resumo
Impact of co-doping of Gadolinium (Gd) and Manganese (Mn) ions on the structural, electrical, optical and magnetic properties of SmCrO3 (SCO) orthochromite compound has been systematically investigated for the first time. The lattice volume expanded with only Mn substitution whereas it shrinks in the co-doped compounds. The tolerance factor decreased while the orthorhombic distortion was found to increase with co-doping. Tilt angle, theta([101]) (degrees) increased in the co-doped compounds. On the contrary, theta([010]) (degrees) initially decreased and then increased. The increased orthorhombic distortion with co-doping also influenced the Raman modes. The electrical resistivity got enhanced in the co-doped samples and its behavior was explained based on Mott's variable range hopping model. Hopping energy and mean hopping distance have also been estimated for the co-doped compounds. The optical bandgap of pristine SCO compound was observed to vary with co-doping, signifying the potential applications of these compounds as photocatalyst. Two compensation temperatures (defined as a temperature where the magnetization changes polarity) were noticed in co-doped compounds. The magnetization reversal was observed in all the co-doped compounds under lower applied magnetic field. The low temperature magnetocaloric effect got enhanced significantly with increasing co-doping content implying the usefulness of these compounds as low temperature refrigerant materials. (C) 2019 Elsevier B.V. All rights reserved.
palavras-chave
EXCHANGE-BIAS; REVERSAL; PEROVSKITE; TEMPERATURE; SPECTROSCOPY; PHONON; RAMAN
categoria
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
autores
Panwar, N; Coondoo, I; Kumar, S; Kumar, S; Vasundhara, M; Rao, A
nossos autores
Indrani Coondoo
Investigador Júnioragradecimentos
Dr. Neeraj Panwar would like to thank the DST SERB, New Delhi, UGC DAE CSR Mumbai and IUAC New Delhi for the grants through Projects ECR/2017/002681, CRS-M-298 and UFR-62317, respectively. Mr. Surendra Kumar is grateful to UGC, New Delhi for Rajiv Gandhi National Fellowship. Dr. M. Vasundhara is greateful to CSIR for the grants through projects MLP0031. This work is supported by national funds (OE), through FCT - Fundacao para a Ciencia e a Tecnologia, I. P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. The authors are also thankful to Dr. Saral Kumar Gupta of Department of Physics, Banasthali Vidyapith for rendering help in the acquisition of scanning electron micrographs and Raman data.