Effect of lanthanum on ferroelectric phase transition of Pb(Ni_1/3Sb_2/3)O₃-Pb(ZrTi)O₃

Ferroelectric phase transition of compositions, Pb_1-zLa_z(NiSb)_0.5((Zr_0.52Ti_0.48)_1-z/4)_0.95O₃ with Z=0.01-0.05 were investigated by studying dielectric constant as a function of temperature at 100 kHz. Compositions were prepared by conventional mixed oxide route. Ferroelectric to paraelectric phase transition temperature was observed to decrease with increase in. Compositions containing 1 to 3% of lanthanum showed sharp phase transition while it was diffused for 4 and 5 mol % of lanthanum. Ferroelectric rhombohedral (FR) to ferroelectric tetragonal (FT) phase transition was also noticed for compositions with 1 and 2 mol% of lanthanum near 170℃. Structural disorder factor (γ) showed better homogeneity for composition with 2 mol % of lanthanum. Moreover, product of piezoelectric coefficient (d₃₃) and voltage coefficient (g₃₃) that is figure of merit indicated the suitability of this composition for energy harvesting applications. (author)