Browsing by Author "Caballero, Amador C."
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Item Evaluation of piezoelectric properties of Bi4Ti 3O12-based ceramics at high temperature(2009) Villegas, Marina; Caballero, Amador C.; Jardiel, Teresa; Aragó, Carmen; Maudes, Jon; Caro, Iñaki; PRINTEX; PROMETALNowadays many industries as aeronautic, aerospace, etc, are claiming for new sensors and actuators that can operate in hostile environments. PZT ceramics are the common materials used in piezoelectric devices, however their low Curie temperature prevents their use at high temperatures. Bi4Ti 3O12-based ceramics show a great potential for high temperature applications. Although piezoelectric parameters of BIT ceramics are well described at room temperature, its behaviour at high temperatures is almost lacking. This paper describes an experimental set-up to measure the piezoelectric properties of high temperature piezoceramics up to 700°C. The variation of piezoelectric parameters of W-doped BIT ceramics as a function of temperature indicates that their operating temperature extends up to 500°C, surpassing the expected one (1/2Tc) in more than 200°C.Item Microwave-assisted reaction sintering of bismuth titanate-based ceramics(2006-04) Azurmendi, Naiara; Caro, Iñaki; Caballero, Amador C.; Jardiel, Teresa; Villegas, Marina; EXTREMAT; PROMETALBismuth titanate-based ceramics, pure and doped with 5 mol% WO3, were prepared by reaction-sintering using a microwave oven. High densities, ≥96% of theoretical density were achieved with very short thermal treatments, with soaking time ranging from 5 to 15 min. Relatively small platelet-like grains were formed, and microstructure seemed not to be strongly affected by doping nor soaking time. Electrical measurements were performed and, as expected, a decrease of electrical conductivity was observed in WO 3-doped materials. The results of reaction-sintered samples, both conventional as well as microwave sintered, are compared with those of samples prepared with previously calcined powders and sintered using microwaves as well as a conventional electric furnace.