Preparation and characterization of ferromagnetic / ferroelectric composite film

Physics Department at the College of Science – University of Diyala, discussed the thesis masters student (Omar Abd Al-Wahhab Ahmed) entitled (Preparation and characterization of ferromagnetic / ferroelectric composite film) on (Thuresday) (2017/3/9) in the Discussions Hall at the Deanship of the College of Science.

In the present work the Cobalt ferrite were synthesized using sol-gel auto combustion as a  chemical methods . Iron nitrate (Fe(NO3)3. 9(H2O), Cobalt nitrate (CO(NO3)2  .6(H2O))  and citric acid  (C6H8O7. H2O) were used in order to get ferrite nanopowders. also the preparation of barium titanate  using barium carbonate (BaCO3) and titanium dioxide (TiO2) by conventional ceramic method.

Samples examined by X-ray diffraction to determine structural properties of the ferrite powder and the ferroelectric phase ,for the measurement of particle size, lattice constant , theoretical powder density and surface area of the granules nanoparticles for prepared powders . The results showed that particle size using Debey- Scherer equation of cobalt ferrite  powder is (45.14 nm), while the barium titanate powder particle size was (37.69nm).

Either from (AFM) analysis  the size particle for cobalt Ferrite was (102.82 nm) and for barium titanate was (78.90 nm). Fouire transforms infrared spectroscopy (FTIR) showed also constitute the phases and the type of impurities found in each.

Three types of composite films prepare by mixing weight fraction (1,2,3,4,5,6,7,8,9,10 wt%) of cobalt Ferrite powder  with polymer polyvinyl alcohol (PVA) for the first group of models , The same as the previous ratios of barium titanate powder with the same polymeric material (PVA) for the second group of models, It is both fillers together so many additions of both materials to (wt% 10) with the amount of polymer PVA (PVA) for the latest of models . And The casting method used in the preparation of composite films.

And make an optical microscope examination of the samples composite films ,which showed the spread reinforcement materials (ceramic) in the matrix material and the homogeneity of composite films.

The electrical properties of the composite films within the frequency range (50Hz-3MHz) at room temperature which included the dielectric constant , dielecteric loss facter and alternating conductivity was studied . The results showed a decrease in dielectric constant and dielecteric loss facter with increasing frequency while alternating conductivity increased with increasing frequency. but both the dielectric constant , dielecteric loss facter and conductivity increased with  increasing the concentration of fillers in the composite films containing fillers cobalt Ferrite or barium titanate . While in the composite films containing cobalt Ferrite and barium titanate in the polymer matrix found that the dielectric constant increases with the concentration of barium titanate either dielecteric loss facter and conductivity both increases with the concentration of cobalt Ferrite.

The electrical properties o the composite films at classic  frequency within the temperatures ℃ (165،145،125،105،85،65،45،25) included conductivity (σ_(d.c))  and activation energy was studied. The results showed increasing (σ_(d.c))conductivity with increasing the temperature for all composite films samples. The activation energy increased with  increase in the concentration of cobalt Ferrite in the matrix polymer of the composite films and the same behavior when  add the barium titanate  to matrix polymer. While the activation energy for the composite films of cobalt Ferrite and barium titanate  in the polymer matrix it was  decreases with increasing concentration of cobalt Ferrite.

The message was acceptance and earned the student a master's degree in solid state physics and materials.