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Proceedings Paper

Phosphide-based materials as hard optical coatings
Author(s): Keith L. Lewis; James Anthony Savage
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Paper Abstract

A requirement exists for more durable windows for airborne applications to improve their survivability under highly erosive conditions. A range of materials show potential including nitrides, phosphides, carbides and diamond. This paper will address the phosphide materials system and review the various possibilities available. Materials such as gallium phosphide show promise for use In the infrared on the basis of their behaviour in bulk form, with significant lattice absorption bands only apparent at wavelengths beyond l2jnn. Other known phosphides include those of Al, B, Si, Mg, In, Zn, Cd, Rb, Ir, Ni, Go, Y, Sc, Ti, Nb, Mo, W, Th as well as several of the rare earth elements. Ternary systen have also been examined, largely as bulk materials. Recently the potential of phosphide materials for infra-red applications has been highlighted by the deinstration of high durability in amorphous coatings of boron phosphide deposited by plasma assisted chemcal vapour deposition. The levels of durability obtained have exceeded those characteristic of diamond-like carbon, whilst allowing simultaneous transmission of both IR bands and the important 1.O6im wavelength. Here there is significant evidence of the role of non-stoichiometry, with P/B ratios of as high as 7 being typical. Some forms of amorphous phosphorus itself have been known to demonstrate remarkable stability, with samples remaining atomically clean in dry air for significant periods of time. Various other forms of high phosphorus polyphosphides are known, such as those containing alkali metals in a bridging configuration between phosphorus skeletons. These can be produced as thin films and exhibit high levels of stability and adhesion.

Paper Details

Date Published: 1 August 1990
PDF: 6 pages
Proc. SPIE 1275, Hard Materials in Optics, (1 August 1990); doi: 10.1117/12.20515
Show Author Affiliations
Keith L. Lewis, Royal Signals and Radar Establishment (United Kingdom)
James Anthony Savage, Royal Signals and Radar Establishment (United Kingdom)

Published in SPIE Proceedings Vol. 1275:
Hard Materials in Optics
Carl-Gustaf Ribbing, Editor(s)

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