The influence of defects on ferroelectric and pyroelectric properties of Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 single crystals

Relaxor-based ferroelectric single crystals 0.72Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 (PMN–0.28PT) were grown by a modified Bridgman technique. The direct current (dc) conductivity was investigated and corresponding conduction mechanisms were discussed. V″Pb−VOV″Pb−VO defects are dominant from 245 °C to 650 °C. The ferroelectric properties of [1 1 1]-oriented PMN–0.28PT were systematically investigated, with the coercive field (Ec) of 5.2 kV cm−1 and remnant polarization (Pr) of 37.8 μC cm−2 at room temperature. Moreover, the dielectric and pyroelectric performances of PMN–0.28PT were measured and the integrated pyroelectric performances greatly enhanced after annealing in oxygen at 500 °C for 20 h. This is due to the decrease of oxygen vacancies in the single crystals when being annealed in the oxygen-rich atmosphere. These make [1 1 1]-oriented PMN–0.28PT crystals a promising candidate for infrared detectors and thermal imagers used at room temperature.

► [1 1 1]-oriented PMN–0.28PT single crystals have high pyroelectric performances.
► Defects V″Pb−VOV″Pb−VO of PMN–0.28PT have been studied by dc conductivity.
► Chemical equilibrium equations are shown to calculate concentration of vacancies.
► Influences of defects on ferroelectric and pyroelectric properties are discussed.
► Oxygen annealing is used to optimize the integrated pyroelectric performances.