Giant pressure sensitivity in piezo/ferro-electric ceramics.

We report the fabrication of single-phase polycrystalline Pb 0.85 Bi 0.10 (Zr 0.52 Ti 0.48 )O 3 (PBiZT) ceramic which shows large polarization, i.e. , ∼40 μC cm -2 and piezoelectric coefficients ∼130 pC N -1 and giant linear change in capacitive reactance and dielectric properties with increasing and decreasing pressure in the range of 1 kHz to 5 MHz. Nearly 70% change in dielectric constant and 56% change in capacitive reactance were obtained in the pressure range of 20-200 MPa, which makes it suitable for applications as a capacitive pressure sensor/gauge. The sensitivity of the device is calculated as 0.66 MPa -1 and 18.2 MPa -1 at 1 MHz and 5 MHz, respectively, which is the highest ever reported value so far for any bulk polycrystalline ceramic. The compressive stress of the device was tested according to the standard test method as a function of linear and volumetric strain, which yields the Young's modulus, Bulk modulus, and Poisson's ratio of the device. These values were further utilized to calculate actual stress in the sample and energy density using ANSYS software, which indicates at least four orders smaller pressure in the sample compared to the applied pressure.