Impurities in Perovskites: Evidence from ESR of Posistor Barium Titanate Ceramics

• Published in: Ferroelectrics Vol. 288; no. 1; pp. 235 - 241
• Main Authors: Yurchenko, L. P., Slipenyuk, A. M., Glinchuk, M. D., Bykov, I. P., Mikheev, V. A., Tkachenko, V. D., Garmash, E. P.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: London Taylor & Francis Group 01.01.2003; Taylor and Francis
• Subjects: Batio 3 Ceramics; Color centers and other defects; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity of specific materials; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Electron paramagnetic resonance and relaxation; Electronic transport in condensed matter; Exact sciences and technology; Impurities; Insulators; Magnetic resonances and relaxations in condensed matter, mössbauer effect; Niobates, titanates, tantalates, pzt ceramics, etc; Physics; Positive Temperature Coefficient Of Resistivity; Posistor effect; Inorganic compounds; Electrical conductivity; Doping; Barium titanates; Defects; g-factor; Niobium additions; Chemical composition; Diffusion; Quaternary compounds; Grain size; Paramagnetic center; Impurity density; ESR; Transition element compounds; Manganese additions; Perovskites; Experimental study; positive temperature coefficient of resistivity; Hyperfine structure; BaTiO3 ceramics; Temperature coefficient; Impurities; Strontium titanates; Cerium additions
• ISSN: 0015-0193; 1563-5112
• DOI: 10.1080/00150190390211639

Room temperature measurements of ESR spectra were performed on BaTiO 3 ferroelectrics doped either by cerium or by niobium and strontium. Both types of samples were doped by manganese. In the samples of first type the most intensive line with g-factor 1,9612 was ascribed to paramagnetic centers Ti 3+ --Ce 3+ . We observed ESR spectra of Fe 3+ --V O centers and Mn 2+ also. In the samples with strontium a spectrum of six intensive lines, which corresponds to the hyperfine structure of Mn 2+, was observed. We study the dependency of Mn 2+ ESR spectrum intensity and electrical resistivity on strontium concentration. This effect was supposed to be related to the decrease of the grain sizes that result in migration of manganese and maybe niobium ions into intergrain air space. The mutual influence of Ce, Mn, Sr and Nb impurities, their charges and position in the lattice on the PTCR effect is discussed.