly increases the Bi/Sr–O1 distance and diminishes the Ir–O1 distance; this implies that the Ir–O1–Ir bond angle increases. With the Sr substitution, the IrO6 local configuration goes from a flattened trigonal antiprism, y<0.5, to an elongated one, y>0.5, passing through an octahedral array, y∼0.5. The electrical consequences of these structural changes observed in this system are qualitatively explained with electronic structure calculations, this behavior agrees very well with those observed in other pyrochlore systems A2M2O7 (A=rare earth cations or Tl+, Pb2+, or Bi3+, and M=Ru or Ir).

Electrical behavior of the Bi2−ySryIr2O7 solid solution.Figure optionsDownload as PowerPoint slideHighlights
► Bi2−ySryIr2O7 crystallizes in the α-pyrochlore structure.
► Local geometry of Ir goes from a flattened trigonal antiprism to an elongated one.
► Electrical resistivity increases with the Sr content in the solid solution.
► Electronic structure analysis relates resistivity with Sr disorder and bond strength.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Solid State Chemistry - Volume 184, Issue 5, May 2011, Pages 1251–1256
نویسندگان
, , ,