Feeding Of Oxygen Research Articles

Depolymerization of lignin by extracellular activity of Pycnoporus cinnabarinus, to obtain cellulose

Abstract Cellulose can be used to produce biofuels and many other products like pharmaceutical goods, food supplements, cosmetics, bio-plastics, etc. Lignocellulosic materials, like O. ficus indica residuals, are a heterogeneous biopolymer formed mainly by lignin, hemicellulose and cellulose. Lignin provides protection to the plants against chemical and microbial degradation, but it can be degraded by white rot fungi species, like Pycnoporus cinnabarinus. Since cellulose molecules are arranged in regular bundles enveloped by hemicellulose and lignin molecules, it is necessary to brake lignin and hemicellulose molecules to recover cellulose for its use in bioprocess. In this work, a biotechnological process for cellulose recovery from cactus waste through depolymerization of lignin by P. cinnabarinus, is presented. The delignification is carried out by aerobic culture in batch stirred bioreactors, with a liquid culture medium enriched with nutrients and minerals with O. ficus indica residuals as the unique carbon source, during eight-day span under continuous feeding of oxygen. A factorial design of experiments (DOE) for eight sets of factor values was selected for this study. The factors were: particle size, pH level, and process temperature. For each experiment, biomass, total reducing carbohydrates (TRC) and dissolved oxygen (DO) concentrations were measured every 24 h. At the end of each experiment, the percentage of delignification, and cellulose recovery was measured by Infrared (IR) spectroscopy. Up to 67% of delignification and 22% of cellulose recovery were obtained by the process. These results were analyzed by a factorial DOE in order to maximize each response individually and to optimize both responses together. The delignification of Opuntia ficus indica thorns has not been previously reported to our knowledge.

In vitro study on how cold plasma affects dentin surface characteristics

PurposeStudies evaluating different features of cold plasma action on dentin surface characteristics are lacking. Thus, this in vitro study aimed to determine the effect of cold plasma under different protocols of exposure time, distance to plasma source, and the association of argon gas with distinct concentrations of oxygen on the wettability, surface energy, total free interaction energy, surface roughness, morphology and chemical composition of dentin. Material and methodsOne hundred and twenty-five bovine dentin samples were used and divided into twenty-five groups according to the exposure time to plasma (15, 30, or 60 s); distance between plasma source and dentin surface (3 or 6 mm); argon gas without plasma generation; and plasma generated by argon gas and association of argon gas with distinct concentrations of oxygen (2 % or 3 %) (n = 5). Contact angle (θ), surface energy (γs) and total free interaction energy (ΔG) were measured using a goniometer (Krüss), while surface roughness (Ra) was evaluated by a profilometer (Mitutoyo). Representative samples were submitted to scanning electron microscopy (JEOL) to ilustrate the morphology and chemical composition of dentin. Data comparing control group with all experimental groups were submitted to ANOVA followed by Tukey's test (α = .05). Data comparing oxygen gas action at different concentrations and argon gas on dentin characteristics were submitted to non-parametric Kruskal–Wallis test, followed by Dunn test for comparison between the groups and methods (α = 0.05). ResultsIn general, argon gas without plasma generation promoted no significant difference on dentin surface characteristics compared to control group (P > .05), differently for the cold plasma that significantly reduced contact angle values and increased total free interaction energy of dentin surface (P < .05). Overall, feeding of oxygen at distinct concentrations promoted significant difference on dentin surface characteristics compared to control group (P < .05). Exposure time and distance protocols interfered with contact angle, surface energy and total free interaction energy analyses for each gas. There was no significant difference on surface roughness (P > .05), morphology and chemical composition of dentin submitted to argon gas, cold plasma, and distinct concentrations of oxygen. ConclusionIn conclusion, plasma generated by argon gas and its feeding with 2 % and 3 % oxygen gas improved the dentin surface characteristics about wettability, surface energy and total free interaction energy. Such treatments preserved the surface roughness, morphology and chemical composition of dentin. The protocols of groups Ar-6mm-15sec, ArO2-3mm-30sec and ArO3-3mm-15sec are recommended for improvement of dentin surface characteristics.

Emerging Biomaterials-Based Strategies for Inhibiting Vasculature Function in Cancer Therapy.

The constant feeding of oxygen and nutrients through the blood vasculature has a vital role in maintaining tumor growth. Interestingly, recent endeavors have shown that nanotherapeutics with the strategy to block tumor blood vessels feeding nutrients and oxygen for starvation therapy can be helpful in cancer treatment. However, this field has not been detailed. Hence, this review will present an exhaustive summary of the existing biomaterial based strategies to disrupt tumor vascular function for effective cancer treatment, including hydrogel or nanogel-mediated local arterial embolism, thrombosis activator loaded nano-material-mediated vascular occlusion and anti-vascular drugs that block tumor vascular function, which may be beneficial to the design of anti-cancer nanomedicine by targeting the tumor vascular system.

Experimental Investigation of the Oxidative Coupling of Methane in a Porous Membrane Reactor: Relevance of Back-Permeation.

Novel reactor configurations for the oxidative coupling of methane (OCM), and in particular membrane reactors, contribute toward reaching the yield required to make the process competitive at the industrial scale. Therefore, in this work, the conventional OCM packed bed reactor using a Mn-Na2WO4/SiO2 catalyst was experimentally compared with a membrane reactor, in which a symmetric MgO porous membrane was integrated. The beneficial effects of distributive feeding of oxygen along the membrane, which is the main advantage of the porous membrane reactor, were demonstrated, although no significant differences in terms of performance were observed because of the adverse effects of back-permeation prevailing in the experiments. A sensitivity analysis carried out on the effective diffusion coefficient also indicated the necessity of properly tuning the membrane properties to achieve the expected promising results, highlighting how this tuning could be addressed.

Indirect Fuel Cell Based on a Redox-Flow Battery Toward the Reduction of Platinum Usage

An indirect fuel cell [1-3], which is composed of a redox-flow battery (RFB) and a chemical reactor to regenerate (oxidize) the catholyte by oxygen and another reactor to regenerate (reduce) the anolyte by a fuel, is constructed as an alternative to a PEFC. We have already proposed a new design for the RFB [4] for our indirect fuel cell, which has a gas phase of hydrogen to separate the catholyte and anolyte to eliminate the crossover of ionic species. In this work, to clarify the possibility to use an indirect fuel cell to reduce the usage of noble-metal catalysts, a non-noble-metal catalyst and a mixture of two molecular catalysts were used in the catholyte and anolyte regenerators, respectively. In the catholyte regenerator, a carbonized hemoglobin powder was used as a solid catalyst. This material has been proved to be effective as an electrocatalyst for oxygen reduction reaction (ORR) in a PEFC [5]. In this work, it was used after immobilization on a polymer sheet support. In the anolyte regenerator, a rhodium complex was used for hydrogen oxidation and another rhodium complex for carbon monoxide oxidation. Although these two complexes contain a noble metal, they are soluble in the electrolyte and used as homogeneous catalysts. Since the active site of such a complex molecular catalyst is a single metal atom, the usage of metal can be reduced compared with a metallic platinum catalyst. This work demonstrates a steady-state operation of the above-mentioned indirect fuel cell by feeding of oxygen and CO-containing hydrogen to the catholyte and anolyte regenerators, respectively. This work was supported by JSPS KAKENHI Grant Number 25289363. [1] A.M. Posner, Fuel, 34 (1955) 330. [2] S. Ashimura, Y. Miyake, Denki Kagaku, 31 (1963) 598. [3] D.-G. Oei, J. Appl. Electrochem. 12 (1982) 41. [4] Z. Siroma, S. Yamazaki, N. Fujiwara, M. Asahi, T. Nagai, T. Ioroi, J. Power Sources, 242 (2013) 106. [5] J. Maruyama, I. Abe, Chem. Mater., 18 (2006) 1303.

In Situ Observations during Chemical Vapor Deposition of Hexagonal Boron Nitride on Polycrystalline Copper.

Using a combination of complementary in situ X-ray photoelectron spectroscopy and X-ray diffraction, we study the fundamental mechanisms underlying the chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) on polycrystalline Cu. The nucleation and growth of h-BN layers is found to occur isothermally, i.e., at constant elevated temperature, on the Cu surface during exposure to borazine. A Cu lattice expansion during borazine exposure and B precipitation from Cu upon cooling highlight that B is incorporated into the Cu bulk, i.e., that growth is not just surface-mediated. On this basis we suggest that B is taken up in the Cu catalyst while N is not (by relative amounts), indicating element-specific feeding mechanisms including the bulk of the catalyst. We further show that oxygen intercalation readily occurs under as-grown h-BN during ambient air exposure, as is common in further processing, and that this negatively affects the stability of h-BN on the catalyst. For extended air exposure Cu oxidation is observed, and upon re-heating in vacuum an oxygen-mediated disintegration of the h-BN film via volatile boron oxides occurs. Importantly, this disintegration is catalyst mediated, i.e., occurs at the catalyst/h-BN interface and depends on the level of oxygen fed to this interface. In turn, however, deliberate feeding of oxygen during h-BN deposition can positively affect control over film morphology. We discuss the implications of these observations in the context of corrosion protection and relate them to challenges in process integration and heterostructure CVD.

Bioreactor performance and functional gene analysis of microbial community in a limited-oxygen fed bioreactor for co-reduction of sulfate and nitrate with high organic input

Limited-oxygen mediated synergistic relationships between sulfate-reducing bacteria (SRB), nitrate-reducing bacteria (NRB) and sulfide-oxidizing bacteria (SOB, including nitrate-reducing, sulfide-oxidizing bacteria NR-SOB) were predicted to simultaneously remove contaminants of nitrate, sulfate and high COD, and eliminate sulfide generation. A lab-scale experiment was conducted to examine the impact of limited oxygen on these oxy-anions degradation, sulfide oxidation and associated microbial functional responses. In all scenarios tested, the reduction of both nitrate and sulfate was almost complete. When limited-oxygen was fed into bioreactors, S0 formation was significantly improved up to ∼70%. GeoChip 4.0, a functional gene microarray, was used to determine the microbial gene diversity and functional potential for nitrate and sulfate reduction, and sulfide oxidation. The diversity of the microbial community in bioreactors was increased with the feeding of limited oxygen. Whereas the intensities of the functional genes involved in sulfate reduction did not show a significant difference, the abundance of the detected denitrification genes decreased in limited oxygen samples. More importantly, sulfide-oxidizing bacteria may alter their populations/genes in response to limited oxygen potentially to function more effectively in sulfide oxidation, especially to elemental sulfur. The genes fccA/fccB from nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB), such as Paracoccus denitrificans, Thiobacillus denitrificans, Beggiatoa sp., Thiomicrospira sp., and Thioalkalivibrio sp., were more abundant under limited-oxygen condition.

Choosing the Parameters of a Blast-Furnace Smelting Technology That Includes the Injection of Coal-Gasification Products

The use of a multi-zone mathematical model developed by the Institute of Ferrous Metallurgy of the Ukrainian Academy of Sciences to study blast-furnace smelting with the injection of coal-gasification products showed that additional coke can be saved by adding flux, increasing the temperature of the blast, and evenly distributing the ore burden across the top of the furnace. Keywords: coal-gasification products, mathematical model, replacement of coke, oxygen, carbon. A previous analysis of blast-furnace smelting technologies that include the injection of coal-gasification products (CGPs) showed that it is possible to significantly increase the amount of coal that can be injected if it undergoes preliminary gasification and the ash is fluidized in tuyere-mounted gasifiers (TMGs) (1). Coke consumption can be reduced by replacing high-grade coals having an ash content of up to 10% (and used in the blast furnace in the form of pulverized-coal fuel, or PCF) with low-grade coals containing up to 25% ash (and used in the blast furnace in the form of CGPs). When CGPs obtained from low-grade coals are injected, it is important to reduce coke consumption to a minimum (190-200 kg/ton) by also injecting PCF obtained from high-grade coals (2, 3). The key to a technology which entails CGP injection with the use of a TMG is equipping the knee-nozzle section of each blast-furnace tuyere with a device that gasifies PCF. The PCF is delivered to this device (gasifier) from the bustle pipe, with the PCF having previously been injected into the hot blast carried by the pipe. The CGPs formed in the gasifier are discharged from the TMG in the tuyere region and enter the tuyere hearth. Choosing efficient parameters for the smelting operation is part of the process of determining whether or not it is feasible to reduce coke consumption by the designated amount. The following are among these parameters when the furnace is to be injected with CGPs obtained from low-grade coals: 1) the temperature of the blast and its oxygen content, as well as the method used to supply the blast and oxygen needed for the gasification of coke and coal in the TMG: 2) the molar consumption of oxygen for gasification of the carbon in the coal, this parameter being calculated as the ratio O/C and expressed in moles/mole; and 3) the method employed to add more flux to the charge in connection with the increased amount flux consumed when high-ash coals are being used. The method used to supply the oxygen and blast needed for the gasification of coke and coal in the TMG is chosen based on the control parameters of the smelting regime and their set points. It has been proposed (1) that part of the oxidiz- ing blast which is sent directly into the furnace to burn coke be delivered via a separate channel that can be constructed in one of two variants: the use of a separate pipe to take a portion of the blast from the bustle pipe and transport it to the tuyere; the feeding of unheated oxygen through a pipe directly into the body of the tuyere to replace an equivalent amount of heat- ed blast. It was shown in (1) that hot blast can be replaced by unheated oxygen when the initial and projected unit consump-

Integrated autothermal oxidative coupling and steam reforming of methane. Part 2: Development of a packed bed membrane reactor with a dual function catalyst

A numerical feasibility study was performed on the integral performance of dual function catalyst particles in a packed bed reactor equipped with a porous membrane for distributive feeding of oxygen. The exothermic oxidative coupling and the endothermic steam reforming of methane (for simultaneous production of ethylene and synthesis gas) are integrated at the level of a porous catalyst particle with distributed activity, where the presence of the intraparticle heat-sink strongly reduces the total reaction heat and the temperature gradients in the reactor, eliminating the need for expensive conventional cooling of the reactor.Numerical simulations, with reaction kinetics taken from the literature, revealed that with distributive oxygen feeding via membranes indeed the local oxygen concentration in the packed bed membrane reactor can be kept low, which combined with a high Thiele modulus for oxidative coupling makes dual function catalysis possible. Using a reforming core diameter of approximately 15–40μm, the steam reforming and oxidative coupling reaction rates could be effectively tuned to achieve autothermal operation, while the methane conversion was enhanced from 34 to 48% at optimum C2 production rates. In addition, it was shown that the temperature profiles in the reactor can be strongly reduced by employing the dual function catalyst and that the use of axial oxygen membrane flux profiles enables the use of a single particle configuration to approach autothermal operation in the entire reactor.

Production, characterization and evaluation of protective Cr oxide coatings against metal dusting

Cr oxide/Cr thin films have been deposited on HK40 steel substrates in order to evaluate their behavior under metal dusting conditions. The films were produced by reactive magnetron sputtering under various conditions of oxygen flow, work pressure, power and bias voltage to find the optimum deposition conditions to form an adequate dense structure with good adhesion to the substrate. The coatings were extensively characterized by scanning electron microscopy, x-ray diffraction and atomic force microscopy. The most promising structures were subjected to metal dusting conditions in a thermobalance (TGA) to evaluate their response to this type of corrosion. The results indicate that lower applied power and slowly graduated feeding of oxygen resulted in coatings with less residual stresses, higher density and better adherence. The TGA experiments showed an improvement in resistance to metal dusting of the coated samples compared to an uncoated one.

Water treatment with pulsed discharges generated inside bubbles

AbstractThe parallel operation of pulsed discharges generated inside bubbles is successfully demonstrated by applying a fast rising voltage to a multielectrode system immersed in treated water. A 10 ppm solution of acetic acid, which cannot be decomposed by ozone, was used as a persistent material and the acetic acid decomposition efficiency was evaluated by measuring the total organic carbon (TOC) values of the solution. The electric conductivity of the solution affected decomposition efficiency because the solution resistance, which was inversely proportional to the conductivity, limited the magnitude of the discharge current flowing along the surface of the bubbles generated by the feeding of oxygen or argon gas. With a nine‐hole electrode system, the discharge power deposited in one discharge was lower, and the acetic acid decomposition efficiency was higher, than the values obtained with a single‐hole electrode system. Lower discharge power seemed to minimize the self‐quenching of OH radicals, and resulted in the efficient decomposition of acetic acid. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(1): 1–7, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20918

Discrete injection of oxygen enhances hydrogen production in circulating fast fluidized bed membrane reactors

The coupling of steam and oxidative reforming reactions of methane in a circulating fast fluidized bed membrane reactor (CFFBMR) has been studied. The study is based on rigorous modeling and simulation viewpoints. The concept of oxygen distribution has been investigated by employing the discrete injection approach. Feeding of oxygen through discrete injection points along the length of the reformer is compared with oxygen feeding through dense perovskite membranes ( La 0.4 Ca 0.6 Fe 0.8 Co 0.2 O 3 - δ ) and the conventional direct feeding of oxygen (co-feed). The results indicate that the discrete injection of oxygen enables to achieve in situ heat integration at low feed temperature. It is also shown that oxygen distribution along the length of the CFFBMR is beneficial in eliminating the hot spot temperature regions. The hydrogen yield shows an optimal value and is significantly affected by many key parameters such as feed temperature, pressure and number of hydrogen membrane tubes. The result also shows that the CFFBMR has a potential to develop complicated bifurcation behavior.

Self Growth of Silica Nanowires on a Si/SiO2Substrate

The growth of amorphous silica nanowires by on-site feeding of silicon and oxygen is reported. The nanowires were grown on a nickel-coated oxidized silicon substrate without external silicon or oxygen sources. Transmission electron microscopy observation revealed that the nanowires, which have diameters of less than 50 ㎚ and a length of several micrometers, were grown using a traditional vapor-liquid-solid mechanism. Blue photoluminescence was observed from these nanowires at room temperature. An approach to grow nanowires without external precursors may be useful when integrating nanowires into devices structures. This can benefit the fabrication of nanowire-based nanodevices.

Feeding of Oxygen Along the Height of a Circulating Fast Fluidized Bed Membrane Reactor for Efficient Production of Hydrogen

The coupling of steam and oxidative reforming of methane has been studied in a circulating fast fluidized bed membrane reactor (CFFBMR). The concept of oxygen distribution has been investigated by employing discrete injection points along the length of the reformer. The addition of oxygen is to supply the necessary heat required by the endothermic reforming reactions from oxidative reforming reactions. An external air membrane separation system is suggested to supply pure oxygen. A mathematical model is used for a systematic simulation in order to investigate the performance of the CFFBMR. Simulation results show that the staging distribution of oxygen and removal of hydrogen by the permselective membrane play an important role in the significant shift of the thermodynamic equilibrium and substantial enhancement of hydrogen yield. It has been shown that the discrete distribution of oxygen has a potential to eliminate the thermal runaway by mitigating the temperature along the length of the CFFBMR. The results indicate that the coupling of endothermic steam reforming and exothermic oxidative reforming reactions allows efficient energy integration without external supply of energy. The exit hydrogen yield shows a maximum value at which the oxygen to methane feed ratio (O/M) is optimal. The locus of maximum exit hydrogen yield is chosen for the sensitivity analysis. The influence of various reformer key parameters is investigated.

Chemical vapor infiltration (CVI) — Part II: Infiltration of porous substrates with diamond by using a new designed hot-filament plant

We designed a new hot-filament plant which features some new operating states for chemical vapor infiltration (CVI) with diamond. Most characteristic for the new hot-filament plant is the possibility of a forced flow of the activated gas species through a porous substrate. Separate feeding of hydrogen, methane and oxygen above or underneath the substrate ensures the production of pertinent carbon growth species like CH 3 directly at or in the substrate or rather in the pore. We infiltrated porous substrates by using several operating states and compared the results with standard processes. For these first experiments we have set the addition of oxygen aside, which was viable for the infiltration experiments described in Part I of the paper. In order to achieve good infiltration results it was necessary to use very low methane concentrations between 0.2% and 0.3%. We were able to infiltrate at high growth rates (> 0.5 μm/h) combined with a good diamond quality (> 90%). Moreover it was possible to alleviate the “bottleneck” effect which we described in Part I of the paper. Raman spectroscopy and SEM were used to characterize the deposited or rather infiltrated diamond.

Development of a Membrane-Assisted Fluidized Bed Reactor. 2. Experimental Demonstration and Modeling for the Partial Oxidation of Methanol

A small laboratory-scale membrane-assisted fluidized bed reactor (MAFBR) was constructed in order to experimentally demonstrate the reactor concept for the partial oxidation of methanol to formaldehyde. Methanol conversion and product selectivities were measured at various overall fluidization velocities, reactor temperatures, methanol and oxygen overall feed concentrations, ratios of gas fed via membranes relative to gas fed via the bottom distributor, and aspect ratios of the fluidized bed. High methanol conversions and high selectivities to formaldehyde were achieved with safe reactor operation (isothermal reactor conditions) at very high methanol inlet concentrations, much higher than currently employed in industrial processes. It was experimentally demonstrated that with distributive feeding of oxygen in a MAFBR the overall formaldehyde yield and throughput could be increased without a pronounced and undesirable conversion of formaldehyde to carbon monoxide. Furthermore, a one-dimensional two-phase phenomenological reactor model has been developed with which the experimentally observed conversion and selectivity as a function of the operating conditions could be well described.

Production of heterologous protein by Methylobacterium extorquens in high cell density fermentation

The green fluorescent protein (GFP) was used as a model protein to study the recombinant protein production by the strain Methylobacterium extorquens ATCC 55366. Scale-up from shake flasks to 20 l fed-batch fermentation was achieved using methanol as a sole carbon and energy source and a completely minimal culture medium. Two different expression vectors were used to express GFP. Clone PCM-GFP containing the vector pCM110 with native promoter of the methanol dehydrogenase P mxaF produced approximately 100-fold more GFP than the clone PRK-GFP containing the vector pRK310 with the heterogeneous promoter P lac . Several fed-batch fermentations with and without selective pressure (tetracycline) were run in a 20 l stirred tank fermenter using the two different clones of M. extorquens. The methanol concentration was monitored with an on-line semiconductor gas sensor in the culture broth. It was maintained at a non-toxic level of 1.4 g l −1 with an adaptative control which regulates the methanol feed rate. The same growth profile was achieved in all fermentations. The maximum growth rate ( μ max) was 0.18 h −1 with an overall yield ( Y X/ S ) of 0.3 g g −1 methanol. With this high cell density fermentation process, we obtained high levels (up to 4 g l −1) of GFP with the clone PCM-GFP. The maximum specific GFP production ( Y GFP/ X ) with this clone was 80 mg g −1 representing approximately 16% of the total cell protein. Additional feeding of pure oxygen to the fermenter permitted a longer phase of exponential growth but had no effect on the total yields of biomass and GFP. The specific GFP production of clone PCM-GFP remained unaffected in the presence or absence of selective pressure (tetracycline), within the initial 50 h of the fermentation culture. These results suggest that M. extorquens ATCC 55366 could be an interesting candidate for overexpression of recombinant proteins.

Activity and resistance to leaching of Cu-based catalysts in the wet oxidation of phenol

The activity and resistance to leaching of a co-precipitated CuCeOx (Cuat:Ceat=1:9; TC, 500 and 800°C) catalyst in the wet oxidation (CWO) of phenol (TR, 150°C; PR, 12atm), with reference to a CuZnAlOx commercial system, has been investigated using a semi-batch “slurry” reactor with continuous feeding of oxygen. The role of homogeneous catalysis by leached Cu2+ ions on the activity pattern of solid catalysts is addressed. Thermal and chemical (“acid washing”) treatments of the CuCeOx catalyst induce marked modifications on the structure and redox properties also altering its CWO activity-selectivity pattern. The whole set of experimental findings leads to infer that the CWO of phenol on Cu-based catalysts proceeds via a homogeneous–heterogeneous path promoted by the leaching of Cu2+ ions.

Comparative Study of the Decomposition of CCl4 in Cold and Thermal Plasma

Decomposition of carbon tetrachloride was studied in an inductively coupled thermal plasma reactor and in a low temperature, non-equilibrium plasma reactor, in neutral and oxidative conditions, respectively. In neutral conditions formation of solid soot, aliphatic- and cyclodienes was observed in equilibrium, and products, such as Cl2 and C2Cl6 were detected in non-equilibrium plasma. Feeding of oxygen into the thermal plasma reactor depressed both soot and dienes formation and induced the formation of oxygen containing intermediates and products. GC-MS analyses of the gaseous products and the extract of the soot referred to as complex decomposition and recombination mechanism at given conditions. Presence of oxygen in the low temperature plasma reactor results in the formation of carbonyl compounds as intermediers. CO2 and Cl2 revealed as final products of CCl4 decomposition in cold plasma.

Epitaxial growth of BaTiO3/SrTiO3 structures on SrTiO3 substrate with automatic feeding of oxygen from the substrate

Thin films of BaTiO3 and SrTiO3 and their superlattice were grown on SrTiO3 substrates using oxygen from the substrates as an oxygen source. Epitaxial growths were carried out by coevaporations of the component metals under ultrahigh vacuum without introducing any oxidants. The growth mechanism in the extremely low oxidation ambient was studied. Oxygen was automatically fed from the substrate to the growing film surface. As a result, oxygen vacancies were incorporated deep into the inside of the SrTiO3 substrate, confirmed by means of positron annihilation. The local oxygen deficiency at the growing surface is buffered by the fast diffusion of incorporated oxygen vacancies into deep inside of the substrate, avoiding decomposition or nucleation of the metallic phases on the surface. The BaTiO3/SrTiO3 interfaces were formed without intermixing, despite considerable amounts of oxygen having moved through the interfaces.