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Pulsed laser deposition of yttria-stabilized zirconia (YSZ) layers on polycrystalline metallic alloy substrates is used to produce an intermediate layer for YBa2Cu3O7−δ (YBCO) thin-film growth. The desired (001) YSZ texture is obtained at 1.0 mTorr oxygen pressure and 70 °C. Significant improvement in (001) texturing is demonstrated by using an ion beam to assist growth. Argon-ion-assisted growth produces layers with alignment of the in-plane crystal axes in addition to the (001)-normal texture. Highly c-axis-oriented biaxially aligned YBCO thin films can be deposited on these layers, with Tc(R=0)=92 K and Jc (77 K, B=0 T)=6×105 A/cm2 and Jc (77 K, 0.4 T)=8×104 A/cm2. With further improvement of the YSZ texture, the YBCO current-carrying capacity of films on polycrystalline metallic alloys may approach that of films on single-crystal substrates.

Electrochemically active thin films of Mg 2 Si in various film thicknesses of 30-380 nm have been prepared with the pulsed laser deposition technique. The thinnest film of 30 nm showed a highly stable cycling behavior at 0.1-1.0 V vs. Li, delivering capacity greater than 2000 mAh/g for more than 100 cycles. Though the film morphology became remarkably rougher with cycling, the films showed good stability. However, the first cycle irreversible capacity loss increased with film thickness. Therefore, lithium adsorption/desorption reaction forming Li-Si alloy at the Si-rich film surface is suggested as one of the sources of the large capacity of the 30 nm film. The superior capacity retention, when compared to porous electrodes of this alloy, may be attributed to a limited structural volume change in the two-dimensional film, shorter lithium diffusion path and enhanced conductivity from stainless steel substrate. The goals of this study are to promote the emerging need of thin film anodes for all solid-state microbatteries and clarify the capacity failure of powder intermetallic anodes for rechargeable lithium batteries.The search for anode materials to replace graphite in rechargeable lithium batteries has intensified over recent years due to concerns about safety during overcharge in the presence of organic electrolyte and a highly oxidizing cathode material such as LiCoO 2 . 1 Considerable effort has been devoted to searching for suitable alternative anodes among lithium binary alloys 2-4 and intermetallics 5-10 which operate a few hundred millivolts above metallic lithium. Magnesium silicide alloys have been studied for this application because Si has a good affinity for lithium. 11-16 Consensus regarding the electrochemical reaction between Li and Mg 2 Si has not been reached. Part of the reason may be due to the fact that Mg 2 Si is a semiconductor whose performance will be dependent on particle morphology and current density, and porous electrodes from alloyed powders show rapid capacity fade over the first ten cycles. It has been generally recognized that lithiation of the alloying metal elements takes place by significant volume change causing electrochemical-mechanical disintegration of particles during cycling. 5-15 Many attempts have been made to improve the electrochemical performance of the alloy anode materials by means of controlling the crystal structure to achieve a small lattice volume change and a particle morphology subject to a minimum mechanical stress, based on the study of capacity failure mechanisms of those alloy anodes. 17-20 Much can be learned regarding the performance of low conductivity materials when they are in thin film form. 16,[21][22][23]

Thin films of LiFePO 4 have been prepared on stainless steel substrates with pulsed laser deposition utilizing an Ar atmosphere. Raman spectral analysis revealed the presence of carbon in the films, even though the targets contained less than a few percent residual carbon. The Raman spectra also suggest the presence of iron oxide species on the surface of the film. Though the film morphology became rough with cycling and thicker films were cleaved; the films showed good stability on cycling. The 75-nm-thick film prepared with a carbon-containing target showed a reversible cycling of more than 90 mAh/g for 60 cycles. The use of the low-carbon ͑Ͻ1 wt %͒, green-colored target significantly lowered the carbon content of the LiFePO 4 film. The low-carbon films cycled stable at moderate current density but with lower capacities such as 80 and 51 mAh/g for the 75 and 335-nm films, respectively. Film capacity and crystallinity improved significantly when the pulsed-laser-deposited target-substrate distance was reduced to less than 5 cm. The 156-nm-thick film produced in this way showed a layered texture in surface morphology and delivered more than 120 mAh/g, keeping its particle morphology on cycling. The excellent capacity retention, despite low-carbon content, can be attributed in part to the enhanced conductivity derived from the excellent adherence between pulsed-laser-deposited film and the substrate.

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