THESIS ON FERRITES

The sol-gel process typically produces ceramic materials at lower temperatures and with smaller grain sizes than standard ceramic techniques, and this proved to be the case. Skip to content Skip to navigation. A material made in a fibrous form has many properties; firstly it can be incorporated into a matrix to form a composite material, imparting any special properties into the whole composite. Puller, Robert Carlyle The synthesis and characterisation of hexagonal ferrite fibres. This thesis presents the manufacture of a range of hexagonal ferrite fme fibres from an inorganic aqueous sol-gel precursor, and their subsequent characterisation both physically and magnetically.

Request changes or add full text files to a record. The fibres were blow spun from a viscous solution using a modified commercial process, and they were collected in both random and aligned forms. It has also been suggested that some properties, such as magnetisation, will be enhanced when the material is an aligned fibre, although this specific case has never been proven previously. Substituted M fcrrites also formed the M phase at similar temperatures, but were more porous and did not have the greatly reduced grain size reported previously. The stoichiometric ferrite sols were made by doping the iron I II sol with solution of metal salts, and these were found to be critical to the stability of the sol, with barium causing particular problems, and titania was added as a second colloidal species.

Hexagonal ferrites are a family of magnetic oxides which include M ferrite, the most commonly used magnetic material in the world today.

The sols were made from the peptisation thesis on ferrites a precipitated iron III hydroxide with a mineral acid, and various combinations of iron III salt and acid were investigated using PCS. The synthesis and characterisation of hexagonal ferrite fibres.

Request changes or add full text files to a record. The stoichiometric ferrite sols were made by doping the iron Thesis on ferrites II sol with solution of metal salts, and these were found to be critical to the stability of the sol, with barium causing particular problems, and titania was added as a second colloidal species.

A material made in a fibrous form has many properties; firstly it can be incorporated into a matrix thesis on ferrites form a composite material, imparting any special properties into the whole composite.

Puller, Robert Carlyle The synthesis and characterisation of hexagonal ferrite fibres.

The sol-gel process typically produces ceramic materials at lower temperatures and with smaller grain sizes than standard ceramic techniques, and this proved to be the case. It has also been suggested that some properties, such as magnetisation, will be enhanced when the material is thesis on ferrites aligned fibre, although this specific case has never been proven previously.

Chloride was found to add structuring to the sol, aiding spinning but resulting in a thixotropic gel if too much was present. It was thesis on ferrites found that there were defmite alignment effects on Ms in all fibres except those which had.

Thesis on ferrites are highly complex crystal structures which usuaUy require high temperatures to form a well sintered product, at the expense of grain growth, which in tum affects the magnetic properties of the material.

They also have more specialist potential applications, such as microwave absorption and catalysis.

Characterization and Applications of Micro- and Nano- Ferrites at Microwave and

The samples were characterised magnetically by VSM, and while the M ferrites proved to have typical Ms values and high coercivities for polycrystalline samples, the ferroxplana ferrites all had Ms equal to or better than the previously reported maximum values. This thesis presents the manufacture of a range thesis on ferrites hexagonal ferrite fme thesis on ferrites from an inorganic aqueous sol-gel precursor, and their subsequent characterisation both physically and magnetically.

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However, both the CozZ and CozW ferrite fibres underwent this process concurrently with the formation of these phases, and it appears to be an unavoidable step under normal conditions, although steam firing or doping with CaO enabled the formation of a majority-Z product without this growth. Provided their microstructure is sufficiently fme, fibres tend to be stronger than the bulk ceramic form, and if fme enough they can even be woven into a cloth.

This is the first’time that the effect thesis on ferrites fibre alignment upon magnetic properties has been demonstrated. PhD thesis, University of Warwick. Substituted M fcrrites also formed the M phase at similar temperatures, but were more porous and thesis on ferrites not have the greatly reduced grain size reported previously.

The best results were found to come from iron III chloride precipitated by ammonia and peptised with HBr, with totally nitrate and chloride based systems proving inferior. Downloads per month over past year. The fibres were blow spun from a viscous solution using a modified commercial process, and they were collected in both thesis on ferrites and aligned forms.

They all exhibit magneto crystalline anisotropy; depending upon the ferrite they can have a preferred direction of magnetisation along the c axis of the hexagonal crystal uniaxialor in the hexagonal plane thesis on ferrites in a cone at an angle to the plane ferroxplana.