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Estudio y control de la conductividad en compuestos de Bi₄Ti₃O₁₂ dopados con Niobio, para aplicaciones de alta temperatura

1999; Elsevier BV; Volume: 38; Issue: 6 Linguagem: Inglês

10.3989/cyv.1999.v38.i6.897

2173-0431

P. Durán-Martı́n, Cyril Voisard, Dragan Damjanović, N. Setter,

Advanced MEMS and NEMS Technologies

Bismuth-based layered compounds have been considered during the last years as interesting materials for high temperature piezoelectric applications, due to their stability and wide thermal range of the ferroelectric activity.The high electrical conductivity present at high temperatures has been a disadvantage for the potential applications of these compounds.On Bi 4 Ti 3 O 12 (BIT), different doping, such as Nb 5+ and W 6+ were used to increase resistivity.It has been shown that Nb 5+ doping modifies piezoelectric response, passing from relatively high hysteretic to linear and almost completely non-hysteretic.In the present work, the effect of Nb 5+ doping related to the conduction response is investigated.Studies of the I-V curves as a function of the temperature allows us, for the first time, to measure the conductivity of these compounds at room temperature (RT) and to discuss which are the microstructural elements that control the conductivity of the material using a serial electrical model.It is shown that at temperatures between RT and 125¡C the grain boundary conductivity limits the total conductivity.At higher temperatures, the material conducts mainly through the bulk of grains.Conduction type, conductivity thermal regimes and chemical composition may explain the change in the piezoelectric behaviour.