Papers by Author: Li Tian Liu

Abstract: Multifunctional BiFeO3 (BFO) thin films were deposited on Bi3.15Nd0.85Ti3O12 (BNdT)/Pt and Pb(Zr1−x,Tix)O3 (PZT)/Pt substrates respectively by sol-gel process. The ferroelectric properties were studied for Metal-Ferroelectric-Mental (MFM) capacitors. The MFM structure exhibited well clockwise capacitance-voltage hysteresis loops due to the ferroelectric polarization of multilayer thin films achieved. The remnant polarization (2Pr) of the BFO/PZT and BFO/PZT multilayer capacitors were 45.1μC/cm2 and 23.2μC/cm2, respectively at the applied voltage of 8V. The leakage current of Pt/BFO/BNdT/Pt is about 3×10-5A/㎝2 at applied voltage of 4V, one order smaller than Pt/BFO/PZT/Pt capacitor. For the BFO/BNdT/Pt, it exhibited a weak saturated ferromagnetic response at room temperature and the multilayer was anti-ferromagnetic. However, for the BFO/PZT/Pt, well-developed M-H loops together with remnant magnetizations can be observed in at room temperature. The highest saturation magnetizations (Ms) of both capacitors were measured to be 2.47emu/cm3.

Abstract: The uniform Sr0.5Ba0.5Bi4Ti4O15 thin films were prepared using a modified Sol-Gel technique and the influence of precursor on the microstructure and characterization of thin films were studied. The stability and uniformity of precursor solution is key issue for the quality of thin films. Ethanolamine is an effective complexation reagent of Bi3+, which could moderate the acidity of precursor. When pH value and concentration of precursor solution was about 3.5 and 0.35M respectively, the smooth and uniform Sr0.5Ba0.5Bi4Ti4O15 thin films could be obtained. The Bi-layered perovskite structure of Sr0.5Ba0.5Bi4Ti4O15 formed at 750°C. The morphology of the grains in Sr0.5Ba0.5Bi4Ti4O15 thin films was elliptoid and the grain size was about 90 ~ 100 nm.

Abstract: The preparation and the microstructure of BaBi4Ti4O15 (BBT) thin films were reported in the paper. BBT thin films were fabricated on silicon substrate using a modified Sol-Gel technique. A key issue of Sol-Gel processing is the chemical reaction and mechanism of precursor solution, which governs the crystallization and characteristics of the final oxide layer. Ethanolamine is an effective complexation reagent of Bi3+, which could moderate the acidity of precursor. When pH value is about 3.5, the stable and uniform BBT precursor solution could be obtained. The Bi-layered perovskite structure of BBT forms at 750°C. The morphology of the grains in BBT thin films is spheroidal and the grain size is about 120nm.