Temperature stable piezoelectric ceramics for cylindrical vibrators of vibratory gyroscopes

The relationships between piezoelectric characteristics of a ceramic cylindrical vibrator and the performance characteristics of a vibratory gyroscope such as in terms of sensitivity and zero offset were assessed by means of an equivalent circuit model. It was confirmed that the temperature stability of the gyroscope depends on temperature variations of the mechanical quality factor (Q(m)), the damped capacitance (C-d) and the resonant frequency (f(r)). The piezoelectric characteristics were investigated in the ternary system of PbTiO3-PbZrO3-Pb(Mn1/3Sb2/3)O-3. It was noticed that reduction of the Pb(Mn1/3Sb2/3)O-3 proportion to less than 5 mol% and addition of MnO, Fe2O3 and Sm2O3 enhances the temperature stabilities of Q(m); C-d and f(r). Consequently, a material having ranges of temperature variations of Q(m), C-d and f(r) of within +12% similar to -29%, +16% similar to -9% and +0.2% similar to similar to -1.1% respectively in the temperature range of -30 degrees C similar to +80 degrees C was developed. Finally a gyroscope having a range of temperature variation of sensitivity of within +/-10% and one of zero offset of within +/-10 degrees/s was obtained, which is applicable to direction sensors of car navigation systems.