Solvent-Free Synthesis of Inorganic Rubidium Copper Halides for Efficient Wireless Light Communication and X-Ray Imaging

Lead-free metal halides have recently received sustained attention because of their nontoxicity, low-cost, as well as excellent stability and optoelectronic properties. However, most of the reported lead-free metal halides are synthesized via slow solution-processing at high temperature in toxic solvents, which may impede their commercial applications. Here, a solvent-free strategy is proposed to synthesize inorganic rubidium copper halides (Rb₂CuX₃, X = Cl, Br) at room temperature, which exhibit efficient violet emission dominated by a self-trapped excitons (STEs) mechanism and attractive stabilities against ultraviolet illumination and heating. Thus, Rb₂CuX₃ powders are employed as emitters and scintillators applied in wireless light communication and X-ray imaging technologies. Under orthogonal frequency division multiplexing modulation, emitters demonstrate a broad −3 dB bandwidth of 26.3 MHz and a high received data rate of 205.1 Mbps. Additionally, flexible scintillation films based on as-prepared powders are fabricated and show outstanding X-ray scintillation properties, including a high spatial resolution of 18.1 lp mm⁻¹ and a low detection limit of 104 nGy_air s⁻¹, as well as promising imaging performance for irregular objects. These results suggest large-scale production of nontoxic Rb₂CuX₃ and their potential commercialization in fields of high-speed light communication and X-ray radiography.     

Sb3+-Doping in Cesium Zinc Halides Single Crystals Enabling High-Efficiency Near-Infrared Emission

Luminescent metal halide materials with flexible crystallography/electronic structures and tunable emission have demonstrated broad application prospects in the visible light region. However, designing near-infrared (NIR) light-emitting metal halides remains a challenge. Here, an enlightening prototype is proposed to explore the high-efficiency broadband NIR emission in metal halide systems by incorporating Sb³⁺ into the Cs₂ZnCl₄ matrix. Combined experimental analysis and density functional theory calculations reveal a modified self-trapped excitons model to elaborate the NIR emission. The high photoluminescence quantum yield of 69.9% peaking at 745 nm and large full width at half maximum of 175 nm, along with excellent air/thermal stability, show the unique advantages of lead-free metal halide Cs₂ZnCl₄:Sb³⁺ as the NIR light source. The substitution of Cl⁻ by Br⁻ further enables the red-shift of emission peak from 745 to 823 nm. The NIR light-emitting diode device based on Cs₂ZnCl₄:Sb³⁺ demonstrates potential as a non-visible light source in night vision. This study puts forward an effective strategy to design the novel eco-friendly and high-efficiency NIR emissive materials and provides guidance for expanding the application scope of luminescent metal halides.     

Woven Fibrous Photodetectors for Scalable UV Optical Communication Device

Fibrous photodetectors (FPDs) have attracted great interest in wearable and consumer electronics, which is a lightweight and flexible tools to achieve efficient light information transmission. However, there is a necessary compromise between high optoelectronic performance and high-level integration. Herein, a woven optoelectronic keyboard consisting of 40 PD button units is extended and integrated from four individual FPDs, with the integration level expanding by 1000%. Each FPD is based on uniform type-II TiO₂/Cs₃Cu₂I₅ heterojunction, which exhibits greatly reduced dark current by eight orders of magnitudes, large rectification ratio up to 33306@± 5V, high on–off ratio of 2.8 × 10⁴@−1 V and self-powered responsivity of 26.9 mA W⁻¹. The vacuum-deposited Cs₃Cu₂I₅ nanoparticles finely passivate the massive defects and serve as a p-type hole transport layer to improve hole transfer efficiency, which greatly promotes the radial transport and collection of photogenerated electrons. Moreover, the photocurrent remains highly stable after bending and twisting states. Intriguingly, the woven optoelectronic keyboards successfully realize logic AND/OR, further identifying the UV light signal as a keying text signal (“A–Z” letters, “0–9” numbers, and four punctuations). This work not only provides a scalable strategy to reduce device redundancy but also shows the great potential of fibrous photodetectors for wearable optical communication.     

Moisture-Induced Reversible Phase Conversion of Cesium Copper Iodine Nanocrystals Enables Advanced Anti-Counterfeiting

Hydrochromic materials have attracted widespread attention in the fields of anti-counterfeiting because of their ability of the reversible light absorption and/or emission properties in response to water. Here, for the first it is demonstrated that the ternary copper halides Cs₃Cu₂I₅ nanocrystals (NCs) possess excellent hydrochromic properties. The prepared Cs₃Cu₂I₅ NCs films can dynamically extract and insert CsI by exposing/removing water to realize the reversible conversion between blue-emissive Cs₃Cu₂I₅ and yellow-emissive CsCu₂I₃. Interestingly, polymethyl methacrylate (PMMA) coated Cs₃Cu₂I₅ can effectively avoid the extraction of CsI and maintain long-term stability in the water. Further, the hydrochromic Cs₃Cu₂I₅ and water-resistant Cs₃Cu₂I₅@PMMA are used as the inks to synergistically act on anti-counterfeiting information to achieve multiple encryption effects, which can clearly identify and authenticate the effective information after moisture decryption. Importantly, the pattern can be re-encrypted to the invalid pattern after water evaporation. In addition, the anti-counterfeiting pattern has excellent stability during repeated encryption/decryption conversion cycles, which can not only balance the accessibility of anti-counterfeiting information but also effectively improve the security of information. This new discovery may not only deepen the understanding of Cs₃Cu₂I₅ but also provide new options for the design of hydrochromic materials for anti-counterfeiting information.     

High Optical Gain of Solution-Processed Mixed-Cation CsPbBr3 Thin Films towards Enhanced Amplified Spontaneous Emission

A solution-processed thin film made of all-inorganic CsPbBr₃ perovskite is a promising candidate for low-cost and flexible green-color lasers. However, the amplified spontaneous emission (ASE) of solution-processed CsPbBr₃ films still experiences a high threshold owing to poor morphology and insufficient optical gain. Here, a multiple-cation doping strategy is demonstrated to develop compact, smooth thin films of Cs_0.87(FAMA)_0.13PbBr₃/(NMA)₂PbBr₄ (FA: formamidinium; MA: methylammonium; NMA: naphthylmethylammonium) with a record high net modal optical gain of ≈ 3030 cm⁻¹ and low propagation loss of 1.0 cm⁻¹. The FA and MA cations improve the crystallization kinetics to form continuous films, and the NMA cations reduce the grain dimension, increase film dispersibility/uniformity, and enhance spatial confinement to promote optical gain. Room-temperature ASE is demonstrated under a low threshold of ≈ 3.8  µ J cm⁻² without degradation after four months of storage in glove box or excitation by 3 × 10⁷ laser pulses. These findings provide insights into enhancing the optical gain and lowering the threshold of perovskite lasers in terms of molecular synthesis and microstructure engineering.     

Inkjet Printing Flexible Thermoelectric Devices Using Metal Chalcogenide Nanowires

Development of flexible thermoelectric devices offers exciting opportunities for wearable applications in consumer electronics, healthcare, human–machine interface, etc. Despite the increased interests and efforts in nanotechnology-enabled flexible thermoelectrics, translating the superior properties of thermoelectric materials from nanoscale to macroscale and reducing the manufacturing costs at the device level remain a major challenge. Here, an economic and scalable inkjet printing method is reported to fabricate high-performance flexible thermoelectric devices. A general templated-directed chemical transformation process is employed to synthesize several types of 1D metal chalcogenide nanowires (e.g., Ag₂Te, Cu₇Te₄, and Bi₂Te_2.7Se_0.3). These nanowires are made into inks suitable for inkjet printing by dispersing them in ethanol without any additives. As a showcase for thermoelectric applications, fully inkjet-printed Ag₂Te-based flexible films and devices are prepared. The printed films exhibit a power factor of 493.8 µW m⁻¹ K⁻² at 400 K and the printed devices demonstrate a maximum power density of 0.9 µW cm⁻² K⁻², both of which are significantly higher than those reported in state-of-the-art inkjet-printed thermoelectrics. The protocols of metal chalcogenide ink formulations, as well as printing are general and extendable to a wider range of material systems, suggesting the great potential of this printing platform for scalable manufacturing of next-generation, high-performance flexible thermoelectric devices.     

Surface-induced highly oriented perylo[1,12-b,c,d]selenophene thin films for high performance organic field-effect transistors

Epitaxial crystallization of perylo[1,12-b,c,d]selenophene (PESE) on highly oriented polyethylene (PE) substrate through vapor phase deposition has been achieved. Oriented PESE crystals with different crystalline morphologies can be fabricated by changing the temperature of PE substrate during vacuum evaporation. When the PE substrate temperature is lower than 70 °C, sparsely dispersed PESE lathlike crystals are produced with their long axis preferentially aligned perpendicular to the chain direction of PE crystals. While the close films of PESE with lathlike crystals aligned with long axis parallel to the chain direction of PE film were obtained above 90 °C. Transistors based on expitaxially crystallized PESE films have been fabricated and the transistor properties were also studied. It is found that transistors show different electrical characteristics depending on the preparation conditions of expitaxially crystallized PESE films. The transistors based on the PESE/PE-SiO₂/Si with PESE deposited on oriented PE film at low temperature, i.e., <70 °C, display a similar poor properties with the PESE/OTS-SiO₂/Si type transistors. However, when the deposition temperature was elevated to 90 °C, the transistors exhibit a maximum field-effect mobility of 4.4 × 10⁻² cm² V⁻¹ s⁻¹ and maximum on/off ratio of 2.0 × 10⁵, which are about 2 orders of magnitudes higher than the PESE/OTS-SiO₂/Si based transistors.     

Metal–organic chemical vapor deposition as an emerging technique for the fabrication of YBa2Cu3Ox tapes

The deposition of YBa₂Cu₃O_x thin films on metal substrates is currently being investigated as the basis for future tape applications. The YBa₂Cu₃O_x coatings, discussed in this report, are deposited by metal–organic chemical vapor deposition (MOCVD). MOCVD is a versatile technique with many opportunities in terms of reaction chamber design and shapes of substrates to be coated. MOCVD equipment for fabrication of YBa₂Cu₃O_x coatings on long length, flexible metal tapes is currently being developed. Tapes of various materials, such as polycrystalline stainless steel, have been investigated. The growth of biaxially aligned buffer layers between the stainless-steel tapes and YBa₂Cu₃O_x coatings is necessary, to prevent interdiffusion, to reduce interfacial reactions and to allow the succeeding growth of aligned YBa₂Cu₃O_x thin films. The superconducting properties of the resulting YBa₂Cu₃O_x/buffer/substrate thin film systems, T_c≈90 K and J_c>10⁵ A cm⁻², are very promising. the major drawbacks in MOCVD of YBa₂Cu₃O_x thin films are the thermo-chemical properties of MOCVD precursors. For example, the traditional solid precursors have limited volatility. The development of new precursor delivery systems using precursor solutions and new solid and liquid precursors have resulted in improved process reliability. Finally, in the standard MOCVD process, which is thermally activated, the reported growth rates are approximately 0.5 μm h⁻¹. An increase by one order of magnitude can be achieved in a photo-assisted MOCVD process.     

Self-Powered Smart Touchpad using Novel Intrinsic Piezo–Tribo Hybrid Nanogenerator

Novel hybrid nanogenerators (HNG) with multifunctional materials are gaining immense interest due to their high electrical output and broad applications in the electronic industry. Intrinsic hybridization of single electrode triboelectric (SE-TE) and piezoelectric (PE) nanogenerators (NGs), that is, double layered (DL)-HNG can eliminate the real-time electrical grounding issues of SE-TE-NG and produces high output (176.41 V, 168.1 mW m⁻²) due to synergistic TE–PE effects of Multifunctional Composite film (MFC). The flexible MFC films are made-up of Cu₂O-doped 0.3Ba_0.7Ca_0.3TiO₃-0.7BaSn_0.12Ti_0.88O₃ nanoparticles (Cu₂O-BCST NPs), which exhibits morphotropic phase boundary along with the polydimethylsiloxane  polymer. Further, DL-HNG scaled up to 4 × 4 matrix (using the 3D-printed mask) can work as a flexible self-powered trackpad (or touch) sensor to control the mouse pointer in computer or touch screen display devices.     

Highly-impermeable Al2O3/HfO2 moisture barrier films grown by low-temperature plasma-enhanced atomic layer deposition

Polymer substrates are essential components of flexible electronic applications such as OTFTs, OPVs, and OLEDs. However, high water vapor permeability of polymer films can significantly reduce the lifetime of flexible electronic devices. In this study, we examined the water vapor permeation barrier properties of Al₂O₃/HfO₂ mixed oxide films on polymer substrates. Al₂O₃/HfO₂ films deposited by plasma-enhanced atomic layer deposition were transparent, chemically stable in water and densely amorphous. At 60 °C and 90% relative humidity (RH) accelerated condition, 50-nm-thick Al₂O₃/HfO₂ had water vapor transmission rate (WVTR) = 1.44 × 10⁻⁴ g m⁻² d⁻¹, whereas single layers of Al₂O₃ had WVTR = 3.26 × 10⁻⁴ g m⁻² d⁻¹ and of HfO₂ had WVTR = 6.75 × 10⁻² g m⁻² d⁻¹. At 25 °C and 40% RH, 50-nm-thick Al₂O₃/HfO₂ film had WVTR = 2.63 × 10⁻⁶ g m⁻² d⁻¹, which is comparable to WVTR of conventional glass encapsulation.     

Consequences of twisting the aromatic core of N,N′-dimethylperylene-3,4,9,10-biscarboximide by chemical substitution for the electronic coupling and electric transport in thin films

Thin films of 1,6,7,12-tetrachloro-N,N^′-dimethylperylene-3,4,9,10-biscarboximide (Cl₄MePTCDI) prepared by physical vapor deposition (PVD) were compared to thin films of the unchlorinated N,N^′-dimethylperylene-3,4,9,10-biscarboximide (MePTCDI) to investigate the influence of a changed molecular structure on the electrical properties of the materials. The films were prepared on microstructured Si/SiO₂ substrates with interdigitated Au electrode arrays of 2 μm electrode distance or on quartz glass with electrode distances in the mm range. The films were investigated by conductance measurements, thermoelectric power, electric field effect, ultraviolet photoelectron spectroscopy (UPS) and atomic force microscopy (AFM). The thickness-dependence of the conductance measured during film growth (in situ) indicated a growth mode in islands (Volmer-Weber), which was confirmed by subsequent AFM. As expected, Cl₄MePTCDI was characterized as an organic n-type semiconductor. Charge transport occurred by a hopping mechanism as revealed by temperature-dependent thermopower and field-effect measurements. Effective electron mobilities at room temperature were found around 10⁻⁵ cm² V ⁻¹ s⁻¹ considerably lower than the values for MePTCDI. A rather constant concentration of mobile electrons of (1–2) × 10¹⁸ cm⁻³ was determined for both materials. The morphology of Cl₄MePTCDI islands indicated amorphous growth as opposed to crystals obtained for MePTCDI, as also revealed earlier by optical spectroscopy and the role of crystallinity in the electrical conduction is discussed.     

Synthesis and characterization of the semiconductor Li0.93Cu0.07Nb3O8: Application to oxygen evolution under visible light

The semiconductor Li_0.93Cu_0.07Nb₃O₈ is prepared by soft chemistry in aqueous electrolyte via Cu²⁺ → Li⁺ exchange between copper nitrate and LiNb₃O₈. The substituted niobate crystallizes in an orthorhombic symmetry and the semiconducting and photo-electrochemical properties are investigated for the first time. The oxide exhibits a dark brown color and the UV–Visible spectroscopy gives an optical gap of 1.42 eV, due to the crystal field splitting of Cu²⁺ in octahedral site. The thermal variation of the conductivity shows that Nb: 4d-electrons are localized and the data are fitted by a small-polaron hopping model σ = σ_o exp {−0.053 eV/kT} with a carrier density thermally activated. The capacitance measurement done in ionic electrolyte (Na₂SO₄, 10⁻² M) indicates n type semiconductor with mixed valences Nb^5+/4+, due to the hetero-valent substitution Li⁺/Cu²⁺, with a flat band potential of 0.28 V_SCE and electrons density of 2.17×10¹⁷ cm⁻³. The Nyquist diagram shows mainly the bulk contribution with a diffusion process. The valence band (6.39 eV below vacuum) derives from O^2-: 2p orbital with a small admixture of Cu²⁺: 3d character while the conduction band is made up of Nb⁵⁺: 4d orbital. The material is successfully tested for the oxygen generation with an evolution rate of 87 µmol mn⁻¹ g⁻¹ under visible light (29 mW cm⁻²) and a quantum yield of 0.35%.     

Preparation and physical properties of the layered niobate Cu0.5Nb3O8: Application to photocatalytic hydrogen evolution

The new layered niobate Cu_0.5Nb₃O₈ is synthesized by soft chemistry in aqueous electrolyte via Cu²⁺→H⁺ exchange between copper nitrate and HNb₃O₈·H₂O. The characterization of the exchanged product is made by means of thermal gravimetry, chemical analysis, X-ray diffraction and IR spectroscopy. Thermal analysis shows a conversion to anhydrous compound above 500 °C. The oxide displays a semiconductor like behavior; the thermal variation of the conductivity shows that d electrons are strongly localized and the conduction is thermally activated with activation energy of 0.13 eV. The temperature dependence of the thermopower is indicative of an extrinsic conductivity; the electrons are dominant carriers in conformity with an anodic photocurrent. Indeed, the Mott–Schottky plot confirms n-type conduction from which a flat band potential of −0.82 V_SCE, an electronic density of 8.72×10¹⁹ m⁻³ and a depletion width of 4.4 nm are determined. The upper valence band, located at ~5.8 eV below vacuum is made up predominantly of Cu²⁺: 3d with a small admixture of O²⁻: 2p orbitals whereas the conduction band consists of empty Nb⁵⁺: 5s level. The energy band diagram shows the feasibility of the oxide for the photocatalytic hydrogen production upon visible light (29 mW cm⁻²) with a rate evolution of 0.31 mL g⁻¹ min⁻¹.     

Modulation Doping Leads to Optimized Thermoelectric Properties in n-Type Bi6Cu2Se4O6 due to Interface Effects

Heterogeneous composites consisting of Bi₆Cu₂Se_3.6Cl_0.4O₆ and Bi₂O₂Se are prepared according to the concept of modulation doping. With prominently increased carrier mobility and almost unchanged effective mass, the electrical transport properties are considerably optimized resulting in a peak power factor ≈1.8 µW cm⁻¹ K⁻² at 873 K, although the carrier concentration is slightly deteriorated. Meanwhile, the lattice thermal conductivity is lowered to ≈0.62 W m⁻¹ K⁻¹ due to the introduction of the second phase. The modified Self-consistent Effective Medium Theory is utilized to explain the deeper mechanism of modulation doping. The enhancement of apparent carrier mobility is derived from the highly active phase interfaces as fast carrier transport channels, while the reduced apparent thermal conductivity is ascribed to the existence of thermal resistance at the phase interfaces. Ultimately, an optimized ZT ≈0.23 is obtained at 873 K in Bi₆Cu₂Se_3.6Cl_0.4O₆ + 13% Bi₂O₂Se. This research demonstrates the effectiveness of modulation doping for optimizing thermoelectric properties once again, and provides the direct microstructure observation and consistent theoretical model calculation to emphasize the role of interface effects in modulation doping, which should be probably applicable to other thermoelectrics.     

Properties of fluorine-doped tin oxide films prepared by an improved sol-gel process

Fluorine-doped tin oxide (FTO) films were prepared by an improved sol-gel process, in which FTO films were deposited on glass substrates using evaporation method, with the precursors prepared by the conventional sol-gel method. The coating and sintering processes were combined in the evaporation method, with the advantage of reduced probability of films cracking and simplified preparation process. The effects of F-doping contents and structure of films on properties of films were analyzed. The results showed the performance index (Φ_TC=3.535×10⁻³ Ω⁻¹ cm) of the film was maximum with surface resistance (R_sh) of 14.7 Ω cm⁻¹, average transmittance (T) of 74.4% when F/Sn=14 mol%, the reaction temperature of the sol was 50 °C, and the evaporation temperature was 600 °C in muffle furnace, and the film has densification pyramid morphology and SnO_2−xF_x polycrystalline structure with tetragonal rutile phase. Compared with the commercial FTO films (Φ_TC=3.9×10⁻³ Ω⁻¹ cm, R_sh=27.4 Ω cm⁻¹, T=80%) produced by chemical vapor deposition (CVD) method, the Φ_TC value of FTO films prepared by an improved sol-gel process is close to them, the electrical properties are higher, and the optical properties are lower.     

Polyoxometalates Facilitating Synthesis of Subnanometer Nanowires

Subnanometer nanowires (SNWs) refer to nanowires with diameters close to the size of a single crystal cell. SNWs show not only qualitative change in nature compared to the bulk materials or nanomaterials with larger size but also show several advantages in assembly and processing due to their polymer-analog properties. However, the synthesis of SNWs is still a great challenge. Herein, a synthesis method of SNWs assisted by polyoxometalates is developed. Based on this method, several kinds of SNWs are prepared successfully, and the properties of the SNWs can be regulated efficiently and effectively, demonstrating the extensibility of this synthesis method. Among these SNWs, Bi₂O₃–PMoO SNWs show good photothermal conversion performance and can be processed into freestanding and flexible films through the wet-spinning method. The Bi₂O₃–PMoO SNW films show good performance in solar steam generation and seawater desalination. The average stable evaporation rate can reach 1.38 kg m⁻² h⁻¹, and the efficiency is ≈ 91.1% under 1 sun illumination. The concentration of ions in the desalted seawater with the Bi₂O₃–PMoO SNWs film are reduced by four orders of magnitude, meeting the quality standards of drinking water and potential for practical utilization of solar energy in the seawater desalination.     

Annealing effects on physical properties of doped CdTe thin films for photovoltaic applications

Polycrystalline Cadmium Telluride (CdTe) thin films were prepared on glass substrates by thermal evaporation at the chamber ambient temperature and then annealed for an hour in vacuum ~1×10⁻⁵ mbar at 400 °C. These annealed thin films were doped with copper (Cu) via ion exchange by immersing these films in Cu (NO₃)₂ solution (1 g/1000 ml) for 20 min. Further these films were again annealed at different temperatures for better diffusion of dopant species. The physical properties of an as doped sample and samples annealed at different temperatures after doping were determined by using energy dispersive x-ray analysis (EDX), x-ray diffraction (XRD), Raman spectroscopy, transmission spectra analysis, photoconductivity response and hot probe for conductivity type. The optical band gap of these thermally evaporated Cu doped CdTe thin films was determined from the transmission spectra and was found to be in the range 1.42–1.75 eV. The direct energy band gap was found annealing temperatures dependent. The absorption coefficient was >10⁴ cm⁻¹ for incident photons having energy greater than the band gap energy. Optical density was observed also dependent on postdoping annealing temperature. All samples were found having p-type conductivity. These films are strong potential candidates for photovoltaic applications like solar cells.     

Reassembly of MXene Hydrogels into Flexible Films towards Compact and Ultrafast Supercapacitors

The freestanding MXene films are promising for compact energy storage ascribing to their high pseudocapacitance and density, yet the sluggish ion transport caused by the most densely packed structure severely hinders their rate capability. Here, a reassembly strategy for constructing freestanding and flexible MXene-based film electrodes with a tunable porous structure is proposed, where the Ti₃C₂T_x microgels disassembled from 3D structured hydrogel are reassembled together with individual Ti₃C₂T_x nanosheets in different mass ratios to form a densely packed 3D network in microscale and a film morphology in macroscale. The space utilization of produced film can be maximized by a good balance of the density and porosity, resulting in a high volumetric capacitance of 736 F cm⁻³ at an ultrahigh scan rate of 2000 mV s⁻¹. The fabricated supercapacitor yields a superior energy density of 40 Wh L⁻¹ at a power density of 0.83 kW L⁻¹, and an energy density of 21 Wh L⁻¹ can be still maintained even when the power density reaches 41.5 kW L⁻¹, which are the highest values reported to date for symmetric supercapacitors in aqueous electrolytes. More promisingly, the reassembled films can be used as electrodes of flexible supercapacitors, showing excellent flexibility and integrability.     

Preparation of high Tc (Yb,Y)Ba2Cu3O7-δ thin films by co-evaporation from effusion cells

We have prepared superconducting thin films of (Yb,Y)Ba₂Cu₃O_7-δ by evaporation of copper, ytterbium or yttrium, and barium fluoride from Knudsen effusion cells. A simple two chamber vacuum system produced stable evaporation rates of 5–10 nm/min using various Knudsen cells without realtime feedback control. Excellent stoichiometry was obtained in the films by optimizing the deposition of Cu from a dual filament cell, Yb from a single filament cell and Y and BaF₂ from high temperature cells. Films were deposited mainly on SrTiO₃ substrates at temperatures ranging from 120 to 600° C and O₂ partial pressure up to 1.5 ⋻ 10⁻⁵ Torr. Post deposition anneals in O₂ and O₂ + H₂O produced films with room temperature resistivities as low as 227μΩ-cm andT _c (R = 0) at 91 K. Films were characterized using x-ray diffractometry, Rutherford backscattering spectrometry, energy dispersive x-ray analysis, scanning electron microscopy as well as electronic transport measurements.