The structure and lattice dynamics of mechanically activated BaTiO 3 was investigated in this study. Phonon behavior and crystal structure stability of the obtained nanocrystalline BaTiO 3 were discussed from the view point of crystallite size effects and microstrains induced by mechanical activation. A systematic study of Raman responses indicates that mechanical activation has a distinct influence on BaTiO 3 lattice spectra affecting the intensity, width, and position of Raman modes. The measured Raman spectra were deconvoluted and phonon parameters were estimated. It has been established that applied mechanical activation leads to a significant decrease in the mean crystallites size, but nevertheless enables formation of tetragonal nanocrystalline BaTiO 3 .M. Hoffman-contributing editor Manuscript No. 31363.

No abstract

Sintering kinetics of the mechanically activated ZnO-TiO2 system was studied. Mixtures of ZnO and TiO2 powders were mechanically activated using a high-energy ball mill for different time intervals from 0 to 300 minutes. Formal phenomenological analyses were performed in order to describe the specimen’s behavior during isothermal sintering at 1100oC. Non-isothermal sintering was investigated by dilatometer measurements up to 1100oC with a constant heating rate. The Dorn method was applied in order to give information on the activation energy.

The aim of this work was analysis of isothermal sintering of zinc titanate ceramics doped with MgO obtained by mechanical activation. Mixtures of ZnO, TiO2 and MgO (0, 1.25 and 2.5%) were mechanically activated 15 minutes in a planetary ball mill. The powders obtained were pressed under different pressures and the results were fitted with a phenomenological compacting equation. Isothermal sintering was performed in air for 120 minutes at four different temperatures. Structural characterization of ZnO-TiO2-MgO system after milling was performed at room temperature using XRPD measurements. DTA measurements showed different activation energies for pure and doped ZnO-TiO2 systems. Thus addition of MgO stabilizes the crystal structure of zinc titanate

Reduction of the specific surface area of porous ZnO during the sintering process was studied. ZnO powder was sintered at temperatures from 673 K to 1173 K. The decrease in the specific surface area was observed as a function of temperature and sintering time. Two different models were involved in order to define the appropriate parameters. The Arrhenius equation was used to give information on the activation energy of sintering. The LSE method was applied for determining optimum parameter values