Conduction in Mn substituted Ni-Zn ferrites

Autor:	S. A. Patil, S. D. Lotke, A. K. Ghatage, B M Kulkarni, B. V. Bhise
Rok vydání:	1996
Předmět:	Materials science Condensed matter physics Mechanics of Materials Electrical resistivity and conductivity Seebeck coefficient Analytical chemistry Ferrite (magnet) General Materials Science Compositional variation Activation energy Thermal conduction Polaron
Zdroj:	Bulletin of Materials Science. 19:527-531
ISSN:	0973-7669 0250-4707
DOI:	10.1007/bf02744824
Popis:	The d.c. electrical resistivity ‘ρ’ and thermoelectric power ‘α’ are studied as a function of temperature for Mn substituted ferrites with general formula Zn0·3Ni0·7+xMnxFe2−2xO4. At lower Mn concentrations, the increase in d.c. resistivity is attributed to the hindering of Verwey mechanism Fe2+ ⇌ Fe3+ due to stable bonds of Mn3+ + Fe2+ pair. The decrease in resistivity at higher Mn concentrations (i.e. whenx > 0·15) is attributed to the formation of Mn3+ cluster and Ni2+ ⇌ Ni3+. The activation energy values show one to one correspondence with resistivity values. The compositional variation of thermoelectric power showsn-type behaviour for the samples withx < 0·2 whereasp-type behaviour for the samples withx ⩾ 0·2. Thep −n transition is attributed to the formation of Ni3+, Fe2+ + vacancies which act asp-type carriers. The temperature dependences ofα, ρ, and mobility clearly confirm the conduction mechanism to be due to polaron hopping.
Databáze:	OpenAIRE
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