Metal Organic Decomposition Process Research Articles

Functionalization of micro-size garnet at the end of optical fiber for magneto-optical applications

We utilized a metal propionate solution to prepare polycrystalline bismuth-substituted yttrium iron garnets through the metal-organic decomposition process. After conducting thorough optimization, we successfully synthesized a garnet that exhibited a high magneto-optic response directly at the end of an optical fiber. A notable achievement of our work lies in the ability to restrict the size and position of the garnet to match the dimensions of the fiber's core. The functionalized fiber was integrated into a magneto-optical sensor setup, offering the flexibility to operate either in the Faraday rotation or magnetic circular dichroism mode.

Highly efficient CoFe2O4 electrocatalysts prepared facilely by metal-organic decomposition process for the oxygen evolution reaction

The novel solution route based on metal-organic decomposition (MOD) process is successfully developed for a facile preparation of CoFe2O4. The electrocatalytic activity of CoFe2O4 for the oxygen evolution reaction (OER) of electrochemical water splitting is investigated as a function of calcination temperature in the range between 300 and 450 °C. It is significantly found that a drastic cation redistribution in octahedral and tetrahedral sites within the spinel structure of 450 °C-calcinated CoFe2O4 p-type semiconductor leads to the dramatic enhancement in hole density and concomitant OER activity. The CoFe2O4 integrated on carbon fiber paper (CFP) exhibits high electrocatalytic performance, including an overpotential (η10) of 359 mV at10 mA cm−2 and a Tafel slope of 53.8 mV dec−1 in 1 M KOH aqueous solution. Based on this work, a design principle of the MOD solution process developed can be applied to preparation of a greater variety of compounds. Also, elucidation of structure-OER activity relationships in spinel-type CoFe2O4 electrocatalysts will be able to advance further.

Investigation of fabrication conditions for VO2 thin films by MOD using carbon thermal reduction

AbstractVanadium dioxide (VO2) thin films were fabricated by metal‐organic decomposition (MOD). To utilize a carbon thermal reduction for obtaining a VO2 composition, the precursor films were fabricated at the temperature Tp from 300°C to 380°C in a N2 atmosphere. From the measurement results of XRD, diffraction peaks indicating VO2 phase were observed with a wide range of firing temperatures from Tf = 560°C to 620°C. Furthermore, the peaks indicating VO2 phase were also observed with a wide range of firing time from tf = 15–45 min. Regarding the surface morphology of the films, the nanoparticles of 100–200 nm were densely packed although small spaces existed between the particles. The R‐T characteristics of the films indicated the phase transition with a rapid resistance change of about three orders of magnitude and hysteresis loop. From these experimental results, it was found that wide windows of firing conditions for fabricating VO2 thin film can be obtained in the MOD process using the carbon thermal reduction.

Heterogeneous nucleation of YBCO via fluorine based MOD process: thermodynamic and kinetic approach

The nucleation of YBa2Cu3O7−δ (YBCO) film deposited via metal organic decomposition (MOD) approach is a complex process that has a key role in YBCO film crystalline orientation and, consequently, superconducting properties. Up to now, several studies have been carried out to clarify this step in the fluorine based MOD route which employs only or partially metals trifluoroacetate for the precursor solution preparation. However, these previous works provided only qualitative indications, whereas a quantitative theoretical investigation seems to be still lacking.In this paper, the free energy for critical nucleus formation of fluorine based MOD YBCO has been determined according to the classical nucleation theory. The volume contribution to the free energy is computed using thermodynamic data on (Y, Ba, Cu, O) systems available from the literature. The free energy barrier for nucleation depends upon nucleus orientation, via the work of adhesion and surface energies of vacuum/nucleus interfaces. The model is applied to describe heterogeneous nucleation of YBCO on (001) SrTiO3 single crystal and provides quantitative information on nucleation barriers as a function of temperature and both precursor and gas phase compositions. Through a kinetic approach, the energy barriers are further employed to estimate the fraction of c-oriented nuclei as a function of temperature and water partial pressure.Comparison with experimental data from literature lends support to the proposed computations. Therefore, the results shown in this work may be useful in designing the YBCO deposition process in order to obtain films with superior superconducting properties avoiding expensive and time-consuming experimental optimizations.

Pyrolysis behaviors dominated by the reaction–diffusion mechanism in the fluorine-free metal–organic decomposition process

In this work, pyrolysis behaviors dominated by the reaction–diffusion mechanism were investigated. And one-dimensional reaction–diffusion model is proposed.

Thin Film of Amorphous Zinc Hydroxide Semiconductor for Optical Devices with an Energy-Efficient Beneficial Coating by Metal Organic Decomposition Process

An effective metal oxide coating with solution processes by the metal organic decomposition method as deposited at room temperature (RT) poses great challenge. In this study, we report the characterization and evaluation of the semiconductor properties of a zinc hydroxide thin film with RT just as deposition by solution coating method. The films worked well as an inter-layer of the organic photovoltaic cell and optimized the film thickness condition with chemical and physical properties. As a result, we achieved a power conversion efficiency performance level, which was almost similar to that in the cells used after calcination in the crystal ZnO inter-layer. The presented process without any additional decomposition energy is expected to make a significant contribution to the realization of a flexible and cost-effective solution process for device fabrication.

Leakage mechanisms of partially self-polarized BiFeO3 film

Partially self-polarized BiFeO3 (BFO) film was fabricated on Pt(111)/Ti/SiO2/Si substrate by a metal organic decomposition process at 480 °C. The influence of soaking times on leakage properties was discussed. The soaking times considered were those that could keep the leakage currents being measured in a steady state condition during the leakage tests. The length of soaking time during leakage measurement should be greater than or equal to 500 ms to rule out the contribution of backswitching to leakage properties. Different leakage characteristics induced by the built-in negative field occurred under positive and negative fields. The "flat-band" feature of the leakage current curves may result from competition between domain switching and the switching of defect complexes. It is suggested that the "unswitched" mode should be adopted during leakage measurement in BFO films. Additionally, negative bias should be adopted in negatively polarized BFO films and positive bias should be adopted in positively polarized BFO films.

High-Performance Solution-Processed Amorphous InGaZnO Thin Film Transistors with a Metal–Organic Decomposition Method

A facile solution process was introduced for the preparation of IGZO thin films via a metal–organic decomposition (MOD) method. The IGZO ink was synthesized by mixing the solutions of gallium acetylacetonate [Ga(C5H7O2)3], zinc acetylacetonate hydrate [Zn(C5H7O2)2·xH2O] dissolved in ethanol, and indium acetylacetonate [In(C5H7O2)3] dissolved in tetrahydrofuran (THF). The deposited films by spin-coating were annealed at moderate process temperature (≤500°C). The relationship between device performance and postannealing temperature was studied. The result demonstrated that mobility of IGZO TFT increased as the annealing temperature increased. Based on the analysis of O 1s statement, the annealing temperature can influence the number of oxygen vacancy to further affect the carrier centration. In addition, the IGZO TFT devices with various Ga molar ratios were compared to demonstrate the influence of the Ga addition. The result demonstrated that the saturated mobilities (μe) decreased and VTH shifted to positive voltage as the Ga molar ratio was increased. It is likely that Ga can offer stronger chemical bonds between metal and oxygen that reduced the concentration of free carriers and thus help reducing VTH. As a result, the optimized performance of IGZO TFT with the mobility of 3.4 cm2V−1s−1 showed the MOD process was a promising approach.

Refining Process of BaZrO3Particles in Coated Conductors by TFA-MOD Method

A wide range of coating thicknesses was utilized in the trifluoroacetate metal-organic decomposition process for (Y, Gd) Ba 2 Cu 3 O 7-δ (YGdBCO) coated conductor including BaZrO 3 (BZO) particles with a thin once-coated thickness(donce), which was developed for improving the critical current density in a magnetic field (Jc(B)). The value of Jc (B) increased as donce decreased to 30 nm, and a sample fabricated with donce = 30 nm exhibited high values of Jc(B) of 0.27 and 1.60 MA/cm 2 at 77 and 65 K, respectively, at 3 T (B//c). However, the value of Jc( B) of a sample with donce = 17 nm was almost the same as or slightly lower than that of the sample with donce = 30 nm. This tendency was explained by the change in the size of the BZO particles in the YGdBCO superconducting films. Additionally, the Cu elemental peak and the valleys of other elements were observed at the same position and at certain intervals in the elemental concentration line profiles along the depth direction of the precursors, fabricated under different donce conditions from 170 to 30 nm. However, the peaks and valleys were extremely suppressed, and the wave structure was barely observed in the sample with donce = 17 nm. The refining of BZO particles by reducing donce could be explained by the limited diffusion due to the existence of the concentration valleys/peaks. Moreover, the effect of the diffusion barrier due to the valleys/peaks might become weaker in the sample with donce = 17 nm.

Effects of aging on fatigue properties in imprinted BiFeO3 film

Predominantly (012)-oriented BiFeO3 (BFO) film was obtained on Pt(111)/Ti/SiO2/Si substrate using a metal organic decomposition process at 480 °C. The thickness of each layer can reach to about 150 nm. Negatively imprinted and obvious constricted phenomena can be observed in P–E hysteresis loop of the film. The leakage measurement was adopted as an effective way to deaging the partially aged sample. The dominant leakage mechanism involved in the BFO film was investigated. The influence of testing process on the distribution of oxygen vacancies and defect complexes was discussed. Obvious differences can be exhibited in fatigue performance for the partially aged and deaged sample. The dependence of fatigue properties on the test frequencies and applied electric fields was studied both for aged and deaged samples.

Photoluminescence properties of Tb3Al5O12:Ce3+ garnet synthesized by the metal organic decomposition method

Tb3Al5O12:Ce3+ garnet (TAG:Ce3+) phosphor was synthesized by the metal organic decomposition (MOD) method and subsequent calcination at Tc = 800–1200°C for 1 h in air. The effects of Ce3+ concentration on the phosphor properties were investigated in detail using X-ray diffraction (XRD) analysis, photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, and PL decay measurements. The maximum intensity in the Ce3+ yellow emission was observed at the Ce3+ concentration of ∼0.20%. PLE and PL decay measurements suggested an evidence of the energy transfer from Tb3+ to Ce3+. Calcination temperature dependence of the XRD and PL intensities yielded an energy of ∼1.5 eV both for the TAG formation in the MOD process and for the optical activation of Ce3+ in its lattice sites. Temperature dependences of the PL intensity for the TAG:Ce3+ yellow-emitting and K2SiF6:Mn4+ red-emitting phosphors were also examined for the future solid-state lighting applications at T = 20–500 K in 10-K steps. The data of TAG:Ce3+ were analyzed using a theoretical model with considering a reservoir level of Et ∼9 meV, yielding a quenching energy of Eq ∼0.35 eV, whereas the K2SiF6:Mn4+ red-emitting phosphor data yielded a value of Eq ∼1.0 eV. The schematic energy-level diagrams for Tb3+ and Ce3+ were proposed for the sake of a better understanding of these ions in the TAG host.

Ferroelectric and dielectric properties of manganese-doped Na0.5Bi0.5TiO3 nanocrystalline thin films prepared by metal organic decomposition: A single-layer thickness-dependent study

2at% Manganese-doped Na0.5Bi0.5TiO3 (NBTMn) thin films with single-layer thicknesses ranging from 15 to 45nm/l were deposited on the indium tin oxide/glass substrates by a metal organic decomposition process and spin coating technique. The influence of single-layer thickness on the crystal structure, surface morphology, insulating ability, ferroelectric and dielectric properties was mainly investigated. Compared with the other films, NBTMn film with a single-layer thickness of 30nm/l exhibits the (110)-preferred orientation and dense structure. Also, it shows the enhanced ferroelectricity with a large remanent polarization (Pr) of 38μC/cm2 due to the preferred orientation and low leakage current density. Meanwhile, a high dielectric tunability of 39% for NBTMn with 30nm/l can be observed by varying the measuring applied voltage and frequency. These results indicate that the suitable layer thickness is beneficial to improve the electrical performances of NBTMn thin film.

Influence of annealing temperature on the microstructure, leakage current and dielectric properties of Na0.5Bi0.5(Ti,Zn)O3 thin films

Lead-free Na0.5Bi0.5(Ti,Zn)O3 (NBTZn) thin films were deposited on indium tin oxide (ITO)/glass substrates via a metal organic decomposition process and annealed at various temperatures from 450 to 600 °C. The influence of annealing temperature on crystallization and electrical properties were investigated. XRD measurement reveals that the film can be crystallized into single perovskite at an annealing temperature as low as 500 °C. The average grain size of the NBTZn sample increases with increasing the annealing temperature from 500 to 600 °C. The leakage current density also increases with the increase in annealing temperature probably due to the variation content of grain boundaries and oxygen vacancies. Compared with other samples annealed at 500 and 600 °C, the film prepared at 550 °C shows enhanced dielectric properties with a relatively high dielectric tunability of 36.4 % and low dissipation factor of 0.13 at 200 kHz.

Influence of precursor solution concentration on the microstructure, leakage current and dielectric tunability of Zn-doped Na0.5Bi0.5TiO3 thin films prepared by metal organic decomposition

Zn-doped Na0.5Bi0.5TiO3 (Zn: NBT) thin films were prepared from precursor solutions with different concentrations (0.08, 0.20 and 0.35M) via a metal organic decomposition process. The effects of the mole concentration of precursor solution on crystallization and electrical properties were investigated. All the films exhibit polycrystalline perovskite structure. The increasing degree of predominant (110) orientation with the decrease of the concentration is ascribed to the highly diluted of the solution, leading to the local grain-on-grain growth. Compared with other films, the 0.20M-film exhibits a strong nonlinear dependence of the dielectric constant on the applied voltage due to the improvement of crystallinity and insulating property. Furthermore, the effect of applied voltage on the dielectric tunability for 0.20M-film is discussed. A higher tunability of 36.8% and figure of merit of 7.4 in Zn: NBT film can be observed at ±16V and 100kHz.

Microstructure, leakage current and dielectric tunability of Na0.5Bi0.5(Ti0.99Zn0.01)O3 thin films: An annealing atmosphere-dependent study

Na0.5Bi0.5(Ti0.99Zn0.01)O3 (NBTZn) thin films were deposited on the indium tin oxide (ITO)/glass substrates annealed under different atmospheres (air, N2, O2, O2/N2) via a metal organic decomposition process. The effects of annealing atmosphere on crystallization and electrical properties were mainly investigated. All the thin films exhibit single perovskite structures with predominant (110) orientation. Large grains are observed in N2 due to the high content of oxygen vacancy. For the film annealed in O2/N2 atmosphere, the lower leakage current density and higher dielectric tunability can be obtained, which may be ascribed to the improvement of crystallization with more homogeneous grain sizes and dense microstructure. Also, the effects of measuring frequency on dielectric constant–electric field characteristic are discussed. A higher tunability of 47.6% and figure of merit of 7.9 at 300kV/cm and 100kHz for NBTZn film can be observed.

Microstructure, ferroelectric and dielectric properties in Nd and Ti co-doped BiFeO3 thin film

Nd (3 %) and Ti (2 %) co-doped BiFeO3 (BNFTO) thin film was deposited on indium tin oxide-coated glass substrate by a metal organic decomposition process. The BNFTO film exhibits a single perovskite phase with random orientation and good insulating property with low leakage current. Asymmetrical polarization–electric field loops are observed in the BNFTO film: This is mainly attributed to the role of oxygen vacancy-related defect complexes in the film. Additionally, the capacitance of the sample is strongly dependent on both the applied voltage and measuring frequency. Furthermore, with the increase in applied voltages or decrease in frequencies, the dielectric tunability is gradually enhanced. The related physics mechanism for the enhanced performance is also discussed. High dielectric constant of 165, dielectric tunability of 27 % and figure of merit of 13.5 are achieved when a measuring frequency of 1 kHz is applied. These present results can be regarded as a base for further development of high-performance BiFeO3 films. Polarization–electric field (P–E) and capacitance–voltage (C–V) curves of the BNFTO film measured under various electric fields and applied bias voltages.

Effects of single-coated layer thickness on the microstructure, leakage current and dielectric tunability of Na0.5Bi0.5(Ti,Zn)O3-δ thin films prepared by metal organic decomposition

Na0.5Bi0.5(Ti,Zn)O3-δ (NBTZn) thin films with various single-coated layer thicknesses (35, 25, 20 and 15 nm) annealed at 550 °C were fabricated on indium tin oxide/glass substrates using a metal organic decomposition process. The effects of single-coated layer thickness on the crystal structure, morphology, leakage current as well as dielectric tunability are investigated. All the films exhibit polycrystalline perovskite structures with different relative intensities of (110) peaks. The highly preferred orientation in the film of 20 nm per layer (nm/l) is consistent with the typical columnar structure observed from cross-sectional morphology. Also, for the film with 20 nm/l, it exhibits the higher tunability of 43.2% and figure of merit of 8.1 at 240 kV/cm and 100 kHz due to well-crystallization and lower content of defects. Meanwhile, the effects of electric field on the tunability for all the NBTZn films and frequency on the dielectric constant-electric field loops for the film of 20 nm/l are discussed.

Effect of defect dipole-induced aging on the dielectric property of Fe3+-doped Na0.5Bi0.5TiO3 thin film

Na0.5Bi0.5(Ti0.94Fe0.06)O3−δ (NBTFe) thin film was deposited on indium tin oxide coated glass substrate by a metal organic decomposition process. The aging effect on the dielectric properties was mainly studied by the dielectric constant–electric field (εr–E) curves. Obvious aging characteristic of abnormal double butterfly εr–E loops was observed in the NBTFe film. This phenomenon can be attributed to the polarization backswitching behavior under the effect of defect dipoles. Furthermore, the double curve can gradually transform into a typical single one during the course of increasing the applied electric field or decreasing the measuring frequency, which can be explained by the progressively enhanced de-aging effect. These present results are discussed based on defect chemistry by the symmetry-conforming principle of defect dipoles.

적외선 센서용 [(Co1-xCux)0.2(Ni0.3Mn0.7)0.8]3O4스피넬 박막의 구조 및 전기적 특성

Co1-xCux)0.2(Ni0.3Mn0.7)0.8)3O4 (0≤x≤1) thin films prepared by metal organic decomposition process were fabricated on SiN/Si substrate for infrared sensor application. Their structural and electrical properties were investigated with variation of Cu dopant. The ((Co1-xCux)0.2(Ni0.3Mn0.7)0.8)3O4 (CCNMO) film annealed at 500℃ exhibited a dense microstructure and a homogeneous crystal structure with a cubic spinel phase. Their crystallinity was further enhanced with increasing doped Cu amount. The 120 nm-thick CCNMO (x=0.6) thin film had a low resistivity of 53 Ω·cm at room temperature while the Co-free film (x=1) showed a significantly decreased resistivity of 5.9 Ω·cm. Furthermore, the negative temperature coefficient of resistance (NTCR) characteristics were lower than -2%/℃ for all the specimens with x≥0.6. These results imply that the CCNMO (x≥0.6) thin films are a good candidate material for infrared sensor application.

Precursor evolution and growth mechanism of BTO/YBCO films by TFA—MOD process

In this study, BaTiO3 (BTO)-doped YBCO films are prepared on LaAlO3 (100) single-crystal substrates by metal—organic decomposition (MOD) using trifluoroacetate (TFA) precursor solutions. The critical current density (Jc) of BTO/YBCO film is as high as 10 MA/cm2 (77 K, 0 T). The BTO peak is found in the X-ray diffraction (XRD) pattern of a final YBCO superconductivity film. Moreover, a comprehensive study of the precursor evolution is conducted mainly by X-ray analysis and μ-Raman spectroscopy. It is found that the TFA begins to decompose at the beginning of the thermal process, and then further decomposes as temperature increases, and at 700 °C BTO nanoparticles begin to appear. It suggests that the YBCO film embedded with BTO nanoparticles, whose critical current density (Jc) is enhanced, is successfully prepared by an easily scalable chemical solution deposition technique.