Effects of manganese addition on pyroelectric properties of (Bi0.5Na0.5TiO3)(0.94)(BaTiO3)(0.06) ceramics

(Bi0.5Na0.5TiO3)(0.94)(BaTiO3)(0.06) (BNBT-6) ceramics without additives and BNBT-6 ceramics with 0-0.8 mass% MnO2 were produced by a conventional ceramic fabrication technique. The effect of MnO2 addition on the pyroclectric coefficient. P, is investigated in detail. The figure of merit, F-D, for specific detectivity of pyroelectric infrared sensors is calculated using the specific heat obtained and other pyroelectric parameters, and the optimal MnO2 content is discussed. The measurement revealed the detailed temperature dependence of the volume specific heat, and the room-temperature volume specific heat of BNBT-6 ceramics (2.8 JK(-1) cm(-3)) is lower than that of PZT (3.1 JK(-1) cm(-3)). The maximum P value, obtained at 0.2 mass% MnO2, was 3.5 x 10(-8) C/cm(2) K. The present BNBT-6 ceramics with 0.2 mass% MnO2 exhibited an excellent FD that was 4.7 x 10(-9) Ccm/J. The BNBT-6 ceramics with 0.2 mass% MnO2 are highly promising as lead-free pyroelectric materials for pyroelectric infrared sensors.