Pb(Zr0.525Ti0.475)O3 piezoceramics, both unmodified and doped with 2 wt% Bi2O3 or Nb2O5, were prepared by the usual techniques, using sintering temperatures from 900° to 1250°C. The microstructural data showed that the sintering temperature which produces minimum porosity is altered by the oxide additions. X‐ray diffraction demonstrated the coexistence of both ferroelectric phases. The lattice parameter measurements showed that the tetragonal and rhombohedra1 unit cells of the two ferroelectric phases depend on the sintering temperature.
A comparative study of electron-beam and pulsed-laser irradiation effects in metallic glasses has been performed in order to understand the relationship between magnetic behavior and select variations in the structural characteristics of alloy phases. Samples of FegiB, 3 5Si3 5C2 metallic glass were irradiated with a pulsed excimer laser (A, = 308 nm,~= 10 ns), with a high-energy electron beam ( 8 = 7 MeV), and with low-energy electron beams (8'=30 and 50 keV). Irradiation-driven changes in the magnetic anisotropy and phase equilibrium of alloy samples were studied by Mossbauer spectroscopy and scanning electron microscopy. Complementary information was obtained using energy-dispersive x-ray analysis. High-energy electron-beam irradiation was found to induce an out-of-plane magnetic anisotropy due to changes in the chemical short-range order. Low-energy electron-beam irradiation resulted in the formation of crystalline regions, in which a-Fe, Fe-Si, Fe,B, Fe2B, and clusters of y-Fe were identified. Interpretation of these results is given in terms of radiation-enhanced diffusion. Pulsed-excimer-laser irradiation was found to induce controlled magnetic anisotropy without onset of bulk crystallization in the Fe8lBl3 5S13 5C& amorphous system. The effect of excimer-laser-induced amorphization was evidenced in thermally annealed Fe81B&3 5S13 5C2 samples and explained using melt model calculations. In all cases studied, the key to explaining the irradiation-induced property modifications is the underlying alloy micro structure.
The diffuse phase transitions (DPT) in the ST‐BT system are theoretically and experimentally justified by the coexistence of two phases (one tetragonal, the other cubic) in the temperature range of the transition. This fact is emphasized by X‐ray identification of both phases at room temperature in (Ba0.76Sr0.24)TiO3 and (Ba0.715Sr0.285)TiO3 solid solutions. The ferroelectric‐para‐electric (F‐P) and the lower ferroelectric transitions are discussed in terms of thermal phase equilibria in the F‐P diagram proposed.
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