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By electron-beam (e-beam) melting, we prepared 0.4 wt% carbon-infused copper (CuCv4), and a copper control without carbon addition (CuCvO). Scanning electron microscopy and helium ion microscopy (HIM) were performed on the as-solidified surface, fracture surface, and ion-polished surface of the CuCv4 sample. The results revealed that graphitic carbon flakes cover the as-solidified surface, and carbon nanoparticles and clusters exist in the fracture and ion-polished surfaces. HIM on the ion-polished surface revealed a unique ripple-shaped feature, which is possibly associated with the infusion of carbon nanoribbons in the copper matrix. The bulk densities were measured to be 8.86 and 8.53 g/cm3, which correspond to relative densities of 98.9% and 96.4% for the CuCvO and CuCv4 samples, respectively. In addition, apparent electrical conductivities were measured to be 56.9 and 57.5 MS/m, respectively, for the e-beam melted CuCvO and CuCv4 samples. These values correspond to true electrical conductivities of 100.5% IACS (International Annealed Copper Standard) and 107.4% IACS after correction for the porosity. Our results reveal remarkable promise of using covetic copper for the next generation conductors in energy applications from microelectronic devices to high-power transmission cables.

A novel cermet (ceramic/metal composite) hydrogen transport membrane (HTM) was characterized for its physical and mechanical properties at both room temperature and at elevated temperature of 850 °C. The density of the HTM cermet was measured as 8.9 g/cm3 at ambient temperature with dynamic Young’s modulus of 145.5 GPa and the dynamic shear modulus (G-value) of 54.29 GPa, whereas the Poisson’s ratio (υ) is calculated to be 0.34. Vickers hardness numbers for the as-received HTM cermet are constant and in the range of 2.0–2.2 GPa, with the change of loading force from 100 to 1000 g. The flexural strength (σ fs) of the HTM cermet is about 356 MPa at room temperature and decreases to 284 MPa at the elevated temperature of 850 °C in both air and nitrogen. A difference in testing atmosphere (air or N2) had insignificant effect on the load–displacement curves during the flexural strength test at the elevated temperature of 850 °C. From the load–displacement curves, HTM cermet behaves much more like elastic material at room temperature; with the temperature increased to 850 °C, its behaviour is much more like a metallic material with fractures preceded by plastic deformation. The initial yielding strength of HTM could be mainly controlled by the yield strength of the soft Pd metal material, and the zirconia fractures before yielding in Pd at room temperature, whereas at 850 °C, the yield stress of the Pd drops dramatically and allows it to work and harden in the constraint of a rigid ceramic. The final failure load is mainly dictated by ceramic fracture, while the initial yielding stress is determined on the yield strength of the soft Pd metal at both room temperature and the elevated temperature of 850 °C.

Mixed ionic and electronic conductors are being explored for use as oxygen transport membrane (OTM) materials. An OTM material, BaFe 0.9 Zr 0.1 O 3− δ (BFZ), was fabricated by conventional solid-state synthesis, and its oxygen permeation flux was measured from 600 to 900 °C. The BFZ is attractive for producing hydrogen because it is a cobalt-free material (resulting in low cost for fabrication) and has high oxygen permeation flux. The oxygen flux through a ≈0.45-mm-thick BFZ membrane exposed to flowing air and helium is ≈2.1 mL min −1 cm −2 at 900 °C, and the activation energy for oxygen transport is 0.43 eV. With the results of the oxygen flux and the electrical conductivity for BFZ, its high oxygen permeability was explained. To show its potential application, the BFZ was tested in coal-gas-assisted water-splitting and ethanol (EtOH) reforming experiments. The hydrogen production rate of a 1.05-mm-thick BFZ tube was comparable to that of a much thinner (≈30 μm) La 0.7 Sr 0.3 Cu 0.2 Fe 0.8 O 3− δ thin-film tube. The EtOH reforming results also indicated significantly better performance of a BFZ disk compared with that of a Ba 0.5 Sr 0.5 Cu 0.2 Fe 0.8 O 3− δ /40 vol.% Ag disk. In addition, the crystal structure and the microstructural behavior of BFZ fabricated in different conditions are discussed.

The purpose of this CRADA is to develop a fabrication process to reduce the manufacturing cost for a very compact, high temperature, film-on-foil high energy-density PLZT (Pb-La-Zr- Ti-O) capacitor. Motivation for this CRADA is derived from the DOE’s Office of Vehicle Technologies (OVT) program, which seeks to advance technologies to improve vehicle fuel efficiency in the mid-term and facilitate the transition to electric drive vehicles over the longterm. The objective of Argonne’s work is to develop and characterize high-performance capacitors on base-metal foils. The PLZT film-on-foil prepared using a spin-coating technique

Palladium films were fabricated by a novel colloidal spray deposition method. Dense, crack-free Pd films with thickness of 5–11 μm were successfully fabricated on porous yttria-stabilized zirconia (YSZ) substrates having pore size of 3–7 μm. Scanning electron microscopy showed that the film has uniform thickness and is well bonded to the substrate. The surface of the Pd film is composed of well-crystallized plate-like grains with diameter of 2–4 μm and has a rough texture. The X-ray diffraction pattern of the as-sintered Pd film indicates (111) preferred crystal orientation. The hydrogen permeation properties of the films were investigated at temperatures of 330–530 °C using 90% H 2 /balance He and N 2 as feed and sweep gases, respectively. The hydrogen permeation of the supported Pd films with thickness of 5–11 μm was limited by both the diffusion of hydrogen through the metal bulk and the gas-phase transport through the support. The resistance of the gas-phase transport through the substrate was lowered significantly by reducing the thickness of the substrate.

Cobalt-free oxygen transport membranes (OTMs), Ba 0.5 Sr 0.5 Cu 0.2 Fe 0.8 O 3−δ (BSCF) and its composites, Ba 0.5 Sr 0.5 Cu 0.2 Fe 0.8 O 3−δ /Ag (BSCF/Ag), were fabricated by conventional solid state synthesis, and their oxygen transport properties were evaluated. The metal (Ag) content in the composite was 10–40 vol.%. Based on oxygen-permeation results, BSCF/40 vol.% Ag with Rh catalyst was selected for testing its ability to supply high-purity oxygen (from air) for ethanol reforming. It was found that the composite played an important role in producing hydrogen from ethanol reforming at 600 °C. The composite with catalyst shifted ethanol conversion toward production of hydrogen and away from production of other products, i.e., using a catalyst increased the selectivity for hydrogen in the reformate. The crystal structure, thermal expansion, coke formation, and the microstructural behavior of the OTMs are discussed.

Ferroelectric film-on-foil capacitors are suitable to replace discrete passive components in the quest to develop electronic devices that show superior performance and are smaller in size. The film-on-foil approach is the most viable method to fabricate such components. Films of Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) were deposited on SrRuO3 (SRO) buffer films over nickel and silicon substrates. High-quality polycrystalline SRO thinfilm electrodes were first deposited by chemical solution deposition. The optimized crystallization temperature of the SRO films was determined by studying the phase, microstructure, and electrical properties. A phase pure, dense, uniform microstructure with grain size < 100 nm was obtained in films crystallized between 700 and 750°C. The room-temperature resistivity of the SRO films crystallized at 700°C was ~800–900 μΩ-cm. The dielectric properties of sol-gel derived PLZT capacitors on SRO-buffered nickel were evaluated as a function of temperature, bias field, and frequency, and the results were compared to those of the same films on silicon substrates. The comparison demonstrated the integrity of the buffer layer and its compatibility with nickel substrates. Device-quality dielectric properties were measured on PLZT films deposited on SRObuffered nickel foils and found to be comparable to those for PLZT on SRO-buffered silicon and expensive platinized silicon. These results suggest that SRO films can act as an effective barrier layer on nickel substrates suitable for embedded capacitor applications.

We have grown ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) films on platinized silicon and LaNiO3-buffered nickel substrates by chemical solution deposition using a sol–gel process based on acetic acid chemistry. The following measurements were obtained under zero-bias field: relative permittivity of ≈960 and dielectric loss of ≈0.04 on the PLZT film grown on Pt/Si substrates, and relative permittivity of ≈820 and dielectric loss of ≈0.06 on the PLZT film grown on LNO-buffered Ni substrates. In addition, a relative permittivity of 125 and dielectric loss of 0.02 were measured at room temperature under a high bias field of 1 × 106 V/cm on PLZT deposited on LNO-buffered nickel substrate. Furthermore, a steady-state leakage current density of ≈8.1 × 10−9 A/cm2 and mean breakdown field strength of 1.7 × 106 V/cm were measured at room temperature. Finally, remanent polarization (Pr) of ≈2.0 × 10−5 C/cm2, coercive electric field (Ec) of ≈3.4 × 104 V/cm, and energy density of ≈45 J/cm3 were determined from room-temperature hysteresis loop measurements on PLZT/LNO/Ni film-on-foil capacitors with 250-μm-diameter platinum top electrodes.

A tubular oxygen transport membrane (OTM) was developed to produce hydrogen via water splitting using fossil sources. In this study, two OTM materials, La0.7Sr0.3Cu0.2Fe0.8O3−δ (LSCF) and BaFe0.9Zr0.1O3−δ (BFZ), were prepared by a conventional solid-state technique. In tests with an LSCF thin-film tube (thickness ≈30 μm) as an OTM, hydrogen was produced by flowing simulated product streams from coal gasification on one side of the OTM and steam on the other side. In this method, the coal gas on the oxygen-permeate side drives the removal of oxygen from the other hydrogen-generation side of the OTM, where hydrogen and oxygen are produced by water splitting. With CO (99.5% purity) flowing on the oxygen-permeate side, the hydrogen production rate of the LSCF tube was measured to be ≈19.6 cm3/min at 900 °C, indicating that hydrogen can be produced at a significant rate by using product streams from coal gasification. Concentration polarization effects were found to lower the hydrogen production rate of the LSCF thin-film tube at high temperatures. This process also yields a CO2-rich product stream that is ready for sequestration. The other candidate OTM material, BFZ, was tested by measuring its oxygen-permeation flux, DC conductivity, and hydrogen production, and by evaluating its microstructure. The dependences of the hydrogen production rate of BFZ disks (thickness, ≈1.6 mm) on water partial pressure and temperature were determined while flowing 80% CO2/He over a graphite rod on the oxygen-permeate side and humidified N2 on the hydrogen-generation side. Preliminary results indicate that BFZ is a promising OTM material.

Bulk relaxor ferroelectrics exhibit excellent permittivity compared to their thin film counterpart, although both show diffuse phase transition (DPT) behavior unlike normal ferroelectrics. To better understand the effect of dead layer and strain on the observed anomaly in the dielectric properties, we have developed relaxor PLZT (lead lanthanum zirconate titanate) thin films with different thicknesses and measured their dielectric properties as a function of temperature and frequency. The effect of dead layer on thin film permittivity has been found to be independent of temperature and frequency, and is governed by the Schottky barrier between the platinum electrode and PLZT. The total strain (thermal and intrinsic) in the film majorly determines the broadening, dielectric peak and temperature shift in the relaxor ferroelectric. The Curie-Weiss type law for relaxors has been further modified to incorporate these two effects to accurately predict the DPT behavior of thin film and bulk relaxor ferroelectrics. The dielectric behavior of thin film is predicted by using the bulk dielectric data from literature in the proposed equation, which agree well with the measured dielectric behavior.

A facile solution chemistry is demonstrated to fabricate high-quality polycrystalline strontium ruthenium oxide (SrRuO3) thin film electrodes on silicon substrates suppressing the formation of unde...

Oxygen transport membranes (OTMs) made of mixed ion-electron conductors can be used to increase the production of hydrogen from fossil and renewable sources. This study describes two methods for producing hydrogen with La{sub 0.7}Sr{sub 0.3}Cu{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (LSCF7328), an OTM material that is easily prepared, exhibits good mechanical properties, and is stable in severe gas conditions. In tests with thin-film (thickness {approx}22 {micro}m) LSCF7328 membranes, hydrogen was produced by flowing simulated product streams from CO{sub 2} gasification of coal on one side of the OTM and steam on the other side. In this method, the so-called coal gas on the oxygen-permeate side drives the removal of oxygen from the other side of the OTM, where hydrogen and oxygen are produced by water splitting. With CO (99.5% purity) flowing on the oxygen-permeate side, the hydrogen production rate was measured to be {approx}4.7 cm{sup 3}/min-cm{sup 2} at 900 C, indicating that hydrogen can be produced at a significant rate by using product streams from coal gasification. This process also yields a CO{sub 2}-rich product stream that is ready for sequestration. In another test, a tubular LSCF7328 was found to increase the hydrogen production from ethanol reforming by supplying high-purity oxygen frommore » air.« less

We have grown ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) films on Hastelloy C276 (HC) substrates by chemical solution deposition. Samples of 1.15-μm-thick PLZT films were prepared on HC with and without lanthanum nickel oxide (LNO) films as an intermediate buffer layer. On samples with and without LNO buffers at room temperature, we measured dielectric constants of ≈1,300 and ≈450 and loss tangents of ≈0.06 and ≈0.07, respectively. For PLZT films grown on HC with LNO buffer, the dielectric constant increases, while the dielectric loss decreases, with increasing temperature. A dielectric constant of ≈2,000 and loss of ≈0.05 were observed at 150 °C. Samples with LNO buffer also exhibited slimmer hysteresis loops and lower leakage current density when compared to samples without LNO buffer. The following results were measured on samples with and without LNO buffers: remanent polarization (Pr) values of 21.3 and 36.4 μC/cm2, coercive electric field (Ec) values of 41 and 173 kV/cm, and leakage current densities of ≈1.1 × 10−8 and ≈1.6 × 10−7 A/cm2, respectively. The energy storage capability was measured at ≈65 J/cm3 for the PLZT film-on-foil capacitor deposited on HC with LNO buffer.

We have deposited Pb{sub 0.92}La{sub 0.08}Zr{sub 0.52}Ti{sub 0.48}O{sub 3} (PLZT) films on nickel and copper substrates to create film-on-foil capacitors that exhibit excellent dielectric properties and superior breakdown strength. Measurements with PLZT films on LaNiO3-buffered Ni foils yielded the following: relative permittivity of 1300 (at 25 C) and 1800 (at 150 C), leakage current density of 6.6 x 10{sup -9} A/cm{sup 2} (at 25 C) and 1.4 x 10{sup -8} A/cm{sup 2} (at 150 C), and mean breakdown field strength {approx}2.5 MV/cm. With PLZT deposited directly on Cu foils, we observed dielectric constant {approx}1100, dielectric loss (tan {delta}) {approx}0.06, and leakage current density of 7.3 x 10{sup -9} A/cm{sup 2} when measured at room temperature.

Antiferroelectric (AFE) Pb0.92La0.08Zr0.95Ti0.05O3 (PLZT) films were grown on nickel foils with lanthanum nickel oxide buffer by chemical solution deposition. We observed field-induced AFE-to-ferroelectric (FE) phase transition. The electric field for the AFE-to-FE phase transition (EAF ≈ 270 kV/cm) and that for the reverse phase transition (EFA ≈ 230 kV/cm) were measured at room temperature on samples with PLZT films of ≈1-µm thickness. Relative permittivity of ≈560 and dielectric loss of 3 can be stored and recovered from the film-on-foil capacitors at 25 and 150 °C, respectively. Highly accelerated life tests were conducted. The projected mean time to failure is >5000 h when the capacitors are operated at room temperature with an applied field of ≈300 kV/cm.

We have deposited ferroelectric (FE) Pb{sub 0.92}La{sub 0.08}Zr{sub 0.52}Ti{sub 0.48}O{sub 3} (PLZT) films on nickel substrates by chemical solution deposition. Energy density of {approx} 46 J/cm{sup 3} has been measured with 1.15-{micro}m-thick PLZT/LNO/Ni film-on-foil capacitors. A series of highly accelerated lifetime tests were performed to determine the reliability of these FE film-on-foil capacitors under high temperature and high field stress. Samples were exposed to temperatures ranging from 100 to 150 C and electric fields ranging from 8.7 x 10{sup 5} V/cm to 1.3 x 10{sup 6} V/cm. The breakdown behavior of the FE PLZT film-on-foil capacitors was evaluated by Weibull analysis. The activation energy was determined to be {approx} 0.35 eV when an electric field of 1.05 x 10{sup 6} V/cm was applied. The voltage acceleration factor was {approx} -6.3 at 100 C. The mean time to failure was projected to be > 3000 h at 100 C with a dc electric field of {approx} 2.6 x 10{sup 5} V/cm.

Fabrication of high-dielectric-strength antiferroelectric (AFE) films on metallic foils is technically important for advanced power electronics. To that end, we have deposited crack-free Pb 0.92 La 0.08 Zr 0.95 Ti 0.05 O 3 (PLZT 8/95/5) films on nickel foils by chemical solution deposition. To eliminate the parasitic effect caused by the formation of a low-permittivity interfacial oxide, a conductive buffer layer of lanthanum nickel oxide (LNO) was coated by chemical solution deposition on the nickel foil before the deposition of PLZT. Use of the LNO buffer allowed high-quality film-on-foil capacitors to be processed in air. With the PLZT 8/95/5 deposited on LNO-buffered Ni foils, we observed field- and thermal-induced phase transformations of AFE to ferroelectric (FE). The AFE-to-FE phase transition field, E AF = 225 kV/cm, and the reverse phase transition field, E FA = 190 kV/cm, were measured at room temperature on a ≈1.15 μm-thick PLZT 8/95/5 film grown on LNO-buffered Ni foils. The relative permittivities of the AFE and FE states were ≈600 and ≈730, respectively, with dielectric loss ≈0.04 at room temperature. The Curie temperature was ≈210 °C. The thermal-induced transition of AFE-to-FE phase occurred at ≈175 °C. Breakdown field strength of 1.2 MV/cm was measured at room temperature.

Hydrogen production via water splitting at 900{degree sign}C has been studied with mixed-conducting SrFeCo0.5Ox (SFC2) membranes. The hydrogen production rate increased with decreasing membrane thickness, but surface reaction kinetics began to dominate the behavior of thin (

Oxygen transport membranes (OTMs) made of mixed oxygen ionelectron conductors can generate significant amounts of hydrogen and oxygen via water splitting at moderate temperatures (500- 900{degree sign}C). Hydrogen production by this method is nongalvanic, and the separated hydrogen is of high purity. This study focuses on results that were obtained with La0.7Sr0.3Cu0.2Fe0.8O3-δ (LSCF7328), one potential OTM material. This material is easily prepared, exhibits good mechanical properties, and is stable in severe gas conditions. In tests of LSCF7328 membranes, the measured hydrogen production rates varied linearly with temperature, indicating that the material undergoes no phase transition, while the thin-film LSCF7328 sample shows a slightly different slope change in the Arrhenius plot. Also determined were the effects of membrane thickness and a Pt-porous layer and the microstructure before and after the measurements. The highest hydrogen production rate, ≈11.4 cm3/min-cm2, was obtained with a ≈50 μmthick LSCF7328 membrane via water splitting at 900{degree sign}C. The effects of surface oxygen exchange kinetics and the importance of porous substrate materials are discussed.

The hydrogen separation properties and thickness dependence of the hydrogen flux for Ni-BCY membranes, containing a proton-conductor (BaCe 0.8 Y 0.2 O 3 − α , i.e., BCY) and an electron-conductor (Ni metal), were studied as a function of temperature in the thickness range of 0.08–1.16 mm. Feed gas was composed of 3.8% H 2 balanced with He (pH 2 O = 0.03 atm) gas and sweep gas contained 100 ppm hydrogen balanced with nitrogen. The hydrogen permeation flux due to ambipolar diffusion dominates over the entire experimental temperature range, but the hydrogen permeation flux through the Ni-metal increases with temperature due to its endothermic hydrogen solubility. The hydrogen flux through the Ni-BCY membranes is inversely proportional to the thickness, indicating that bulk diffusion is the rate limiting step down to a thickness of 80 µm. For thicker (> 640 µm) membranes, the flux decreases monotonically as the temperature increases up to 900 °C, whereas the flux for thinner (

Development of electronic devices with better performance and smaller size requires the passive components to be embedded within a printed wire board (PWB). The “film-on-foil” approach is the most viable method for embedding these components within a PWB. We have deposited high-permittivity ferroelectric lead lanthanum zirconate titanate (Pb0.92La0.08Zr0.52Ti0.48O x , PLZT 8/52/48) films on base metal foils by chemical solution deposition. These prefabricated capacitor sheets can be embedded into PWBs for power electronic applications. To eliminate the parasitic effect caused by the formation of a low-permittivity interfacial oxide, a conductive buffer layer of lanthanum nickel oxide (LNO) was applied by chemical solution deposition on nickel foil before the deposition of PLZT. With a ≈0.7-μm-thick ferroelectric PLZT film grown on LNO-buffered nickel foil, we measured capacitance densities of 1.5 μF/cm2, breakdown field strength E b >1.2 MV/cm, and leakage current density of 2 × 10–8A/cm2. The dielectric relaxation current decay obeys the Curie-von Schweidler law, with exponent n = 0.85 and 0.94 for PLZT grown directly on Ni and that grown on LNO-buffered Ni foils, respectively. When compared with samples deposited directly on Ni substrate, PLZT grown on LNO buffered Ni substrates exhibit slimmer hysteresis loop and better energy storage capability. With these desirable characters, PLZT film-on-foil capacitors hold particular promise for use in high-voltage embedded passives.

The effect of metal-to-oxide grain boundary layer in \( {\text{Ni}} - {\text{BaCe}}_{{0.8}} {\text{Y}}_{{0.2}} {\text{O}}_{{3 - \delta }} \) (BCY) cermet membrane on hydrogen permeation was studied by applying the different size of oxide grain on Ni-BCY membranes. Two types of cermet membranes having different grain size of oxide were prepared by using different starting particle size of oxide powder. The hydrogen flux of coarse-oxide-grain membrane showed higher flux than that of small-oxide-grain membrane. It was understood that the negative potential at metal-to-oxide grain boundary, reference to the bulk oxide (\( \phi _{0} < \phi _{\infty } = 0 \)), was developed, and the accumulation of the effectively positively charged protons may occur at the grain boundary layer (space charge layer), which may result in providing highly conductive proton path by shifting the charge neutrality condition from \( {\left[ {OH^{ \bullet }_{O} } \right]} = {\left[ {Y^{/}_{{Ce}} } \right]} \) to \( {\left[ {OH^{ \bullet }_{O} } \right]} = n \).

Biaxially textured YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) films were grown on inclined-substrate-deposited (ISD) MgO-textured metal substrates by pulsed laser deposition. CeO{sub 2} was deposited as a buffer layer prior to YBCO growth. CeO{sub 2} layers of different thickness were prepared to evaluate the thickness dependence of the YBCO films. The biaxial alignment features of the films were examined by X-ray diffraction 2{theta}-scans, pole-figure, {phi}-scans and rocking curves of {Omega} angles. The significant influence of the CeO{sub 2} thickness on the structure and properties of the YBCO films were demonstrated and the optimal thickness was found to be about 10 nm. High values of T{sub c} = 91 K and J{sub c} = 5.5 x 10{sup 5} A/cm{sup 2} were obtained on YBCO films with optimal CeO{sub 2} thickness at 77 K in zero field. The possible mechanisms responsible for the dependence of the structure and the properties of the YBCO films on the thickness of the CeO{sub 2} buffer layers are discussed.

Significant amounts of hydrogen or oxygen can be generated at moderate temperatures (500–900 °C) if a mixed-conducting (i.e., electron- and ion-conducting) membrane is used to remove either oxygen or hydrogen as it is generated. We demonstrated this in a previous study using cermet (i.e., ceramic–metal composite) membranes composed of an oxygen ion conductor, Gd-doped CeO 2 (CGO), and an electronic conductor, Ni. In the present study, we show several ways to increase the hydrogen production rate by water dissociation with mixed-conducting membranes. Producing CGO/Ni membranes with a finer microstructure enlarged the triple-phase-boundary area, and increased the hydrogen production rate to ≈ 10 cm 3 ( STP ) / min - cm 2 . Using a single-phase, mixed-conducting membranes [ SrFeCo 0.5 O x ( SFC 2 ) ] also produced higher hydrogen production rates, relative to dual-phase cermet membranes.

Bulk samples of a novel cermet (ceramic/metal composite) hydrogen transport membrane (HTM) were subjected to thermal cycling in the temperature range between 25-850°C to study phase transformations and microstructural changes under thermal shock. Scanning electron microscopy (SEM) and electron probe micro analyzer (EPMA) with energy dispersive spectroscopy (EDS) were used to characterize the microstructural and chemical changes in the membrane upon thermal cycling. SEM & EPMA analyses indicated that the temperature gradient during thermal cycling produced more micro-cracks inside the HTM disc, whereas, the chemical reaction between Pd and oxygen to form PdO disturbed the continuity of the metal palladium (Pd) - Yttria Stabilized Zirconia (YSZ) dual phases interconnection system from surface down. The agglomerates of un-crystallized YSZ grains found to be the inherent in the cracks of the as-received HTM. A combination of trans-granular and inter-granular crack propagation results around the YSZ grains and the new precipitates. Based on the electron fractography analyses by both SEM and EPMA, the micro voids coalescence develops ahead of the crack tips in the cross-section of the HTM after 500 thermal cycles.

Composite membranes consisting of Ni metal and Ba(Zr 0.1 Ce 0.7 Y 0.2 )O 3 (or Ni–BZCY7) have been developed for separation of hydrogen from gas mixtures to replace Ni–BCY20 (Ni–BaCe 0.8 Y 0.2 O 3 ), which has poor stability in CO 2 and H 2 O-containing atmosphere. Hydrogen fluxes through these cermet membranes were measured as a function of temperature, membrane thickness, and partial pressure of hydrogen in various atmospheres. Results indicated that the Ni–BZCY7 membrane is chemically stable and display high hydrogen permeability. A maximum flux of 0.805 cm 3 min −1 cm 2 was obtained for a dense cermet membrane of 266-μm-thick at 900 °C using 100% H 2 as the feed gas and 100 ppm H 2 /N 2 as the sweep gas. The stable performance of Ni–BZCY7 cermet membrane during exposure to a wet gas containing 30% CO 2 for about 80 h indicated that it is promising for practical applications.

Successful development of hydrogen separation membranes based on mixed ionic and electronic conductors may improve the economics of hydrogen production. While high proton conductivity has been reported for many perovskite-type oxides in a humid atmosphere, materials with both high proton conductivity and good chemical stability under conditions for practical hydrogen separation are yet to be developed. In this paper, we report the effect of Zr-doping in BZCYs [Ba(Zr0.8-xCexY0.2)O3-α] (0.4 ≤ x ≤ 0.8) on the proton conductivity and chemical stability. A novel Ni−BZCY7 [Ni−Ba(Zr0.1Ce0.7Y0.2)O3-α] cermet (metal−ceramic composite) membrane appears to have not only high proton conductivity but also adequate stability in a CO2- and H2O-containing atmosphere.

The effect of tensile bend strain on the critical current of YBa2Cu3O7−x (YBCO)-coated conductors was evaluated as a function of YBCO film thickness. The YBCO-coated conductors were fabricated on Hastelloy C276 metal substrates templated with MgO by inclined substrate deposition. It was observed that a conductor with 0.2 µm thick YBCO retained 90% of the unstrained critical current until a strain of ≈0.4%, whereas for a conductor with 0.5 µm thick YBCO film the critical strain value was ≈0.2%. At strains higher than the critical strain, the critical current dropped precipitously. The inverse dependence of bend strain tolerance on the YBCO film thickness is in reasonable agreement with analytical prediction. This inverse dependence was used to approximate the fracture toughness of the YBCO film, which was found to be in general agreement with the literature.

Long length textured MgO template on Hastelloy C276™ (HC) has been successfully deposited in a reel-to-reel (R2R) electron beam (e-beam) evaporation system by inclined substrate deposition (ISD). High deposition rate up to 10 nm s−1 with exposure length of 7 cm has been realized. The MgO template showed good in-plane texture of 9.5°–11.5° measured from the (002) phi scans. Experimental results reveal that MgO in-plane texture is formed by the preferred growth direction of normal and one of the MgO {200} planes rotates to the in-flux direction. A new expression, termed the 'two-thirds relationship', between the inclination angle α and the tilted angle of the (00l) plane from the substrate normal, β, has been summarized. YBa2Cu3O7−δ (YBCO) film deposited by pulsed laser deposition (PLD) on strontium ruthenate (SRO) buffered ISD MgO showed Tc of 91 K with transition width of 1 K. Critical current measurement indicated an Ic of 110 A cm−1 at 77 K in self-field for 0.68 µm YBCO film, corresponding to a Jc of 1.6 MA cm−2.

Inclined substrate deposition (ISD) is an effective method for the fast production of highly textured template films for YBa2Cu3Ox (YBCO) coated conductors (CCs). By electron-beam evaporation of MgO targets, we deposited biaxially textured ISD-MgO films with φ-scan full-width at half maximum (FWHM) of ≈10 ◦ on flat metallic tapes. Cube-on-cube epitaxial growth was demonstrated for YBCO grown on ISD-MgO buffered metallic tapes with an SrRuO3 buffer. A transport critical current density of Jc > 1.6 × 10 6 Ac m −2 was measured at 77 K in self-field on short-length flat-tape CCs produced with the ISD architecture. We have grown biaxially textured ISD-MgO template films on round wire surfaces. An in-plane FWHM of 18 ◦ wa sm easured on ISD-MgO deposited on cylindrical surfaces. CC wires with a low aspect ratio and, therefore, low AC losses, are highly desirable in order to facilitate cable winding without compromising the mechanical integrity or engineering current density of the CCs. This work discusses the prospects of using the ISD process to produce low aspect ratio round-wire CCs. (Some figures in this article are in colour only in the electronic version)

Non-perovskite SrFeCo0.5O x (SFC2) was found to have high electronic and ionic conductivities as well as structural stability. At 800°C in air, total and ionic conductivities of 17 and 7 S·cm−1 were measured, respectively; the ionic transference number was calculated to be ≈0.4. This material is unique because of its high electronic conductivity and comparable electronic and ionic transference numbers. X-ray diffraction analysis showed that air-sintered SFC2 consists of three phase components, ≈75 wt% % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX! % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX % garmWu51MyVXgatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wz % aebbnrfifHhDYfgasaacH8qrps0lbbf9q8WrFfeuY-Hhbbf9v8qqaq % Fr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qq % Q8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeWaeaaakeaaca % qGtbGaaeOCamaaBaaaleaacaaI0aaabeaakmaabmaabaGaaeOraiaa % bwgadaWgaaWcbaGaaGymaiabgkHiTiaadIhaaeqaaOGaae4qaiaab+ % gadaWgaaWcbaacbiGaa8hEaaqabaaakiaawIcacaGLPaaadaWgaaWc % baGaaGOnaaqabaGccaqGpbWaaSbaaSqaaiaaigdacaaIZaGaeyySae % lcciGae4hTdqgabeaaaaa!4A5B! $${\text{Sr}}_{4} {\left( {{\text{Fe}}_{{1 - x}} {\text{Co}}_{x} } \right)}_{6} {\text{O}}_{{13 \pm \delta }}$$ , ≈20 wt% perovskite % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX! % MathType!MTEF!2!1!+- % feaaeaart1ev0aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHX % garmWu51MyVXgatuuDJXwAK1uy0HwmaeHbfv3ySLgzG0uy0Hgip5wz % aebbnrfifHhDYfgasaacH8qrps0lbbf9q8WrFfeuY-Hhbbf9v8qqaq % Fr0xc9pk0xbba9q8WqFfea0-yr0RYxir-Jbba9q8aq0-yq-He9q8qq % Q8frFve9Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeWaeaaakeaaca % qGtbGaaeOCamaabmaabaGaaeOraiaabwgadaWgaaWcbaGaaGymaiab % gkHiTiaadIhaaeqaaOGaae4qaiaab+gadaWgaaWcbaacbiGaa8hEaa % qabaaakiaawIcacaGLPaaacaqGpbWaaSbaaSqaaiaaiodacqGHsisl % iiGacqGF0oazaeqaaaaa!46B5! $${\text{Sr}}{\left( {{\text{Fe}}_{{1 - x}} {\text{Co}}_{x} } \right)}{\text{O}}_{{3 - \delta }}$$ , and ≈5 wt% rock salt CoO. Argon-annealed SFC2 contains brownmillerite Sr2(Fe1−x Co x )2O5 and rock salt CoO. Dense SFC2 membranes were able to withstand large pO2 gradients and retain mechanical strength. A 2.9-mm-thick disk membrane was tested in a gas-tight electrochemical cell at 900°C; an oxygen permeation flux rate ≈2.5 cm3(STP)·cm−2·min−1 was measured. A dense thin-wall tubular membrane of 0.75-mm thickness was tested in a methane conversion reactor for over 1,000 h. At 950°C, the oxygen permeation flux rate was ≈10 cm3(STP)·cm−2·min−1 when the SFC2 thin-wall membrane was exposed with one side to air and the other side to 80% methane balanced with inert gas. Results from these two independent experiments agreed well. The SFC2 material is a good candidate as dense ceramic membranes for oxygen separation from air or for use in methane conversion reactors.

Argonne National Laboratory has established and implemented a coordinated set of characterization methods for coated-conductor specimens that can be applied in a manner compatible with further processing or utilization of the respective specimen. These characterization methods include measurements of superconductor transport properties, phase composition, microstructure, and epitaxy quality for YBCO-coated conductors that range in size up to multi-meters. Recent progress will be reported on the integrated application of Raman microscopy, magneto-optical imaging, and focused-ion-beam-assisted electron microscopy to a meter-length tape produced by SuperPower, Inc. This non-destructive, multifaceted characterization approach has allowed us to develop a seamless methodology for the interrogation of coated-conductor tapes during the course of sequential high-temperature treatments. The aim of this research effort is to identify performance-limiting defects, clarify their origin/cause, and prescribe methods to eliminate them during coated conductor manufacturing.

The hydrogen permeability of SrCe0.95Eu0.05O3−δ was studied as a function of temperature, hydrogen partial pressure (PH2) gradient, and water vapor partial pressure (PH2O) gradient. The effect of the microstructure on hydrogen permeability through a 1.72 mm thick membrane was investigated. The ambipolar conductivity calculated from hydrogen permeation fluxes showed the same PO2 and PH2 dependence as the electronic conductivity, for the experimental conditions. The small grained membrane showed higher hydrogen permeability when compared with the larger grained membrane over the entire temperature range investigated.

YBCO-coated conductors with high current-carrying capability are desirable for electric power transmission applications. Inclined-substrate deposition (ISD) is capable of producing high-quality biaxially textured template films, which are important for fabrication of YBCO-coated conductors. We have grown biaxially textured ISD-MgO template films on flexible metallic substrates at deposition rates of 2-10 nm/sec. Columnar grains with a roof-tile-shaped surface structure were observed on the ISD-MgO films. X-ray pole figure analysis revealed that the ISD-MgO film is biaxially textured and its c-axis is titled at an angle from the substrate normal. Strontium ruthenium oxide (SRO) buffer films were epitaxially grown on ISD-MgO by pulsed laser deposition prior to the deposition of YBCO. Low /spl phi/-scan full-width at half maximum (FWHM) values of 6/spl deg/ and 7/spl deg/ were observed for YBCO and SRO, respectively. T/sub c/ of 91 K with a sharp transition and transport J/sub c/ over 1.4 MA/cm/sup 2/ at 77 K in self-field were measured on YBCO coated conductors grown with ISD MgO architectures using a SRO buffer.

Thin films of BaCe 0.8 Y 0.2 O 3− δ (BCY) were prepared by a colloidal spray deposition method. Dense, crack-free BCY films with thickness of ≈10 μm and a grain size of 2–7 μm were successfully deposited on porous NiO/BCY substrates. Scanning electron microscopy showed that the films have uniform thickness and are well bonded to the substrate. The hydrogen pumping characteristics of the films were investigated at temperatures of 500–700 °C, and show that the hydrogen evolution rates agree very well with those expected by Faraday's law up to the current limit (2 A) of the galvanostat. A maximum current density of 2.1 A/cm 2 was measured at 700 °C with an applied voltage of 1 V.

Biaxially textured MgO thin films were grown by ion-beam-assisted deposition. The film growth parameters of film thickness, ion-to-atom arrival ratio (r-value), ion beam angle, and ion beam voltage were studied. Film characterization was performed by X-ray diffraction, pole figure analysis, and atomic force microscopy (AFM). Full-width half-maximum (FWHM) of MgO (220) ϕ-scans and MgO (002) ω-scans, respectively, were used to evaluate in-plane and out-of-plane film texture. MgO (220) ϕ-scan FWHM of 3.2° and MgO (002) ω-scan FWHM of 1.2° was achieved on amorphous Si3N4-coated Si substrates using a 1500-V ion source oriented at 45° to the substrate normal and an r-value of 0.90. Depositions on metallic substrates yielded MgO (220) ϕ-scan FWHM values of 5.2° and MgO (002) ω-scan FWHM of 2.5°. Root-mean-square surface roughness of these films as measured by AFM was ≈2.3 nm.

YBa2Cu3O7?? (YBCO) films were fabricated on SrRuO3 (SRO)-buffered MgO templates grown on Hastelloy C276 metallic substrates, on which the MgO layers had been deposited by inclined substrate deposition (ISD) using electron beam evaporation. YBCO and SRO films were deposited by pulsed laser deposition (PLD). ISD-MgO substrates fabricated with two different substrate inclination angles (? = 35? and 55?) were used to grow YBCO films. High transport critical current density, Jc = 1.4 ? 106?A?cm?2, has been measured at 77?K in self-field for YBCO film grown on ISD-MgO with ? = 35?, whereas YBCO film grown on ISD-MgO with ? = 55? had a lower Jc = 0.5 ? 106?A?cm?2. X-ray pole figure patterns revealed a cube-on-cube orientation relationship among YBCO, SRO, and ISD-MgO films, with the c-axis of the YBCO film being tilted. X-ray ? and -scans revealed good in-plane and out-of-plane textures of YBCO film grown on ISD-MgO substrate. The YBCO film grown on ISD-MgO with substrate inclination angle ? = 35? had a YBCO(005) -scan full width at half maximum (FWHM) = 5.8? and a YBCO(007) ?-scan FWHM = 2.8?, while YBCO film with ? = 55? had YBCO(005) -scan FWHM = 5.4? and YBCO(007) ?-scan FWHM = 2.6?.

Mixed-conducting Sr-Fe-Co oxides have potential applications in dense ceramic membranes for high-purity oxygen separation and/or methane conversion to produce syngas (CO + H2), because of their combined high electronic/ionic conductivity and significant oxygen permeability. SrFeCo0.5Oy has been synthesized by the solid-state reaction method. Conductivities were measured at elevated temperatures in various gas environments and increased as temperature and oxygen partial pressure (pO2) increased in the surrounding environment. Neutron powder diffraction experiments revealed that in a high pO2 environment the SrFeCo0.5Oy material consists of three different phases. The relative concentration of each component phase is dependent on temperature and pO2 in the surrounding environment. In air, Sr2(Fe, Co)3Oy (236-phase) is the majority phase and consists of >75 wt% of the total, whereas the perovskite and rocksalt phases account for ∼20 and

Inclined substrate deposition (ISD) is an attractive technique for rapid production of high-quality template layers for YBCO-coated conductors. We have grown biaxially textured magnesium oxide (MgO) films on metallic substrates by ISD at rapid deposition rates, 20–100 A s−1. Scanning electron microscopy of the ISD MgO films showed columnar grain structures with a roof-tile-shaped surface. X-ray diffraction pole figure analysis revealed that the ISD MgO film is biaxially aligned with the c-axis tilted from its substrate normal. Tilt angles of and were measured on ISD MgO films deposited at 55° and 35° inclination angles, respectively. A full width at half maximum (FWHM) of was observed in the -scan for short-length ISD MgO films. A 1 m long tape of ISD MgO grown on a metallic substrate was fabricated by a reel-to-reel method. This tape has an average -scan FWHM of 16.1° with a standard deviation of 2.6°. YBCO films were grown on strontium ruthenium oxide (SRO)-buffered ISD MgO substrates by pulsed laser deposition. A superconducting critical transition temperature Tc = 91 K and critical current density Jc = 1.1 × 106 A cm−2 were measured at 77 K in self-field for a sample that is 0.3 µm thick, 2.9 mm wide, and 1.0 cm long.

Several Ag–Cu alloys (0–0.25 at.% Cu) were studied as potential substrates for the direct pulsed laser deposition of YBCO without intermediate buffer layer. The microstructural characteristics of films and substrates were analyzed by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy, whereas the superconducting properties of the films were determined by inductive and transport methods. The properties of the YBCO films were significantly influenced by small concentrations of Cu in the substrate; YBCO films on a substrate with 0.2 at.% Cu exhibited the best superconducting properties.

Inclined substrate deposition (ISD) has great potential for rapid production of high-quality template layers for YBCO-coated conductors. We have grown biaxially textured magnesium oxide (MgO) films on metallic substrates by ISD at deposition rates, 20–100 A/s. Scanning electron microscopy of the ISD MgO films showed columnar grain structures with a roof-tile-shaped surface. X-ray diffraction and pole figure analysis revealed that the c -axis of the ISD MgO is tilted at an angle with respect to the substrate normal. A full width at half maximum (FWHM) of ≈10° was observed in the φ -scan for MgO films. Yttria-stabilized zirconia (YSZ) and ceria (CeO 2 ) buffer layers were epitaxially grown on ISD MgO by pulsed laser deposition (PLD) prior to YBCO deposition by PLD. The YBCO films grown on YSZ/CeO 2 buffered ISD MgO substrates were biaxially aligned with the YBCO c -axis normal to the substrate surface. A critical current density of J c >1.2×10 6 A/cm 2 was measured at 77 K in self-field.

The superconducting, crystalline, and morphological properties of YBCO films deposited on SrRuO3-buffered MgO substrates were studied at various deposition temperatures. The film deposited at T = 770 °C had the best superconducting properties (critical current density of 2.5 × 106 A cm−2 and critical transition temperature of 91 K). Scanning electron micrographs of this film revealed uniform and well-connected grains. X-ray analyses revealed that the Y BCO/SrRuO3/MgO film fabricated at 770 °C had good in-plane and out-of-plane textures. Raman spectroscopy showed that this film had the best out-of-plane texture and orthorhombic I domains.

The hydrogen permeability of SrCe0.95Eu0.05O3−δ and SrCe0.95Sm0.05O3−δ was studied as a function of temperature, hydrogen partial pressure (PH2) gradient, and water vapor partial pressure (PH2O) gradient. Under a 100% dry hydrogen condition at 1123 K, the hydrogen permeation rates of dense membranes (1.72 mm thick) are ≈3.19×10−9 mol/cm2 s for SrCe0.95Eu0.05O3−δ and 2.33×10−9 mol/cm2 s for SrCe0.95Sm0.05O3−δ. Under wet hydrogen conditions at 1123 K, the hydrogen permeation rates are ≈2.89×10−9 and 1.21×10−9 mol/cm2 s, respectively, for the same materials. The dopant dependence of hydrogen permeability is explained in terms of the ionization potential of the dopant. Electronic conductivity was calculated from hydrogen permeation fluxes; activation energies for electron conduction under both dry and wet conditions were also calculated. The PH2O dependence of electronic conductivity and hydrogen permeability is discussed.

Cermet (ceramic-metal composite) hydrogen separation membranes consisting of barium oxide, cerium oxide, yttrium oxide and palladium were characterized by utilizing X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). Characterization was performed at room temperature and 650 °C, and after exposure to hydrogen. Changes in both elemental composition and oxidation states were observed at elevated temperatures and as a function of time. Permeation of hydrogen through the membranes also changed with time and temperature.

Biaxially textured magnesium oxide (MgO) films used as template layers for YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO)-coated conductors have been grown efficiently and consistently by inclined substrate deposition (ISD). Further improvement in texture and a decrease in surface roughness were obtained by depositing a homoepitaxial MgO layer on the ISD MgO layer at an elevated temperature and flat angle. The texture of the ISD layer was studied as a function of thickness by X-ray diffraction and scanning and transmission electron microscopy. Surface roughness of the ISD and homoepitaxial layers was investigated by atomic force microscopy. Based on the results, the optimal thickness of the ISD layer was determined.

Inclined substrate deposition (ISD) has the potential for rapid production of high-quality biaxially textured buffer layers, which are important for YBCO-coated conductor applications. We have grown biaxially textured MgO films by ISD at deposition rates of 20 - 100 /spl Aring//sec. Columnar grains with a roof-tile surface structure were observed in the ISD-MgO films. X-ray pole figure analysis revealed that the [002] planes of the ISD-MgO films are tilted at an angle from the substrate normal. A small /spl phi/-scan full-width at half maximum (FWHM) of /spl ap/ 9/spl deg/ was observed on MgO films deposited at an inclination angle of 55/spl deg/. In-plane texture in the ISD MgO films developed in the first 0.5 /spl mu/m from the interface, then stabilized with further increases in film thickness. YBCO films deposited by pulsed laser deposition on ISD-MgO-buffered Hastelloy C276 substrates were biaxially aligned with the c-axis parallel to the substrate normal. T/sub c/ of 91 K with a sharp transition and transport J/sub c/ of 5.5 /spl times/ 10/sup 5/ A/cm/sup 2/ at 77 K in self-field were measured on a YBCO film that was 0.46-/spl mu/m thick, 4-mm wide, 10-mm long.