Ferroelectric Ba0.7Sr0.3TiO3(BST) and partially Pb2+ substituted for Ba2+ ceramics (Ba0.7-xPbx)Sr0.3TiO3 (x=0.1-0.4,BPST) were prepared by using conventional solid-reaction method.XRD analysis shows that the samples microstructure changes from cubic phase to tetragonal one with the Pb2+ content increasing.ESEM analysis shows that the Pb2+ substituted samples have a denser and more uniform surface morphology than that of pure BST.Measured electrical properties suggest that the Pb2+ substitution for Ba2+ in the BST system enhances the ferroelectric performance obviously when x=0.2.In addition,the substitution increases the samples Curie temperature (Tc).(Ba0.5Pb0.2)Sr0.3TiO3 ceramic has good ferroelectric properties measured at a maximal electric field of 30 kV/cm under the condition of room temperature.The corresponding saturated polarization (Ps),remnant polarization (Pr) and coercive field (Ec) is respectively 15.687 μC/cm2,8.100 μC/cm2 and 6.611 kV/cm.The measured Tc of (Ba0.5Pb0.2)Sr0.3TiO3 is 117 ℃.
(Ba_(0.4)Pb_(0.3))Sr_(0.3)TiO_3 thin films were fabricated via pulsed laser deposition(PLD)technique on Pt/TiO_2/SiO_2/Si substrate.The crystallization of the films was characterized by XRD and FSEM,and the experimental results suggested deposition parameters,especially the deposition temperature was the key factor in forming the perovskite structure.The dielectric properties of the film deposited with optimized parameters were studied by an Agilent 4294A impedance analyzer at 1 MHz.The dielectric constant was 772,and the loss tangent was 0.006.In addition,the well-shaped hysteresis loop also showed that the film had a well performance in ferroelectric.The saturated polarization P,remnant polarization Pr and coercive field E were about 4.6μC/cm^2,2.5μC/cm^2 and 23 kV/cm(the coercive voltage is 0.7 V),respectively.It is suggested the film should be a promising candidate for microwave applications and nonvolatile ferroelectric random access memories (NvFeRAMs).
