Papers by Keyword: Piezoelectric Coefficient

Abstract: BiScO₃-xPbTiO₃ (BS-PT) of perovskite type structure (with x~0.64) were prepared by solid state ceramic process with addition of calcium fluoride (CaF₂) in different molar ratios (0.5, 1.0 and 4.0 mol%). The doped compositions were found to have different symmetry compared with parent material. The 0.5 mol% doped sample was found to possess enhanced rhombohedral phase as compared to other compositions while he Curie temperature (T_c) was not affected appreciably. Small dielectric peaks were observed, indicating phase transition, at temperature lower than T_c in all the samples except 4.0% doped composition. At room temperature doping reduced the loss factor. d₃₃ and P_r reduced rapidly with doping. The characteristics of BS-PT ferroelectric ceramics became harder with the addition of CaF₂.

Abstract: The PSZTM ceramics from Pb_0.94Sr_0.06(Zr_0.52Ti_0.48)O₃ doped with 0.1 mol% Mn were prepared by a solid state reaction and. Two different methods were used to calculate the amount of Mn-dopant into PSZT powder. One was calculated rely on B-site precursor represented by B method. The other was computed based on the amount of calcined PSZT called C method. This study was to investigate the effect of the two different calculating formulations of Mn doped PSZT ceramics by B and C methods on phase formation, microstructure, physical and electrical properties. The results were observed that phase identification showed the formation of perovskite structure in both cases. Besides, the mechanical quality factor (Q_m) of the PSZTM ceramics derived from B method was two times higher than those from C method. Nevertheless, the dielectric constant (K), piezoelectric coefficient (d₃₃) and planar coupling coefficient (k_p) of the PSZTM ceramics from B method were slightly lower than those of derived from C method. This could be drawn the conclusion that PSZTM with 0.1 mol% Mn prepared by B method can be used as hard-type piezoelectric material.

Abstract: This Paper has analyzed the relationship between the generation of multiple piezoelectric effects and boundary conditions of piezoelectrics and the experiments have studied tertiary piezoelectric effect of piezoelectric quartz which is applied extensively in engineering practice. We processed our experiment by piezoelectric quartz crystal unit made by two pieces of X-cut piezoelectric quartz, parallel connected it to a capacitor with the equivalent capacitance of about 1,000 times of that of piezoelectric quartz crystal unit and then got the result of pure primary piezoelectric effect excluding tertiary induced effect; then compared it with conventional primary piezoelectric effect and concluded that tertiary piezoelectric effect of piezoelectric quartz is about 1.7% of primary piezoelectric effect; thus quantified longitudinally tertiary piezoelectric effect of piezoelectric quartz crystal, concluded that piezoelectric coefficient of tertiary effect of X-cut piezoelectric quartz is about 0.04 pC/N by experiment and got relative uncertainty and standard uncertainty of the results by such experiment methods respectively as 9.49×10^-3 and 1.37×10^-2. This study on tertiary piezoelectric effect has provided a new approach for improving precision and sensitivity of piezoelectric sensors.

Abstract: Lead-free (Ba_0.97Ca_0.03) (Zr_0.18Ti_0.82) O₃ (BCZT) ceramic is prepared by sol-gel technique. The sample shows a pure perovskite structure through the XRD pattern. Well-developed grain morphology and a dense microstructure are acquired at an optimistic sintering temperature (~1330°C). The BCZT ceramic shows a surprisingly high piezoelectric coefficient of d₃₃=675 pm/V. The switching current curves are acquired in the different external fields by TF-2000 Ferroelectric Analyzer. It is found that with increasing the temperature, there is a decrease in the coercive field (Ec), and with increasing the electric field, there is an increase in the switching current obviously. Sintering temperature has an effect on switching current. The effect of temperature and electrical field on switching current is analyzed from viewpoint of the energy.

Abstract: This paper presents the effect of nitrogen concentration (C_N) on aluminum-nitride bonding formation, structure and morphology of the aluminum nitride films. The films on the unheated substrates were deposited by radio frequency reactive magnetron sputtering technology using an aluminum target under argon/nitrogen mixture atmosphere. The FTIR and Raman spectra of the films confirmed their absorption bands corresponding to E₁ (TO), A₁ (TO), and E₂ (high) vibration modes of the infrared active aluminum-nitride bonding. The crystallographic orientation of the films was optimized under C_N of 40%. The cross-sectional FE-SEM image of the film under this condition showed the columnar structure. The dense columnar grains were uniformly observed on the films surface under all C_N, except for C_N of 20%. The bulk resistivity and piezoelectric property were investigated via the metal-insulator-metal structures. The results showed that the resistivity was in a range of 10¹⁴-10¹⁵ Ωcm while the effective piezoelectric coefficient was 11.03 pm/V.

Abstract: In this paper, theoretical analysis is performed on the influence of multiple piezoelectric effects on piezoelectric coefficients. And a kind of classical piezoelectric ceramics was adopted to conduct the experimental validation. The experimental results of short-circuit boundary condition are obtained by the methods that a capacitor whose capacitance is much larger than that of the stack is parallel with PZT-5. Influence results are obtained through comparing them with open-circuit piezoelectric coefficient. Experimental result shows that multiple piezoelectric effects make piezoelectric coefficient of PZT-5 be altered by 18%.

Abstract: In this study, aluminum nitride (AlN) thin films reactively sputter deposited from an aluminium target are characterized both under material related aspects as well as on device level for resonantly driven gyroscopes. The first topic comprises a qualitative evaluation of the c-axis orientation by applying a wet chemical etching procedure in phosphoric acid to specimens synthesized under varying sputter deposition conditions. Samples with a high c-axis orientation show a low etch rate and smooth surface characteristics on the etched areas and vice versa. Furthermore, a quantitative determination of the piezoelectric coefficients is presented including the impact of the silicon substrate on the change in AlN film thickness under excitation. With this advanced approach, the d33 and the d31 coefficients are gained simultaneously with high accuracy comparing FEM simulations and interferometric measurements. Finally, AlN are applied to bulkmicromachined gyroscopes to stimulate the drive mode. Parasitic effects on the performance generated by the microactuator elements are identified and potential improvements are proposed.