Optical Properties of Au-Pt and Au-Pt-In Alloys

Shiraishi, Takashi; Hisatsune, Kazuhito; Tanaka, Yasuhiro; Miura, Eri; Takuma, Yasuko

doi:10.1007/bf03214825

Cited by 25 publications

(17 citation statements)

References 8 publications

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“…In particular, bimetallic platinumbased catalysts have been proposed as promising alternatives to the exceedingly expensive pure Pt electrocatalysts and are already widely used in industry and for proton exchange membrane (PEM) fuel cells. 1,2 Among numerous possible metal combinations, Au-Pt NPs have been studied intensively because of their optical properties, 3 their potential as selective oxidation 4,5 and dehydrogenation catalysts, 6 electrocatalysts, 7,8,9 and selective sensors. Cationic Au-Pt clusters have shown unique reactivity for C-N coupling of methane and ammonia.…”

Section: Introductionmentioning

confidence: 99%

Bimetallic Au-Pt nanoparticles synthesized by radiolysis: Application in electro-catalysis

et al. 2010

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Section: Introductionmentioning

confidence: 99%

Bimetallic Au-Pt nanoparticles synthesized by radiolysis: Application in electro-catalysis

et al. 2010

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“…3. This marked decrease in reflectance in the long-wavelength range in the Au-Pt binary alloy was considered to be due to the formation of "virtual bound state" of electrons [3], as first suggested by Friedel [4]. By adding a small amount of base metals (In, Sn, Fe) to the parent alloy AP10, reflectance in the long-wavelength range slightly increased.…”

Section: Methodsmentioning

confidence: 72%

“…We evaluated color difference, E*, between the reference alloy AP10 and the other experimental alloys according to the equation (3). The results of the evaluation are presented in Fig.…”

Section: Color Differencementioning

confidence: 99%

“…The amount of base metals added was restricted up to 2 at.% for the ternary alloys and 4 at.% for the quaternary alloys. Since Pt has a strong decolorizing effect [3], a ratio of Pt to Au concentrations in atomic percentage was controlled to be constant at 1 : 9 in all the experimental alloys to highlight the effects of alloying base metals, as indicated in the right column in Table 1.…”

Section: Introductionmentioning

confidence: 99%

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Variations of color with alloying elements in Pd-free Au–Pt-based high noble dental alloys

Shiraishi

Takuma

Miura

et al. 2007

Materials Science and Engineering: B

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The effects of alloying addition of a small amount of base metals (In, Sn, Fe, Zn) on color variations in Pd-free Au-Pt-based high noble dental alloys were investigated in terms of rectilinear and polar color coordinates. The ternary Au-Pt-X (X = In, Sn, Fe, Zn) and quaternary Au-Pt-In-Y (Y = Sn, Fe, Zn) alloys were prepared from high purity component metals. The amount of alloying base metals, X and Y, were restricted up to 2 at.%. The alloying addition of a small amount of Fe, In, Sn, to a binary Au-10 at.% Pt alloy (referred to as AP10) effectively increased chroma, C*. On the other hand, the addition of Zn to the parent alloy AP10 did not change color coordinates greatly. The increase in chroma in the present Au-Pt-based high noble alloys was attributed to the increase in the slope of spectral reflectance curve at its absorption edge near 515 nm. It was found that the addition of a small amount of Fe to the parent alloy AP10 markedly increased lightness, L*, and the addition of Sn gave a very light tint of red to the parent alloy. Although red-green chromaticity index a* contributed to chroma to some extent, contribution of yellow-blue chromaticity index b* was much greater in determining chroma in this Pd-free Au-Pt-based multi-component alloys. The present results are expected to be valuable in case color is to be taken into account in designing Pd-free Au-Pt-based high noble dental alloys.

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“…Due to this effect, the absorption process of light starts in the infrared range (15). In fact, marked decreases in reflectance in the long-wavelength range were evidenced when Au was alloyed with Pd (7) and with Pt (8,16). Based on the "virtual bound states" theory by Friedel (15) and the previously reported experimental evidences for the binary Au-Pd (7) and Au-Pt (8, 16) systems, it may be reasonable to mention that an enhanced formation of "virtual bound states" would occur when both Pd and Pt are added to Au.…”

Section: Figurementioning

confidence: 99%

Optical properties of Au−Pt−Pd-based high noble dental alloys

Shiraishi

Geis-Gerstorfer

2006

Gold Bull

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of Au-Pt-Pd-based high noble dental alloys. That is, by increasing e/a-value, a*-, b*-, C*-coordinates systematically increased, giving a slight gold tinge to the parent Au-Pt-Pd alloy within the limitation that the structure of an alloy is a single phase. The addition of Sn of 2 mass % or more produced a small amount of the second phase of possible intermetallic compounds between Sn and Pd or Pt. The coexistence of a small amount of the second phase of possible intermetallic compounds further increased a gold tinge. However, the inclusion of 4 mass % Sn to the parent Au-Pt-Pd alloy gave a very light tint of red to the alloy. Results of the present study are expected to be useful in controlling colour of Au-Pt-Pd-based high noble dental alloys. KeywordsGold alloy, dental alloy, colour, spectral reflectance, spectrophotometric colourimetry, chromaticity index IntroductionThe use of porcelain-fused-to-metal (PFM) dental restorations has achieved widespread acceptance, and several high nobility alloys are available for this specific application (1). Among various types of alloys for PFM restorations, the Au-PtPd-based high noble alloys have the advantage of having been around for some considerable time and clinical experience has shown that they are extremely successful (2). In particular, the bond between the ceramic and the metal is very strong and highly reliable (2). Concerning the formulations of these Au-Pt-Pd-based high noble alloys for porcelain bonding, high Au contents are required to ensure biocompatibility and large Pt and Pd concentrations are necessary to raise the melting range sufficiently above the porcelain firing temperature to prevent distortion during porcelain application (2, 3). A minimum content of about 5% Pd is recommended to increase the sag resistance (4). Base metals such as In, Sn, Zn are added to form a thin oxide film at the surface of the alloy during the porcelain firing cycle (4). In addition to the extremely successful clinical experience, the attraction of the Au-Pt-Pd-based high noble alloys is with the light-yellow colour (b* typically ranges from 9 to 12) (3). German et al. (5) mentioned that although the primary concerns about cast dental restorations are with biocompatibility and corrosion and tarnish resistance, it would be naïve to discount the strong emotional attachment to selected alloy colours involving gold. According to German (3), it is easier to meet the physical and mechanical property requirements for a ceramo-metal alloy using just the Au-Pdbased alloys. However, these alloys tend to be very light in colour (b* 6-8) and have not been universally accepted in spite of the very attractive properties (3). The whitish colour of these Au-Pd-based PFM alloys is considered to be due to the very high level of Pd content of 35 to 45%. Hence, it is suggested that colour control must be taken into account as one of the criteria in manufacturing dental gold alloys not only for crown and bridge restorations but also for PFM restorations.In the present study, we designed sev...

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Optical Properties of Au-Pt and Au-Pt-In Alloys

Cited by 25 publications

References 8 publications

Bimetallic Au-Pt nanoparticles synthesized by radiolysis: Application in electro-catalysis

Bimetallic Au-Pt nanoparticles synthesized by radiolysis: Application in electro-catalysis

Variations of color with alloying elements in Pd-free Au–Pt-based high noble dental alloys

Optical properties of Au−Pt−Pd-based high noble dental alloys

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