Papers by Author: Miguel Algueró

Abstract: Although characterization of piezoceramics from resonance is a customary technique, the works dealing with the determination of the ten elastic, dielectric and piezoelectric coefficients that are needed in the full matrix characterization of such 6mm symmetry materials are rather scarce. Even more, if the complex characterization is foreseen, thus accounting with the three types of losses, few are the methods avaliable to obtain the material linear coefficients. This work deals with such complex characterization by the use of Alemany et al. automatic iterative method. This method has been applied to the four modes of resonance that are sufficient for the purpose: (1) the length extensional mode of long rods, length poled, (2) the thickness extensional mode and (3) the radial mode of a thin disk, thickness poled, and (4) the thickness shear mode of a thin plate. Recent work of the authors has shown the limits in characterizing materials that arise from the use of the Standard shear geometry and, therefore, and alternative geometry is used here. This work presents the matrix characterization of some piezoceramics and the Finite Element Analysis (FEA) simulation based on such characterization, of the samples used as a reliability criteria of the results obtained by comparison of the experimental and simulated values at resonance of the electrical parameters.

Abstract: Ceramics of morphotropic phase boundary (MPB) Pb(Mg1/3Nb2/3)O3-PbTiO3 have been processed from powders synthesized by mechanochemical activation of oxides. Their properties have been characterised and are compared with those of a MPB Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramic material by the columbite route. Current experiments on texturing by templated grain growth from the powders synthesised by mechanochemical activation are briefly described. MPB Pb(Zn1/3Nb2/3)O3-PbTiO3 has also been mechanosynthesised, though perovskite is not stable under heating and ceramics cannot be processed. Pb(Fe1/2Nb1/2)O3 is being investigated as a means of stabilising the perovskite, and MPB ceramic materials of the ternary system have been successfully prepared.