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0888-V08-09.1

Studies of Bi4-xGdxTi3O12 Bifunctional Material Maharaj S. Tomar*, Physics and Geology Department, University of Texas, Edinburg, TX 78451-2999, *on leave of absence from University of Puerto Rico, Mayaguez, Ricardo E. Melgarejo, Raúl Singhal, Luis M. Angelats, Physics Department, University of Puerto Rico Mayagüez, PR 00681-9016, Ram S. Katiyar, Physics Department, University of Puerto Rico, San Juan, PR 00931-3343. ABSTRACT Gadolinium-substituted Bi4Ti3O12 (Bi4-xGdxTi3O12) were synthesized by sol-gel process for different compositions, and thin films were deposited on Pt (Pt/TiO2/SiO2/Si) substrate by spin coating. Post annealed films at 700° C were investigated for their structural properties using xray diffraction and Raman spectroscopy indicating solid solution for compositions: x = 0.00, 0.46, 0.56, and 0.85 where Bi ion is replaced by Gd-ion. Sol-gel derived Pt/Bi4-xGdxTi3O12 film/Pt capacitor structure was tested for dielectric, ferroelectric, and leakage current responses. Films showed ferroelectricity with polarization, Pr = 22 µC/cm2 for composition: x = 0.46. Magnetic response of the powder sample for composition: x = 0.85 was tested using SQUID, which showed super-paramagnetic at room temperature and magnetic at 5 K with magnetic coercivity (Hc) = 29 Oe and very small ferromagnetic polarization (σr) = 5.4 x 10-4 emu/g. INTRODUCTION The materials having two or more than two distinct properties are inherently important for interesting physics and applications. Mixed metal oxides including perovskite and layered structures have played an important role as dielectrics, ferroelectrics, and ionic conductors. Aurivillius phase materials consist of alternating perovskite-like An-1BnO3n+1 and fluorite-like Bi2O2 layers, where A is a mono-, di, or trivalente cation, B is a cation with valence 4, 5 or 6, and n is the number of perovskitelike lalyers1,2. Bi4Ti3O12 is one of the few compounds within the Aurivilllius family3,4 that has a monoclinic ferroelectric structure, with one component of the polarization in the plane of the layers, and the other perpendicular to this plane. The origin of the ferroelectric polarization within the layers may be5 due to the large displacement of Bi3+ cations in the peorvskite A site with respect to the chain of TiO6 octahedra. The Bi3+ ion in A site is strongly underbonded, and Ti4+ ion in the B site is slightly overbonded. Thus, the partial replacement of Bi3+ by suitable trivalent cations, could modify the polarization behavior6,7 of the material system. A partial substitution of Bi-ion by Gd ion in Bi4-xMxTi3O12 may have interesting properties. Initial experimental results are presented on the synthesis, structural, dielectric, ferroelectric, and magnetic properties of sol-gel derived Bi4-xMxTi3O12 material. EXPERIMENTAL DETAILS For the synthesis, we used bismuth nitrate, Gadolinium nitrate, and titanium isopropoxide were used as the precursors for Bi, Gd, and Ti respectively, and acetic acid and methoxy ethanol were the solvents. With the proper processing of t