Structural, thermal and electrical properties of Pr0.5Sr0.5Co1 - yNiyO3 - σ perovskite-type oxides

Kostogloudis, GCh; Ftikos, Ch

dc.contributor.author	Kostogloudis, GCh	en
dc.contributor.author	Ftikos, Ch	en
dc.date.accessioned	2014-03-01T01:47:29Z
dc.date.available	2014-03-01T01:47:29Z
dc.date.issued	1998	en
dc.identifier.issn	01672738	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/25228
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-0032097517&partnerID=40&md5=5925afc8a025fb1a95eb5ce68bf5c075	en
dc.subject	Crystal structure	en
dc.subject	Electrical conductivity	en
dc.subject	Ni-substituted praseodymium strontium cobaltite	en
dc.subject	Perovskite	en
dc.subject	Thermal expansion	en
dc.subject.other	Composition effects	en
dc.subject.other	Crystal lattices	en
dc.subject.other	Electric conductivity measurement	en
dc.subject.other	Lattice constants	en
dc.subject.other	Metal insulator boundaries	en
dc.subject.other	Nickel compounds	en
dc.subject.other	Phase transitions	en
dc.subject.other	Praseodymium compounds	en
dc.subject.other	Thermal effects	en
dc.subject.other	Thermal expansion	en
dc.subject.other	Praseodymium strontium cobalite	en
dc.subject.other	Perovskite	en
dc.title	Structural, thermal and electrical properties of Pr0.5Sr0.5Co1 - yNiyO3 - σ perovskite-type oxides	en
heal.type	journalArticle	en
heal.publicationDate	1998	en
heal.abstract	Perovskite oxides in the system Pr0.5Sr0.5Co1 - yNiyO3 - σ (0 < y < 1) were prepared and characterized by X-ray powder diffraction, dilatometry and electrical conductivity measurements. The Pr0.5Sr0.5CoO3 - σ end member has an orthorhombic GdFeO3 structure, while when Ni is substituted for Co, a tetragonal phase is formed, the concentration of which increases linearly in the range 0 < y < 0.6. Above y = 0.6 the tetragonal is the only phase present. The lattice parameters of all compositions were determined at room temperature. Ni is introduced in the bivalent state in the range 0 < y < 0.4, while Ni3+ is introduced in the range 0.4 < y < 1. An orthorhombic-to-tetragonal phase transition was detected by dilatometer measurements for compositions with y = 0.2, 0.4 and 0.6. The phase transition temperature decreases with increasing Ni content. The linear thermal expansion coefficient (TEC) is always higher for the high temperature modification. The formation of oxygen vacancies V..o) and the concurrent thermal reduction of Co4+, Co3+ and Ni3+ cations to the lower valence states, were considered responsible for the steeper thermal expansion curves at high temperatures. The TEC generally decreases with increasing Ni content, due to the increase of the size of the unit cell. Pr0.5Sr0.5CoO3 - σ and Pr0.5Sr0.5NiO3 - σ end members show semi-metallic behavior, while the substitutionally-mixed compositions are semi-conductors and exhibit a metal-insulator (M-I) transition when the temperature is raised. The conductivity in the semiconducting region can be described by the small polaron hopping conductivity model. The introduction of Ni2+ cations in the Co-rich compositions is preferably electronically compensated by the formation of V..o. © 1998 Elsevier Science B.V. All rights reserved.	en
heal.journalName	Solid State Ionics	en
dc.identifier.volume	109	en
dc.identifier.issue	1-2	en
dc.identifier.spage	43	en
dc.identifier.epage	53	en