JP6664687B2 - Pt alloy, jewelry and ornaments - Google Patents

Description

  The present invention relates to a platinum (Pt) alloy, jewelry and ornaments.

  Since ancient times, platinum represented by the element symbol Pt has a peculiar white luster and has chemically stable properties. For this reason, it is often referred to as platinum and is widely used in jewelry or ornaments. Have been.

Platinum is generally used utilizing a unique and shiny silver color inherent in platinum.
However, due to the luster or stable properties of platinum, colored Pt alloys can be applied to jewelry or decoration applications while taking advantage of the luster of platinum, or in addition to jewelry or decoration in anticipation of the chemical stability of platinum. There is a demand for application to such uses.

As a technique related to the coloring of platinum, a document showing that the color changes by adding copper (Cu) to Al ₂ Pt has been reported (for example, see Non-Patent Document 1).

Attempts have been made to add various kinds of colors by adding, for example, copper (Cu) to an intermetallic compound Al ₂ Pt containing platinum and aluminum (for example, see Patent Documents 1 and 2). Further, there is a disclosure of a composite material having a first phase containing Pt as a main component and a second phase containing at least Cu and Au and further containing Pd and Ag (for example, see Patent Document 3).

JP 2009-30154 A JP-A-3-158430 JP 2009-30156 A

J. Hurly and P.T.Wedepohl, Journal of Materials Science, 28, 5648 (1993), “Optical properties of colored platinum intermetallic compounds”

  However, in the techniques described in the above-mentioned papers and patent documents, although copper or the like is added to platinum to develop a hue other than the hue peculiar to platinum, it is considered that each of them comprises a plurality of phases such as a mixture. And color tone cannot be designed. There has been no report on the composition of an alloy having a single-phase structure that can easily secure a stable color tone and can be designed with a uniform color tone.

  The present invention has been made in view of the above, and has a single-phase structure and a hue different from the hue specific to platinum (preferably, a warm hue having a reflection spectrum having a high intensity at a wavelength of 550 nm or more. The object of the present invention is to provide a Pt alloy exhibiting (1), jewelry and ornaments, and to achieve this object.

Specific means for achieving the above object include the following aspects.
<1> In a crystal lattice of an alloy including a platinum element (Pt) and at least one type of metal element A other than Pt, a transition metal element M different from the metal elements A and Pt is formed as a solid solution atom. It is a Pt alloy that exists and has a single-phase structure.
<2> The Pt alloy according to <1>, wherein the crystal structure is a fluorite-type crystal structure.
<3> The metal element A according to <1> or <2>, wherein the metal element A is an element selected from aluminum (Al), gallium (Ga), tin (Sn), manganese (Mn), and indium (In). It is a Pt alloy.
<4> The transition metal element M exists as a solid solution atom by penetrating into voids inside the crystal lattice in the crystal structure or replacing the metal element A or Pt in the crystal lattice. <1> ~ The Pt alloy according to any one of <3>.
<5> The Pt alloy according to any one of <1> to <4>, wherein the intensity of the average reflection spectrum at a wavelength of 350 nm to 500 nm is smaller than the intensity of the average reflection spectrum at a wavelength of 550 nm to 800 nm.
<6> Composition formula: (Al ₂ Pt) _1−x M _x [M represents a transition metal element different from metal elements A and Pt, and x satisfies 15 atomic% <x <25 atomic%. . ] The Pt alloy according to any one of <1> to <5>.
<7> The platinum alloy according to any one of <1> to <6>, wherein the transition metal element M is copper (Cu).
<8> A jewelry containing the Pt alloy according to any one of <1> to <7>.
<9> A decorative article containing the Pt alloy according to any one of <1> to <7>.

  According to the present invention, a Pt alloy having a single-phase structure and exhibiting a hue different from the hue specific to platinum (preferably, a warm color hue having a high reflection spectrum intensity at a wavelength of 550 nm or more), and Jewelry and decorations are provided.

It is a diagram of a crystal structure for explaining the Al 2 crystal lattice inside the voids in the _Pt (site). FIG. 2 is a diagram of a crystal structure for explaining that Cu invades voids (sites) in FIG. 1 and Cu exists as a solid solution atom. FIG. 4 is a diffraction diagram of powdery Pt alloys having different Cu ratios, as measured by powder X-ray diffraction. It is a graph which shows the intensity of the reflection spectrum with respect to wavelength. 5 is a photograph showing a state in which a polished alloy piece (a jewelry material) is accommodated in a holder during reflection spectrum measurement. It is a Pt-Sn state diagram. FIG. 3 is a phase diagram of a ternary alloy containing Al, Pt, and nickel (Ni).

  Hereinafter, the Pt alloy of the present invention and jewelry and ornaments using the Pt alloy will be described in detail.

<Platinum alloy>
In the Pt alloy of the present invention, a metal element A and a transition metal element M different from Pt are solidified in a crystal lattice of a crystal structure of an alloy including a platinum element (Pt) and at least one metal element A other than Pt. It exists as a dissolved atom and has a single-phase structure.

Conventionally, attempts have been made to add various kinds of colors by adding, for example, copper (Cu) to an intermetallic compound (for example, Al ₂ Pt) containing Pt and a metal element other than Pt. However, in each case, the color is only affected by being made into a mixed system to form a plurality of phases. In a system in which a plurality of phases are generated, it is not possible to design a nonuniform color tone.
In view of the above situation, in the platinum alloy of the present invention (hereinafter, also referred to as a Pt alloy), the metal elements A and Pt are included in the crystal lattice of the crystal structure of the alloy including Pt and the metal element A other than Pt. It has a single-phase structure in which different transition metal elements M exist.
In the crystal lattice of a Pt alloy containing Pt and a metal element A other than Pt, a transition metal element M having an atomic radius different from that of the Pt and the metal element A is present as a solid solution atom, whereby the structure of the Pt alloy is obtained. Changes according to the ratio of the transition metal element M, and the electronic state of the alloy can be continuously changed according to the ratio of the transition metal element M. At this time, the transition metal element M forms a solid solution in the Pt alloy, so that a Pt alloy which is a solid solution having a changed electronic state is obtained. Based on such knowledge, in the present invention, the absorption wavelength of the Pt alloy can be continuously changed, and the hue of the Pt alloy observed from the outside can be changed to a desired hue (for example, a yellow hue to a red hue ( A Pt alloy adjusted to a warm hue (including pink and orange) can be provided. The Pt alloy having a single-phase structure can be designed with a color tone, so that the color tone can be easily controlled, and has high value as jewelry and ornaments.

  The present invention is based on the finding that the change in hue of a Pt alloy affects the electronic state of the alloy itself due to the change in the location of the transition metal element M in the alloy and the structure of the alloy. The location of the transition metal element M can be determined by the type of the transition metal element M. Further, the change in the structure of the alloy is adjusted by the difference between the form in which the transition metal element M has penetrated or the form in which the transition metal element M has been substituted.

  The Pt alloy of the present invention has a crystal structure including the metal elements A and Pt. The metal element A may include not only one kind but also two or more kinds.

The metal element A includes a nonmetal element and a metal element other than Pt, and also includes a metalloid element such as aluminum (Al). As the metal element A, an element that easily forms an alloy with Pt is preferable. Examples of preferable elements include aluminum (Al), gallium (Ga), tin (Sn), manganese (Mn), and indium ( In) selected from metal elements.
Among them, the case where the metal element A is solely included in the crystal structure of the alloy is preferable.

The crystal structure of the alloy containing the metal elements A and Pt is preferably a fluorite type (CaF ₂ type) crystal structure. In the case of an alloy having a fluorite type crystal structure, by including a transition metal element M other than the metal element A and Pt, the absorption wavelength of the alloy (that is, the hue of the alloy) can be improved while maintaining a single-phase structure. It can be changed suitably.
When the Pt alloy has a fluorite-type crystal structure, a mode in which two or more metal elements A are included in the crystal structure of the Pt alloy may be used.

Examples of the alloy containing the metal element A and having a fluorite crystal structure include Al ₂ Pt, Ga ₂ Pt, MnPtSn, and PtSn ₂ .

  In the Pt alloy of the present invention, a transition metal element M different from the metal element A and the platinum element is contained in the crystal lattice in the crystal structure of the alloy. By including a transition metal element M having a different atomic radius from the metal elements A and Pt in the crystal structure of the metal elements A and Pt, the crystal structure swells or contracts and changes the electronic state. Can be. This changes the light absorption wavelength of the alloy itself. Therefore, a change in hue when the alloy is observed from the outside can be brought about.

  In the platinum alloy of the present invention, the ratio of the transition metal element M to the metal elements A and Pt [M / (A + Pt)] is more than 0 atom% / 100 atom% and 25 atom% / 75 atom from the viewpoint of the number of void sites. % Or less, and more preferably 5 atomic% / 95 atomic% or more and 20 atomic% / 80 atomic% or less.

  The transition metal element M may be present inside the crystal lattice in the crystal structure of the alloy by entering voids inside the metal crystal lattice. In this case, the crystal lattice is deformed by the size of the atomic radius of the transition metal element M, and the electronic state of the entire alloy is changed by the type of the transition metal element M. Generally, when the atomic radius of the transition metal element M is the same as or smaller than the atomic radii of the metal elements A and Pt, the interstitial crystal structure (interstitial type) in which the transition metal element M enters the voids inside the crystal lattice of the alloy (Solid solution).

“A void inside the crystal lattice in the crystal structure of the alloy” refers to a site in the crystal structure where a metal element given from outside the structure can enter the original crystal structure of the alloy (hereinafter also referred to as an intra-crystal void). )). For example, in the case of Al ₂ Pt, as shown in FIG. 1, it refers to a 4b site which is a space in the crystal into which the transition metal element M can enter.

  Further, the transition metal element M may be present inside the crystal lattice in the crystal structure of the alloy by entering by replacing the metal element A or Pt in the crystal lattice of the metal. Also in this case, as in the case of the interstitial crystal structure, the crystal lattice is deformed by the size of the atomic radius of the transition metal element M, and the electronic state of the entire alloy is changed by the type of the transition metal element M. Generally, when the atomic radius of the transition metal element M is larger than the atomic radii of the metal elements A and Pt, the transition metal element M replaces the atoms forming the crystal lattice and enters the substitution type crystal structure (substitution type solid solution). ) Easy to be.

The fact that the crystal structure of the alloy is an interstitial crystal structure or a substitutional crystal structure means that the lattice constant of the crystal structure of the alloy (eg, Al ₂ Pt) or the size of the unit cell is a theoretical value (eg, the lattice constant of Al ₂ Pt or (Calculated value of the unit cell size).
Note that the fact that the transition metal element M has entered the crystal lattice of the metal as a solid solution atom is confirmed by the absence of peaks of an unknown phase and a second phase in a diffraction pattern obtained by powder X-ray diffraction measurement. It is possible.

The lattice constant of the crystal structure of the alloy or the size of the unit cell is compared with the theoretical value by the diffraction angle of Al ₂ Pt (= the angle 2θ between the incident X-ray direction and the diffracted X-ray direction) by powder X-ray diffraction measurement. (Θ: Bragg angle)) and its X-ray intensity. Changes in the lattice constant or unit cell size can be confirmed by peak shifts. For example, in the powder X-ray diffraction measurement of FIG. 3, in a range where the diffraction angle 2θ of Al ₂ Pt is a high angle of 75 ° (degree) or more, the specific diffraction peak gradually shifts to the low angle side with the Cu ratio. It can be confirmed from that.

  The Pt alloy of the present invention has a single phase structure. The Pt alloy of the present invention is different from the metal phase forming the alloy in that the metal element A, Pt, and the transition metal element M are all present in a single phase. Are distinguished from conventional alloys in which the element

The fact that the alloy has a “single-phase structure” can be confirmed from a diffraction pattern obtained by powder X-ray diffraction measurement. Specifically, for example, as shown in the powder X-ray diffraction measurement of FIG. 3, Cu-containing Al ₂ Pt [eg (Al ₂ Pt) ₈₀ Cu ₂₀ ] is compared with Cu-free Al ₂ Pt. Since no different peaks appear at any of the diffraction angles (2θ), it can be understood that there is no peak of the unknown phase and the second phase, and the structure has a single phase structure.

In the platinum alloy of the present invention, the intensity (R ₁ ) of the average reflection spectrum at a wavelength of 350 nm to 500 nm is preferably smaller than the intensity (R ₂ ) of the average reflection spectrum at a wavelength of 550 nm to 800 nm. The average reflection spectrum intensity _{R 1} is smaller than an average reflection spectrum intensity _{R 2,} of the visible light region, the absorption wavelength 350 nm to 500 nm (particularly absorption bluish hue to purplish) is large, the wavelength range of 350 nm to 500 nm A platinum alloy that reflects a hue of a warm color (e.g., a yellow hue to a red hue that is a complementary color of a blue hue to a purple color) corresponding to a wavelength region of 570 nm to 750 nm, which is a complementary color of the hue, that is, a warm color hue. Indicates that it is a platinum alloy exhibiting a hue. The yellow to red hues include orange to pink.
In the Pt alloy, as the ratio of the transition metal element M increases, the crystal lattice expands or contracts (for example, when M = Cu, the crystal lattice expands with an increase in the amount of Cu; that is, for example, as shown in FIG. (The diffraction peak shifts to the lower angle side within the range of 2θ ≧ 75 °), and the minimum value of the reflection spectrum in the visible region (that is, the maximum absorption wavelength) shifts accordingly. For example, in the case of M = Cu, the wavelength shifts to the wavelength region on the reddish hue side (that is, for example, the minimum value shifts to the longer wavelength side as shown in FIG. 4).
In particular, the strength of the average reflectance spectrum at wavelengths 450nm~500nm is more preferably less than intensity _{R 2} of average reflection spectrum at a wavelength 550Nm～800nm.
The above-mentioned reflection spectrum is a value obtained by measuring a wavelength range of 200 nm to 800 nm using an ultraviolet-visible near-infrared spectrophotometer (UV-2600, manufactured by Shimadzu Corporation).

As the platinum alloy of the present invention, an alloy represented by the following composition formula is preferable from the viewpoint of exhibiting a warm hue (particularly a pink to red hue).
<Composition formula>
(Al ₂ Pt) _1-x M _x
In the formula, M represents a transition metal element different from the metal element A and the platinum element.
Further, x represents the atomic ratio [atomic%] in the composition, and can be in the range of 0 atomic% <x <25 atomic%, and more preferably, 15 atomic% <x <25 atomic%. .
Note that the metal element A refers to a metal element not containing a platinum element, and the range of the metal element is as described above.

  As M, among the transition metal elements, copper (Cu), nickel (Ni), cobalt (Co), chromium (Cr), vanadium (V), silver (Ag), and gold (Au) are preferable, and more preferably. , Cu.

  If x is greater than 15 atomic%, the platinum alloy reflects pink to reddish hues. That is, a platinum alloy exhibiting a pink to reddish hue is obtained. When x is less than 25 atomic%, the hue does not easily approach the red hue, and a pink hue is easily obtained.

The platinum alloy of the present invention can be produced by mixing a metal atom A (for example, Al), Pt, and a transition metal element M (for example, Cu) using a vacuum arc melting apparatus and performing arc melting. .
Arc melting is performed by placing a sample prepared as a raw material for supply of each element on the same water-cooled copper hearth, performing vacuum evacuation to a predetermined pressure, and applying a desired current value under an inert gas atmosphere. I can do it. For example, after evacuation, arc melting may be performed under an inert gas of, for example, 0.01 MPa to 0.1 MPa.

The pressure at the time of arc melting can be adjusted, for example, to a range of 1 × 10 ⁻² Pa or less by vacuuming.

  As the inert gas atmosphere, an atmosphere replaced with a nitrogen gas or a rare gas (such as helium (He) or argon (Ar)) is preferable.

  It is preferable that the current value applied at the time of arc melting be adjusted in a range of, for example, 20 A (ampere) to 100 A. The voltage application time may be appropriately selected depending on the case, for example, voltage application for 5 to 30 seconds is performed four times, for example.

<Jewellery and ornaments>
The jewelry and ornaments of the present invention include the above-described platinum alloy of the present invention. Since the above-mentioned platinum alloy of the present invention is used for jewelry, a treasure exhibiting a different hue (preferably a warm hue) and luster from the case of using general Pt due to the colored Pt alloy. A jewelry is obtained, and is expected to have a value as a jewelry as well as a jewelry so-called platinum.
In addition, since the above-described platinum alloy of the present invention is used for a decorative article, in various applications, it exhibits a hue (preferably a warm color hue) and luster different from those in the case of using conventional general Pt, In addition, a stable decoration effect is expected over a long period of time. Since the colored platinum alloy of the present invention has a single-phase structure, it is controlled to have a uniform color tone, and has high value as jewelry and ornaments.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention. Unless otherwise specified, “parts” are based on mass.

(Example 1)
-Weighing-
As a platinum (Pt) raw material, a Pt plate (shape: plate, purity: 99.95%) manufactured by Katagiri Kikinzoku Kogyo Co., Ltd. is prepared, and as a copper (Cu) raw material, a Cu plate piece (shape) manufactured by Hirano Kiyoemon Co., Ltd. is used. : Chip, purity: 99.99%). Further, Al particles (shape: grain, purity: 99.99%) manufactured by Kojundo Chemical Laboratory Co., Ltd. were prepared as an aluminum (Al) raw material.

The above-mentioned Pt plate and Cu plate piece were cut out to the following size using a nipper (N-31, manufactured by HOZAN) to obtain a sample.
Pt sample: 3 mm to 5 mm × 3 mm to 5 mm × 1 mm to 2 mm plate material Cu sample: 3 mm to 7 mm plate material Further, since the above Al particles are particles having a diameter of 3 mm to 5 mm, they are used as a sample (Al sample) as it is. Was.

Then, the Pt sample, the Cu sample, and the Al sample were adjusted so that the total amount became 0.7 g while changing the Cu content (5 at%, 10 at%, 15 at%, and 20 at%). By weighing, four types of mixed raw materials were obtained. The compositions of the obtained four mixed raw materials are (Al ₂ Pt) ₉₅ Cu _5, (Al ₂ Pt) ₉₀ Cu _10, (Al ₂ Pt) ₈₅ Cu _{15, and} (Al ₂ Pt) ₈₀ Cu ₂₀ , respectively. .
The mixed raw materials were weighed so that the number of lumps was one or two.

−Arc melting−
Next, the mixed samples weighed as described above were respectively placed on a water-cooled copper hearth using an ultra-small vacuum arc melting apparatus (NEV-AD 03, manufactured by Nissin Giken Co., Ltd.), and evacuated for about 2 hours. After the pressure reached 3 × 10 ⁻³ Pa, the current value was adjusted to about 50 A to 100 A in an argon atmosphere to arc-melt each mixed sample, and four types of 5 mm to 7 mm granular alloy samples (Pt, Pt alloy made of Cu and Al).

-Cut-
Each of the alloy samples produced through arc melting was fixed to a precision cutting machine (Isomet 5000, manufactured by BUEHLER), and the number of revolutions was 3,800 rpm using a DISCO blade (GC320PB). It was cut into two pieces under the condition of 2 mm / min to obtain an alloy piece.

-Polishing-
For each of the alloy samples, one of the alloy pieces obtained by cutting was fixed to a sample table, and water-resistant abrasive paper was # 1000, 2000, 4000 using a rotary polishing machine (Doctor Wrap ML-180, manufactured by Maruto). And polished sequentially. Thereafter, the alloy piece was removed from the sample table, and intermediate finishing and final finishing were sequentially performed while holding the alloy piece by hand, thereby producing a jewelry material (jewelry).
The intermediate finish and the final finish were performed using the following abrasives.
<Intermediate finish>
・ Buff: Trident 40-7518 (8 inch), manufactured by BUEHLER ・ Abrasive: Metadai single crystal diamond suspension 40-6531, manufactured by BUEHLER
<Final finish>
・ Buff: Mastertex 40-7778 (8 inches), manufactured by BUEHLER ・ Abrasive: Masterprep 40-6377-064, manufactured by BUEHLER

-Pulverization-
In addition, for each of the alloy samples, the other of the alloy pieces obtained by cutting was ground in acetone for about 10 minutes using an agate mortar. After the acetone was vaporized, the crushed sample, 18 zirconia balls (10 mm), and ethanol (to the extent that the sample and the balls were immersed) were put into a zirconia pot (45 mL), and the ball mill (P-6) was used. And Fritsch Japan Co., Ltd.) under the conditions of a rotation speed of 500 rpm for 30 minutes. Then, it was further rotated in the reverse direction at the same rotation speed, and crushed for 30 minutes. Thus, an alloy powder was produced.

-Preparation of comparative sample-
Next, the Pt sample and the Al sample were weighed so that the total amount was 0.7 g as described below, to obtain a mixed sample for comparison. Since a Cu sample was not used, the composition of the mixed sample for comparison was Al ₂ Pt. Note that the mixed sample was weighed so that the number of lumps could be reduced to one or two.
Then, using a micro vacuum arc melting apparatus (NEV-AD 03, manufactured by Nissin Giken Co., Ltd.), the weighed mixed sample for comparison was placed on a water-cooled copper hearth, and mixed for comparison under the same conditions as above. The sample was arc melted to produce a granular comparative sample (Al ₂ Pt alloy) of 5 mm to 7 mm.

  Using the produced comparative sample, the comparative sample is cut into two pieces to obtain an alloy piece in the same manner as the above-mentioned alloy sample, and one of the alloy pieces is polished to provide a comparative jewelry material (jewelry article). ) Was prepared, and the other alloy piece was pulverized to prepare a comparative alloy powder.

-Measurement and evaluation-
The following measurements were performed using jewelry materials and alloy powders obtained from the four alloy samples or the comparative samples prepared as described above. The measurement results are shown in FIGS.

(1) Powder X-Ray Diffraction Measurement Each of the alloy powders obtained above was packed in a glass sample container of 20 mm × 20 mm × 0.2 mm, and an X-ray diffractometer (Mini Flex 600, radiation source: CuKα, Rigaku Corporation) X-ray powder diffraction measurement was performed at a diffraction angle 2θ of 20 ° to 80 ° under the condition of 1 ° / min.

FIG. 3 shows the measurement results. Note that “Al ₂ Pt calc.” In FIG. 3 indicates a calculated value (theoretical peak) of the diffraction intensity of Al ₂ Pt at a diffraction angle 2θ = 20 ° to 80 °.
As shown in FIG. 3, the diffraction peak of Al ₂ Pt is a theoretical peak calculated, and an alloy sample containing Cu ((Al ₂ Pt) _1−x Cu _x , x (atomic%) = 5) 10, 15, 20; the same applies hereinafter) in comparison with Al ₂ Pt not containing Cu, in which the peaks of the unknown phase and the second phase do not exist. This indicates that the alloy sample containing Cu ((Al ₂ Pt) _1-x Cu _x ) has a single-phase structure Pt alloy regardless of the Cu content.

Further, it can be seen that the diffraction peak appearing in the range where the diffraction angle (2θ) is 75 ° or more gradually shifts to the lower angle side as the Cu content increases. This indicates that the crystal lattice of the Pt alloy expands as the Cu content increases. That is, the alloy sample containing Cu ((Al ₂ Pt) _1-x Cu _x ) is an interstitial solid solution in which Cu has entered voids (4b sites) inside the Al ₂ Pt crystal lattice.

(2) Reflection spectrum Using a UV-visible spectrophotometer (UV-2600, manufactured by Shimadzu Corporation), each of the jewelry materials obtained above was housed in a holder as shown in FIG. Represents barium sulfate.) And the reflection spectrum was measured in the wavelength range of 200 nm to 800 nm.

FIG. 4 shows the measurement results.
As shown in FIG. 4, platinum (metal Pt) showing a flat reflection spectrum in the visible light region, whereas the Pt alloy which is the comparative sample (Al ₂ Pt) has a minimum value of the reflection spectrum (wavelength 400 nm) around 400 nm. The maximum absorption wavelength). Further, it can be seen that as the amount of Cu in the crystal lattice of the Pt alloy increases, the minimum value (maximum absorption wavelength) of the reflection spectrum continuously shifts to the longer wavelength side. That is, the hue of the Pt alloy continuously changes toward the wavelength region exhibiting a reddish hue. When the Cu content in the Pt alloy reaches 15 atomic%, a reddish hue is exhibited. In particular, when the Cu content in the Pt alloy becomes 20 atomic% [(Al ₂ Pt) ₈₀ Cu ₂₀ ], good A pink Pt alloy was obtained.
From the viewpoint of adjusting the hue exhibited by the Pt alloy pink-reddish hue, Pt _alloy has a composition of _{(Al 2 Pt) 1-x} Cu x (15 atomic% <x <25 atomic%) Is preferred.

In the embodiment described above, according to the present invention, Cu, which is a transition metal element M, is present as a solid solution atom in a void of Al ₂ Pt (metal element A = Al) having a fluorite type (CaF ₂ type) crystal structure. Although the Pt alloy described above is specifically described as an example, the present invention is not limited to the present embodiment.
The platinum alloy (Pt alloy) of the present invention has an Al ₂ Pt in which the metal element A is Al even when the metal element A forming the crystal lattice of the alloy is other than Al, for example, Sn, Ga, Mn, or In. The same effect as that of the Pt alloy of the above-described embodiment using the same can be obtained. In this regard, as shown in FIG. 6, for example, Sn ₂ Pt in which the metal element A = Sn can have a fluorite-type (CaF-type) crystal structure like Al ₂ Pt. When the transition metal element M invades or substitutes in the crystal lattice, it is possible to have a crystal structure similar to that of Al ₂ Pt. The same can be said for the case where the metal element A is a metal element A other than Al and Sn (for example, Ga, Mn, In, etc.).

In addition, even when the transition metal element M is, for example, nickel (Ni) other than Cu, the same effect as the Pt alloy of the above embodiment in which Cu has penetrated the voids of Al ₂ Pt can be obtained. In this regard, as shown in FIG. 7, Pt alloy is Ni in the gap for example Al 2 _Pt penetrated is also possible to adopt the same crystal structure as that of Cu in the gap Al 2 _Pt invaded. The same can be said for the case where the metal element M is a transition metal element of Co, Cr, V, Ag, or Au other than Cu and Ni.

  Since the platinum alloy of the present invention has a hue different from that of ordinary Pt while having the original luster and chemical stability of Pt, it can be used in jewelry applications where noble metals are used, or in metal-like appearance and hardness. Alternatively, the present invention can be widely applied to decorative applications such as plating and paint that require durability and the like.

Claims (6)

Fluorite-type crystal structure of an alloy containing platinum element (Pt) and at least one metal element A selected from aluminum (Al), gallium (Ga), tin (Sn), manganese (Mn), and indium (In) The transition metal element M different from the metal elements A and Pt exists as interstitial solid solution atoms penetrating into the voids inside the crystal lattice in the fluorite-type crystal structure , and has a single-phase structure. Pt alloy. The Pt alloy according to claim 1, wherein the intensity of the average reflection spectrum at a wavelength of 350 nm to 500 nm is smaller than the intensity of the average reflection spectrum at a wavelength of 550 nm to 800 nm. Composition formula: (Al2Pt) 1-xMx [M represents a transition metal element different from the metal elements A and Pt, and x satisfies 15 atomic% <x <25 atomic%. The Pt alloy according to claim 1 or 2, wherein The Pt alloy according to any one of claims 1 to 3 , wherein the transition metal element M is copper (Cu). A jewelry comprising the Pt alloy according to any one of claims 1 to 4 . A decorative article comprising the Pt alloy according to any one of claims 1 to 4 .