Optimization of pyroelectric figure of merit of PNN-PZ-PT composition at morphotropic phase boundary

Ternary compounds are proven to be a more fascinating, owing to their potential to span a broader composition region of morphotropic phase boundary (MPB) – enhanced piezoelectric, electrostrictive, dielectric and ferroelectric properties. To activate defects dipoles, we perform MnO₂ doping in ternary MPB compound 0.55 Pb(Ni_1/3Nb_2/3)O₃-0.135PbZrO₃-0.315PbTiO₃ [PNN-PZ-PT]. Temperature dependent dielectric spectroscopy reveals relaxor-ferroelectric nature of the synthesized ceramics. With the poling treatment, P-E loop of xMn-PNN-PZ-PT is softened, which emphasizes that the poling introduces higher order structural instability in MPB structure. The evolution of structural instability is as evidenced by the emergence of additional anomaly in thermal profile of dielectric constant due to electrical poling of xMn-PNN-PZ-PT and no systematic difference between polarizing behaviour of poled and unpoled specimen (Arrott plots). In association with defects dipoles, pyroelectric response based figure of merits (FOMs) of PNN-PZ-PT are improved. FOMs are characteristics of pyroelectric materials that insights about their suitability for specific application. F_i is suppressed with MnO₂ doping and F_v, F_e and $F_e^{\ast }$ increases with MnO₂ doping. Our study reveals that tailored and precise acceptor doping is crucial for the simultaneous optimization of all pyroelectric FOMs.