Author(s)

Sarkarainadar Balamurugan

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In this work, the syntheses and characterization of oxygen deficient perovskite cobalt oxides prepared under ambient pressure conditions with different “x” in the Co(Sr_1-xY_x)O_3–δ; 0.05 ≤ x ≤ 0.4 series are reported. The system studied in the present investigation undergoes structural phase transition at room temperature from cubic to tetragonal symmetry. The samples with x ≥ 0.2 show a tetragonal structure with I4/mmm space group, while the samples with 0.05 ≤ x ≤ 0.15 reveal cubic with pm3m group symmetry. Quite similar to Ho-substituted system [J. Appl. Phys. 103, 07B903 (2008)], the present Y-doped magnetization data clearly show the appearance of an enhanced ferromagnetic component at ~350 K for 0.15 ≤ x ≤ 0.225. Unlike the Ho-substituted system, the present narrow compositions behave as hard ferromagnet with quite high coercive field, H_c = 11.02, 12.25 and 14.0 kOe for x = 0.15, 0.2 and 0.225 compositions, respectively at T = 10 K. All the compositions show a semiconducting-like behaviour and some interesting features of temperature dependence of magnetoresistance (MR) are observed. The Co(Sr_1-xY_x)O_3–δ samples seemly to obey variable range hopping conduction model showing a linear ln ρ versus T–1/4 dependence at the temperature range 80 K ≤ T ≤ 300 K.

Oxygen Deficient Perovskites, CoSrO_3–δ, Y-Doping: Room Temperature Ferromagnet, Physical Properties

S. Balamurugan, "Physical-Properties of Oxygen-Deficient Co-Based Perovskites: Co(Sr_1-xY_x)O_3–δ (0.05 ≤ x ≤ 0.4)," World Journal of Condensed Matter Physics, Vol. 1 No. 4, 2011, pp. 145-152. doi: 10.4236/wjcmp.2011.14021.