Evolution of Iron Electronic State in the Solid Solutions Gd2-xSr1+xFe2O7-δ

2012 ◽  
Vol 194 ◽  
pp. 116-119 ◽  
Author(s):  
Anastasya Shilova ◽  
Irina Chislova ◽  
V. Panchuk ◽  
V. Semenov ◽  
Irina Zvereva
Keyword(s):  
Electronic State ◽  
Oxidation State ◽  
Solid Solutions ◽  
Sol Gel ◽  
Ceramic Technology ◽  
Isovalent Substitution ◽  
The Difference ◽  
Perovskite Type ◽  
Ordered State ◽  
Magnetically Ordered

The present study is devoted to the non-isovalent substitution of Gd+3 for Sr+2 in matrix of Gd2-xSr1+xFe2O7 with perovskite-type intergrowth structure and to the investigation of oxidation state of iron depending on the method of synthesis and the content of solid solutions. Mössbauer spectroscopy showed the difference in the structure of complex ferrite Gd2SrFe2O7 obtained by ceramic technology (iron in single Fe+3 magnetically ordered state) from oxides obtained by the sol - gel technology (Fe+3 in the three different surroundings and presence of Fe+4).

scholarly journals Spray‐dried sol‐gel glass‐ceramic powders based on the tunable thermal expansion of quartz and keatite solid solutions

2021 ◽  
Author(s):  
Alessio Zandona ◽  
Gundula Helsch ◽  
Aurina Martínez Arias ◽  
Alfred P. Weber ◽  
Joachim Deubener
Keyword(s):  
Thermal Expansion ◽  
Solid Solutions ◽  
Glass Ceramic ◽  
Sol Gel ◽  
Ceramic Powders ◽  
Spray Dried

Electronic state of 57Fe probe atoms in perovskite-type Ni(III) and Cu(III) oxides

2010 ◽  
Vol 74 (3) ◽  
pp. 384-388
Author(s):  
I. A. Presniakov ◽  
V. S. Rusakov ◽  
A. V. Sobolev ◽  
G. Demazeau ◽  
M. E. Matsnev ◽  
...  
Keyword(s):  
Electronic State ◽  
Perovskite Type

Effect of Complexing Agent on Morphology and Crystal Structure of La1-xCexCoO3 (x=0, 0.2, and 0.4) Perovskite-Type Mixed Oxides Catalyst Prepared by Sol-Gel Method

2010 ◽  
Vol 658 ◽  
pp. 29-32 ◽  
Author(s):  
Kanit Soongprasit ◽  
Duangdao Aht-Ong ◽  
Viboon Sricharoenchaikul ◽  
Duangduen Atong
Keyword(s):  
Crystal Structure ◽  
Polyvinyl Alcohol ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Value Added ◽  
Molar Ratio ◽  
Complexing Agent ◽  
Nitrate Hexahydrate ◽  
Mixed Oxide Catalysts ◽  
Perovskite Type

. La1-xCexCoO3 (x=0, 0.2, and 0.4) perovskite-type mixed oxides using polyvinyl alcohol (PVA) as complexing agent at two molar ratio of metal ion to PVA (1:1 and 1:2) were successfully prepared by sol-gel process. The precursor included lanthanum (II) nitrate hexahydrate, cerium (II) nitrate hexahydrate, and cobalt (II) nitrate hexahydrate where polyvinyl alcohol was added as complexing agent. The suitable condition of Cerium (Ce) substitution and PVA molar ratio were established for further application in hydrocarbon conversion to high value added products. TGA thermogram of as-prepared precursor showed that PVA absolutely decomposed at temperature higher than 500°C. XRD patterns of calcined catalyst showed both LaCoO3 rhombohedral and CeO2 cubic structures that confirmed the formation of mixed crystal structure. Nevertheless, Co3O4 slightly appeared with low peak intensity which came from the oxidation reaction of as-prepared catalyst during calcinations. XRD showed that PVA did not effect to crystal structure of synthesized catalyst. Higher PVA content added in the precursor cause the reduction of crystal growth of catalyst in calcinations step. In contrast, morphology of catalyst is directly related with PVA content such that the spongy and sheet-like structure were formed with increasing PVA content which prevented the agglomeration of particles. The results showed that PVA content play an important role in morphology of perovskite-type mixed oxide catalysts but did not affected to their crystal structures.

ChemInform Abstract: Nanometric Solid Solutions of the Fluorite and Perovskite Type Crystal Structures: Synthesis and Properties

ChemInform ◽  
2013 ◽  
Vol 44 (28) ◽  
pp. no-no
Author(s):  
Snezana Boskovic ◽  
Slavica Zec ◽  
Branko Matovic ◽  
Zorana Dohcevic-Mitrovic ◽  
Zoran Popovic ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Solid Solutions ◽  
Perovskite Type ◽  
Type Crystal

Sintering and Oxygen Ionic Conducting Properties of Bi2V0.9Co0.1O5.5-δ Derived from an EDTA-Citrate Precursor

2007 ◽  
Vol 124-126 ◽  
pp. 731-734
Author(s):  
Feng Zhang ◽  
Qing Xu ◽  
Duan Ping Huang ◽  
Wen Chen ◽  
Han Xing Liu ◽  
...  
Keyword(s):  
Sol Gel ◽  
Fine Powder ◽  
Synthesis Process ◽  
Complexing Agents ◽  
Aurivillius Phase ◽  
Disorder Phase Transition ◽  
Dense Microstructure ◽  
Ionic Conducting ◽  
Sintering Properties ◽  
The Difference

Bi2V0.9Co0.1O5.5-δ with a pure Aurivillius phase was synthesized by a sol-gel method using EDTA and citric as mixed complexing agents. It was found that homogeneous and fine powder (100-200 nm) with a pure Aurivillius phase can be produced by calcining the complex precursor at 450 °C for 1h in air. The sintering properties of Bi2V0.9Co0.1O5.5-δ were investigated in the range of 560-680 °C with respect to relativity density. Sintering at 640 °C was ascertained to be preferred for Bi2V0.9Co0.1O5.5-δ, producing a dense microstructure with uniform grains around 3-5 μm. The Bi2V0.9Co0.1O5.5-δ ceramic exhibits an oxygen ionic conductivity of 1.0×10-1 S·cm-1 at 600 °C. The difference between the activation energies for the ionic conducting in low and high temperature regions is qualitatively interpreted in terms of an order-disorder phase transition. This research demonstrates the advantage of the EDTA-citrate method in preparing Bi2V0.9Co0.1O5.5-δ with respect to the simplicity of synthesis process, desired morphology of synthesized powder, low sintering temperature and superior ionic conducting properties of ceramic specimen.

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