Function Of N2 Partial Pressure Research Articles

Structural and optical properties of sputtered gadolinium nitride films

Rare-earth (RE) materials have high magnetic moments and form a wide range of magnetic structures. There has been speculation in the literature that rare-earth nitrides may form half-metallic ferromagnetics. This is surprising because, based on a simple ionic model, trivalent rare-earth nitrides would be expected to be insulators with a similar electronic structure to the divalent rare-earth chalcogenides. However if it is the case that they are half-metallic or narrow gap insulators, then they have potential applications in spin-filtering devices. In the present investigation, We have deposited GdN films on glass substrate at room temperature by Ar/N2 mixed gas plasma-radio frequency (rf) sputtering method. The structure and the complex optical properties as well as the energy gap of GdN thin films as a function of N2 partial pressure are determined.

Fabrication of Continuous‐SiC‐Fiber‐Reinforced SiAlON‐Based Ceramic Composites by Reactive Melt Infiltration

A technique for fabrication of β′‐SiAlON‐based ceramics in three‐dimensional woven fabrics of BN‐coated SiC (Hi‐Nicalon™) fibers was developed by reactive melt infiltration in a controlled N2 atmosphere. β′‐SiAlON was produced in situ by the reaction of β‐Si3N4, AlN, and Y‐Al‐Si‐O molten glass. The wettability of the fibers with the molten glass was improved by infiltration and pyrolysis of perhydropolysilazane, resulting in fully dense matrix composites. The reaction between the fiber and molten glass could be depressed by increasing the N2 partial pressure during the melt infiltration. The inhibition of the interfacial reaction may be related to the formation of carbon and oxynitride on the SiC fiber, in agreement with thermodynamic calculations as a function of N2 partial pressure. The fabricated composites had a high ultimate flexure strength and a large work of fracture at room temperature. Degradation of the mechanical performance of the composites was small, even at 1773 K in an argon atmosphere.

Single-phase aluminum nitride films by dc-magnetron sputtering

Single-phase aluminum nitride films were deposited onto fused quartz and single-crystal sapphire by current-controlled, reactive, de magnetron sputtering from an aluminum metal target. Optical and structural properties were observed to correlate systematically with the composition of the sputter gas over a wide range of nitrogen partial pressures. A transition in the electrical conductivity of the deposited films occurred as a function of N2 partial pressure. This transition is driven by the condition of the target surface. When the N2 partial pressure was high and the target surface was substantially covered with AlNx, the deposited film was insulating, stoichiometric AlN. When the N2 partial pressure was low and the target surface was substantially Al°, the deposited film was conducting, substoichiometric AlNx.