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Pure BiFeO3(BFO) and Gd-transition metal co-doped (Bi0.9Gd0.1)(Fe0.975B0.025)O3±δ(B= Ni, Mn, Cu, Ti, and V, denoted by BGdFNi, BGdFMn, BGdFCu, BGdFTi, and BGdFV) films were deposited by using a chemical solution deposition. Enhanced electrical properties were observed for the co-doped films. The BGdFMn film showed the largest 2Prvalue (105.3 μC/cm2at 1470 kV/cm) and the smallest leakage current density (1.49 × 10−5A/cm2at 100 kV/cm). The enhanced electrical properties for the co-doped films are related to the decrease of oxygen vacancies, the stabilization of perovskite structure, and the lattice distortion by the doping elements. [ABSTRACT FROM AUTHOR]

Lead-free polycrystalline (K0.48Na0.52)1+x(Nb0.55Ta0.45)O3(x = 0, 0.01, 0.02 and 0.03) thin films have been grown on Pt(111)/Ti/SiO2/Si substrates using KrF excimer laser ablation to investigate the effects of A-site ion excess. The film at x = 0.01 exhibited good ferroelectric hysteresis loop with a remnant polarization 2Prof 30 μC/cm2and coercive field 2Ecof 61 kV/cm. The piezoelectric coefficientd33,fof the KNNT film with x = 0.01 was found to amount to 79 pm/V. These improved ferroelectric and piezoelectric properties were attributed to the excess of A-site Na and K ions. [ABSTRACT FROM PUBLISHER]

Pure Bi6Fe2Ti3O18and 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 Bi5.99Fe2Ti2.75V0.03O18thin 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. [ABSTRACT FROM PUBLISHER]

We have evaluated the ferroelectric and electrical properties of pure BiFeO3(BFO) and (Bi0.9Ho0.1)(Fe0.975Ti0.025)O3+δ(BHFTO) thin films on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. The improved electrical properties were observed in the BHFTO thin film. The leakage current density of the co-doped BHFTO thin film showed three order lower than that of the pure BFO, 1.22 × 10−6A/cm2at 100 kV/cm. The remnant polarization (2Pr) and the coercive electric field (2Ec) of the BHFTO thin film were 61 μC/cm2and 1190 kV/cm at an applied electric field of 800 kV/cm and at a frequency of 1 kHz and these values decreased with increasing measurement frequency, 35 μC/cm2and 920 kV/cm at 10 kHz, respectively. Also, the 2Prand the 2Ecvalues were fairly saturated above 30 kHz. [ABSTRACT FROM PUBLISHER]

Multiferroic Bi(Fe0.9Mnx0.1)O3(x= 2+, 3+, and 4+) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a pulsed laser deposition method. The effects of different oxidation states of Mn used as a starting material on crystal structure, leakage current, dielectric, and ferroelectric properties were investigated. No significant change in the crystal structure was observed while electrical properties were affected by the oxidation states of Mn. A frequency-dependent dielectric relaxation region was observed in the films with Mn3+and Mn2+, indicating the presence of space charges such as oxygen vacancies. [ABSTRACT FROM AUTHOR]

Pure Bi5FeTi3O15and its doped compounds, such as Bi4.15La0.75FeTi3O15and Bi4.15Nd0.85FeTi3O15thin films, were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. The crystalline structures and the surface morphologies of the thin films were identified by using an X-ray diffractometry, a Raman spectroscopy, and a scanning electron microscopy. In addition, the comprehensive electrical properties of the thin films, such as ferroelectric hysteresis loops and leakage current densities, were characterized by using a precision materials analyzer and an electrometer at room temperature, respectively. [ABSTRACT FROM AUTHOR]

Effects of heat-treat procedure and sintering temperatures were investigated in 0.67Bi1.05FeO3-0.33BaTiO3ceramics. The structure, dielectric, ferroelectric, and piezoelectric properties of ceramics made by normal cooling or quenched cooling process were investigated. All ceramics show single pseudo-cubic perovskite crystal structure. Although the structure was not changed but other properties were much changed by heat-treatment. The normally cooled ceramic showed ‘pinched’ ferroelectric hysteresis loops with remanent polarization value of about 10 μC/cm2. On the contrary, the quenched ceramic showed ‘normal’ ferroelectric hysteresis loops with remanent polarization value of about 17 μC/cm2. The piezoelectric constantd33value of 13 pC/N in normally cooled ceramic was improved to 39 pC/N in quenched ceramic. These improved results were attributed to the reduced populations of defects made during the heat-treatments. [ABSTRACT FROM AUTHOR]

A phenomenological approach to explain the change of phase transition temperatures (TC) of Pb(Zr,Ti)O3-BiFeO3(PZT-BF) mixed system was proposed. By introducing coupling terms independent of composition together with the averaged free energy terms, the change of TCwas well explained in PbTiO3-BiFeO3(PT-BF) mixed system. From the parameters obtained from PT-BF system ofa1anda11in Landau-Devonshire theory, we could explain the change of TCin PZT-BF system in tetragonal phase. [ABSTRACT FROM PUBLISHER]

The microstructure, dielectric and leakage current characteristics of Bi(Fe1-xTix)O3 (x = 0-0.2) polycrystalline ceramics have been investigated. Phase transformation from rhombohedral to orthorhombic symmetry occurs at around x∼0.2. Average grain size decreases rapidly and then saturates with the size of few μm above x = 0.025. The steplike decrease in ε for the composition of x = 0 and 0.01 are related dielectric relaxation. Leakage currents were much decreased by about 6 orders of magnitude above x = 0.025. Similarly to the results of SEM images and dielectric constants, leakage currents were changed with Ti substitution. [ABSTRACT FROM AUTHOR]

Randomly oriented and c-axis-oriented Bi3.15Pr0.85Ti3O12 (BPT) thin films were prepared by a chemical solution deposition method. Ferroelectric and leakage current properties were strongly related to the crystallographic orientation of BPT thin film. The values of remnant polarization (2Pr) and leakage current density were 74 μC/cm2 at 250 kV/cm and 3.4 × 10-8 A/cm2 at 125 kV/cm for the randomly oriented thin film, respectively, and 16 μC/cm2 and 6.9 × 10-6 A/cm2 for the c-axis-oriented thin film, respectively. The result indicates that the polarization vector of BPT thin films is not oriented along the c-axis. [ABSTRACT FROM AUTHOR]

V-doped Na0.5Bi4.5Ti4O15 (Na0.5Bi4.5-x/3Ti4-xVxO15, NaBTiV-x, x = 0.00, 0.01, 0.03, and 0.05) thin films were prepared on a Pt(111)/Ti/SiO2/Si(100) substrate by a chemical solution deposition method. NaBTiV-0.01 thin film exhibited the most outstanding electrical properties among them. The value of remnant polarization (2Pr) was 61 μC/cm2 and the leakage current density of the thin film capacitor was approximately one order of magnitude lower than that of pure Na0.5Bi4.5Ti4O15 thin film capacitor. We consider that the enhanced properties may be related to reduced oxygen vacancies by doping vanadium. [ABSTRACT FROM AUTHOR]

Ferroelectric and leakage current behaviors of Zn-Mn co-doped polycrystalline BiFeO3 (BFO) thin films fabricated by a pulsed laser deposition were investigated in comparison with un-doped BFO thin films. Ferroelectric hysteresis loop was observed in Zn-Mn co-doped BFO film capacitor: 2Pr = 109 μC/cm2 and 2EC = 674 kV/cm with maximum electric field of 600 kV/cm. And leakage current was reduced with Zn-Mn co-doping at low electric field region and 10 mol% Bi-excess BFO film has best leakage current behavior in a wide electric field range. [ABSTRACT FROM AUTHOR]

Effects of Bi(Zn0.5Ti0.5)O3 (BZT) substitution in Pb(Zr1-xTix)O3 (PZT) piezoelectric ceramics were investigated. Morphotropic phase boundary was observed at x = 0.48 and high piezoelectric properties were observed similarly to the un-substituted PZT ceramics. Piezoelectric properties were improved with 5 mol% BZT substitution. The ferroelectric transition temperatures were decreased by about 45°C with 5 mol% BZT substitution contrary to the increase of the transition temperature with BZT substitution in PbTiO3. [ABSTRACT FROM AUTHOR]

The effects of Bi(Zn0.5Ti0.5)O3 (BZT) substitution in BaTiO3 (BT) or (Bi0.5Na0.5)TiO3 (BNT) piezoelectric ceramics were studied. (1-x)BaTiO3-xBi(Zn0.5Ti0.5)O3 (x = 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.30, and 0.40) and (1-y)(Bi0.5Na0.5)TiO3-yBi(Zn0.5Ti0.5)O3 (y = 0, 0.01, 0.025, 0.05, 0.10, and 0.20) ceramics were prepared by a solid state reaction method. The structures and surface morphologies have been examined using an X-ray diffraction and scanning electron microscopy, respectively. The grain size and density increased with increasing the amount of BZT in both systems. Curie temperatures (TC) were decreased as BZT substituted. Piezoelectric properties also decreased with the substitution of BZT. [ABSTRACT FROM AUTHOR]

Cr-substituted BiFeO3 (BFCr-3 mol%) thin films were deposited on Pt(200)/TiO2/SiO2/Si substrates by a chemical solution deposition. The coated films were annealed in the temperature range of 500°C∼ 600°C for 30 min under nitrogen atmosphere. The electrical properties of BFCr thin films were found to be sensitive to the annealing temperature. It was found that BFCr thin films exhibited good ferroelectric properties, such as an improved leakage-current density and P-E hysteresis characteristics. The BFCr thin film annealed at 525°C exhibits a low leakage current density of 9.2 × 10- 7 A/cm2 at an applied electric field of 100 kV/cm. The films exhibited a well-saturated hysteresis loop with a remanent polarization (Pr) of 47 μC/cm2 at room temperature. The reason for the improved leakage current and ferroelectric properties in BFCr thin films can be attributed to the effects of increased grain size and oxygen vacancies reduced by Cr doping. [ABSTRACT FROM AUTHOR]

5 mol % La3 +, Nd3 + or Y3 +-cosubstituted BiFe0.97Cr0.03O3 thin films (denoted by BLaFCr, BNdFCr, and BYFCr, respectively) have been successfully deposited on Pt (200)/TiO2/SiO2/Si substrates by a chemical solution deposition method. Well-saturated ferroelectric hysteresis loops and low leakage current densities have been observed in BLaFCr, BNdFCr, and BYFCr thin films with single-phase structure. The values of remanent polarization (Pr) and coercive field (Ec) were 64 μ C/cm2 and 275 kV/cm, 61 μC/cm2 and 290 kV/cm, and 31 μ C/cm2 and 315 kV/cm for BLaFCr, BNdFCr and BYFCr thin films at the maximum electric field of 712 kV/cm, respectively. In the present study, the differences in values of Pr seem to be related to the doped ionic radii. [ABSTRACT FROM AUTHOR]