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We prepared pure BiFeO3(BFO) and co-doped (Bi0.9Nd0.1)(Fe0.975V0.025)O3+δ(BNFVO) thin films on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. Improved electrical properties were observed in the co-doped BNFVO thin film. The leakage current density of the co-doped BNFVO thin film was four orders of magnitude lower than that of the pure BFO, 2.6 × 10−7A/cm2at 100 kV/cm. The remnant polarization (2Pr) and the coercive electric field (2Ec) of the co-doped BNFVO thin film were 56 μC/cm2and 1393 kV/cm at an applied electric field of 1110 kV/cm and at a frequency of 1 kHz, and the values decreased with increasing measurement frequency to 18 μC/cm2and 1282 kV/cm at 10 kHz, respectively. We also confirmed that the remnant polarization (2Pr) and the coercive electric field (2Ec) were fairly saturated above a measurement frequency of 20 kHz for the BNFVO thin film. [ABSTRACT FROM AUTHOR]

Bismuth ferrite BiFeO3(BFO) and holmium (Ho)-chromium (Cr) co-doped bismuth ferrite (Bi0.9Ho0.1)(Fe0.975Cr0.025)O3, (BHFCr) thin films were deposited on Pt(111)/Ti/SiO2/Si substrates by using a chemical solution deposition method. Effects of Ho and Cr co-doping on the micro-structures, ferroelectric properties and leakage current densities of the thin films were investigated. The single-phase rhombohedral perovskite structures of the thin films were confirmed by an X-ray diffraction analysis. From the electrical property studies, the BHFCr thin film showed enhanced electrical properties compared to the BFO thin film. The improved electrical properties of the BHFCr thin film are correlated with greatly improved microstructure, stabilization of the perovskite structure and defects compensation. [ABSTRACT FROM AUTHOR]

It has been well known that BiFeO3 (BFO) exhibits two interesting physical properties simultaneously, which invoked multi-ferroic device applications to change electrical properties by controlling magnetic properties of BFO or vice versa. However, BFO has a high leakage current density, which may be attributed to bismuth and/or oxygen vacancies in the structure. In order to reduce the leakage current, a thin layer of dielectric SrTiO3 (STO) has been deposited on the top of BFO films by pulsed laser deposition. Improvement in leakage current and remnant polarization was observed in the STO capped BFO thin films. [ABSTRACT FROM AUTHOR]

(Na0.53+x K0.47)(Nb0.55Ta0.45)O3 (NKNT) ceramics prepared by a solid state process were investigated at 0 ≤ x ≤ 0.02 to determine the effects of Na content in NKNT ceramics. With Na nonstoichiometry, piezoelectric properties were varied but grains were all cube-like perovskites with no impurity phases. Piezoelectric coefficient (d 33) was sensitive to Na content while polymorphic phase transition (PPT) temperature was not. PPT temperature between orthorhombic and tetragonal phases (T O-T) was around room temperature within the compositional range tested. The highest d 33 obtained was 330 pC/N at Na0.545 (x = 0.015) increased from 310 pC/N at Na0.53 (x = 0), which was due to the morphotropic phase boundary (MPB) effect around (Na0.53K0.47) of NKNT ceramics. [ABSTRACT FROM AUTHOR]

The effects of Li substitution on K in (Na0.53K0.47-x Li x )NbO3 (NKLN) ceramics prepared by a solid state process were studied at 0 ≤ x ≤ 0.09. Phase purity was maintained up to x = 0.04, then a secondary phase started emerging. With increasing Li substitution, partial melting appeared to occur and grain size increased. Polymorphic phase transition (PPT) temperatures, T O-T between orthorhombic and tetragonal phases and T C between tetragonal and cubic phases, were significantly affected by Li substitution. With increasing x, T O-T decreased while T C increased extending the tetragonal phase region. The highest d 33 of 220 pC/N was obtained at x = 0.07 mol at which high apparent density of the sintered pellets was obtained despite the formation of an impurity phase. [ABSTRACT FROM AUTHOR]

(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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Ferroelectric K0.5Bi4.5Ti4O15 (KBTi) and Cr-doped K0.5Bi4.5Ti4O15 ((K0.5Bi4.5Ti3.97 Cr0.03O15-δ), (KBTC)) thin films were prepared on Pt(111)/Ti/SiO2/Si substrates by using a chemical solution deposition method. The thin films were annealed at 750°C for 3 min by a rapid thermal annealing process under oxygen atmosphere. Compared to pure KBTi thin film, there was no structural change while improved ferroelectric and leakage current properties were observed. The values of remnant polarization (2Pr ) and coercive field (2Ec ) were 50.9 μC/cm2 and 244 kV/cm at an applied electric field of 300 kV/cm, respectively. The 2Pr we observed is compatible with that of doped bismuth layer-structured ferroelectric thin films. Leakage current density was 6.00 × 10−7 A/cm2 at 200 kV/cm. The enhanced properties of KBTC could be explained by a defect dipole (Cr′Ti-V) and increased average grain size. [ABSTRACT FROM AUTHOR]

K nonstoichiometry effects in (Bi0.5K0.5+x)TiO3 (BKT) ceramics were studied with K contents varying in the range of -8≤ x ≤+1 mol% from the stoichiometric K0.5. Within the range tested, a single BKT phase region was found to be at -1≤ x ≤+1 mol% and secondary phases started emerging with further K deficiency. Despite the formation of secondary phases, BKT perovskite with tetragonal symmetry was retained at all compositions. For nonstoichiometric BKT perovskite, a composition dependent structure property relation was observed; a decrease in tetragonality (c/a) caused piezoelectric coefficient (d33) enhanced while depolarization temperature (Td) reduced and vice versa. [ABSTRACT FROM AUTHOR]

A new type of bismuth-based relaxor, such as Bi 2 (Y 1/2 Nb 1/2 ) 2 O 7 and Bi 2 (Mg 1/3 Nb 2/3 ) 2 O 7 thin films were fabricated on Pt/Ti/SiO 2 /Si substrate by a sol-gel spin coating process. The films exhibit characteristic diffused phase transition. The temperature dependent reciprocal dielectric constant characteristics of the films deviates from the Curie-Weiss law in the temperature range over the dielectric constant maximum temperature ( T m ). The diffuseness of the phase transition of the thin films was estimated by calculating the difference between T m and T cw (starting temperature following the Curie-Weiss law). For the thin films annealed at 750°C, the temperature T m , the Curie-Weiss temperature Θ, the Curie-Weiss constant c and the temperature T cw were measured at frequency of 10 3 Hz, respectively. [ABSTRACT FROM AUTHOR]

The formation of phase-pure BiFeO 3 (BFO) thin films using a chemical solution deposition on platinium electrode has been investigated systematically by changing the annealing condition of the films. From the X-ray diffraction results, it was found that the formation of the phase-pure BFO was favorable under lower oxygen partial pressure, slower heating rate and Pt(200)/Ti/SiO 2 /Si(100) substrate. The remanent polarization ( P r ) and coercive field ( E c ) values of the phase-pure BFO thin film annealed at 600°C in nitrogen atmosphere by conventional furnace annealing method are approximately 0.9 μC/cm 2 and 20 kV/cm, respectively. [ABSTRACT FROM AUTHOR]

Well c-axis oriented 320 nm and 160 nm thick ZnO thin films were deposited with pulsed laser deposition on Pt/Ti/SiO 2 /Si(100) substrates. Diode characteristics of Au/ZnO/Pt in electrical conductivity were observed. The conductivity in forward bias was sensitive to the hydrogen annealing but almost insensitive in reverse bias. The conductivity of 320 nm thick film in forward bias increased from 6.1 × 10 -5 Ω -1 cm -1 in as-deposited film to 3.3 × 10 -3 Ω -1 cm -1 in hydrogen annealed one at 200 &circle; C. The observed dielectric constant 70 was much higher than that of ceramic ZnO. Dielectric anomaly at about 1 kHz was observed and attributed to the space charge. [ABSTRACT FROM AUTHOR]

Lanthanides (La3+, Nd3+, Sm3+ and Eu3+) doped Bi4Ti3O12 (BIT) films fabricated on p-type Si(100) substrates by a sol-gel spin coating process. The films were characterized by X-ray diffractometer and scanning electron microscope. Memory windows calculated from the measured C-V hysteresis curves were approximately 3.5, 0.85, 0.8, and 0.54 V for La-, Nd-, Sm-, and Eu-doped BIT films with a sweep voltage of ± 10 V, respectively. The effects of lanthanides substitution for Bi3+ in the perovskite layer on the electrical properties, such as C-V and I-V characteristics, have been reported. [ABSTRACT FROM AUTHOR]