Magnetic and dielectric studies of barium hexaferrite (BaFe12O19) ceramic synthesized by chemical route

Nanosize particles of barium hexaferrite were prepared by co-precipitation route using solution of iron and barium chlorides with a Fe+3/Ba+2 molar ratio of 11. Water and a mixture of water/ethanol with volume ratio of 1:3 were used as solvents. Co-precipitated powders were calcined at various temperatures. XRD results showed that single phase barium hexaferrite forms at 900°C for sample synthesized in aqueous solution and its formation is resulted from the reaction between mainly crystalline phases, while this temperature decreased to 700°C for sample synthesized in water/ethanol solution and the formation of barium hexaferrite consists of reactions between amorphous phases with crystalline phases. SEM micrographs of the calcined samples at 800°C indicated that the morphology of particles was affected by the type of solvent. Nano size particles of barium hexaferrite with mean particle size of almost 80 nm were observed in the SEM micrograph of sample synthesized in water/ethanol solution after calcination at 800°C. Barium hexaferrite crystallites with mean size of 35 nm, which was approximately consistent with size obtained from XRD line broadening technique, could be seen in TEM image of this sample after calcination at 700°C.

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Dielectric studies of polycrystalline bismuth titanate Bi12TiO20 ceramic synthesized via economical chemical route

Indian Journal of Physics ◽

10.1007/s12648-020-01919-9 ◽

2020 ◽

Author(s):

M K Verma ◽

L Singh ◽

A Kumar ◽

V Kumar ◽

N B Singh ◽

...

Keyword(s):

Bismuth Titanate ◽

Dielectric Studies ◽

Chemical Route

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Electrical, Magnetic and Dielectric Properties of Cobalt-Doped Barium Hexaferrite BaFe12−xCoxO19 (x = 0.0, 0.05, 0.1 and 0.2) Ceramic Prepared via a Chemical Route

Journal of Electronic Materials ◽

10.1007/s11664-020-08364-8 ◽

2020 ◽

Vol 49 (11) ◽

pp. 6436-6447

Author(s):

Atendra Kumar ◽

Manish Kumar Verma ◽

Shruti Singh ◽

Tapas Das ◽

Laxman Singh ◽

...

Keyword(s):

Dielectric Properties ◽

Barium Hexaferrite ◽

Chemical Route ◽

Magnetic And Dielectric Properties

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Crystallization of barium hexaferrite

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122216 ◽

1992 ◽

Vol 50 (1) ◽

pp. 362-363

Author(s):

Chung-kook Lee ◽

Yolande Berta ◽

Robert F. Speyer

Keyword(s):

Size Distribution ◽

Raw Materials ◽

Barium Hexaferrite ◽

Recording Media ◽

Magnetic Recording Media ◽

Promising Candidate ◽

Crystallization Method ◽

Temperature Heat ◽

High Density Magnetic Recording ◽

Temperature Heat Treatment

Barium hexaferrite (BaFe12O19) is a promising candidate for high density magnetic recording media due to its superior magnetic properties. For particulate recording media, nano-sized single crystalline powders with a narrow size distribution are a primary application requirement. The glass-crystallization method is preferred because of the controllability of crystallization kinetics, hence, particle size and size distribution. A disadvantage of this method is the need to melt raw materials at high temperatures with non-reactive crucibles, e.g. platinum. However, in this work, we have shown that crystal growth of barium hexaferrite occurred during low temperature heat treatment of raw batches.

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Structures of chemically stabilized ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150459 ◽

1993 ◽

Vol 51 ◽

pp. 924-925

Author(s):

Pratibha L. Gai ◽

M. A. Saltzberg ◽

L.G. Hanna ◽

S.C. Winchester

Keyword(s):

High Temperature ◽

Calcium Nitrate ◽

Nitrate Hexahydrate ◽

Chemical Route ◽

Cubic Form ◽

Tetragonal Form ◽

Wet Chemical ◽

Wet Chemical Route ◽

Final Composition ◽

Aluminium Nitrate Nonahydrate

Silica based ceramics are some of the most fundamental in crystal chemistry. The cristobalite form of silica has two modifications, α (low temperature, tetragonal form) and β (high temperature, cubic form). This paper describes our structural studies of unusual chemically stabilized cristobalite (CSC) material, a room temperature silica-based ceramic containing small amounts of dopants, prepared by a wet chemical route. It displays many of the structural charatcteristics of the high temperature β-cristobalite (∼270°C), but does not undergo phase inversion to α-cristobalite upon cooling. The Structure of α-cristobalite is well established, but that of β is not yet fully understood.Compositions with varying Ca/Al ratio and substitutions in cristobalite were prepared in the series, CaO:Al2O3:SiO2 : 3-x: x : 40, with x= 0-3. For CSC, a clear sol was prepared from Du Pont colloidal silica, Ludox AS-40®, aluminium nitrate nonahydrate, and calcium nitrate hexahydrate in proportions to form a final composition 1:2:40 composition.

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