Thermal Decomposition Of Organometallic Compounds Research Articles

Technology for obtaining VO2 films from the gas phase during thermal decomposition

The paper considers the process of obtaining films of vanadium dioxide by the method of deposition of inorganic coatings and films from the vapor phase during the thermal decomposition of organometallic compounds. In recent years, there has been a growing interest in the practical use of organometallic compounds. This has led to the development of many devices that include various vapor deposition techniques. This technology is currently being used as the latest technology. The design of the technological installation for pyrometric film deposition is presented and the principle of operation is given. In the course of the study, film samples were obtained and experimental work was carried out. The results obtained are presented in the form of graphs.

Multi-nucleation of single-walled carbon nanotubes in floating catalyst chemical vapor deposition

Floating-catalyst CVD (FCCVD) is a highly promising technique for the scalable synthesis of single-walled carbon nanotubes (SWCNTs). The number concentration (NC) of catalyst particles is one of the process parameters which mainly influences yield of as-produced SWCNTs. In the conventional FCCVD methods, catalyst particles are usually synthesized by thermal decomposition of organometallic compounds inside the FCCVD reactor. Being in-situ catalyst formation in conventional FCCVD, it is an open question that how many SWCNTs a single catalyst particle can grow? Herein, we employed our novel spark discharged based FCCVD technique which decouples the formation of catalyst particles and SWCNTs synthesis into two subsequent process to investigate effects of catalyst NC on SWCNTs synthesis. The NC of both catalyst particles and SWCNTs in gas-phase were quantitatively compared using differential mobility analyzer (DMA). The DMA measurements corroborated with atomic force microscopy and X-rays photoelectron spectroscopy revealed that under carefully chosen reaction conditions in FCCVD, a single catalyst particle can grow more than one SWCNTs. We propose that after the growth of 1st SWCNT, the catalyst particle detach itself to start nucleating 2nd SWCNT and this process continues as long as the catalyst remains in the growth region of the FCCVD reactor.

Comments on multiple publications reporting single heating rate kinetics

This note alerts one to multiple Applied Organometallic Chemistry publications that report the single heating rate kinetics for thermal decomposition of organometallic compounds. It is stressed that the single heating rate approach is known to produce erroneous kinetic parameters. Its use is also against the recommendations of the International Confederation for Thermal Analysis and Calorimetry that advises the multiple heating rate approach to be used instead. Examples of the failure are provided and an appeal is made to the community for adopting the multiple heating rate approach.

Nickel Nanoparticles Decorating Graphite Flake Surface Using Planetary Ball Milling: Physical Characterization and Methanol Electrooxidation Investigation

In recent years, several researches have been conducted in order to investigate the physical and chemical method for obtain the metallic nanoparticles, such as co-precipitation, hydrothermal, thermal decomposition of organometallic compounds, electrochemical, and ball milling method [1-4]. The particle size, shape and crystallinity depend on the selected synthesis method. In this sense the ball milling technique is one of the widely used to produce metallic nanoparticles, being the method feasible for large production [4]. A simple approach was proposed to obtain graphite surface decorated with nickel nanoparticles (Ni NPs) from dry ball milling process. Ni NPs were obtained after 40 h of high energy milling and 100, 200, 300 and 400 rpm ball rotation speeds. Both Ni NPs and graphite decorated samples were characterized by Scanning Transmission (STEM), Raman Spectroscopy, Scanning Electron Microscopy, X-ray diffraction pattern (XRD). The electrocatalytic activity of Ni/Graphite samples were evaluated from methanol oxidation in alkaline medium using electrochemical techniques. Good agreement between STEM and XRD results can be found, reporting average diameter size of 4.9 nm and average crystallite size of 5.50 nm for Ni NPs. The methanol electrooxidation electrocatalytic activity was more efficient for Ni/Graphite with 100 rpm compared to Ni/Graphite others. REFERENCES M. Freire, T.S. Ribeiro, I.F. Vasconcelos, J.C. Denardin, E.B. Barros, M. Giuseppe, L. Carbone, S.E. Mazzetto, P.B.A. Fechine, MZnFe2O4 (M = Ni, Mn) cubic superparamagnetic nanoparticles obtained by hydrothermal synthesis, J. Nanopart. Res. 15 (2013) 1-12.Alonso, P. Riente, J.A. Sirvent, M. Yus, Nickel nanoparticles in hydrogen-transfer reductions: Characterisation and nature of the catalyst, Appl. Catal. A 378 (2010) 42–51.Aghazadeh, A.N. Golikand, M. Ghaemi, Synthesis, characterization, and electrochemical properties of ultrafine b-Ni(OH)2 nanoparticles, Int. J. Hydrogen Energy 36 (2011) 8674-8679.F. de Carvalho, S.N. de Medeiros, M.A. Morales, A.L. Dantas, A.S. Carriço, Synthesis of magnetite nanoparticles by high energy ball milling Appl. Surf. Sci. 275 (2013) 84-87.

Effective size control through solvents in microwave aided synthesis of GSH- CdTe quantum dots

Highly luminescent GSH capped CdTe quantum dots (GSH-CdTe QDs) were prepared through a facile microwave (MW) aided wet chemical method. The mechanism of effective size control through the solvents is proposed. The Small angle X-ray scattering (SAXS) measurements show that the size dispersion of QDs can be precisely controlled through the selection of appropriate solvents. The high boiling point and high loss tangents were found to be effective in controlling the size dispersion in MW aided synthesis. The PL studies show that the sharpness of the emission peaks depends on the size dispersion. Keyword: GSH(Glutathione),Luminescent, Microwave (MW), Small angle X-ray scattering (SAXS), Quantum dots. I. Introduction QDs are being intensively used for producing solar panels (1,2) optoelectronic devices (3) and as fluorescent probes in bio-imaging and bio-sensing (4-6) among other applications. QDs have many advantages such as sharp emission spectra, higher chemical stability, tunable optical properties, photochemical stability and high quantum yields as compared to organic fluorescent material. These properties have broadened the range of applications of QDs in advance studies like protein trafficking (7) and in the treatment of cancer (8-10). Synthesis of QDs through high temperature thermal decomposition of organo-metallic compounds in high boiling point (B.P.) toxic organic solvents needs long reaction time and involves complex synthesis procedures producing QDs with poor biocompatibility (10-16). So there is a quest for new, simpler and efficient synthetic routes with alternative solvents. Present study focuses on synthesis of size controlled CdTe QDs through a fast and facile MW (17) aided wet chemical route. Glutathione (GSH)-capped CdTe QDs (GSH-CdTe) were synthesized under mild conditions. These GSH-CdTe QDs show similar optical properties as QDs synthesized using more complicated and expensive methods. MW irradiation is used as an efficient heating source which creates numerous nucleation sites in the solution, leading to the formation of homogeneous and size controlled nanoparticles (18). Synthesis of ZnS QDs using different polar solvents with high MW absorption is already reported (19).Moreover, the quantum confinement effects in QDs are size dependent and are instrumental in determining their optical properties, so the solvents were chosen carefully to get a better control over the particle size distribution of CdTe QDs. A mechanism to describe the role of solvents in controlling the size dispersion is proposed for a better understanding of the process. II. Experimental Present study describes a simple protocol for the aqueous synthesis of CdTe QDs using CdCl2, K2TeO3 and GSH.CdCl2 and K2TeO3 were used as the Cd 2+ and Te 2- sources. The interaction between these two compounds with microorganisms is well studied(20-23).Further, a biological thiol and a tri-peptide GSH works both as a reducing and capping agent for the aqueous synthesis of CdTe QDs(24), found in abundance in cells and are suitable for the stabilization of CdSe and CdTe QDs(25,26). Moreover, all of the operations could be performed in air avoiding the need for inert atmosphere due to the fact that K2TeO3 is air stable. The synthesis of CdTe QDs and their subsequent coating were as follows-

Facile synthesis route of porous MnCo2O4and CoMn2O4nanowires and their excellent electrochemical properties in supercapacitors

Two types of porous cobalt manganese oxide nanowires (MnCo2O4 and CoMn2O4) with different structures have been successfully synthesized by thermal decomposition of organometallic compounds for the first time. Nitrilotriacetic acid (NA) was used as a chelating agent to coordinate Co(II) and Mn(II) ions in various molar ratios, in a hydrothermal condition. The microstructure of as-synthesized cobalt manganese oxides, composed of numerous nanoparticles, completely retains the 1D network structure of the Co–Mn–NA coordination precursors without structure collapse. Electrochemical properties of the cobalt manganese oxide materials have been tested for supercapacitors at room temperature. Both the MnCo2O4 and CoMn2O4 electrodes display the outstanding capacitive behaviors and superior electrochemical properties. The CoMn2O4 nanowire shows excellent capacitance and desirable rate performance (2108 F g−1 at 1 A g−1 and 1191 F g−1 at 20 A g−1) compared to that of the MnCo2O4 nanowire (1342 F g−1 at 1 A g−1 and 988 F g−1 at 20 A g−1). Electrochemical impedance spectra (EIS) results also reconfirm that the CoMn2O4 nanowires display more facile electrolyte diffusion and higher capacitor response frequency than MnCo2O4 nanowires. This can be ascribed to the facile electrolyte/OH− ion penetration and better Faradaic utilization of the electroactive surface sites that generated by the smaller particle size and higher surface area.

Preparation of Magnetite Nanoparticles by Thermal Decomposition of Iron (III) Acetylacetonate with Oleic Acid as Capping Agent

The thermal decomposition of organometallic compounds was used to synthesize magnetite nanoparticles in high boiling point organic solvent containing stabilizing surfactants. Iron (III) acetylacetonate was used as the organometallic precursor in this work. Thermal decomposition of cationic metal center leads directly to the metal oxide, in the presence of 1,2-hexadecanediol, oleylamine, and oleic acid in diphenyl ether. Characterization with the Particle Size Analyzer (PSA) showed the size of the obtained magnetite nanoparticles was 2.1 ± 0.9 nm with polydispersity index of 0.327. The morphology and chemical structure of the obtained magnetite nanoparticle was characterized by using of Transmition Electron Microscopy (TEM) and Fourier-Transformed Infrared (FTIR) spectroscopy. The application of magnetite nanoparticles in the industrial wastewater treatment was also discussed.

Synthesis of porous magnetic ferrite nanowires containing Mn and their application in water treatment

Two kinds of porous magnetic ferrite nanowires containing manganese (MnFe2O4 and Mn doped Fe3O4) have been successfully synthesized by thermal decomposition of organometallic compounds, using nitrilotriacetic acid (NA) as a chelating agent to coordinate with various ratios of Fe(II) and Mn(II) ions. The resultant MnFe2O4 and Mn doped Fe3O4 nanostructures are superparamagnetic, and have magnetization saturation values of about 45.9 and 48.7 emu g−1 for MnFe2O4 and Mn doped Fe3O4, respectively. The Brunauer–Emmett–Teller specific surface areas of the MnFe2O4 and Mn doped Fe3O4 are 37.8 and 45.4 m2 g−1, respectively. The as-prepared porous MnFe2O4 and Mn doped Fe3O4 nanowires exhibit excellent ability to remove heavy metal ions and organic pollutant in waste water. In addition, these porous magnetic ferrites may be useful in other fields such as biomedicine and Li-ion batteries.

Porous nickel cobaltite nanorods: desired morphology inherited from coordination precursors and improved supercapacitive properties

A facile and general method for the synthesis of porous complex oxides is highly desirable owing to their significant applications for energy storage. In this contribution, the porous nickel cobaltite nanorods have been successfully prepared by thermal decomposition of organometallic compounds, using nitrilotriacetic acid (NTA) as a chelating agent to coordinate with the Ni and Co ions. The obtained precursors were demonstrated to be one-dimensional nanorods. The resultant porous nickel cobaltite nanorods basically preserved the morphology of the precursors. In addition, these nanoparticles show good crystallinity. The as-prepared nickel cobaltite displays nanorod-like morphology with about 1 μm length and about 100 nm diameter. With a large surface area of 103.4 m2 g−1, this novel material exhibited high specific capacitance of 1078 F g−1 and 704 F g−1 at current densities of 1 and 20 A g−1, respectively. This suggests that about 65% of the capacitance is still retained when the charge–discharge rate is increased from 1 A g−1 to 20 A g−1. The specific capacitance retention is 94.4% after 2500 cycles, suggesting its excellent cycling stability. In addition, these porous nickel cobaltite nanorods may be useful in other fields such as Li-ion batteries and Li-O2 batteries.

Synthesis and anomalous magnetic properties of LaFeO 3 nanoparticles by hot soap method

Nanocrystalline LaFeO 3 particles were synthesized at low temperatures by using hot soap technique. The synthesis was based on the thermal decomposition of organometallic compounds precipitated in a hot coordinating solvent. Moderate heat treatment at low temperature far below the combustion point of organic compounds produced spherical LaFeO 3 nanoparticles with average diameter of about 15 nm. The crystalline phase, structure and particle size of obtained products were characterized by X-ray diffraction, infrared spectroscopy and transmission electron microscopy observations. In spite of the antiferromagnetic nature of bulk LaFeO 3, the obtained nanoparticles exhibited anomalous large magnetization. Superparamagnetic behavior with a blocking temperature of about 30 K was observed in both magnetization and Mössbauer spectroscopic analyses.

Synthesis and characterization of monodisperse CdSe quantum dots in different organic solvents

Nearly monodisperse CdSe quantum dots (QDs) have been prepared by a soft solution approach using air-stable reagents in different organic solvents. This scheme is a supplement to the conventional thermal decomposition of organometallic compounds at higher temperatures. CdSe nanocrystals of different sizes could be obtained by simply changing the solvent. This method is reproducible and simple and thus can be readily scaled up for industrial production. The reaction process was monitored by the temporal evolution of the UV-Vis absorption and room temperature photoluminensce spectra. The structures of the CdSe quantum dots were determined by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The phase-transfer of oleic acid-stabilized CdSe nanocrystals into PBS buffer solutions was also studied for their potentials in biological applications.

Preparation of Pb(Zr,Ti)O3 Thin Films by Sol-Gel Technique

In the preparation of Pb(Zr,Ti)O3 thin films by the sol-gel technique, the following procedures are involved: evaporation of solvents, thermal decomposition of organometallic compounds and crystallization. In this study, a thermodynamic approach was employed for the sol-gel technique, and the processing conditions were determined. For the processes of evaporation and thermal decomposition, the processing conditions were determined by applying Ozawa's method [Bull. Chem. Soc. Jpn. 38 (1965) 1881]. By means of both the X-ray diffraction technique and scanning electron microscope technique, crystal structure and surface morphology were evaluated. It was observed that the perovskite phase began to form at 500° C and was completed at 600° C. Moreover, a dense Pb(Zr,Ti)O3 thin film was also formed by annealing at 700° C for 120 min.

Preparation of (Ba, Pb)TiO<sub>3</sub> Thin Films by the Thermal Decomposition of Organometallic Compounds

Barium isopropoxide, lead naphthenate and titanium isopropoxide were mixed into a homogeneous solution. The homogeneous solution was spin-coated on silicon substrates and the obtained films were fired at 800°C in O2. The dielectric constant of the films depended on the Ba/Pb molar ratio. Maximum value, which was 300, was obtained at Ba/Pb=50/50. The dielectric constant of the films were different from those previously reported for the bulk materials. This seems to be caused by the existence of the residual stress which was derived from the difference of thermal expansion coefficient between the films and the Si substrate. The fluctuation of the composition (Pb/Ba ratio) in the film was observed in (Ba, Pb)TiO3 system by SIMS analysis. This fluctuation seemed to have occurred because barium alkoxide was more reactive to water than lead naphthenate.

Preparation and properties of tin-doped indium oxide thin films by thermal decomposition of organometallic compounds

Transparent and conductive tin-doped indium oxide thin films were prepared on sodalime and quartz glass substrates by thermal decomposition of organometallic compounds. The optical transmittance of the films was 90 % in the visible region. The electrical resistivity changed from 6 − 8 × 10 −3 Ω cm to 3 – 4 × 10 − Ω cm depending on composition and after annealing in vacuum, it decreased by a factor of 2–10.

Preparation and properties of tin-doped indium oxide thin films by thermal decomposition of organometallic compounds

Transparent and conductive tin-doped indium oxide thin films were prepared on sodalime and quartz glass substrates by thermal decomposition of organometallic compounds. The optical transmittance of the films was 90 % in the visible region. The electrical resitivity changed from 6 – 8 × 10 −3 Ω cm to 3 – 4 × 10 −2 Ω cm depending on composition and after annealing in vacuum, it decreased by a factor of 2–10.

Electrical Properties of PbTiO3 Thin Films by Thermal Decomposition of Organometallic Compounds

PbTiO3 thin films were deposited by thermal decomposition of organometallic compounds and their electrical properties were studied. The dielectric constant of these films was estimated to be about 200. D–E hysteresis loops were observed in the films deposited on Pt plates. Remanent polarization and coersive force were about 37µC/cm2 and 130 kV/cm, respectively. Measured pyroelectric coefficient (dPr/dT) after applying a field of 150 kV/cm was 1×10-8 C·cm-2·K-1.

Preparation of ferroelectric PZT films by thermal decomposition of organometallic compounds

Transparent PZT thin films with perovskite structure were successfully obtained by thermal decomposition of organometallic compounds at the temperatures of 500 to 700° C. The films deposited on platinum substrates were smooth and uniform, but microcrackings were observed in the films deposited on fused silica substrates. The ratio of metal composition in the PZT film agreed with that in the mixture of starting materials. Films obtained at 700° C on platinum substrate showed a hysteresis loop. A spontaneous polarization was 35.65μC cm−2, a saturation remanent polarization was 30.56μC cm−2 and a coercive field was 45 kV cm−1. Dielectric constant and dielectric loss angle were about 300 and 0.05, respectively.

Preparation of ferroelectric PZT films by thermal decomposition of organometallic compounds

Preparation of ferroelectric PZT films by thermal decomposition of organometallic compounds

Oriented thin films of CdS grown on glass and InP (111)A by thermal decomposition of organometallic compounds

Oriented thin films of CdS grown on glass and InP (111)A by thermal decomposition of organometallic compounds

Low Temperature Deposition of Metal Nitrides by Thermal Decomposition of Organometallic Compounds

Decomposition reaction of dialkylamides of boron, silicon, tin, titanium, zirconium, niobium, and tantalum was investigated. The amides of transition metals decomposed to the corresponding nitrides at 300°–500°C, whereas those of boron, silicon, and tin yielded elemental deposits at higher temperatures. In the deposition of titanium nitride from titanium tetrakis(dimethylamide), two optimum temperatures at 400° and at 800°C in nitrogen or hydrogen atmosphere were found, but in argon only low temperature deposition was possible. The low and high temperature processes are discussed in relation to mass spectral analysis of the exhaust gases formed at various decomposition temperatures of titanium amide.