Effect of various parameters on the microstructure and magnetic properties of sintered Sr-hexaferrite

Sr-hexaferrite powders with Fe/Sr molar ratio of 11 was synthesized via conventional ceramic route. Powders were milled for 5–25 h, then pressed to make green compacts by applying a pressure of 100–400 MPa. In other series, K2CO3 was used in starting materials. K2CO3/SrCO3 mixing molar ratio was 0.0...

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Main Authors: Sanam Garehbaghi, Abbas Kianvash
Format: Article
Language:English
Published: Elsevier 2019-03-01
Series:Results in Physics
Online Access:http://www.sciencedirect.com/science/article/pii/S2211379718328808
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spelling doaj-feccb71da5d942448636df104dea957c2020-11-24T21:20:54ZengElsevierResults in Physics2211-37972019-03-011215591568Effect of various parameters on the microstructure and magnetic properties of sintered Sr-hexaferriteSanam Garehbaghi0Abbas Kianvash1Department of Material Engineering, Faculty of Mechanical Engineering, University of Tabriz, Tabriz 51666-14766, Iran; Corresponding author.Department of Material Engineering, Faculty of Mechanical Engineering, University of Tabriz, Tabriz 51666-14766, IranSr-hexaferrite powders with Fe/Sr molar ratio of 11 was synthesized via conventional ceramic route. Powders were milled for 5–25 h, then pressed to make green compacts by applying a pressure of 100–400 MPa. In other series, K2CO3 was used in starting materials. K2CO3/SrCO3 mixing molar ratio was 0.05 and 0.5. First series were calcined at 1250 °C, and the second series were calcined at 1000 °C for 2 h. The XRD characterization results revealed Sr-hexaferrite structure has been produced in both series; Crystallite size is constant then increases while lattice strain rises by variation of milling time from 5 h to 25 h. (BH)max and Br increase by increasing milling time to 25 h and (BH)max reaches to optimized value of 24.75 kJ/m3. SEM was used for microstructure investigation; particle morphologies are hexagonal shape. Addition of slight amount of K2CO3 makes SrFe12O19 crystallites get less platelet shape and more regular shape. By increasing pressure morphology of the grain enhances in regularity. Magnetic properties were measured via permagraph; By increasing sintering temperature from 1150 °C to 1200 °C, density increases from 3.38 g/cm3 to 4.85 g/cm3. Maximum energy product varies from 9.54 kJ/m3 to 25.27 kJ/m3. Between the sintering temperatures of 1200–1250 °C maximum energy product stays at the highest values, But after 1250 °C drops to 3.82 kJ/m3. As density increases, remanence (Br) and maximum energy product [(BH)max] first increase at the pressure range of 100–200 MPa until it reaches to a optimize value of 15.20 kJ/m3 at 200 MPa. Keywords: Sr-hexaferrite, Lattice strain, Williason-Hall, Salt-melt, Sinter-aid, Milling time, Demagnetization curvehttp://www.sciencedirect.com/science/article/pii/S2211379718328808
collection DOAJ
language English
format Article
sources DOAJ
author Sanam Garehbaghi
Abbas Kianvash
spellingShingle Sanam Garehbaghi
Abbas Kianvash
Effect of various parameters on the microstructure and magnetic properties of sintered Sr-hexaferrite
Results in Physics
author_facet Sanam Garehbaghi
Abbas Kianvash
author_sort Sanam Garehbaghi
title Effect of various parameters on the microstructure and magnetic properties of sintered Sr-hexaferrite
title_short Effect of various parameters on the microstructure and magnetic properties of sintered Sr-hexaferrite
title_full Effect of various parameters on the microstructure and magnetic properties of sintered Sr-hexaferrite
title_fullStr Effect of various parameters on the microstructure and magnetic properties of sintered Sr-hexaferrite
title_full_unstemmed Effect of various parameters on the microstructure and magnetic properties of sintered Sr-hexaferrite
title_sort effect of various parameters on the microstructure and magnetic properties of sintered sr-hexaferrite
publisher Elsevier
series Results in Physics
issn 2211-3797
publishDate 2019-03-01
description Sr-hexaferrite powders with Fe/Sr molar ratio of 11 was synthesized via conventional ceramic route. Powders were milled for 5–25 h, then pressed to make green compacts by applying a pressure of 100–400 MPa. In other series, K2CO3 was used in starting materials. K2CO3/SrCO3 mixing molar ratio was 0.05 and 0.5. First series were calcined at 1250 °C, and the second series were calcined at 1000 °C for 2 h. The XRD characterization results revealed Sr-hexaferrite structure has been produced in both series; Crystallite size is constant then increases while lattice strain rises by variation of milling time from 5 h to 25 h. (BH)max and Br increase by increasing milling time to 25 h and (BH)max reaches to optimized value of 24.75 kJ/m3. SEM was used for microstructure investigation; particle morphologies are hexagonal shape. Addition of slight amount of K2CO3 makes SrFe12O19 crystallites get less platelet shape and more regular shape. By increasing pressure morphology of the grain enhances in regularity. Magnetic properties were measured via permagraph; By increasing sintering temperature from 1150 °C to 1200 °C, density increases from 3.38 g/cm3 to 4.85 g/cm3. Maximum energy product varies from 9.54 kJ/m3 to 25.27 kJ/m3. Between the sintering temperatures of 1200–1250 °C maximum energy product stays at the highest values, But after 1250 °C drops to 3.82 kJ/m3. As density increases, remanence (Br) and maximum energy product [(BH)max] first increase at the pressure range of 100–200 MPa until it reaches to a optimize value of 15.20 kJ/m3 at 200 MPa. Keywords: Sr-hexaferrite, Lattice strain, Williason-Hall, Salt-melt, Sinter-aid, Milling time, Demagnetization curve
url http://www.sciencedirect.com/science/article/pii/S2211379718328808
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