Pyroelectric and dielectric properties of lead-free BaTi0.925((Yb0.85Fe0.15)(0.5)Nb-0.5)(0.075)O-3 ceramic

Abstract : The effect of the low amount of Fe3+ doping on the structure and the dielectric properties of the ceramic BaTi0.925(Yb0.5Nb0.5)(0.075)O-3 (BTYN75) was studied in this work. The new lead-free ceramic BaTi0.925((Yb0.85Fe0.15)(0.5)Nb-0.5)(0.075)O-3 (BTYN75-Fe) was synthesized with the solid-state reaction method at 1673 degrees K for 3 h. The substitution of Yb3+ by Fe3+ affected the structure of BTYN75-Fe. The structural analysis BTYN75-Fe showed the coexistence of Pm3m-cubic symmetry (similar to 22%) and P4mm-tetragonal symmetry (similar to 78%) at room temperature. Dielectric properties of BTYN75-Fe were studied in detail upon heating and cooling as a function of frequency. Compared with pure BTYN75, the low amount of the iron Fe3+ resulted in a slight reduction of the dielectric loss and enhanced the dielectric constant. From temperature variation of dielectric constant, Curie temperature (T-C) and the depolarization temperature (T-d) were determined and equal to T-C = 310 K and T-d = 284 K, respectively. The pyroelectric coefficient (p) of BTYN75-Fe measured upon heating recorded a high value of 18.74 nCcm(-2) K-1 at T-d higher than many other lead-free pyroelectric materials. The figure of merits (FOMs) of BTYN75-Fe was also evaluated in this work.