Effects of Gamma Irradiation on Functional Response of Relaxor-Ferroelectric Thin Films

This work investigates the radiation response of relaxor-ferroelectric, lead magnesium niobate-lead titanate (PMN-PT) thin films, as an alternative material for microelectromechanical system (MEMS) devices in harsh environments. PMN-PT (0.7Pb[Mg_1/3Nb_2/3]O₃-0.3PbTiO₃) thin films were fabricated via chemical solution deposition onto platinized Si wafers and exposed to gamma radiation doses up to 10 Mrad(Si). The functional response of the thin films was measured before and after irradiation, and the resulting changes were reported. Within the radiation dose range studied, dielectric permittivity, tunability, and saturated polarization showed <5% change, and saturated piezoelectric coefficient <10% change. Additionally, PMN-PT thin films showed equivalent or superior radiation tolerance compared with lead zirconate titanate thin films previously studied. Higher chemical heterogeneity and greater domain wall mobility are expected to contribute to overall greater radiation tolerance in PMN-PT thin films. Nonlinear trends were found in dielectric and piezoelectric response with increasing dose, showing enhanced response at low doses of radiation before degradation at high doses. However, such variations were also within the experimentally observed dispersion of the data. The results are expected to impact systems to be deployed in areas of high radiation exposure, including systems used in aerospace, medical physics, X-ray/high-energy source measurement tools, and continuous monitoring of nuclear power applications.