Influence of neodymium and lanthanum doping in the pyroelectric properties of strontium barium niobate (SBN) thin films

Strontium barium niobate thin films (SBN) are ferroelectric materials that can exhibit excellent pyroelectric and electro-optic properties. These properties make the SBN a very interesting material for a large variety of applications that include pyroelectric sensors. SBN thin films with a nominal composition (Sr0.75Ba0.25)Nb2O6, known as SBN75/25, doped with lanthanum or neodymium (1.0, 1.5 and 2.0 mol%) were obtained by a chemical method, in order to investigate the influence of the doping on their pyroelectric responsivity. The pyroelectric response was obtained through voltage measurements in the films, caused by the incidence of a square laser pulse applied with a different repetition rate. Structural and dielectric characterizations revealed a single polycrystalline SBN phase and a decrease of the dielectric permittivity due to the doping. The experimental results show that the additions of the dopant elements increase the pyroelectric response of the films and decrease the frequency dependence of the pyroelectric voltage responsivity RV, compared with the undoped one.