Improved Pyroelectric Properties of CaBi4Ti4O15 Ferroelectrics Ceramics by Nb/Mn Co-Doping for Pyrosensors
The pyroelectric properties of Nb(Mn)-doped and Nb/Mn co-doped CaBi4Ti4O15 (CBT) bismuth layer-structured ferroelectric ceramics were investigated. It was found that Nb/Mn co-doping resulted in stronger enhancement of pyroelectric properties than that of single Nb or Mn doping. The mechanism of doping effect was explained by the distortion of the [BO6] octahedra induced by the doped Nb and Mn cations occupying the B-site of the pseudoperovskite structure. A large pyroelectric coefficient of 84.4 μC/m2K was obtained at room temperature for Nb/Mn co-doped CBT (CBTN-Mn) ceramics, higher than that of pure, Nb or Mn-doped counterparts, being on the order of 35.9, 58.2, 44.0 μC/m2K, respectively. The enhanced pyroelectric coefficient together with reduced dielectric constant (99) and dielectric loss (0.002) led to greater improvement of figures of merit (FOMs), including FOMs for voltage responsivity (Fv ~ 3.95 x 10−2 m2/C) and detectivity (Fd ~ 2.44 x 10−5 Pa−1/2), in CBTN-Mn ceramics. Furthermore, the temperature variations of Fv and Fd were found to be 24% and 68%, respectively, over a broad temperature range from room temperature to 350°C, making CBTN-Mn ceramics potential candidate for high-temperature pyroelectric devices.