کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1333581 979085 2009 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Evidence of local defects in the oxygen excess apatite La9.67(SiO4)6O2.5 from high resolution neutron powder diffraction
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی معدنی
پیش نمایش صفحه اول مقاله
Evidence of local defects in the oxygen excess apatite La9.67(SiO4)6O2.5 from high resolution neutron powder diffraction
چکیده انگلیسی

From neutron diffraction data collected at 3 K on a powder of La9.67(SiO4)6O2.5 composition and a careful examination of the average structure, a model was proposed to explain the oxygen over-stoichiometry in the apatite structure. This model leads to realistic distances to neighbouring atoms. Moreover, it accounts perfectly for the maximum oxygen content observed in these materials. Up to 0.5 oxygen atom located at the vicinity of the 2a   site (0, 0, 14) would be shifted to a new interstitial position in the channel at (−0.01, 0.04, 0.06), creating a Frenkel defect, with the possibility of a maximum occupancy in this site equal to twice the Frenkel defect numbers. This structural model is in good agreement with the oxygen diffusion pathways recently proposed by Bechade et al. (2009) using computer modeling techniques. It supports preferred oxygen diffusion pathways via interstitial oxygen atoms and vacant sites along [0 0 1], close to the centre of the La(2)-O channels.

legendStructural defect position and possible conduction mechanism along the c-axis (representation of two adjacent unit-cells)Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Solid State Chemistry - Volume 182, Issue 12, December 2009, Pages 3358–3364
نویسندگان
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