Three types of amorphous-titania films prepared by ion- and electron-beam techniques have been annealed thermally. An amorphous-crystalline transformation is found in each of these film types at around 350 °C. Its resulting microcrystalline structure and the exact transition temperature appear to be dictated by the rutile microcrystalline seed present in the as-deposited films under different deposition conditions. An amorphous film with a weak rutile seed crystallizes at a lower temperature into the anatase structure, while a film with a relatively strong rutile base crystallizes into the rutile structure at a somewhat higher temperature. It is demonstrated that Raman spectroscopy is a simple and effective tool for characterization of these submicron-thick amorphous films and for the dynamical study of such a phase transformation. Accompanying this amorphous-crystalline transformation, a two-order increase in elastic light scattering is noted implying optical degradation associated with microcrystalline boundaries. In addition, results of the anatase–rutile transformation at a temperature near 900 °C are presented.

This work investigates the charge transfer and Al(Ga) p-Ni d hybridization effects in the intermetallic Ni3Al (Ni3Ga) alloy using the Ni L3,2 and K edge and Al (Ga) K x-ray absorption near edge structure (XANES) measurements. We find that the intensity of near-edge features at the Ni L3 edge in the Ni3Al (Ni3Ga) alloy decreased with respect to that of pure Ni, which implies a reduction of the number of unoccupied Ni 3d states and an enhancement of the Ni 3d state filling in the Ni3Al (Ni3Ga) alloy. Two clear features are also observed in the Ni3Al (Ni3Ga) XANES spectrum at the Al (Ga) K edge, which can be assigned to unoccupied Al 3p-(Ga 4p-) derived states in Ni3Al (Ni3Ga). The threshold at the Al K-edge XANES for Ni3Al shifts towards the higher photon energy relative to that of pure Al, suggesting that Al loses some p-orbital charge upon forming Ni3Al. On the other hand, the Ni K edge shifts towards the lower photon energy in Ni3Al (Ni3Ga) relative to that of pure Ni, suggesting a gain of charge at the Ni site. Thus both Al and Ni K-edge XANES results imply a transfer of charge from Al 3p orbital to Ni sites. Our theoretical calculations using the spin-polarized first-principles pseudofunction method agree with these results.

The electronic structures of Ni 3 Al, Ni 3 Ga, Ni 3 In, and NiGa are studied by x-ray absorption near-edge spectra ͑XANES͒ at the Ni and Ga K edges. The XANES spectra are compared with those calculated with theory. The experimental XANES features for these compounds reflect the Ni-and Ga-p unoccupied density of states. The calculated magnetic moments for Ni 3 Al, Ni 3 Ga, and Ni 3 In are between 0.7-0.8 B /cell. The number of 3d holes per Ni atom is calculated for Ni 3 Al, Ni 3 Ga, and Ni 3 In. These numbers show correlation with heats of formation of the bulk compounds.

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