Characterization and thermal expansion of Sr2Feð‘�? Mo2−ð�?�¥O6 double perovskites

Bulletin of materials science

C Vishnuvardhan Reddy²  G Bhikshamaiah²  Y Markandeya¹  Y Suresh Reddy²  Shashidhar Bale¹ 

[1] Department of Physics, Nizam College, Osmania University, Hyderabad 500 001, India$$Department of Physics, Nizam College, Osmania University, Hyderabad 500 001, IndiaDepartment of Physics, Nizam College, Osmania University, Hyderabad 500 001, India$$;Department of Physics, Osmania University, Hyderabad 500 007, India$$Department of Physics, Osmania University, Hyderabad 500 007, IndiaDepartment of Physics, Osmania University, Hyderabad 500 007, India$$

关键词: Solâ€�?�gel chemistry;    oxides;    crystal structure;    electron microscopy;    thermal expansion.;   

DOI  :  

学科分类：材料工程

来源: Indian Academy of Sciences

【 摘 要 】

Double perovskite oxides Sr₂Fe_ð‘�?Mo_{2−ð�?��?}O₆(ð‘�? = 0.8, 1.0, 1.2, 1.3 and 1.4) (SFMO) of different compositions were prepared by solâ€�?�gel growth followed by annealing under reducing atmosphere conditions of H₂/Ar flow. X-ray powder diffraction studies revealed that the crystal structure of the samples changes from tetragonal to cubic at around ð‘�? = 1.2. Lattice parameters and unit cell volume of these samples found to decrease with the increase in Fe content. The characteristics absorption bands observed in the range 400â€�??1000 cm^âˆ�?1 of Fourier transform infrared spectra indicate the presence of FeO₆ and MoO₆ octahedra and confirm the formation of double perovskite phase. The value of g ∼ 2.00 obtained from electron spin resonance studies indicates that Fe is in 3+ ionic state in the SFMO samples. Dilatometric studies of these samples reveal that the average value of coefficient of thermal expansion ($overline{alpha}$) increases with the increase in temperature or Fe content in SFMO samples. The low value of coefficient of thermal expansion 1.31 Ã�? 10^âˆ�?6°C^âˆ�?1 obtained for Sr₂Fe_0.8Mo_1.2O₆ in the present study in the temperature range of 40â€�??100°C makes it useful as anode material in fuel cells. The coefficient of thermal expansion ($overline{alpha}$) and the unit cell volume (ð‘�??) of SFMO samples vary inversely with composition in agreement with Grüneisen relation.

【 授权许可】

Unknown