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Abstract  

In this paper the influence of alkaline-earth admixtures on the synthesis of lanthanum chromites of La1–xMxCrO3 (x=0; 0.3; M=Ca, Sr, Ca+Sr) type was studied. The formation mechanism as well as the phase composition evolution, under non-isothermal and isothermal conditions, were investigated by thermal analysis and X-ray diffraction. The structure of the compounds and of the solid solutions formed depends on the solute type by means of the structural distortion induced. The crystallinity of the chromites obtained is obviously influenced by both the temperature and the thermal treatment plateau.

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Abstract

Acceptor doped lanthanum chromites are potential interconnect materials to be used in high temperature Solid Oxide Fuel Cells (SOFC). However, instability of these materials when exposed to low oxygen partial pressure causes a volume expansion that can be detrimental to the SOFC performance. The stability of La0.8Sr0.2Cr0.97V0.03O3 is determined as function ofpO2 and temperature by isothermal thermogravimetry and dilatometry. The experimental data are analysed using a simple model for the defect chemistry. The relation between expansion behaviour and change in defect chemistry is discussed using a simple structural model.

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Journal of Thermal Analysis and Calorimetry
Authors: Érika Marinho, A. Souza, Danniely de Melo, Iêda Santos, Dulce Melo, and Walquíria da Silva

Abstract  

Because of their electrical, magnetic and catalytic properties rare earth and transition metal mixed oxides are important compounds. Lanthanum chromites have been extensively used as solid oxide fuel cell (SOFC) interconnect materials. In this work, lanthanum chromites partially substituted by alkaline earth metals were synthesized by the urea combustion process. TG and DSC techniques were used to evaluate the presence of the organic material in the powder after reaction on the hot plate. The powders were calcinated at 900C and characterized by XRD and SEM. The results show that the particles have nanometric dimensions and the perovskite structure was formed.

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LaCrO3 powder from lanthanum trisoxalatochromate(III) (LTCR) precursor

Microwave aided synthesis and thermal characterization

Journal of Thermal Analysis and Calorimetry
Authors: Y. Malghe and S. Dharwadkar

Abstract  

Lanthanum chromite LaCrO3, an important catalyst and interconnect material used in solid oxide fuel cell was prepared from lanthanumtrisoxalatochromate(III) hydrate [LaCr(C2O4)3]·9H2O (LTCR) employing microwave heating technique. The compound LTCR heated in microwave heating system gave pure LaCrO3 at 500°C within one hour. However LTCR heated in silicon carbide furnace yielded LaCrO3 at 900°C. BET surface area of LaCrO3 prepared by microwave and conventional heating techniques were found to be 2.8 and 1.2 m2 g−1, respectively. Thermogravimetry, differential thermal analysis and X-ray diffraction techniques were used to optimize the conditions for the microwave processing of the precursor.

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Abstract  

The synthesis of strontium-doped lanthanum chromite, La1−xSrxCrO3 (x=0.1 and 0.3), used as an interconnect material for solid oxide fuel cells (SOFC), was investigated using two unconventional synthesis methods: (1) organic precursors’ method based on the thermal conversion of complex combination resulted in the oxidation reaction of 1,2-ethanediol by La3+, Sr2+ and Cr3+ nitrates; (2) combustion synthesis based on the exothermic redox reaction of La3+, Sr2+ and Cr3+ nitrates with urea and glycine as fuels. We also used a mixture of urea and glycine as fuel. The samples were characterized by means of thermal analysis and X-ray diffraction.

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Journal of Thermal Analysis and Calorimetry
Authors: Adney Luís A. da Silva, Guilherme G. G. Castro, and Mariana M. V. M. Souza

-like lanthanum chromites are interesting materials for application in solid oxide fuel cells (SOFCs) due to chemical and thermal stability, mechanical strength, and high electrical conductivity [ 2 , 3 ]. The electrical conductivity of these materials can be

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Introduction Transition metal and rare earth oxides have been known to exhibit interesting magnetic, electrical, and catalytic properties bringing tremendous potentialities to these materials. Lanthanum chromites [ 1 ], for

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Journal of Thermal Analysis and Calorimetry
Authors: A. Caneiro, L. Mogni, N. Grunbaum, and F. Prado

disadvantages of the SOFC is the high cost of the interconnection material (lanthanum chromites) and the present challenge is to reduce the operation temperature in order to replace lanthanum chromites by less expensive materials such as stainless steel. FC

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