Study of Crystal Structure and Electrical Properties on Lead Titanate and Lead Zirconate Titanate Based Ceramic Oxides

Abstract

The lead based perovskite material (PT, PZT) has so many technological applications such as:multilayer capacitor, dielectric resonator, thin film resistor, piezoelectric transducers, elecrostrictive actuators, hydrogen sensor, electro optical modulator, laser host, switch magnetic bubble memory etc. The property of the lead based material can also be enhanced by substituting different transition
materials within the perovskite.Again there is a very less report on the detailed crystal structure study (Employing the Rietveld Method) of the modified lead based perovskite ceramics.There were no detailed study on crystal structure and physical properties of Pb1-xLaxTiO3 (PLT) at high
concentration of La content.The introduction of an optimized amount of lanthanum (La) not only increases the stability but also softens the ferroelectric properties of the material.Also there was not much report on the detailed crystal structure (Employing the Rietveld method) and physical properties of B site modification of PLT with general formula (Pb0.70La0.30)(Ti1-xAx)O3,(A = Mn and Al). The main objective to study this material was to explore the structural and electrical properties of both iso(Mn3+) and aliovant (Al3+) substitution on the B site of Pb0.7La0.3TiO3 cubic perovskite. Manganese (Mn3+) as an acceptor ion may replace Ti4+ site and the addition segregates at grain boundaries. Mn doping in lead titanate is also a good candidate for fabricating piezoelectric devices. Mn belongs to valence unstable ions; it can affect the stability of the material.Aluminium does not have a bonding d-orbit or d-electrons, and has a stable valence and solely displays a valence of 3+,different from the isovalent substitutions for Ti4+.So the aliovalent substitutions of Al3+ for Ti4+ in Pb0.7La0.3TiO3 would be interesting for studying the doping effect on the crystal structure, lattice dynamics and electrical properties.The oxygen ion vacancy concentration in rare earth (La3+) and manganese modified lead titanate could have an important contribution to the electrical response of these materials. There are lots of reports on the structural and electrical properties of modified lead zirconate titanate ceramics in the MPB region. But there is hardly found few reports on the detailed crystalvii structure (Employing the Rietveld method) of lead zirconate titanate in and around the MPB region which overcomes the existence of two phases.The doping substituent can either occupy A-site, Bsite or both as donor or acceptor based on chemical valance with respect to the original ions.The substitution of the transition elements of the B-site will modify the electrical properties of the ferroelectric materials.It is also well known that the fluctuation of the oxidation state of the transition metal ions (Fe3+, Mn3+) results in the formation of oxygen ion vacancies to reserve the local electrical neutrality and causes thermally activated conduction.