Authors:Dariusz Bochenek, Małgorzata Płońska, Julian Dudek, and Zygmunt Surowiak
Results of investigations on selected ceramic ferroics and multiferroics by TA method were presented. The authors of the work
used the thermal analysis both to optimize a process of producing the ceramic ferroics and multiferroics and to examine phase
transitions in that type of materials. In the case of synthesis of the ferroics and multiferroics as a result of sintering
of a mixture of simple oxides, the TA method enables to determine the optimum synthesis temperature and temperatures of re-crystallization
and disintegration of compounds and solid solutions. In the case of the sol–gel method, temperatures of dehydratization, burning
of an organic phase, and crystallization of an amorphous powder formed from the residual gel were determined by the TA method.
The TA method was also used to control a process of compacting and sintering the powders at high temperatures (Ts > 1,200 K), thus in a process of ceramic specimen formation. During rapid phase transitions, the ferroelectric specimens
of a first type emit (in the cooling process) or absorb (in the heating process) so called latent heat of the phase transitions.
On the DTA courses, it may be manifested in a form of exo- or endothermic peaks in the Curie temperature area (TC). The test materials included the ferroelectric ceramics of composition x/65/35 PLZT (ferroic for x < 9 at%) and mixed bismuth oxide layered perovskites (M-BOLP) of composition Bi5TiNbWO15 with <m> = 1.5 and the mutliferroic Pb(Fe1−xNbx)O3 ceramics (PFN) and Bi5TiFeO15 (BTF).
Authors:Diego M. Gil, M. Carolina Navarro, M. Cristina Lagarrigue, J. Guimpel, Raúl E. Carbonio, and M. Inés Gómez
Multi-ferroics are materials that are magnetically ordered, being at the same time in a ferroelectric state. The coupling between the electric and magnetic polarizations, i.e., the magnetoelectric effect, imparts
Authors:M. Navarro, M. Lagarrigue, J. De Paoli, R. Carbonio, and M. Gómez
In order to investigate the formation of the multiferroic BiFeO3, the thermal decomposition of the inorganic complex Bismuth hexacyanoferrate (III) tetrahydrate, Bi[Fe(CN)6]·4H2O has been studied. The starting material and the decomposition products were characterized by IR spectroscopy, thermal analysis,
laboratory powder X-ray diffraction, and microscopic electron scanning. The crystal structures of these compounds were refined
by Rietveld analysis. BiFeO3 were synthesized by the decomposition thermal method at temperature as low as 600 °C. There is a clear dependence of the
type and amount of impurities that are present in the samples with the time and temperature of preparation.