Pulsed laser deposition was used to deposit thin films of calcium hydroxylapatite (Calo(P04)6(OH)z), or HA, on polished substrates of Ti-6A1-4V. Thin films of pure, crystalline HA, uncontaminated by other calcium phosphate phases, were deposited over a range of temperatures between 400 and 800 "C. The HA films were polycrystalline with a preferred (001) crystallographic orientation, as determined by transmission electron microscopy and x-ray diffraction. Adhesion of the HA films to the Ti-6A1-4V substrates was excellent when films were deposited at temperatures 5 600 "C; in a scratch test, mean pressures of ca. 10'' Nm-' produced conformational cracking in a film deposited at 600 "C, but no decohesion from the substrates.

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Highly ordered superlattices are typically created through the sequential deposition of two different materials. Here, we report our experimental observation of spontaneous formation of superlattices in coevaporation of Au and Ni under energetic ion bombardment. The superlattice periodicities are on the order of a few nanometers and can be adjusted through the energy and flux of ion beams. Such a self-organization process is a consequence of the bombardment-induced segregation and uphill diffusion within the advancing nanoscale subsurface zone in the film growth. Our observations suggest that ion beams can be employed to make tunable natural superlattices in the deposition of phase-separated systems with strong bombardment-induced segregation.

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The initial stages of growth of ͑001͒Cu films on ͑001͒Ag substrates have been investigated using the temperature-accelerated dynamics ͑TAD͒ simulation method. The acceleration provided by TAD made it possible to simulate the deposition of Cu on ͑001͒Ag at 77 K using a deposition rate of 0.04 ML/s, which matched previously reported experiments. This simulation was achieved without a priori knowledge of the significant atomic processes. The results showed that the increased in-plane lattice parameter of the pseudomorphic Cu reduces the activation energy for the exchange mode of surface diffusion, allowing short-range terrace diffusion and the formation of compact Cu islands on the second film layer at 77 K. Some unexpected complex surface diffusion processes and off-lattice atomic configurations were also observed.

The nature of the buffer layers needed for the single crystal deposition of cubic SiC on Si substrates was studied. It is concluded that the buffer layer is a stressed monocrystalline layer of cubic SiC.

Extended x-ray absorption fine structure analysis of amorphous and partially crystallized samples of the soft magnetic alloy Fe73.5Nb3Cu1Si13.5B9 reveals that, even before heat treatment, a portion of the Cu is present in the form of tiny, close packed clusters. Analysis of the Nb-free alloy Fe76.5Cu1Si13.5B9 shows that the Cu clusters are not present in the quenched ribbons, but that fcc Cu precipitates form during heat treatment. Results suggest that the Cu clusters act to catalyze nucleation of Fe-rich nanocrystals, but that these clusters are formed on a finer scale when Nb is added to the alloy, perhaps because it helps to lower the solubility of Cu in the amorphous phase.

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