Transport and magnetic properties of PrCo 1−x Ni x O 3 (x = 0.0–0.7)

• Published in: Journal of physics. D, Applied physics Applied physics, 2011-08, Vol.44 (30), p.305402
• Main Authors: Tomeš, P, Aguirre, M H, Robert, R, Shkabko, A, Otal, E H, Weidenkaff, A
• Format: Article
• Language: English
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/44/30/305402

The influence of Ni substitution on the transport and magnetic properties of the perovskite PrCo 1− x Ni x O 3 ( x = 0.0–0.7) has been investigated by synthesizing and characterizing different samples. The unit cell volume of orthorhombic crystal structure expands with increasing Ni content, affecting the distortion of M –O (I, II)- M bond angles ( M = Co, Ni). The expansion of the unit cell volume can be attributed to the larger ionic radii of Ni 2+ and to the stabilization of the intermediate-spin state in the low-spin cobalt matrix. The electrical conduction mechanism varies with the Ni content with noticeable change from variable range hopping to nearest neighbour hopping in compositions 0.07 ⩽ x ⩽ 0.29. The Seebeck coefficient is positive for samples with 0.0 < x < 0.49. Only PrCo 0.3 Ni 0.7 O 3 has a negative Seebeck coefficient. The ZFC/FC curves and M ( H ) hysteresis loops reveal both a spin-glass behaviour and ferromagnetic ordering below the Curie temperature ( T C ) for Ni-substituted samples. By the combination of Seebeck coefficient data and the measured effective magnetic moment μ eff , the mixed valences of Co 3+ /Co 4+ and Ni 2+ /Ni 3+ in PrCo 1− x Ni x O 3 compounds were determined and the values are in agreement with x-ray photoemission spectroscopy measurements.