Crystal Structure, Magnetism, and Dielectric Properties of La1-xBixNi0.5Mn0.5O3

• Published in: Journal of the Physical Society of Japan 2008, Vol.77 (8)
• Main Authors: KOBAYASHI, Yoshihiko, SHIOZAWA, Masanori, SATO, Keisuke, ABE, Kohji, ASAI, Kichizo
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectric loss and relaxation; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Magnetic properties and materials; Magnetomechanical and magnetoelectric effects, magnetostriction; Permittivity (dielectric function); Physics
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/jpsj.77.084701

We have synthesized the polycrystalline La1-xBixNi0.5Mn0.5O3 for x=0-0.9 by soft chemical synthesis, and investigated the crystal structure, and the magnetic and the dielectric properties. The crystal has a monoclinic P21/c structure with centrosymmetry for 0≤x≤0.7, and has a monoclinic C2 structure with non-centrosymmetry for 0.8≤x≤0.9 at room temperature. The ferromagnetic Curie temperature (TCM) decreases monotonically from 300 K at x=0 to 150 K at x=0.9, while the Ni2+-Mn4+ configuration is kept independent of Bi-content. For x≥0.5, An anomalous increment of the dielectric constant with increasing temperature and the maximum in the dielectric loss accompanied with frequency dispersion were observed around 150 K, which is close to TCM. However, no evidence showing a ferroelectric ordering was observed below 400 K. For x=0.7, the increment of the dielectric constant induced by the magnetic field is 7% at TCM at 9 T. The temperature and the magnetic field dependence of the dielectric properties is discussed based on Maxwell-Wagner model assuming an inhomogeneity of samples and a negative magnetoresistance.