کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7744244 | 1498220 | 2018 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
A-site substitution effect on crystal structure and properties of Nd1âxAxMn0.5Fe0.5O3âδ (ACa, Sr, Ba; xâ¯=â¯0, 0.25)
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
الکتروشیمی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: A-site substitution effect on crystal structure and properties of Nd1âxAxMn0.5Fe0.5O3âδ (ACa, Sr, Ba; xâ¯=â¯0, 0.25) A-site substitution effect on crystal structure and properties of Nd1âxAxMn0.5Fe0.5O3âδ (ACa, Sr, Ba; xâ¯=â¯0, 0.25)](/preview/png/7744244.png)
چکیده انگلیسی
The effect of A-site substitution by alkaline earth metals (ABa, Sr, Ca) on the crystal structure and properties of the Nd1âxAxMn0.5Fe0.5O3âδ (xâ¯=â¯0, 0.25) perovskite-like oxides were studied in the temperature range of 25-1000â¯Â°C in air. The Nd1âxAxMn0.5Fe0.5O3âδ samples were synthesized by the citrate-nitrate combustion technique. X-ray powder diffraction (XRPD) patterns were refined by the Rietveld method using orthorhombic unit cell for NdMn0.5Fe0.5O3âδ and Nd0.75Ba0.25Mn0.5Fe0.5O3âδ (sp. gr. Pnma); and monoclinic unit cell for Nd0.75Ca0.25Mn0.5Fe0.5O3âδ and Nd0.75Sr0.25Mn0.5Fe0.5O3âδ (sp. gr. P21/n). The refinement results for the single-phase samples revealed that the unit cell volume decreased while decreasing the size of A-dopant in Nd1âxAxMn0.5Fe0.5O3âδ. Oxygen content and oxidation state of Mn in Nd1âxAxMn0.5Fe0.5O3âδ increased in the row: Nd0.75Ca0.25Mn0.5Fe0.5O2.81, Nd0.75Sr0.25Mn0.5Fe0.5O2.85, Nd0.75Ba0.25Mn0.5Fe0.5O2.93 at all temperature studied. Oxygen non-stoichiometry of the Nd1âxAxMn0.5Fe0.5O3âδ samples was almost independent of temperature even at high temperatures except for NdMn0.5Fe0.5O3âδ. The thermal expansion coefficient (TEC) for Nd0.75Ba0.25Mn0.5Fe0.5O3âδ was found to be 10.1â¯Ãâ¯10â6â¯Kâ1 in the range of 25-800â¯Â°C. Temperature dependencies of total conductivity possessed semiconductor-type behavior and were interpreted within the small polaron hopping mechanism. The maximum value of conductivity (25â¯S/cm) was obtained for Nd0.75Ba0.25Mn0.5Fe0.5O3âδ at 1000â¯Â°C in air. The Seebeck coefficient values decreased with temperature from positive to negative values indicating that both electrons and electron holes may contribute to the electric conductivity of the oxides.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Solid State Ionics - Volume 323, 1 October 2018, Pages 64-71
Journal: Solid State Ionics - Volume 323, 1 October 2018, Pages 64-71
نویسندگان
A.R. Gilev, A. Hossain, E.A. Kiselev, V.A. Cherepanov,