Chinnambedu Murugesan Raghavan

Structure and Multiferroic Properties of V-doped Bi6Fe2Ti3O18 Thin Films Prepared by Chemical Solution Deposition

Pure Bi6Fe2Ti3O18 and vanadium (V) doped Bi6Fe2Ti3O18 (Bi5.99Fe2Ti2.75V0.03O18) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by a chemical solution deposition method. The Bi5.99Fe2Ti2.75V0.03O18 thin film exhibited improved electrical and multiferroic properties, such as leakage current densities, dielectric properties, ferroelectric and ferromagnetic properties. We consider that the improved properties might be related to the reduced concentration of oxygen vacancies and the decreased mobility of oxygen vacancies by V doping.

Structural and Multiferroic Properties of Chemical-Solution-Deposited (Bi0.95La0.05)(Fe0.97Cr0.03)O3/NiFe2O4 Double-Layered Thin Film

The structural, electrical, and multiferroic properties of the double-layered (Bi0.95La0.05)(Fe0.97Cr0.03)O3/NiFe2O4 thin film deposited on a Pt(111)/Ti/SiO2/Si(100) substrate by a chemical solution deposition method are reported. The formation of the perovskite-based distorted rhombohedral and spinel phases was confirmed by X-ray diffraction analysis and Raman spectroscopy. The surface morphology and film thickness were analyzed by field emission scanning electron microscopy. The low leakage current density (5.83×10-7 A/cm2 at 100 kV/cm) was measured from the double-layered thin film. Potential multiferroic properties, such as a well-saturated ferroelectric hysteresis loop with large 2 Pr (61 µC/cm2) and 2 Ec (652 kV/cm) (at an applied electric field of 952 kV/cm), and a ferromagnetic hysteresis loop having 2 Mr (18.6 emu/cm3) with 2 Hc (0.943 kOe) (at an applied magnetic field of 20 kOe), were observed from the double-layered thin film.

Effects of Annealing Atmosphere on Structure and Electrical Properties of (Bi0.9Eu0.1)(Fe0.9Mn0.1)O3 Thin Films

(Eu, Mn) co-doped bismuth ferrite [(Bi0.9Eu0.1)(Fe0.9Mn0.1)O3 (BEFMO)] thin films were deposited on Pt(111)/Ti/SiO2/Si substrates by using a chemical solution deposition method. The coated films were annealed in N2, air and O2 atmospheres at 550°C for 30 min. Effects of annealing atmosphere on the crystal structure, ferroelectric properties and leakage current density of the BEFMO thin films were investigated. The single-phase rhombohedral perovskite crystal structure of all the samples was confirmed by x-ray diffraction analysis. From the electrical studies, the BEFMO thin film annealed in air atmosphere showed better electrical properties than O2 and N2 atmosphere annealed samples. The largest remnant polarization 96.4 μC/cm2 at an electric field 1060 kV/cm was obtained from the BEFMO thin film annealed in air.

Effects of Excessive Bi on the Structure and the Properties of Aurivillius Bi

The effects of excessive Bi on the structural, electrical and multiferroic properties of the La-doped Bi6Fe2Ti3O18 (Bi5.25La0.75Fe2Ti3O18) thin films prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method are reported. The structures of the thin films were studied by using X-ray diffraction, Raman scattering spectroscopy and scanning electron microscopy. From the experimental comparisons, a low electrical leakage current of 1.84 × 10-5 A/cm2 at 100 kV/cm and enhanced ferroelectric properties, such as a large remnant polarization (2Pr) of 10.5 μC/cm2 and a low coercive field (2Ec) of 400 kV/cm at 485 kV/cm, were observed for the 5% Biexcess La-doped Bi6Fe2Ti3O18 thin film. The formation of a stable bismuth layer-structured phase, a lower c-axis orientation, an optimum crystallinity and a dense microstructure with a smooth surface morphology correlate with the improved electrical and multiferroic properties of the 5% Bi-excessive Bi6Fe2Ti3O18 thin film.

_{5.25}

Thin films of BiFeO3 (BFO), Bi0.9Eu0.1Fe0.975Cu0.025O3-δ (BEuFC) and Bi0.9Dy0.1 Fe0.975Cu0.025O3-δ (BDyFC) were prepared on Pt(111)/Ti/SiO2/Si(100) substrates via a chemical solution deposition method. X-ray diffraction and Raman studies show distorted rhombohedral perovskite crystal structure for all the samples. Micro structural features and morphological changes of the BFO, BEuFC and BDyFC were examined by using a FE-SEM analysis. The leakage current density was found to be greatly reduced for the BEuFC and the BDyFC thin films. The largest remnant polarization (2Pr) 68 μC/cm2 (at 1336 kV/cm) and the lowest coercive field (2Ec) 845 kV/cm (at 931 kV/cm) were observed from the BEuFC and the BDyFC thin films, respectively.

La

The structural and electrical properties of BiFeO3 (BFO) and rare earth metal ions (Re) co-substituted (Bi0.9Re0.1)(Fe0.9Mn0.1)O3-δ (Re = Nd, Sm, Ce and Tb) thin films prepared on Pt(111)/Ti/SiO2/Si(100) substrates via a chemical solution deposition method were investigated. The significant decrease of leakage current density and improved ferroelectric properties were observed from the co-substituted thin films. The largest remnant polarization (2Pr) (61.7 μC/cm2) and the lowest coercive field (2Ec) 657 kV/cm at 931 kV/cm were measured from the (Bi0.9Ce0.1)(Fe0.9Mn0.1)O3-δ thin film. The leakage current density value of (Bi0.9Sm0.1)(Fe0.9Mn0.1)O3-δ thin film (3.29 × 10−5A/cm2) was found to be two order lower than that of the pure BFO.