Rongfeng Zhu

Mn:0.15Pb(In_1/2Nb_1/2)O₃-0.55Pb(Mg_1/3Nb_2/3)O₃-0.30PbTiO₃ (Mn:PIMNT) pyroelectric chips were prepared by a two-step annealing method. For the two steps, annealing temperatures dependence of microstructure, defects, surface stress, surface roughness, dielectric properties and pyroelectric properties were studied comprehensively. The controlling factors influencing the pyroelectric properties of the Mn:PIMNT crystals were analyzed and the optimum annealing temperature ranges for the two steps were determined: 600–700 °C for the first step and 500–600 °C for the second step. The pyroelectric properties of the thin Mn:PIMNT chips were significantly enhanced by the two-step annealing method via tuning oxygen vacancies and eliminating surface stress. Based on Mn:PIMNT pyroelectric chips annealed at the most favorable conditions (annealed at 600 °C for the first step and 500 °C for the second step), infrared detectors were prepared with specific detectivity D* = 1.63 × 10⁹ cmHz^1/2W⁻¹, nearly three times higher than in commercial LiTaO₃ detectors.

The [111]‐oriented rhombohedral Mn‐doped 0.15Pb(In _1/2 Nb _1/2 )‐0.55Pb(Mg _1/3 Nb _2/3 )O ₃ ‐0.30PbTiO ₃ (Mn:PIMNT(15/55/30)) crystal and the [001]‐oriented tetragonal Mn‐doped 0.29Pb(In _1/2 Nb _1/2 )‐0.29Pb(Mg _1/3 Nb _2/3 )O ₃ ‐0.42PbTiO ₃ (Mn:PIMNT(29/29/42)) crystal were poled under different conditions. The pyroelectric performance of the two crystals as a function of poling temperature, as well as the relationship with ferroelectric domain configuration and phase structure was investigated systematically. The pyroelectric properties of the two crystals enhance with rising the poling temperature, which can be attributed to the improvement of the single state. And for the rhombohedral Mn:PIMNT(15/55/30) crystal locating near morphotropic phase boundary (MPB), the increase of tetragonal phase induces the deterioration of pyroelectric properties. Due to more residual tetragonal phase, the pyroelectric coefficient of the Mn:PIMNT(15/55/30) crystal poled at 150°C is lower than that poled at 100°C. In general, both the crystals poled above T _C achieve nearly single state, exhibiting the best pyroelectric properties with relatively high Curie temperature ( T _C ), where P = 9.71 × 10 ⁻⁴ C m ⁻² K ⁻¹ , F _i = 3.88 × 10 ⁻¹⁰ m V ⁻¹ , F _v = 0.068 m ² C ⁻¹ and F _d = 29.7 × 10 ⁻⁵ Pa ^−1/2 for the rhombohedral Mn:PIMNT(15/55/30) crystal ( T _C = 171°C) and P = 6.78 × 10 ⁻⁴ C m ⁻² K ⁻¹ , F _i = 2.71 ×10 ⁻¹⁰ mV ⁻¹ , F _v = 0.1 m ² C ⁻¹ , F _d = 23.54 × 10 ⁻⁵  Pa ^−1/2 for the tetragonal Mn:PIMNT(29/29/42) single crystal ( T _C = 251°C), meeting the stable operation of infrared detector at relatively high environmental temperatures.