Abstract
The application of thin coatings of the purple gold intermetallic compound AuAl2 provides a possible alternative to the use of this material in the bulk form. Here we explore the properties of AuAl2 coatings prepared by vacuum deposition onto heated substrates. Control of the thickness and microstructure of the deposit allowed the optical properties of the film to be tuned over a wide range. The properties were characterised using CIE LAB colour coordinates, and by measurement and calculation of reflection and transmission spectra. Reflection colours could be varied at will between dark-silver through to light purple, and were largely a function of the degree of crystallization of the deposit. Transmission colours could be varied from light to dark greenish-brown, and were a function of both microstructure and film thickness. The complex refractive indices,n(λ) +i.k(λ), and ε1(λ)+ε2(λ), of AuAl2 were determined from the experimental measurements and are provided in tabular form. Proof-of-concept jewellery items were successfully produced to showcase the decorative aspects of this technology. Finally the possibility of using AuAl2 as a spectrally selective coating on architectural glass was considered. Use of it would certainly provide a degree of solar screening with a somewhat more neutral colour than elemental Au coatings, but the figure-of-merit,T vis /T sol, for the pure Au film is always better when compared at the same luminance.
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References
W.C. Roberts-Austen,Proc. Roy. Soc., 1892,50, 367
C. Cretu and E. van der Lingen,Gold Bull., 1999,32, 115
R.W. Cahn,Nature, 1998,396, 523
K.E. Saeger and J. Rodies,Gold Bull., 1977,10, 10
C.T. Heycock and F.H. Neville,Proc. R. Soc. Lond., 1899,66, 20
C.W. Corti, Blue, black and purple! The special colours of gold, in International Jewellery Symposium, St Petersburg, Russia (International Jewelry Symposium, St Petersburg) 2006
N.S. Stoloff, C.T. Liu and S.C. Deevi,Intermetallics, 2000,8, 1313
M.B. Cortie and C.E. Mavrocordatos,Metallurgical Transactions A, 1991,22A, 11
S. Steinemann, Intermetallic compound, method for producing the compound, and use of the compound,US Patent 4,911,762 (1990)
anon.,http://www.aspial.com
K. Wongpreedee, T. Tansakul, H.J. Schustere and K. Chookruvong, Purple gold: Past, present, and future to ductile intermetallics, in Gold2006: New Industrial Applications for Gold, Limerick, Ireland (World Gold Council) 2006
S. Fukayama, Purple sintered gold alloy for ornamentation, Japanese Patent JP 62240729 (1987)
S. Yamazaki, N. Ishii and K. Sawada, Noble metal ornament member and its production method, and ornament part and accessory part, Japanese Patent JP 2003/183710 (2003)
M. Yukio, Purple gold alloy wire and its manufacture, Japanese Patent JP 4176829 (1992)
O. Watanabe and H. Yamamoto, 18-Karat purple gold, Japanese Patent JP 61030642 (1986)
P.C. Loh, Jewelry alloy composition,United States Patent 6,929,776 (2005)
J.H. Wernick, A. Menth, T.H. Geballe, G. Hull and J.P. Maita,J. Phys. Chem. Solids, 1969,30, 1949
H.M. Tutuncu, H. Altuntas, G.P. Srivastava and G. Ugur,Physica Status Solidi (c), 2004,1, 3027
H.R. Philipp,Physica Status Solidi (a), 1982,69, 547
S. Morohashi, T. Imamura and H. Shibayama,Japanese Journal of Applied Physics, 1982,21, L661
C. Mitterer, H. Lenhart, P.H. Mayrhofer and M. Kathrein,Intermetallics, 2004,12, 579
D. van Vechten, L.B. Holdeman, R.J. Soulen and J. Toots,Journal of Low Temperature Physics, 1983,51, 329
M.B. Cortie, A.I. Maaroof and G.B. Smith,Gold Bull., 2005,38, 15
A.I. Maaroof, M.B. Cortie and G.B. Smith,J. Opt. A: Pure Appl. Opt., 2005,7, 303
A. Mortari, A. Maaroof, D. Martin and M.B. Cortie,Sensors and Actuators B, 2007,123, 262
M.B. Cortie, A.I. Maaroof, N. Stokes and A. Mortari,Australian J. of Chemistry, 2007,60, 524
S.K. Prasad. Advanced Wirebond Interconnection Technology (Springer, New York, 2004)
E. Philofsky,Solid-State Electronics, 1970,13, 1391
J.A. Rayne,Physics Letters, 1963,7, 114
J.T. Longo, P.A. Schroeder and D.J. Sellmyer,Physics Letters, 1967,25A, 747
J.T. Longo, P.A. Schroeder and D.J. Sellmyer,Physical Review, 1969,182, 658
J.E. Schirber and A.C. Switendick,Sol. Stat. Comm., 1970,8, 1383
G.C. Carter, I.D. Weisman and L.H. Bennett,Phys. Rev. B, 1972,5, 3621
T.K. Sham, M.L. Perlman and R.E. Watson,Phys. Rev. B, 1979,19, 539
S. Hufner, J.H. Wernick and K.W. West,Sol. Stat. Comm., 1972,10, 1013
J.C. Fuggle, E. Kallne, L.M. Watson and D.J. Fabian,Phys. Rev. B, 1977,16, 750
P.M.T.M. van Attekum, G.K. Wertheim, G. Crecelius and J.H. Wernick,Phys. Rev. B, 1980,22, 3998
I. Perez, B. Qi, G. Liang, F. Lu, M. Croft and D. Wieliczka,Phys. Rev. B, 1988,38, 12233
J.G. Nelson, W.J. Gignac, S. Kim, J.R. Lince and R.S. Williams,Phys. Rev. B, 1985,31, 3469
W.J. Brya,Sol. Stat. Comm., 1971,9, 2271
L.-S. Hsu, G.Y. Guo, J.D. Denlinger and J.W. Allen,J. Phys. Chem. Solids, 2001,62, 1047
S.S. Vishnubhatla and J.P. Jan,Philosophical Magazine, 1967,16, 45
L.Y. Chen and D.W. Lynch,Physica Status Solidi (b), 1988,148, 387
E308-01, Standard Practice for Computing the Colors of Objects by Using the CIE System, American Society for Testing and Materials (ASTM), 2001
J.H. Weaver and H.P.R. Frederikse. in CRC Handbook of Chemistry and Physics (ed. Lide, D.R.) 12 (CRC Press, Boca Raton, 2001)
G159-98, Standard Tables for References Solar Spectral Irradiance at Air Mass 1.5: Direct Normal and Hemispherical for a 37° Tilted Surface, American Society for Testing and Materials (ASTM), 1998
P. Laven, MiePlot. A computer program for scattering of light from a sphere using Mie theory & the Debye series, http://www.philiplaven.com/ mieplot.htm, accessed 10th April 2007
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Ms Supitcha Supansomboon is a materials scientist in the Department of General Science, Faculty of Science, Srinakharinwirot, University, Bangkok, Thailand. She specialises in the materials engineering aspects of jewellery, but also holds a Gradate Diploma in Materials Engineering and an M.Eng on the properties of silk from King Mongkut’s University of Technology Thonburi in Thailand.
Dr Abbas Maaroof is a Post Doctoral Researcher at the University of Technology Sydney, Australia. A graduate of the Universities of Baghdad, Iraq, and Reading, U.K., he specialises in the fabrication and characterization of thin films, and in optics and optical phenomena.
Prof. Michael Cortie is the Director of the Institute for Nanoscale Technology at the University of Technology Sydney. The Institute specialises in the optical properties of materials at the nanoscale, and in precious metals nanotechnology. Michael is a graduate of the Universities of Witwatersrand and Pretoria, in South Africa but now resides in Australia.
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Supansomboon, S., Maaroof, A. & Cortie, M.B. “Purple glory”: The optical properties and technology of AuAl2 coatings. Gold Bull 41, 296–304 (2008). https://doi.org/10.1007/BF03214887
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DOI: https://doi.org/10.1007/BF03214887