resumo
Polycrystalline samples of (1-x) Na0.5K0.5NbO3-(x) GdFeO3 (designated as NKN-GF) (x = 0.01, 0.02. 0.04. 0.6 and 0.10), were prepared by a conventional solid-state reaction technique. Preliminary structural studies at room temperature suggest that compounds are formed in a single perovskite phase. Compositions with x = 0.02-0.04 possess orthorhombic structure while for x = 0.06-0.10 show tetragonal structure. The diffraction peaks shift slightly to a higher angle with increasing concentration of x. The ferroelectric phase-transition of these materials, shows a shift in the transition temperature towards the higher-temperature side with increased GF concentration. The magnetization increases with the increase in GF content which is clearly perceptible in the evolution of hysteresis loops indicating that GdFeO3 doped NKN has introduced ferromagnetic contribution. This may be attributed to variation in the oxygen stoichiometry, doping at different crystallite sites and change in the magnetic anisotropy. (C) 2011 Elsevier BM. All rights reserved.
palavras-chave
FREE PIEZOELECTRIC CERAMICS; SINGLE-CRYSTAL; POLARIZATION; MECHANISM; BEHAVIOR
categoria
Materials Science; Physics
autores
Rai, R; Sharma, S; Rani, R; Valente, MA; Kholkin, AL
nossos autores
Andrei Kholkin
Investigador Jubilado
Radheshyam Rai
Bolseiro de pós-Doutoramentoagradecimentos
Radheshyam Rai is grateful to the Foundation for Science and Technology of Portugal (FCT) for financial support (grant SFRH/BPD/38001/2007). Seema Sharma gratefully acknowledges Department of Science and Technology. Govt of India (Grant number-SR/S2/CMP-39/2006), for providing financial support for this work.