Journal of Thermal Analysis and Calorimetry
Volume/Issue:
Volume 59: Issue 3
Vacancy Contents in MnZn Ferrites From TG Curves
Authors:
O. Ayala Centro de Investigación en Materiales Avanzados Miguel de Cervantes 120, Chihuahua Chihuahua 31110 Mexico

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D. Lardizábal Centro de Investigación en Materiales Avanzados Miguel de Cervantes 120, Chihuahua Chihuahua 31110 Mexico

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A. Reyes Centro de Investigación en Materiales Avanzados Miguel de Cervantes 120, Chihuahua Chihuahua 31110 Mexico

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M. Rosales Centro de Investigación en Materiales Avanzados Miguel de Cervantes 120, Chihuahua Chihuahua 31110 Mexico

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J. Matutes Centro de Investigación en Materiales Avanzados Miguel de Cervantes 120, Chihuahua Chihuahua 31110 Mexico

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A. González Arias Universidad de La Habana Dpto. Física Aplicada, Facultad de Física 10400 Cuba

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Pages:
943–949
Online Publication Date:
02 Nov 2004
Publication Date:
01 Mar 2000
Article Category:
Research Article
DOI:
https://doi.org/10.1023/a:1010138712125
Restricted access

Abstract  

Expressions for calculating the cation vacancy contents of MnZn ferrites from thermogravimetric curves are presented together with some experimental data. In a single-phase MnZn ferrite synthesized by conventional ceramic procedures, the O2 evolution accompanying ferrite formation follows the formal equation. Mn2+σα Znσβ Fe3+2σ(1–γ) [V ]σ/4(1–2γ) O4 =σ'/σ Mn2+σ(α–2ϕ) Znσβ Fe2+2σθ Mn3+2σϕ Fe3+2σ(1–γ–θ) [V ]σ/4(1–2γ–3ϕ) O4 +σ'φ/2O2 (g) where α and β denote the MnO and ZnO mole fractions in the primary mixture γ=α+β, θ and ϕ depend on the quantities of Fe2+ and Mn3+ formed, respectively, φ=θ–ϕ and σ'/σ is a function of the former parameters. Even though the relative amounts of Fe2+ /Fe3+ and Mn2+ /Mn3+ remain uncertain, the vacancy content [V ] of the ferrite can be determined because it depends on φ alone, which is related to the change in mass of the sample as the synthesis takes place through the equation φ=(1.5–γ) µβ /µO2 (1–mf /mi ) Here, mi and mf are the masses of the sample before and after O2 evolution, µB is the formula mass of the ferrite and µO2 is the O2 molar mass. Practically vacancy-free single-phase MnZn ferrite samples were obtained by sintering in air at 1250°C and cooling in pure N2 .

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Cover Journal of Thermal Analysis and Calorimetry
Journal of Thermal Analysis and Calorimetry
Print ISSN:
1388-6150
Online ISSN:
1572-8943

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Journal of Thermal Analysis and Calorimetry
Language English
Size A4
Year of
Foundation		 1969
Volumes
per Year		 1
Issues
per Year		 24
Founder Akadémiai Kiadó
Founder's
Address		 H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
Publisher Akadémiai Kiadó
Springer Nature Switzerland AG
Publisher's
Address		 H-1117 Budapest, Hungary 1516 Budapest, PO Box 245.
CH-6330 Cham, Switzerland Gewerbestrasse 11.
Responsible
Publisher		 Chief Executive Officer, Akadémiai Kiadó
ISSN 1388-6150 (Print)
ISSN 1588-2926 (Online)

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