Metal Organic Decomposition Method Research Articles

Longitudinal spin Seebeck effect in Nd2BiFe5−xGaxO12 prepared on gadolinium gallium garnet (001) by metal organic decomposition method

Nd2BiFe5−xGaxO12 thin films with the Ga composition x = 0, 0.5, and 1.0 are prepared on (001) oriented gadolinium gallium garnet substrates by a metal organic decomposition method. Only (001) peaks are observed in x-ray diffraction patterns for all the films, suggesting that the highly oriented Nd2BiFe5−xGaxO12 thin films were formed. Increasing Ga composition, the saturation magnetization decreases, and the perpendicular easy axis is enhanced due to the decrease of the shape anisotropy. Longitudinal spin Seebeck effects (LSSEs) in Nd2BiFe5−xGaxO12 thin films with a Pt layer of 10 nm in thickness were investigated. Magnetic field dependence of the thermoelectric voltage caused by the LSSE in Nd2BiFe5−xGaxO12 films indicates the hysteresis loop with the small coercivity reflecting the magnetization curve. The decrease of LSSE voltage in Nd2BiFe5−xGaxO12 is clearly observed with the decrease of Fe composition.

Characteristics of up-conversion phosphor prepared by metal–organic decomposition method

Oxides can be formed from many materials by air sintering after coating a substrate with a metal–organic decomposition (MOD) solution. This enables the preparation of thin films by simple processes such as spin coating. The up-conversion (UC) phosphor produced by the MOD method has a multifunctional potential for use in applications such as displays and solid-state lighting. In this study, a simple TiO2–ZnO mixed oxide system was examined for use as the base material and host crystal of rare-earth (RE) elements for UC phosphor. The maximum emission luminescence of the UC phosphor was obtained when the mixing ratios of the base materials TiO2 : ZnO and additive materials Yb2O3 : Er2O3 were and , respectively. When the mixing ratio of the phosphor, Ti : Zn : Yb : Er, was , 550 nm green and 650 nm red emissions were produced. The UC emission intensity could be controlled by varying the mixing ratio of the rare-earth materials.

Strain-controlled MO Effect on Highly Bi-substituted Neodymium Iron Gallium Garnet Thin Films

Controlling magnetization of magneto-optical materials by voltage instead of electric current is expected to reduce power consumption and miniaturize functional elements in magneto-optical devices such as magneto-optical spatial light modulator. In this study, highly Bi-substituted neodymium iron gallium garnet, Nd0.5Bi2.5Fe4.5Ga0.5O12, thin film on gadolinium gallium garnet substrate prepared by metal organic decomposition method, which has excellent magneto-optical properties in visible wavelength region, was investigated as one of candidates for such devices. The thin film was cemented on a lead zirconate titanate polycrystal chip to apply external stress to the thin film. When the stress was applied, increase of coercivity has been observed by magneto-optical Kerr microscope due to reverse magnetostrictive effect. The result suggested the possibility of the Nd0.5Bi2.5Fe4.5Ga0.5O12 thin film as strain-mediated voltage controlled magneto-optical devices.

Longitudinal Spin Seebeck Effect in Bi-substituted Neodymium Iron Garnet on Gadolinium Gallium Garnet Substrate Prepared by MOD Method

Bi-substituted Neodymium Iron Garnet (Nd3-xBixFe5O12, Bi:NIG) thin films with the Bi composition x=0-1.0 are prepared on both the (001) and (111) oriented gadolinium gallium garnet (GGG) substrates by a metal organic decomposition method. Crystalline qualities and magnetic properties of these films are examined by X-ray diffraction, atomic force microscopy and vibrating sample magnetometer. Longitudinal spin Seebeck effects (LSSEs) are investigated by means of the inverse spin Hall effect in a Pt film. The increase of LSSE voltage in Bi:NIG(x=0-1.0)/Pt bilayers on GGG(001) is observed with the increase of Bi composition. In the case of GGG(111), the LSSE voltage for Bi:NIG(x=1.0) is also larger than that for NIG.

Preparation of (11n) Oriented Bi2Sr2CaCu2O8+x Thin Films by the Metal-organic Decomposition Method

We report on the preparation of (11n) oriented thin films of Bi2Sr2CaCu2O8+x (Bi2212), which were fabricated by the metal-organic decomposition method on SrTiO3 (110) and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements. By controlling the post-deposition annealing condition (temperature 640°C ≤ Ta ≤ 780°C and time 30min ≤ ta ≤ 120min), films with only the Bi2212 (117) XRD peak were obtained under the condition Ta = 780°C and ta = 30min. Furthermore, by forming films with a double-layer structure, films are found to have better crystallinity. Film properties are discussed on basis of SEM and resistivity measurements.

Structural and Luminescence Properties of EuAlO3 Ternary Compound and Al2O3−Eu2O3 Compositions

EuAlO3 ternary compound and Al2O3−Eu2O3 compositions are synthesized by metal-organic decomposition method and their structural and luminescence properties are investigated using X-ray diffraction analysis, photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, and luminescence lifetime measurements. The effects of calcination temperature on the structural and Eu3+ emission properties are studied in detail. Temperature dependence of the PL intensity at T = 20–450 K exhibits clear thermal quenching behavior, yielding quenching energies of 14 meV and 0.22 eV at low and high temperature regions, respectively. The stable phase of orthorhombic EuAlO3 is formed at activation energy of ∼0.8 eV. The schematic energy-level diagram for Eu3+ in EuAlO3 is also proposed for the sake of a better understanding of the PL and PLE processes in this host material. The luminescence decay characteristics indicate that the decay times are given by the concentration quenching-limited values in the Eu2O3-rich materials. The measured Eu3+-emission decay times are τav ∼ 20 μs in the (1 − x)Al2O3 : xEu2O3 compounds with x = 0.5 (EuAlO3) and 1.0 (Eu2O3). These values are much smaller than τav ∼ 500 μs in Al2O3:Eu3+ (x = 0.05).

MoP-36 DRY PEEL-OFF METHOD OF TRANSFER PZT THIN CAPACITOR TO FLEXIBLE POLYMER USING SAMs

This paper describes a new transfer method to realize wearable devices with embedded capacitors providing high permittivities and thinner structures. To miniaturize passive elements, such as capacitor on flexible substrate[1], lead zirconate titanate (PZT) thin films are formed on a Si substrate by MOD (metal organic decomposition) method, then can be easily transferred into a polymer (polydimethylsiloxane, PDMS or polyimide) without any chemical contamination. The thin film capacitor is composed of sandwich structure of PZT between two metal electrodes. To embed the capacitor layers in the polymer substrate, three kinds of self-assembled monolayers (SAMs) are investigated for adhesion or anti-adhesion layer among metal, polymer and Si substrate, respectively. As modifying the MOD's sintering process for PZT layers, thin capacitor in 1-μm-thick with perovskite structure is successfully transferred and embedded in a PDMS substrate.

Humidity sensing properties of K0.5Na0.5NbO3 powder synthesized by metal organic decomposition

K0.5Na0.5NbO3 (KNN) powder is synthesized via a metal-organic decomposition (MOD) method and characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and energy dispersive spectrometer (EDS). A humidity sensor, which is consisted of five pairs of AgPd interdigitated electrodes and an Al2O3 ceramic substrate, is fabricated by spin-coating the KNN powder on the substrate. The humidity sensing properties of the KNN humidity sensor are investigated at room temperature within the relative humidity (RH) range of 11–95%. The variations of the KNN humidity sensor impedance are about four orders of magnitude within the whole humidity range from 11% to 95% RH at the frequencies of 60Hz and 100Hz. The response time and recovery time of the KNN humidity sensor are all about 8s and 18s, and their maximum hystereses are all around 2% RH at 60Hz and 100Hz. Furthermore, at low RH and frequency conditions, the dielectric dissipation factor (DF) values of the KNN humidity sensor are small and hardly change, indicating that the KNN humidity sensor is of good insulating properties and reliability. The KNN powder is of broader potential applications for fabricating high performance humidity sensors.

Effect of Annealing Temperature on the Structures and Properties of Bi<sub>4.15</sub>Nd<sub>0.85</sub>Ti<sub>3</sub>FeO<sub>15</sub> Thin Films

To investigate the effect of annealing temperature on the structures and properties of Bi4.15Nd0.85Ti3FeO15 (BNTF), their thin films with four perovskite slabs were deposited on Pt/Ti/SiO2/Si substrates by the metal-organic decomposition method. Good remanent polarization and excellent fatigue resistance were observed at room temperature. The BNTF thin films annealed at 780°C presented better ferroelectricity than those annealed at 700°C-780°C. Ferromagnetic of BNTF thin films was not observed at room temperature.

Fabrication and NO2 gas-sensing properties of reduced graphene oxide/WO3 nanocomposite films

One-pot polyol process was combined with the metal organic decomposition (MOD) method to fabricate a room-temperature NO2 gas sensor based on tungsten oxide and reduced graphene oxide (RGO/WO3) nanocomposite films. Fourier Transform infrared spectrometer (FTIR), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the microstructure and morphology of the fabricated films. The electrical and NO2 gas-sensing properties of WO3 to which various amounts of RGO were added were measured in detail as a function of concentration of NO2 gas at room temperature, to elucidate the contribution of RGO to the NO2 gas-sensing capacity. The NO2 gas-sensing mechanism of the RGO/WO3 nanocomposite films were explained by considering their composition and microstructures. The sensor that was based on a nanocomposite film of RGO/WO3 exhibited a strong response to low concentrations of NO2 gas at room temperature, satisfactory linearity and favorable long-term stability.

Improved photoelectrochemical activity of CaFe2O4/BiVO4 heterojunction photoanode by reduced surface recombination in solar water oxidation.

A bismuth vanadate photoanode was first fabricated by the metal-organic decomposition method and particles of calcium ferrite were electrophoretically deposited to construct a heterojunction photoanode. The characteristics of the photoanodes were investigated in photoelectrochemical water oxidation under simulated 1 sun (100 mW cm(-2)) irradiation. Relative to the pristine BiVO4 anode, the formation of the heterojunction structure of CaFe2O4/BiVO4 increased the photocurrent density by about 60%. The effect of heterojunction formation on the transfer of charge carriers was investigated using hydrogen peroxide as a hole scavenger. It was demonstrated that the heterojunction formation reduced the charge recombination on the electrode surface with little effect on bulk recombination. The modification with an oxygen evolving catalyst, cobalt phosphate (Co-Pi), was also beneficial for improving the efficiency of CaFe2O4/BiVO4 heterojunction photoanode mainly by increasing the stability.

Dramatic effects of chlorine doping on Jc and microstructure of fluorine-free MOD Y123 thin films

Chlorine doped Y123 thin films have been successfully prepared by the fluorine-free metal organic decomposition (FF-MOD) method on SrTiO3(100) single crystal substrates. The rectangular Ba2Cu3O4Cl2 (Ba2342) columns were epitaxially grown in the film without degrading crystallinity and transition temperature (Tc) of Y123. Cl-doped Y123 films maintained high Tc of 90.5–91.5 K and they showed higher critical current density (Jc) than the Cl-free films particularly in magnetic fields. The high Jc feature was observed in thick films up to ∼0.93 μm in thickness. In addition, Cl and Hf co-doped Y123 films maintained high crystallinity and showed further improved Jc of 1.1 MA cm−2 at 40 K under 5 T. These suggested that Ba2342 precipitates have two effects on FF-MOD processed Y123 films. One is an increase in pinning force and the other is improvement of crystallinity of Y123 because of the good lattice matching between Y123 and Ba2342.

Synthesis of novel CeO2–BiVO4/FAC composites with enhanced visible-light photocatalytic properties

To utilize visible light more effectively in photocatalytic reactions, a fly ash cenosphere (FAC)-supported CeO2–BiVO4 (CeO2–BiVO4/FAC) composite photocatalyst was prepared by modified metalorganic decomposition and impregnation methods. The physical and photophysical properties of the composite have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and UV–Visible diffuse reflectance spectra. The XRD patterns exhibited characteristic diffraction peaks of both BiVO4 and CeO2 crystalline phases. The XPS results showed that Ce was present as both Ce4+ and Ce3+ oxidation states in CeO2 and dispersed on the surface of BiVO4 to constitute a p–n heterojunction composite. The absorption threshold of the CeO2–BiVO4/FAC composite shifted to a longer wavelength in the UV–Vis absorption spectrum compared to the pure CeO2 and pure BiVO4. The composites exhibited enhanced photocatalytic activity for Methylene Blue (MB) degradation under visible light irradiation. It was found that the 7.5wt.% CeO2–BiVO4/FAC composite showed the highest photocatalytic activity for MB dye wastewater treatment.

Effect of pre-crystallization on the preparation of thick Bi-YIG films by the metal–organic decomposition method

Bismuth-substituted yttrium iron garnet films with a thickness of about 0.8–1.2μm were fabricated on glass substrates by using a metal–organic decomposition method. We observed that thick samples fabricated by intermediate short time sintering (pre-crystallization process) showed enhanced magneto-optical properties, good crystallinity, and high saturation magnetization. For the sample prepared with the pre-crystallization process the Faraday rotation angle was measured to be −3.75°/μm which was larger compared to the thick film prepared without pre-crystallization. The lattice constant and the grain size of the film were about 12.45Å and 43.8nm, respectively.

Metal–organic decomposition synthesis of tungsten oxide nanoparticles and evaluation of visible-light-driven photocatalytic ability

To develop a simple fabrication method for a highly efficient visible-light-driven photocatalyst, we investigated the photocatalytic ability of tungsten oxide (WO3) nanoparticles prepared on substrate surfaces by the metal–organic decomposition (MOD) method. Using this method, the diameter of WO3 nanoparticles was varied from 70 to 250 nm by simply adjusting the baking temperature. The WO3 nanoparticles prepared under optimal conditions showed that their photocatalytic ability under visible light is 10 times higher than that of TiO2 fabricated by the MOD method under optimal conditions.

Preparation and characterization of fly ash cenospheres supported CuO–BiVO4 heterojunction composite

Novel fly ash cenospheres supported CuO–BiVO4 heterojunction composites (CuO–BiVO4/FACs) were prepared by modified metalorganic decomposition and impregnation methods. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectra (XPS), and UV–vis diffused reflectance spectroscopy (DRS) techniques. The XPS and SEM analyses indicated that Cu was present as CuO dispersed on the surface of BiVO4. The DRS spectra revealed that the composites had improved optical adsorption in the visible light region, and the composites exhibited enhanced photocatalytic activity for methylene blue (MB) degradation under visible light irradiation. It was found that the 5wt% CuO-loaded composite showed the highest photocatalytic activity for MB dye wastewater treatment. FACs, a by-product generated in coal-firing power plants, were used as a low cost support which favored phase separation after the reaction owing to their low density.

Manufacture of $\hbox{GdBa}_{2}\hbox{Cu}_{3}\hbox{O}_{7 - x}$ Superconducting Thin Films Using High-Thermal-Stability Precursors Playing the Role of Intermediate-Phase Grain-Growth Inhibitors

We have developed a fluorine-free metal-organic decomposition method using acrylic acid as the solvent for the synthesis of GdBCO superconducting thin films. Commonly used propionic acid was also used to make a comparison with acrylic acid. Acrylic acid was found to be polymerized during drying, resulting in high thermal stability of the precursor solution. Due to the elevated decomposition temperature of the organic compounds in the acrylic-acid-based precursor, the formation of intermediate phases such as CuO was found delayed; therefore, the grain growth and phase segregation were suppressed. The superior quality of pyrolyzed films induced by the use of polymerizable acrylic acid is reflected in the J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> of the GdBCO films, which achieved 1.2MA/ cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Effects of niobium content on electrical and mechanical properties of (Na0.85K0.15)0.5Bi0.5Ti(1-x)Nb x O3 thin films

(Na0.85K0.15)0.5Bi0.5Ti(1-x)Nb x O3 (NKBT-N100x) thin films were deposited on Pt/Ti/SiO2/Si(100) substrates by metal–organic decomposition method and annealed in oxygen atmosphere at 750 °C. The effects of niobium concentration on the microstructures, ferroelectric, piezoelectric, leakage current and mechanical properties of the NKBT-N100x (x = 0, 0.01, 0.03, 0.05) thin films have been investigated in detail. The NKBT-3N thin film has the largest remnant polarization (7 μC/cm2) and statistically averaged d 33eff (140 pm/V), the smallest leakage current, elasticity modulus (102.0 Gpa), hardness (5.1 Gpa) and residual stress (297.0 Mpa). The evaluation of residual stresses of these thin films will offer useful guidelines of safe working condition for their potential application in microelectromechanical system.

Structural Analysis of ZnO Film Deposited by Means of Metal Organic Decomposition Method

ZnO films were deposited on glass substrates by means of a metal organic decomposition (MOD) method. We investigated the effect of annealing temperature, time and the number of laminated layers on the film structure on the basis of X-ray diffraction measurements. We found the optimum conditions of the temperature and the time to be 600°C and 40 minutes for the preparation, respectively. In addition, the layer-by-layer forming was not found to degrade the film from viewpoint of X-ray line width.

Nd3-xBixFe4GaO12(x = 2, 2.5) films on glass substrates prepared by MOD method

We studied Nd3-XBiXFe4GaO12 films to obtain perpendicular magnetic anisotropy as well as large Faraday effect. NdBi2Fe4GaO12 (Bi2:NIGG) and Nd0.5Bi2.5Fe4GaO12 (Bi2.5:NIGG) films were obtained on Nd2BiFe4GaO12 (Bi1:NIGG) layer prepared on glass substrates by metal-organic decomposition (MOD) method. Bi2:NIGG and Bi2.5:NIGG films showed large Faraday rotation angles of 7.5 and 10.5 degree/µm, at a wavelength of 520 nm, respectively. Those films have perpendicular magnetic anisotropy with a coercivity of 350 Oe and a saturation magnetic field of 730 Oe.