Keele Research Repository

The work described in this thesis is concerned
with the measurement of the large zero-field splittings
of ferric iron substituted into a number of mixed metal oxide host lattices.
The first chapters give an outline of the crystal field approach to the interpretation of E.P.R. spectra
with particular emphasis on the zero-field splitting of
S-state ions and the approximations underlying the conventional spin Hamiltonian. There follows a survey of previous measurements on S-state ions in various host lattices and a discussion of the previously reported E.P.R. spectra in the crystals chosen for study in the present work.
Chapter V contains a description of the 4mm. spectrometer on which the bulk of the measurements were made and a summary of the experimental techniques.
The final chapter is devoted mainly to a discussion of the results obtained from a series of measurements on
strontium titanate and lead titanate. The zero-field splitting experienced by ferric iron substituted at the titanium site in both these lattices has been measured and in addition small cubic variations of the E.P.R. spectra have been found. The significance of the results has been discussed from the viewpoint of a simple point-charge model.