Rolling-assisted Biaxially Textured Substrates Research Articles

High in-field critical current densities in epitaxialNdBa2Cu3O7−δ films on RABiTS by pulsed laser deposition

We report the epitaxial growth and superconducting properties forNdBa2Cu3O7−δ (NdBCO) films grown on rolling-assisted, biaxially-textured substrates (RABiTS)by pulsed laser deposition. At the optimum deposition temperature of760 °C, the criticalcurrent densities, Jc, at 77 K, self-field, of NdBCO films ranging in thickness from 0.13 to0.25 µm were found tobe in the range 2.2–3.4 MA cm−2, with a lower thickness corresponding to a higherJc. Comparedto epitaxial YBa2Cu3O7−δ (YBCO) films, these NdBCO samples are found to have superior field and angular dependences ofJc. In an applied field of 1 T, NdBCO of the same thickness has more than twice theJc of YBCO films with a significantly enhancedJc peak for a fieldapplied parallel to the c-axis. These results suggest the presence of an increased density ofc-axis correlated pinning centres within NdBCO films compared to YBCO films.

Grain orientations and grain boundary networks of YBa2Cu3O7−δ films deposited by metalorganic and pulsed laser deposition on biaxially textured Ni–W substrates

We report a detailed study of the grain orientations and grain boundary (GB) networks in YBa2Cu3O7-δ (YBCO) films ∼0.8 μm thick grown by both the in situ pulsed laser deposition (PLD) process and the ex situ metalorganic deposition (MOD) process on rolling-assisted biaxially textured substrates (RABiTS). The PLD and MOD growth processes result in columnar and laminar YBCO grain structures, respectively. In the MOD-processed sample [full-width critical current density Jc(0 T, 77 K) = 3.4 MA/cm2], electron back-scatter diffraction (EBSD) revealed an improvement in both the in-plane and out-of-plane alignment of the YBCO relative to the template that resulted in a significant reduction of the total grain boundary misorientation angles. A YBCO grain structure observed above individual template grains was strongly correlated to larger out-of-plane tilts of the template grains. YBCO GBs meandered extensively about their corresponding template GBs and through the thickness of the film. In contrast, the PLD-processed film [full width Jc(0 T, 77 K) = 0.9 MA/cm2] exhibited nearly perfect epitaxy, replicating the template grain orientations. No GB meandering was observed in the PLD-processed film with EBSD. Direct transport measurement of the intra-grain Jc(0 T, 77 K) values of PLD and MOD-processed films on RABiTS revealed values up to 4.5 and 5.1 MA/cm2, respectively. As the intra-grain Jc values were similar, the significantly higher full-width Jc for the MOD-processed sample is believed to be due to the improved grain alignment and extensive GB meandering.

Mechanical properties of pure Ni and Ni-alloy substrate materials for Y–Ba–Cu–O coated superconductors

Mechanical properties of rolling-assisted, biaxially-textured substrates (RABiTS) and substrates for ion-beam assisted deposition (IBAD) coated superconductors are measured at room temperature, 76, and 4 K. Yield strength, Young’s modulus, and the proportional limit of elasticity are determined, tabulated and compared. Results obtained are intended to serve as a database of mechanical properties of substrates having the same anneal state and texture as those incorporated in the general class of RE–Ba–Cu–O coated conductor composites (RE = rare earth). The RABiTS materials measured are pure Ni, Ni–13at.%Cr, Ni–3at.%W–2at.%Fe, Ni–10at.%Cr–2at.%W, and Ni–5at.%W. The IBAD substrate materials included Inconel 625 and Hastelloy C-276. The Ni alloys are substantially stronger and show higher strains at the proportional limit than those of pure Ni. Substrates fully coated with buffer layers, ≈1 μm of Y–Ba–Cu–O, and 3–5 μm of Ag have similar mechanical properties (at 76 K) as the substrate alone. Somewhat surprisingly, plating an additional 30–40 μm of Cu stabilizer onto high-yield-strength (690 MPa) Hastelloy coated conductors ∼100 μm thick, reduces the overall yield strength of the composite structure by only about 10–12% at 76 K and 12–14% at room temperature; this indicates that the Cu layer, despite its relatively soft nature, contributes significantly to the overall strength of even high-strength coated conductors.

Processing Dependence of Texture, and Critical Properties of YBa2Cu3O7−δ Films on RABiTS Substrates by a Non‐Fluorine MOD Method

YBa2Cu3O7−δ (YBCO or Y123) films on rolling‐assisted biaxially textured substrates (RABiTS) were prepared via a fluorine‐free metallorganic deposition (MOD) through spin coating, burnout, and high temperature anneal. The effects of substrate texture and surface energy of the CeO2 cap layer were investigated. Except for the commonly accepted key factors, such as the textures of substrate and buffer layers, we found some other factors, for example, the deposition temperature of the cap layer, are also critical to the epitaxial growth of Y123 phase. With the CeO2 cap layer deposited at relative high temperature of 700°C, a critical current density, Jc, over 1 MA/cm2 has been demonstrated for the first time on Ni‐RABiTS by a fluorine‐free MOD method. Whereas for samples with CeO2 cap layers deposited at a lower temperature of 600°C, even though XRD data showed a better texture on these buffer layers, texture degradations of YBCO grains under the optimized processing conditions were observed and a lower oxygen partial pressure around 40 ppm was necessary for the epitaxial growth of Y123 phase. As a result, Jc fell to 0.45 MA/cm2 at 77 K. The observed phenomena points to the change of surface energy and reactivity of the CeO2 cap layer with respect to the CeO2 deposition temperature. In this paper, the YBCO phase diagram was also summarized.

Studies of solution deposited cerium oxide thin films on textured Ni-alloy substrates for YBCO superconductor

Cerium oxide (CeO 2) buffer layers play an important role for the development of YBa 2Cu 3O 7− x (YBCO) based superconducting tapes using the rolling assisted biaxially textured substrates (RABiTS) approach. The chemical solution deposition (CSD) approach has been used to grow epitaxial CeO 2 films on textured Ni–3 at.% W alloy substrates with various starting precursors of ceria. Precursors such as cerium acetate, cerium acetylacetonate, cerium 2-ethylhexanoate, cerium nitrate, and cerium trifluoroacetate were prepared in suitable solvents. The optimum growth conditions for these cerium precursors were Ar–4% H 2 gas processing atmosphere, solution concentration levels of 0.2–0.5 M, a dwell time of 15 min, and a process temperature range of 1050–1150 °C. X-ray diffraction, AFM, SEM, and optical microscopy were used to characterize the CeO 2 films. Highly textured CeO 2 layers were obtained on Ni–W substrates with both cerium acetate and cerium acetylacetonate as starting precursors. YBCO films with a J c of 1.5 MA/cm 2 were obtained on cerium acetylacetonate-based CeO 2 films with sputtered YSZ and CeO 2 cap layers.

Benefits of current percolation in superconducting coated conductors

The critical currents of coated conductors fabricated by metal-organic deposition (MOD) on rolling-assisted biaxially textured substrates (RABiTS) and by pulsed laser deposition (PLD) on ion-beam assisted deposition (IBAD) templates have been measured as a function of magnetic field orientation and compared to films grown on single crystal substrates. By varying the orientation of magnetic field applied in the plane of the film, we are able to determine the extent to which current flow in each type of conductor is percolative. Standard MOD/RABiTS conductors have also been compared to samples whose grain boundaries have been doped by diffusing Ca from an overlayer. We find that undoped MOD/RABiTS tapes have a less anisotropic in-plane field dependence than PLD/IBAD tapes and that the uniformity of critical current as a function of in-plane field angle is greater for MOD/RABiTS samples doped with Ca.

High Critical Current YBa2Cu3O7−δ Thick Films on Improved Rolling‐Assisted Biaxially Textured Substrates (RABiTS™)

YBa2Cu3O7−δ (YBCO) films with thicknesses ranging from 1.0 to 6.4 μm were deposited by pulsed laser deposition on rolling‐assisted biaxially textured substrates (RABiTS). The RABiTS were of the configuration CeO2/YSZ/Y2O3/Ni–3 at.% W. As the YBCO film thickness increased, Ic continued to increase and reached ∼300 A/cm width for a 4.3 μm‐thick YBCO film. Commonly observed mechanisms for Jc decrease with increasing YBCO film thickness were not observed. Homogeneous microstructures obtained in even the thickest YBCO films, suggest that the Ic/width can still be enhanced considerably.

Evidence for Extensive Grain Boundary Meander and Overgrowth of Substrate Grain Boundaries in High Critical Current Density ex Situ YBa2Cu3O7−x Coated Conductors

It has been generally accepted that YBa2Cu3O7−x (YBCO) films deposited on deformation textured polycrystalline metal tapes result in YBCO grain boundary (GB) networks that essentially replicate the GBs of the underlying substrate. Here we report that for thicker YBCO films produced by a BaF2 ex situ process, this is not true. Using electron backscatter diffraction combined with ion milling, we have been able to map the evolution of the YBCO grain structure and compare it to the underlying template in several coated conductors. For thin (≤0.5 μm) YBCO films deposited on rolling-assisted biaxially textured substrates (RABiTS), the YBCO GBs nearly directly overlap the substrate GBs. For 0.7–1.4 μm YBCO films, the GBs were found to meander along the substrate GBs and along the sample normal, with displacements several times the film thickness. In very thick films (2.5–2.9 μm), the YBCO grains can completely overgrow substrate grains and GBs, resulting in a substantial disconnection of the YBCO and substrate GB networks. Similar behavior is found for BaF2 ex situ YBCO films on ion-beam-assisted deposition-type templates. The ability of the YBCO to overgrow substrate grains and GBs is believed to be due to liquid-phase mediated laminar grain growth. Although the behavior of the YBCO GB networks changes with YBCO film thickness, the samples maintained high critical current density (Jc) values of >2 MA/cm2 for films up to 1.4 μm thick, and up to0.9 MA/cm2 for 2.5–2.9-μm-thick films.

Improved YBCO Coated Conductors Using Alternate Buffer Architectures

The Rolling-Assisted Biaxially Textured Substrates (RABiTS) process has been identified as one of the leading candidates for the fabrication of high performance YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) coated conductors. The RABiTS process uses standard thermomechanical processing to obtain long lengths of flexible, biaxially oriented substrates with smooth surfaces. The strong biaxial texture of the metal is then transferred to the superconductor by the deposition of intermediate oxide buffers that serve both as a chemical and structural buffer. The typical three-layer RABiTS architecture consists of an e-beam Y/sub 2/O/sub 3/ seed, sputtered YSZ barrier and a sputtered CeO/sub 2/ cap layer. Chemical solution deposition of buffer layers offers potential cost advantage relative to physical vapor deposition (PVD) processes. Our main goal of this study is to develop simplified buffer architectures and demonstrate high J/sub c/ Metal-Organic Deposition (MOD)-YBCO films on all-MOD buffers. La/sub 2/Zr/sub 2/O/sub 7/ (LZO)/CeO/sub 2/ buffers have been identified as potential candidates for this study. MOD-YBCO films with a critical current, I/sub c/ of 212 A/cm have been achieved on MOD-LZO seeds with sputtered YSZ and CeO/sub 2/ cap layers. In addition, MOD-YBCO films with a critical current, I/sub c/ of 140 A/cm have been achieved on all MOD buffers of LZO/CeO/sub 2/ for the first time. This offers a potential toward fabrication of lower cost YBCO coated conductors.

Transport Measurements and<tex>$J_rm c$</tex>Simulations for RABiTS Based Coated Conductors—Doping and Grain Architecture

The critical current density in RABiTS (rolling assisted biaxially textured substrates) based coated conductors is limited by the network of small-angle grain boundaries up to a texture dependent crossover field H/sub co/. The current flow through this network is percolative in nature and thus depends on misorientation angle distribution, the width and length of the tape, and on the grain shape. These dependencies were simulated using a fast and simple limiting path algorithm on real grain boundary networks obtained by electron backscattering diffraction (EBSD) and cross-checked with transport measurements. A strong dependence of J/sub c/ on conductor width below 20 grains and a large increase in J/sub c/ for elongated grains was found. H/sub co/ of tapes with very sharp cube textures are around 1 T at 77 K. Hence, the intra-grain pinning must be increased for a further improvement of coated conductors applied in higher magnetic fields. With transport measurements on YBa/sub 2/(Cu/sub 1-x/Zn/sub x/)/sub 3/O/sub 7-/spl delta// single crystalline thin films, the possibility of a J/sub c/ increase due to Zn doping was investigated. Monolayer films with Zn contents up to 0.2%, however, showed a decrease in J/sub c/ and H/sub irr/, whereas multilayer films with x=0.017% and x=0.025% Zn) showed an increase in J/sub c/ at 77 K.

Liquid mediated growth and the bimodal microstructure of YBa2Cu3O7−δ films made by the ex situ conversion of physical vapor deposited BaF2 precursors

YBa2Cu3Oy (YBCO) films produced by the ex situ conversion of BaF2-based precursors deposited by physical vapor deposition on ion-beam assisted deposited (IBAD) yttrium-stabilized zirconia (YSZ) and rolling-assisted biaxially textured substrates (RABiTS) templates are characterized by a bi-axially aligned, laminar grain structure that results from the anisotropic growth characteristics of the YBCO phase and its precipitation from a transient liquid phase during the conversion process. A bimodal microstructure characterizes these films and is defined by large, well-formed YBCO grains with Y2O3 precipitates in the bottom region of the film and small YBCO grains with a high density of stacking faults in the upper half. Ba2Cu3Oy or Ba–O–F/CuO second phase layers were often found between large YBCO grains in the bottom half of the films. YBCO grain sizes exceeded 50 μm within the plane of the film in some cases. Conversely, discrete secondary phases of Y2Cu2O5, Y2O3, and Ba2Cu3Oy/Ba–O–F could be found among the much smaller YBCO grains in the top portion of the bimodal structure. The dividing line of the bimodal structure was generally at one half of the film thickness, although exceptions to this trend were found. The highest critical current densities (Jc) and best film alignments for a given film thickness were found in samples where the layers of Ba2Cu3Oy or Ba–O–F were minimized or eliminated from the films. Samples quenched after partial conversion show the segregation of CuO to the top region of the film and the lateral growth of large YBCO grains from a precursor mix of Y2Cu2O5 and Ba–O–F. The data demonstrate that transient liquid phases are part of the conversion process of BaF2-based YBCO films. The control of both CuO segregation and the amount of liquid phases generated during the initial stages of phase formation is needed for optimizing the ex situ conversion process for high-Jc coated conductors.

High performance YBCO films by the hybrid of non-fluorine yttrium and copper salts with Ba–TFA

High performance YBCO films have been fabricated using a metallorganic deposition (MOD) approach consisting of a hybrid of Ba–trifluoroacetate (Ba–TFA) with non-fluorine containing Cu and Y solution precursors on rolling-assisted-biaxially-textured substrates (RABiTS). A high J c of 2.4 MA/cm 2 at 77 K for 0.6 μm YBCO films on RABiTS corresponding to an I c over 140 A/cm-w was obtained. T c measurements showed sharp transitions with zero resistance above 90 K. Extrapolation of the normal state resistivity results in an intercept below zero at 0 K, indicating the absence of second phases at grain boundaries. This first report on obtaining high J c with significantly reduced fluorine in the precursor is important for scale-up to manufacturing since the volume of corrosive hydrofluoric gas (HF), which is a by-product of the conversion, is greatly reduced.

Epitaxial NiO buffer layer by chemical enhanced surface oxidation epitaxy on Ni–5%W RABiTS for YBCO coated conductors

For the deposition of YBa 2Cu 3O 7− δ (YBCO) on metallic substrates like Ni-based rolling assisted biaxially textured substrates (RABiTS), buffer layers (e.g. NiO, CeO 2, Y-stab. ZrO 2) are necessary. In the beginning of the deposition process of oxide layers, often the formation of misoriented NiO (especially NiO(1 1 1)) is observed. It has been shown that a biaxially textured (0 0 1)-oriented NiO buffer layer can be grown by Surface Oxidation Epitaxy (SOE) at high temperatures (⩾1000 °C) on many Ni-based RABiTS including micro-alloyed Ni, NiCr or NiV. RABiTS with high W content show very good mechanical properties but reveal some problems using the SOE method for producing a NiO buffer layer suitable for YBCO coated superconducting tapes. We found a chemical pretreatment which makes it possible to grow (0 0 1)-oriented, biaxially textured NiO buffer layers on Ni with high (5%) W content at temperatures ranging from 320 °C to 1300 °C and at ambient air. In this paper we report the influence of the chemical pretreatment, the oxidation time and the oxidation temperature on the properties of self oxidized NiO layers as well as the influence of the oxidation process on the substrate properties. By the deposition of a subsequent La 0.7Ca 0.3MnO 3 (LCMO) buffer layer, YBCO was grown epitaxially on Ni–5%W-RABiTS with first results showing a critical current density J c of 1 × 10 5 A/cm 2 and a critical temperature T c of 89 K.

Growth of YBCO films on MgO-based rolling-assisted biaxially textured substratestemplates

We have developed a simple alternative buffer layer architecture for the rolling-assistedbiaxially textured substrates (RABiTS) approach. Buffer layers with both oxygen andmetal diffusion barrier properties are of interest. Cube textured magnesium oxide MgObuffers were grown directly on biaxially textured Ni and Ni–W3 at.% substrates usingelectron beam evaporation. We have also grown epitaxial MgO layers on 2 m longtextured Ni–W3 at.% tapes in a reel-to-reel e-beam evaporation. Highly texturedLaMnO3 (LMO) buffers were grown on MgO-buffered Ni substrates using rfsputtering. MgO and LMO buffers have been proved to be good oxygendiffusion barriers and Ni diffusion barriers, respectively. YBCO films with aJc of1 × 106 A cm−2 at 77 K and self-field were grown on this newly developed architecture of LMO/MgO/Niusing pulsed laser deposition.

Growth of Biaxially Textured CeO2/YSZ/CeO2 and SrTiO3 Buffer Layers on Textured Ni Substrates by Pulsed Laser Deposition

Biaxially textured CeO2/YSZ/CeO2 and SrTiO3 buffer layers have been grown by pulsed laser deposition (PLD) on rolling assisted biaxially textured substrates (RABiTS) made of Ni. Full width at half maximum (FWHM) of the ω scan, φ scan of these buffer layers were comparable to the Ni substrates indicating good epitaxial growth on RABiTS. Atomic force microscopy (AFM) and scanning electron microscope (SEM) measurements showed that these buffer layers were smooth and crack-free. CeO2/YSZ/CeO2/Ni and SrTiO3/Ni buffer layers prepared by this technique can be used as templates for the growth of high-Tc superconductors coated conductors. Unlike CeO2 seed layers, which could be easily epitaxially grown on RABiTS Ni substrates in forming gas, cube-on-cube epitaxial growth of SrTiO3 on RABiTS Ni substrates can be achieved only in a narrow window of deposition temperatures and forming gas pressure.

Identification of a self-limiting reaction layer in Ni–3 at.% W rolling-assisted biaxiallytextured substrates

Analytical transmission electron microscopy was used to identify the presenceof a self-limiting reaction layer developed within rolling-assisted biaxiallytextured Ni–3 at.% W substrates during the pulsed laser deposition of thickYBa2Cu3O7−δ (YBCO) films. Improvements in YBCO film quality and physicalproperties were attributed in part to the development of aNiWO4 layer at the buffer–substrate interface. The formation ofNiWO4 between NiO and the Ni–3 at.% W substrate was observed to restrict the growth of NiO withinthe coated conductor during YBCO deposition at elevated temperatures. A 5–8 nm thickNiWO4 layer, identified through both electron diffraction and energy dispersive spectroscopy,was found to limit NiO growth to between 20 and 25 nm in thickness. TheNiWO4 layer was found to have a [100] orientation relationship to the substrate normal, withmultiple variants observed.

The RABiTS Approach: Using Rolling-Assisted Biaxially Textured Substrates for High-Performance YBCO Superconductors

AbstractThis article provides an overview of the fabrication of epitaxial, biaxially aligned buffer layers on rolling-assisted biaxially textured substrates (RABiTS) as templates for YBCO films carrying high critical current densities.The RABiTS technique uses standard thermomechanical processing to obtain long lengths of flexible, biaxially oriented substrates with smooth surfaces.The strong biaxial texture of the metal is conferred to the superconductor by the deposition of intermediate metal and/or oxide layers that serve both as a chemical and a structural buffer.Epitaxial YBCO films with critical current densities exceeding 3 106A/cm2at 77K in self-field have been grown on RABiTS using a variety of techniques and demonstrate magnetic-field-dependent critical current values that are similar to those of epitaxial films on single-crystal ceramic substrates.The RABiTS architecture most commonly used consists of a CeO2(sputtered)/YSZ (sputtered)/Y203(e-beam)/Ni-W alloy.The desired texture of the base metal has been achieved in 100 m lengths and 10cm widths.Scaleable and cost-effective techniques are also being pursued to deposit the epitaxial multilayers.The results discussed here demonstrate that this technique is a viable route for the fabrication of long lengths of high-critical-current-density wire capable of carrying high currents in magnetic fields and at temperatures accessible by cooling with relatively inexpensive liquid nitrogen (up through the 77K range).

Development and evolution of biaxial texture of rolled nickel tapes by ion beam bombardment for high Tc coated conductors

High quality YBa 2Cu 3O 7 − x films on metallic substrates with high critical current densities well over 10 6 A/cm 2 can be prepared by the rolling assisted biaxially textured substrates (RABiTS) method. Nickel or its alloys have been used as biaxially textured substrates formed through a specific rolling and high temperature annealing procedures. In this paper, we report a newly developed process for developing biaxial texture in rolled Ni tape by argon ion beam bombardment. It is named the ion-beam structure modification (ISM) process. In the ISM processed Ni foils, X-ray diffraction ω scans showed the full width-half maximum (FWHM) value of the (2 0 0) peak was 5.7°. And the electron back scattering diffraction (EBSP) analysis based on scanning electron microscopy showed good {1 0 0} 〈0 0 1〉 cubic orientation and the mean grain size was determined as about 25 μm. The texture evolution of rolled Ni foils during ISM process is reported also. For ISM process, local temperature elevation and distribution arises from the ion bombardment, coupled with anisotropic incident ion penetration and propagation as a result of channeling effects in the metal lattice, are expected to play the major roles in the development of grain reorientation in the Ni foil. Due to the simplicity and efficiency of the ISM process, the technique shows a great promise for application in the industrial scale production of long-lengths of superconductor tapes.

Electron backscattered Kikuchi diffraction technique: for a better understanding of epitaxial superconducting film growth on buffered Ni (RABiTS) tapes

A reel-to-reel MOCVD system has been designed to synthesize high quality YBCO coated tapes on Ni RABiTS (Rolling Assisted Biaxially Textured Substrates). Special buffer layer stackings have been deposited to improve the quality of the superconductor. Several buffer layers architectures rose in dense YBCO films with a similar texture, but fluctuations in critical current densities (Jc) were measured. Therefore, a more accurate and detailed measurement method such as Electron Backscattered Kikuchi Diffraction (BKD) has been used to assess the crystalline quality of the stackings. The studied sequence here was NiW /NiO /YSZ /CeO2 /YBCO. The grain and the subgrain structure as well as their size and disorientation have been analysed for each layer. First on Ni tape, secondly on the protecting NiO (200) buffer layer, then on the following CeO2 (200) film. Finally, unpublished BKD diagrams of the subsequent YBCO (001) films have been reported here. The grain evolution has been successfully studied showing the buffer layer effect on the grain growth. In this work we highlight the correlation between the misorientation of the grains (inducing NiO (111) growth and cracks) and the grain boundary morphology (size, grooves). (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Effects of Conversion Parameters on the Transport Properties of YBCO Films in the BaF2 Ex Situ Process

The effects of conversion parameters on transport properties of YBa2Cu3O7-δ (YBCO) films on rolling assisted biaxially textured substrates (RABiTS) in the BaF2 ex situ process were investigated for total pressures Ptotal between 0.1 and 1.3 atm, water vapor pressures PH2O between approximately 7 and 70 Torr and processing temperatures TS between 700 and 790 °C. For this study, a 0.3-μm-thick Y–BaF2–Cu–O precursor film was deposited on a 1-cm-wide Ni=3 at.% W RABiTS with a buffer layer architecture of CeO2/YSZ/Y2O3/Ni deposited in single passes in various reel-to-reel systems for each layer. Under the conditions of Ptotal = 0.1 atm, TS = 740 °C and PO2 approximately 150 mTorr, JC > 2 MA/cm2 was obtained at 77 K and self field for PH2O ≤ 20 Torr. At higher PH2O (=70 Torr), however, the maximum attainable JC decreased. In addition, the JC at these higher PH2O dropped rapidly with increased dwell time. The highest JC, 2.5 MA/cm2, was achieved at 730 °C with Ptotal = 0.1 atm and PH2O approximately 7 Torr. Finally, the variation of IC with wet conversion time was performed at each processing temperature.