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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Tribological behavior of N-doped ZnO thin films by metal organic chemical vapor deposition under lubricated contacts

N-doped ZnO thin films were deposited on 304L stainless steel through the pyrolysis of zinc acetate and ammonium acetate in different ratios at a temperature of 420 degrees C using metal organic chemical vapor deposition. Compositional and structural analyzes of the films were performed by using Rutherford backscattering spectroscopy and X-ray diffraction. The frictional behavior of the thin films and 304L stainless steel substrate was evaluated using a ball-on-flat configuration with reciprocating sliding under marginally lubricated and fully flooded conditions. Al alloy (2017) was used as ball counterface, while basestock synthetic polyalfaolefin oil (PAO10) without additives was used as lubricant. The flat and ball counterface surfaces were examined to assess the wear dimension and failure mechanism. Under marginally lubricated condition, N-doped ZnO thin films provided significant reduction in friction, whereas the films have minimal or no effect in friction under fully flooded condition. N-doped ZnO thin films showed a significant effect in protecting the ball counterface as wear volume was reduced compared with that of the substrate under the marginally lubricated condition. Under the fully flooded condition, with the exception of one of the films, the wear volume of the N-doped ZnO thin films ball reduced compared with that of the substrate. In all the ball counterfaces for N-doped ZnO thin films under both conditions, wear occurred through abrasive mechanism of various degrees or mild polishing. Thus, superfluous lubrication of N-doped ZnO thin films is not necessary to reduce friction and wear.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Oxygen and relative humidity monitoring with films tailored for enhanced photoluminescence

In this study, approaches to generate porous or doped sensing films, which significantly enhance the photoluminescence (PL) of oxygen optical sensors, and thus improve the signal-to-noise (S/N) ratio, are presented. Tailored films, which enable monitoring the relative humidity (RH) as well, are also presented. Effective porous structures, in which the O 2 -sensitive dye Pt octaethylporphyrin (PtOEP) or the Pd analog PdOEP was embedded, were realized by first generating blend films of polyethylene glycol (PEG) with polystyrene (PS) or with ethyl cellulose (EC), and then immersing the dried films in water to remove the water-soluble PEG. This approach creates pores (voids) in the sensing films. The dielectric contrast between the films’ constituents and the voids increases photon scattering, which in turn increases the optical path of the excitation light within the film, and hence light absorption by the dye, and its PL. Optimized sensing films with a PEG:PS ratio of 1:4 (PEG’s molecular weight M w ~8000) led to ~4.4× enhancement in the PL (in comparison to PS films). Lower M w ~200 PEG with a PEG:EC ratio of 1:1 led to a PL enhancement of ~4.7×. Film-dependent PL enhancements were observed at all oxygen concentrations. The strong PL enhancement enables (i) using lower dye (luminophore) concentrations, (ii) reducing power consumption and enhancing the sensor’s operational lifetime when using organic light emitting diodes (OLEDs) as excitation sources, (iii) improving performance when using compact photodetectors with no internal gain, and (iv) reliably extending the dynamic range.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Investigation of fuel film formation and soot emissions in a GDI engine during cold-start with Split-injection strategies

This study investigates the impact of fuel-film formation on engine-out soot emissions in a gasoline direct injection (GDI) engine under cold-start conditions. Split-injection strategies were applied by varying the number of injections, injection duration, and total fuel quantity to affect wall wetting and control the average in-cylinder equivalence ratio. A combined experimental and numerical approach was employed to analyze fuel-film deposition, combustion efficiency, and engine-out soot and unburnt hydrocarbons (UHC) emissions. In particular, fuel film distribution estimated by means of non-reacting, 3-D, computational fluid dynamics (CFD) simulations, together with experimentally measured soot data, were used to investigate fuel film formation and its role in soot generation. In the experiments, a skip-fired engine control strategy was applied to mimic the transient nature of engine cold-start operation. The results indicate that, under the same total number of injections, increasing the average in-cylinder equivalence ratio through longer injection durations improves combustion stability, as indicated by the decrease of the coefficient of variation of IMEP n (Net Indicated Mean Effective Pressure) from 6.0 % to 0.6 %. However, this strategy leads to higher soot emissions, which increased by nearly an order of magnitude, primarily due to enhanced wall-film formation. In contrast, increasing the number of injections while maintaining a constant equivalence ratio significantly impacts fuel-film deposition and, consequently, soot emissions, with a fivefold reduction of the measured engine-out soot, decreasing from 3.5 mg to 0.7 mg. A soot-film correlation was developed and achieved a high coefficient of determination (r 2 = 0.95) and was further extended to account for spark timing effects. These findings confirm the effectiveness of split-injection for avoiding wall film formation and soot emissions, and the critical role of fuel film in soot generation, supporting the hypothesis that pool fires play a crucial role in contributing to soot formation under these cold-start conditions. In conclusion, the study also indicates the value of a predictive soot-film correlation for developing cold-start emission control strategies.

Engine Cold-start↗
DOE OSTI2020

Thermal stability of oxidized ultrathin Li films on TZM for plasma facing components

For improved understanding of the behavior of Li plasma facing components (PFCs) in the presence of oxygen impurities, we report on the thermal stability of ultrathin (up to 1.0 nm) LiO x films on a titanium-zirconium-molybdenum (TZM) alloy substrate over the temperature range of 310–1400 K. LiO x films were prepared by either post-oxidation of Li films or Li films deposited on an oxygen-precovered TZM surface. Thermal stability of these films was studied using a combination of temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and low-energy ion scattering (LEIS). For post-oxidized Li films, TPD showed that no Li desorption occurred until temperatures above 620 K, and then Li desorbed from the surface via at least three desorption peaks. The O 1s XPS spectra on the post-oxidized films at 310 K indicate the formation of lithium oxide (Li2O) and peroxide/hydroxide (Li 2 O 2 /LiOH). The peroxide/hydroxide converts to oxide after heating to 680 K with no desorption of Li or O 2 , and then this film decomposes to liberate Li into the gas phase while leaving oxygen at the TZM surface. Heating the LiO x films to 1070 K led to a solid-state reaction with surface Mo atoms of the substrate to form a condensed binary lithium molybdenum oxide (LixMoOy) phase, which upon further heating decomposed to liberate gas phase binary lithium molybdenum oxide species. Li deposition on an oxygen-precovered TZM surface formed a complex, highly stable, oxygen rich, Li-O-Mo interfacial oxide. Li desorption from multilayer Li films on oxygen-precovered TZM surfaces occurred in a metallic Li multilayer peak and three other oxide-derived peaks. These results support the improved thermal stability of oxidized lithium as compared to metallic Li and have implications for Mo impurity transport into the plasma at high temperatures.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Electrochemical properties of Li[Li{sub 0.2}Mn{sub 0.54}Co{sub 0.13}Ni{sub 0.13}]O{sub 2} cathode thin film by RF sputtering for all-solid-state lithium battery

The Li[Li{sub 0.2}Mn{sub 0.56}Ni{sub 0.13}Co{sub 0.13}]O{sub 2} thin films were prepared by radio frequency magnetron sputtering on Pt/Ti/SiO{sub 2}/Si substrate with target contained a 5% excess of lithium precursor. Thin films were deposited under various deposition conditions such as working pressure, gas ratio of Ar and O{sub 2}, and the temperature of in-situ annealing treatment. The thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The electrochemical property was estimated by a WBC3000 cycler with Li|Li[Li{sub 0.2}Mn{sub 0.54}Ni{sub 0.13}Co{sub 0.13}]O{sub 2} half-type cell at 1C charge/discharge rate. The (0 0 3) and (1 0 4) diffraction peaks which represent layered {alpha}-NaFeO{sub 2} type structure (space group R-3m) were observed. Optimal magnetron sputtering conditions were detected. The 500 Degree-Sign C annealed thin film after deposited at 10 m Torr in Ar:O{sub 2}=3:1 shows a high discharge capacity of around 62 {mu}Ah/cm{sup 2} {mu}m with a high cyclic retention. - Graphical abstract: The Li[Li{sub 0.2}Mn{sub 0.56}Ni{sub 0.13}Co{sub 0.13}]O{sub 2} films is suitable for Lithium thin film battery. The film exhibits great discharge capacity (62 {mu}Ah/cm{sup 2} {mu}m) up to 200 cycles. Highlights: Black-Right-Pointing-Pointer High capacity thin films were deposited by RF magnetron sputtering. Black-Right-Pointing-Pointer Sputtering conditions were optimized by structural and electrochemical analysis. Black-Right-Pointing-Pointer Li[Li{sub 0.2}Mn{sub 0.56}Ni{sub 0.13}Co{sub 0.13}]O{sub 2} thin film shows a high capacity, 62 {mu}Ah/cm{sup 2} {mu}m. Black-Right-Pointing-Pointer The thin film shows an excellent cycling stability up to 200 cycles.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Investigations of the crystallization mechanism of CrSb and CrSb{sub 2} multilayered films using in-situ X-ray diffraction and in-situ X-ray reflectometry

Chromium and antimony multilayered films with variable elemental layer thickness were deposited on (1 0 0)-Si substrate cooled with liquid nitrogen. The stoichiometry of the films was adjusted to Cr:Sb=1:1 and 1:2. The thickness of Cr-Sb repeating units of these multifilms was varied between 11.4 and 102.5 A. Satellite maxima in the X-ray reflectivity curves observed for films in the as-deposited state demonstrate an alternating stacking of the evaporated elements. The reactivity of the superlattice reactants was investigated with temperature dependent in-situ X-ray diffractometry and X-ray reflectometry. The crystallization temperature of CrSb depends on the double-layer thickness and is about 90 Degree-Sign C for a Cr:Sb ratio of 1:1 and double-layer thickness of 53.7 A where nucleation and crystal formation occurs at the element interfaces, while for a thin double-layer thickness (11.4 A) first interdiffusion of the elements occurs before crystallization starts, i.e., an amorphous intermediate is formed prior to crystallization of CrSb. A decomposition reaction into CrSb{sub 2} occurs at about 230 Degree-Sign C, and up to about 575 Degree-Sign C, CrSb, CrSb{sub 2} and amorphous Cr coexist. For the ratio Cr:Sb=1:2 and a thin double-layer thickness prior to crystallization of CrSb{sub 2} nano-sized crystallites with a composition near CrSb{sub 2} nucleate and grow. These crystallites are then successively transformed in long-range ordered crystals exhibiting a pronounced preferred orientation. For films with a thicker repeat unit first formation of CrSb is observed which then reacts with elemental Sb yielding crystalline CrSb{sub 2}. An activation energy for interdiffusion of Cr and Sb of about 1.8 eV is estimated for a film with Cr:Sb=1:1 exhibiting a double-layer thickness of about 53.7 A and an energy for crystal growth of about 1.1 eV. For the film with the thinner double-layer thickness of 11.4 A a lower value of the activation energy for interdiffusion is obtained. For CrSb{sub 2} the energy for crystal growth is about 3.0 eV being significantly larger than for CrSb. Specific resistivity and Hall coefficient measurements were performed for crystalline CrSb and CrSb{sub 2} films. The temperature-dependent resistivity measurement exhibits a metallic behavior for CrSb and semi-conducting properties for CrSb{sub 2}. - Graphical abstract: The compound CrSb{sub 2} crystallizes from the amorphous state via intermediate formation of CrSb. Highlights: Black-Right-Pointing-Pointer CrSb and CrSb{sub 2} crystallize at very low temperatures in multilayered films. Black-Right-Pointing-Pointer Film thickness determines crystallization at interfaces or from amorphous intermediate. Black-Right-Pointing-Pointer Prior to crystallization of CrSb{sub 2}, highly textured CrSb crystallizes first. Black-Right-Pointing-Pointer Depending on the film thickness CrSb{sub 2} exhibits different preferred orientations.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Bismuth(III) dialkyldithiophosphates: Facile single source precursors for the preparation of bismuth sulfide nanorods and bismuth phosphate thin films

Two different phase pure materials (Bi{sub 2}S{sub 3} and Bi{sub 2}P{sub 4}O{sub 13}) have been prepared under different conditions using the same single source precursors. Solvothermal decomposition of the complexes, Bi(S{sub 2}P(OR){sub 2}){sub 3} [where, R=Methyl (Me) (1), Ethyl (Et) (2), n-Propyl (Pr{sup n}) (3) and iso-Propyl (Pr{sup i}) (4)] in ethylene glycol gave orthorhombic bismuth sulfide nanorods, whereas aerosol assisted chemical vapor deposition (AACVD) of the same precursors deposited monoclinic bismuth tetraphosphate (Bi{sub 2}P{sub 4}O{sub 13}) thin films on glass substrates. Surface study of the thin films using SEM illustrated the formation of variety of nanoscale morphologies (spherical-, wire-, pendent-, doughnut- and flower-like) at different temperatures. AFM studies were carried out to evaluate quality of the films in terms of uniformity and roughness. Thin films of average roughness as low as 1.4 nm were deposited using these precursors. Photoluminescence studies of Bi{sub 2}P{sub 4}O{sub 13} thin films were also carried out. - Graphical abstract: Solvothermal decomposition of bismuth(III) dialkyldithiophosphates in ethylene glycol gave Bi{sub 2}S{sub 3} nanoparticles, whereas aerosol assisted chemical vapor deposition of these single source precursors deposited Bi{sub 2}P{sub 4}O{sub 13} thin films. Display Omitted - Highlights: • Preparation of phase pure orthorhombic Bi{sub 2}S{sub 3} nanorods and monoclinic Bi{sub 2}P{sub 4}O{sub 13} thin films. • Use of single source precursors for deposition of bismuth phosphate thin films. • Use of solvothermal decomposition and AACVD methods. • Morphology controlled synthesis of Bi{sub 2}P{sub 4}O{sub 13} thin films. • Bi{sub 2}S{sub 3} nanorods and Bi{sub 2}P{sub 4}O{sub 13} thin films using same single source precursors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Homoepitaxy of ZnO and MgZnO Films at 90 °C

The aqueous synthesis of uniform single crystalline homoepitaxial zinc oxide, ZnO, and magnesium zinc oxide, Mg{sub x}Zn{sub 1−x}O, films under very low temperature conditions at T=90 °C and ambient pressure has been explored. A maximum Mg content of 1 mol% was recorded by energy dispersive spectroscopy. The growth on the polar (0 0 0 1) and (0 0 0 1¯) faces resulted in films that are strongly different in their structural and optical quality as evidenced by high-resolution X-ray diffraction, secondary electron microscopy, and photoluminescence. This is a result of the chemistry and temperature of the solution dictating the stability range of growth-governing metastable species. The use of trisodium citrate, Na{sub 3}C{sub 6}H{sub 5}O{sub 7}, yielded coalesced, mirror-like homoepitaxial films whereas adding magnesium nitrate hexahydrate, Mg(NO{sub 3}){sub 2}·6H{sub 2}O, favors the growth of films with pronounced faceting. - Graphical abstract: Homoepitaxial ZnO films grown from aqueous solution below boiling point of water on a ZnO substrate with off-orientation reveal parallel grooves that are characterized by (1 0 1{sup ¯} 1) facets. Adding trisodium citrate yields closed, single-crystalline ZnO films, which can further be functionalized. Alloying with MgO yields MgZnO films with low Mg content only. - Highlights: • A simple method to synthesize uniform single crystalline homoepitaxial ZnO and MgZnO films. • ZnO growth on (0 0 0 1) and (0 0 0 1{sup ¯}) face resulted in films that are strongly different in their structural and optical quality. • Single crystalline MgZnO film was fabricated under mild conditions (90 °C and ambient pressure). • Mg incorporation of nearly 1 mol% was obtained while maintaining single phase wurtzite structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Aqueous phase deposition of dense tin oxide films with nano-structured surfaces

Dense tin oxide films were successfully fabricated in an aqueous solution. The pH of the solutions was controlled to pH 1.3 by addition of HCl. Precise control of solution condition and crystal growth allowed us to obtain dense tin oxide films. Concave–convex surface of fluorine-doped tin oxide (FTO) substrates was entirely-covered with the continuous films. The films were about 65 nm in thickness and had nano-structured surfaces. Morphology of the films was strikingly different from our previous reported nano-sheet assembled structures. The films were not removed from the substrates by strong water flow or air blow to show strong adhesion strength. The aqueous solution process can be applied to surface coating of various materials such as nano/micro-structured surfaces, particles, fibers, polymers, metals or biomaterials. - Graphical abstract: Dense tin oxide films of 65 nm were successfully fabricated in an aqueous solution. They had nano-structured surfaces. Concave-convex substrates were entirely-covered with the continuous films. - Highlights: • Dense tin oxide films of 65 nm were successfully fabricated in an aqueous solution. • They had nano-structured surfaces. • Concave–convex substrates were entirely-covered with the continuous films.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Fabrication of graphene/polyaniline composite multilayer films by electrostatic layer-by-layer assembly

A novel graphene/polyaniline composite multilayer film was fabricated by electrostatic interactions induced layer-by-layer self-assembly technique, using water dispersible and negatively charged chemically converted graphene (CCG) and positively charged polyaniline (PANI) as building blocks. CCG was achieved through partly reduced graphene oxide, which remained carboxyl group on its surface. The remaining carboxyl groups not only retain the dispersibility of CCG, but also allow the growth of the multilayer films via electrostatic interactions between graphene and PANI. The structure and morphology of the obtained CCG/PANI multilayer film are characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Ultraviolet–visible absorption spectrum (UV–vis), scanning electron microscopy (SEM), Raman spectroscopy and X-Ray Diffraction (XRD). The electrochemical properties of the resulting film are studied using cyclic voltammetry (CV), which showed that the resulting CCG/PANI multilayer film kept electroactivity in neutral solution and showed outstanding cyclic stability up to 100 cycles. Furthermore, the composite film exhibited good electrocatalytic ability toward ascorbic acid (AA) with a linear response from 1×10{sup −4} to 1.2×10{sup −3} M with the detect limit of 5×10{sup −6} M. This study provides a facile and effective strategy to fabricate graphene/PANI nanocomposite film with good electrochemical property, which may find potential applications in electronic devices such as electrochemical sensor. - Graphical abstract: A novel graphene/polyaniline (CCG/PANI) film was prepared by layer-by-layer assembly. - Highlights: • A novel graphene/polyaniline (CCG/PANI) film was prepared by layer-by-layer assembly. • The water dispersible and negatively charged graphene (CCG) was used as building block. • CCG was achieved through partly reduced graphene oxide with carboxyl group on its surface. • CCG/PANI film kept electroactivity in neutral solution and showed good stability. • Good electrocatalytic ability toward ascorbic acid was also demonstrated.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

A compositional gradient Ce1−xZrxO2 buffer architecture for producing high-performance YBCO film

Highlights: • The compositional gradient CZO buffer architecture can help improve the biaxial texture of YBCO film. • The high density stacking faults are directly observed via a spherical aberration corrected transmission electron microscope. • The enhanced flux pinning force and current-carrying capacity of YBCO films are achieved as a result of lattice strains. - Abstract: In this work, YBCO films were epitaxially grown on Ce{sub 1−x}Zr{sub x}O{sub 2} (CZO) buffered yttria stabilized zirconia (YSZ) single crystal substrates through a fluorine-free sol-gel process. The influence of two different CZO buffer architectures on the microstructure and superconducting properties of YBCO films was investigated. According to XRD results in combination with (S)TEM analysis, it was confirmed that YBCO film grown on the gradient CZO buffer layer (CZO-G) exhibits better in-plane and out-of-plane texture than YBCO film deposited on the uniform CZO buffer layer (CZO-20). And besides, the superconducting performances especially the current-carrying capacity under magnetic field of the former was much higher than that of the latter, which means that the enhanced flux pinning force will be presented in YBCO film on CZO-G buffer layer. The maximum pinning force of the YBCO film grown on CZO-G buffer architecture is up to 17.67 GN/m{sup 3} @ 65 K. HR-STEM analysis shows that the stacking faults within YBCO matrix gave rise to the considerable nanoscale lattice-strains which may suppress the formation of Copper pairs and produce nanoscale non-superconducting regions served as pinning centers to significantly improve the flux pinning performance of YBCO film. Given the above, it has been implied that high-performance YBCO coated conductor can be developed by using a compositional gradient Ce{sub 1−x}Zr{sub x}O{sub 2} films as buffer architecture.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2012

Preparation of nanocrystalline PbS thin films and effect of Sn doping and annealing on their structural and optical properties

Highlights: Black-Right-Pointing-Pointer We deposited nanocrystalline PbS thin films by chemical bath deposition technique. Black-Right-Pointing-Pointer We examined the effect of Sn doping and annealing on their structural and optical properties. Black-Right-Pointing-Pointer The crystallite size increases with increasing doping concentration in pure PbS. Black-Right-Pointing-Pointer The band gap of pure PbS was 1.8 eV which is higher than bulk PbS. Black-Right-Pointing-Pointer Band gap reduces with increasing doping concentration in pure PbS. -- Abstract: Nanocrystalline PbS and Sn doped PbS thin films were successfully deposited on suitably cleaned glass substrate at constant room temperature, using the chemical bath deposition technique. Before, adding Sn doping content, the pure PbS thin films were deposited at room temperature for several dipping times to optimize the deposition time. After deposition, the films were also annealed at 400 Degree-Sign C for 1 h in air. The crystal structures of the films were determined by X-ray diffraction studies. The films were adherent to the substrate and well crystallized according to cubic structure with the preferential orientation (2 0 0). The crystallite size of the pure PbS thin films at optimized deposition time 30 min was found to be 40.4 nm, which increased with Sn content in pure PbS thin film. The surface roughness was measured by AFM studies. The band gaps of the films were determined by transmission spectra. Experiments showed that the growth parameters, doping and annealing, influenced the crystal structure, and optical properties of the films.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Bi-substituted iron garnet films for one-dimensional magneto-photonic crystals: Synthesis and properties

Graphical abstract: Faraday hysteresis loops for Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12} film on glass-ceramic substrate (a), Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} film on gallium–gadolinium garnet (b) and for glass-ceramic/SiO{sub 2}/Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12}/Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12} structure (c). Highlights: ► Bismuth-substituted iron garnet films as magneto-optical layers in magneto-photonic crystals. ► It is impossible to crystallize the films with high Bi content on amorphous substrates. ► The crystallization of the films can be achieved by their deposition on buffer layer with low bismuth content. -- Abstract: The crystallization processes in Bi{sub 2.8}Y{sub 0.2}Fe{sub 5}O{sub 12}, Bi{sub 2.5}Gd{sub 0.5}Fe{sub 3.8}Al{sub 1.2}O{sub 12}, Bi{sub 1.5}Gd{sub 1.5}Fe{sub 4.5}Al{sub 0.5}O{sub 12} and Bi{sub 1.0}Y{sub 0.5}Gd{sub 1.5}Fe{sub 4.2}Al{sub 0.8}O{sub 12} garnet films deposited by reactive ion beam sputtering on (1 1 1) gadolinium–gallium garnet substrates, optical glass-ceramic and SiO{sub 2} films have been studied. Films were annealed at low pressure in oxygen atmosphere and in the air. The possibility of preparation of crystalline garnet films with high concentration of bismuth on the SiO{sub 2} films using a buffer layer with low concentration of Bi has been shown. This allows to produce one-dimensional magneto-photonic crystals with high effective Faraday rotation (several tens of°/μm for the visible optical spectrum).

36 MATERIALS SCIENCE↗
DOE OSTI2012

Preparation of reduced graphene oxide/gelatin composite films with reinforced mechanical strength

Highlights: ► We used and compared different proportion of gelatin and chitosan as reducing agents. ► The mechanical properties of the films are investigated, especially the wet films. ► The cell toxicity of the composite films as biomaterial is carried out. ► The water absorption capabilities of the composite films also studied. -- Abstract: Graphene oxide (GO) was reduced by chitosan/gelatin solution and added to gelatin (Gel) to fabricate reduced graphene oxide/gelatin (RGO/Gel) films by a solvent-casting method using genipin as cross-linking agent. The structure and properties of the films were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and UV–vis spectroscopy. The addition of RGO increased the tensile strength of the RGO/Gel films in both dry and wet states, but decreased their elongation at break. The incorperation of RGO also decreased the swelling ability of the films in water. Cell cultures were carried out in order to test the cytotoxicity of the films. The cells grew and reproduced well on the RGO/Gel films, indicating that the addition of RGO has no negative effect on the compatibility of the gelatin. Therefore, the reduced graphene oxide/gelatin composite is a promising biomaterial with excellent mechanical properties and good cell compatibility.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Structural and optical studies of chemically deposited Sn{sub 2}S{sub 3} thin films

Highlights: ► Sn{sub 2}S{sub 3} films were deposited at 30 °C by chemical bath deposition. ► The deposition time of the chemical bath was adjusted to 20 h, 22 h, and 24 h. ► Effect of deposition time on structural and optical properties of Sn{sub 2}S{sub 3} thin films were investigated. ► The presence of characteristic bonds of Sn{sub 2}S{sub 3} was observed from Raman shift experiment. ► The direct band gap of thin films constant were calculated. -- Abstract: Sn{sub 2}S{sub 3} thin films were grown on commercial glass substrates by chemical bath deposition at room temperature. The structural and optical properties of Sn{sub 2}S{sub 3} thin films were studied as a function of deposition time. The thin films were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and UV–vis spectroscopy. The XRD pattern showed that the Sn{sub 2}S{sub 3} thin films had an orthorhombic polycrystalline structure. The lattice constants of the thin films were a = 8.741 Å, b = 14.034 Å and c = 3.728 Å. The characteristic bonds of Sn{sub 2}S{sub 3} were observed at 66.3, 111.7, 224.7 and 308.9 cm{sup −1} using Raman shift experiment. The optical energy band gap of the thin films decreased from 2.12 eV to 2.03 eV with increasing deposition time from 20 to 24 h. The optical constants of the thin films were obtained using the experimentally recorded transmission data as a function of the wavelength.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Preparation and optical properties of Zn{sub 0.85}Sb{sub 0.1}O alloy films

Graphical abstract: Top SEM image (a) and SAED pattern (b) of ZnSbO film grown on Si(1 1 1) substrate at 600 °C. Highlights: ► We discuss the deposition of ZnSbO thin films by pulsed laser deposition (PLD). ► The films showed a high resistivity of ∼10{sup 4} Ω cm, suggesting the efficient compensation of intrinsic donor-like defects. ► The ternary Zn{sub 0.9}Sb{sub 0.1}O film show a reduction in the band gap of ∼ 40 meV with reference to undoped ZnO films. - Abstract: Zn{sub 0.85}Sb{sub 0.1}O films were synthesized by pulsed laser deposition (PLD). The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) measurements were carried out to evaluate the microstructure of the films. These films exhibited a single-phase hexagonal structure with (0 0 2) preferred orientation, despite the high Sb content of ∼10% and the resulting large lattice distortion in the films. Moreover, the films showed semiconductor properties with high resistivity of ∼10{sup 4} Ω cm, which was possibly related to a compensation of intrinsic defects. Compared with the undoped ZnO, a reduction in the band gap by 40 meV was clearly observed in ultraviolet–visible absorption spectra.

36 MATERIALS SCIENCE↗
DOE OSTI2014

A comparative study of physico-chemical properties of CBD and SILAR grown ZnO thin films

Graphical abstract: Schematic model indicating ZnO nanorods by CBD (Z{sub 1}) and nanograins by SILAR (Z{sub 2}). - Highlights: • Simple methods for the synthesis of ZnO thin films. • Comparative study of physico-chemical properties of ZnO thin films prepared by CBD and SILAR methods. • CBD outperforms SILAR method. - Abstract: In the present work, nanocrystalline zinc oxide (ZnO) thin films have been successfully deposited onto glass substrates by simple and economical chemical bath deposition (CBD) and successive ionic layer adsorption reaction (SILAR) methods. These films were further characterized for their structural, optical, surface morphological and wettability properties. The X-ray diffraction (XRD) patterns for both CBD and SILAR deposited ZnO thin films reveal the highly crystalline hexagonal wurtzite structure. From optical studies, band gaps obtained are 2.9 and 3.0 eV for CBD and SILAR deposited thin films, respectively. The scanning electron microscope (SEM) patterns show growth of well defined randomly oriented nanorods and nanograins on the CBD and SILAR deposited samples, respectively. The resistivity of CBD deposited films (10{sup 2} Ω cm) is lower than that of SILAR deposited films (10{sup 5} Ω cm). Surface wettability studies show hydrophobic nature for both films. From the above results it can be concluded that CBD grown ZnO thin films show better properties as compared to SILAR method.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Directly patternable SnO{sub 2} thin films incorporating Pt nanoparticles

Highlights: • Direct-patterning of SnO{sub 2} films incorporated with Pt nanoparticles. • Pt incorporated SnO{sub 2} thin films by using photochemical solution deposition. • Reduction catalytic behavior of Pt nanoparticles. • Progress reduction of SnO{sub 2} with increasing amount of Pt nanoparticles. • Enhanced electrical conductivity of SnO{sub 2} films with Pt nanoparticles incorporation. - Abstract: Direct-patterning of SnO{sub 2} films incorporating Pt nanoparticles was performed by using a photochemical solution deposition without a photoresist or dry etching. Incorporating Pt nanoparticles into these films had a slight effect on their crystallinity and almost no effect on their transmittance. The inclusion of Pt nanoparticles enhanced the electrical conductivity of the SnO{sub 2} thin films compared to their pristine forms. The chemical bonding state of the films was analyzed by X-ray photoelectron spectroscopy to investigate the effect of the Pt nanoparticles on the carrier concentration in the film. It was concluded that the reduction of SnO{sub 2} thin films by Pt nanoparticles progressed as a result of the presence of the Pt nanoparticles, causing an oxygen deficiency to develop in SnO{sub 2} and thereby influencing the carrier concentration of the film.

36 MATERIALS SCIENCE↗