Navegando por Autor "Simões, A. Z."

Agora exibindo 1 - 2 de 2

Photoluminescence of BaZrO3 explained by a order/disorded transformation
(Springer, 2015-02-13) Aguiar, E. C.; Simões, A. Z.; Paskocimas, Carlos Alberto; Cilense, M.; Silva, Elson Longo da; Varela, José A.
A hydrothermal (HTMW) microwave method was used to synthesize ordered–disordered BaZrO3 (BZ) nanoparticles at temperature of 140 °C with times ranging from 15 min to 2 h. X-ray diffraction results verified the formation of BZ crystallites at a soaking time of 2 h while infrared data showed no traces of carbonate. Field emission scanning microcopy revealed a homogeneous size distribution of nanometric BZ powders. HTMW produced nanoparticles of pure BZ phase, with a size ranging from 40 to 80 nm. These results are in agreement with Raman scattering values which show that the HTMW synthesis route is rapid and cost effective. This method could be used as an alternative to obtain BZ nanoparticles as compared to other chemical methods. Intense photoluminescence in disordered BZ powders was observed at room temperature. The key of mystery of the intense PL emission is related to order–disorder structural in BZ lattice
Temperature dependence on the electrical properties of Ba(Ti0.90Zr0.10)O3:2V ceramics
(Elsevier, 2010-10-01) Moura, F.; Simões, A. Z.; Paskocimas, Carlos Alberto; Zaghete, Maria Aparecida; Varela, José A.; Silva, Elson Longo da
Barium zirconium titanate ferroelectric ceramics modified with vanadium Ba(Ti0.90Zr0.10V0.02)O3 (BZT:2V) were prepared from powders synthesized using the mixed oxide method. The effect of temperature on the structural and electrical properties of BZT:2V ceramics was investigated. X-ray diffraction data evidenced no secondary phases. As temperature decreases, the maximum dielectric permittivity decreased. The fine-grained sample showed a ‘relaxor-like’ ferroelectric behavior. The dielectric permittivity reaches a maximum value (ɛm ∼ 16,000 at 1 kHz) for the BZT:2V ceramics sintered at 1623 K for 4 h. Remnant polarization (Pr) and coercive field were also temperature dependent

SIGAA

Navegando por Autor "Simões, A. Z."