Treatment method for modifying the reflected colour of a sapphire material surface

Abstract

A treatment method for modifying the reflected color of a sapphire material surface comprising bombardment by a single- and/or multi-charged gas ion beam so as to modify the reflected color of the treated sapphire material surface, wherein the ions are selected from ions of the elements from the list consisting of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), boron (B), carbon (C), nitrogen (N), oxygen (O), fluorine (F), silicon (Si), phosphorus (P) and sulphur (S).

Claims

1. A treatment method for modifying the reflected colour of a sapphire material surface comprising bombardment by a gas ion beam so as to produce an ion implanted layer in the sapphire material, wherein: the gas ion beam comprises single and multi-charged ions, and comprises 10% or more of multi-charged ions, the acceleration voltage is chosen in a range between 5 kV and 1000 kV; the dose of implanted gas ions per unit of surface area of each ion beam is chosen in a range between 10.sup.12 ions/cm.sup.2 and 10.sup.18 ions/cm.sup.2; and, the dose of implanted gas ions and the acceleration voltage are further chosen so that to obtain a modified reflected colour of the treated sapphire material surface compared to the untreated sapphire material surface; and, the ions of the gas ion beam are selected from ions of the elements from the group consisting of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), boron (B), carbon (C), nitrogen (N), oxygen (O), fluorine (F), silicon (Si), phosphorus (P) and sulphur (S).

2. The treatment method of claim 1, wherein the ions are selected from ions of the elements from the group consisting of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), nitrogen (N) and oxygen (O).

3. The treatment method of claim 1, wherein ions for bombardment by the gas ion beam are produced by an electron cyclotron resonance (ECR) source.

4. The treatment method of claim 1, wherein the acceleration voltage is chosen in a range between 10 kV and 100 kV.

5. The treatment method of claim 1, wherein the dose of implanted gas ions per unit of surface area is chosen in a range between 10.sup.16 ions/cm.sup.2 and 10.sup.18 ions/cm.sup.2.

6. The treatment method of claim 1, wherein the dose of implanted gas ions per unit of surface area is chosen to obtain an atomic concentration of implanted ions greater or equal to 5% and equal or less than 20%.

7. The treatment method of claim 1, wherein the sapphire material is movable in relation to the gas ion beam at a speed, V.sub.D, between 0.1 mm/s and 1000 mm/s.

8. The treatment method of claim 7, wherein the same zone of sapphire material is moved under the gas ion beam along a plurality, NP, of passes at the speed V.sub.D.

9. The treatment method of claim 1, wherein the treatment comprises bombardment of the sapphire material surface by a plurality of gas ion beams so as to produce an ion implanted layer in the sapphire material, and wherein the acceleration voltage and/or the element of the ions beams differ from a gas ion beam to another gas ion beam.

10. The treatment method of claim 1, wherein the method comprises bombardment a first and a second sapphire material surface, each by one or by a plurality of gas ion beam(s) so as to produce in the sapphire material an ion implanted layer on the first sapphire material surface and an ion implanted layer on the second sapphire material surface, wherein the first and the second sapphire material surface are substantially parallel surfaces separated by a transparent medium and wherein the acceleration voltage and/or the element of the beam(s) for the treatment of the second sapphire material surface differs from respectively the acceleration voltage(s) and/or the element of the ion beam(s) for the treatment of the first sapphire material surface.

11. The treatment method of claim 9, wherein the ions of the different gas ion beams are ions of the same element and wherein the acceleration voltage of the ion beams differ from a gas ion beam to another gas ion beam.

12. The treatment method of claim 11, wherein the acceleration voltage of the ion beams differ by a value between 5 and 50 kV.

13. The treatment method of claim 1, wherein the acceleration voltage and the dose of implanted gas ions are further chosen according to additional choice rules and; wherein the additional choice rules comprise using data gathered in a step prior to bombardment by the gas ion beam of the sapphire material to be treated, wherein: said step consists in choosing one type of single- and multi-charged ions of the elements from the list consisting of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), boron (B), carbon (C), nitrogen (N), oxygen (O), fluorine (F), silicon (Si), phosphorus (P) and sulphur (S), performing a plurality of experiments with sapphire materials similar to the one to be treated by using said ions to be bombarded and varying the implanted single- and/or multi-charged gas ion dose per unit of surface area and the acceleration voltage until determining desired implanted single- and/or multi-charged gas ion dose per unit of surface area ranges and acceleration voltage ranges so as to produce an ion implanted layer suitable for obtaining a modified reflected colour of the sapphire material surface; and choosing a single- and multi-charged gas ion dose per unit of surface area and an acceleration voltage value within the ranges of the preceding step and treating the sapphire material to be treated with said ions said values.

14. The treatment method of claim 13 wherein data resulting from the plurality of experiments are gathered and handled so as to provide guidelines of colour variation of a sapphire surface according to the element of the single- and multi-charged ions beam, the acceleration voltage and the ion dose per unit of surface area.

15. The treatment method of claim 14 wherein the choice of the element of the single- and multi-charged ions beam, of the single- and multi-charged gas ion dose per unit of surface area and of the acceleration voltage value is done so as to fulfil the requirements of a colour target for the reflected colour of a sapphire material surface.

16. A part made of synthetic sapphire material comprising at least one surface treated according to the method of claim 1, wherein the dominant wavelength, .sub.DT, of the reflected colour of the treated surface is shifted from at least +50 nm or at least 50 nm from the dominant wavelength, .sub.DU, of the reflected colour of the untreated sapphire material surface.

17. The treatment method according to claim 1, wherein the sapphire material is a synthetic sapphire material of a solid part selected from the group consisting of a screen, a window, a watch glass, a lighting device part, and an optical component.

18. The treatment method of claim 10, wherein the ions of the different gas ion beams are ions of the same element and wherein the acceleration voltage of the ions beams differ from a gas ion beam to another gas ion beam.

19. The treatment method of claim 18, wherein the acceleration voltage of the ion beams differ from a value comprised between 5 and 50 kV.

20. The treatment method of claim 1, wherein the ions of the gas ion beam are selected from ions of the elements from the group consisting of nitrogen (N) and oxygen (O).

21. The treatment method of claim 1, wherein the ions of the gas ion beam are ions of oxygen (O).

22. The treatment method of claim 1, wherein the dose of implanted gas ions per unit of surface area is chosen in a range between 210.sup.16 ions/cm.sup.2 and 210.sup.17 ions/cm.sup.2.

23. The treatment method of claim 11, wherein the acceleration voltage of the ion beams differs by a value of 10 to 20 kV.

24. A part made of synthetic sapphire material comprising at least one surface treated according to the method of claim 1, wherein the dominant wavelength, .sub.DT, of the reflected colour of the treated surface is shifted from at least +100 nm or at least 100 nm from the dominant wavelength, .sub.DU, of the reflected colour of the untreated sapphire material surface.

25. The treatment method of claim 17, wherein the screen is a touch screen, the lighting device part is a light emitting device (LED) part, and the optical component is a device lens.

Description

(1) Examples will now be described with reference to the accompanying drawings wherein:

(2) FIG. 1 is a sketch of a sapphire material crystal;

(3) FIGS. 2 to 6 are transmission diagrams of sapphire material samples treated by the method of the present invention;

(4) FIGS. 7 to 10 are diagrams used to discuss results of sapphire material samples treated by the method of the present invention;

(5) FIGS. 11 to 14 illustrate examples of modifying the reflected colour of sapphire material surfaces thanks to the method of the present invention;

(6) FIGS. 15 to 19 are transmission diagrams of sapphire material samples treated by the method of the present invention.

(7) Some elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale.

(8) Nevertheless, transmission diagrams have been drawn to scale. Transmission diagrams illustrate variation of a (or of a plurality of) coefficient of transmission (T) (also usually called power transmission coefficient or transmittance) as a function of light wavelength. The wavelength range comprises the visible wavelength range.

(9) Transmission diagrams result from measurements made with a spectrophotometer where an incident light beam passes through two main faces of a sample and where the light transmission through the said sample is measured at a plurality of wavelengths. Said two main faces are usually parallel faces.

(10) Transmission diagrams of sapphire material samples treated by the method of the present invention have been measured with a UV-5200 UV/VIS Spectrophotometer commercialized by METASH Company. In those measurements, the medium facing (and contacting) each of the main faces of the sapphire material samples is air.

(11) FIG. 1 is a sketch of a sapphire material single-crystal where one can distinguish the crystallographic main features of such a crystal; the sapphire (corundum) single-crystal structure can be represented by ordering octahedron where O.sup.2 ions are in tops (peaks) of the octahedrons and Al.sup.3+ ions are inside of the octahedrons. FIG. 1 shows the structure of the primary planes of the sapphire crystal corresponding to the structure system of sapphire. Shown in this figure are the following planes: C-plane is (0001); A-plane is (1120) and R-plane is (1012). Planes nomenclature corresponds to usual crystallographic nomenclature.

(12) As here above mentioned, commonly available sapphire material is substantially colourless and substantially neutral in term of chromaticity. As here above mentioned, each face of an untreated sapphire material sample reflects approximately 7.75% of incident light; thus the transmission of an untreated sapphire material sample is approximately 84.5% in the visible range.

(13) The inventors have performed tests with sapphire material samples which have been treated according to the present invention.

(14) Used sapphire material samples are either circular or square plates with respectively one inch diameter and 10 mm side; their thickness is equal to or less than 1 mm.

(15) In the following examples, these single- and multi-charged gas ions were emitted by an ECR source (electron cyclotron resonance source).

(16) FIGS. 2 to 5 show transmission diagrams of sapphire material samples treated by the method of the present invention that have been measured after treating sapphire material samples according to following experimental conditions:

(17) As far as FIGS. 2 to 5 are concerned: the single- and/or multi-charged gas ion beam is a single- and multi-charged oxygen ion, O.sup.+, O.sup.2+, O.sup.3+, beam; estimated distribution of O ions is following: 60% of O.sup.+, 30% of O.sup.2+, 10% of O.sup.3+.

(18) As far as FIGS. 2 and 3 are concerned: only a face of the sapphire material samples has been treated;

(19) As far as FIGS. 4 and 5 are concerned: both faces of the sapphire material samples have been treated.

(20) As far as FIGS. 2 and 4 are concerned: plan(s) A of the sapphire material samples has (have) been treated.

(21) As far as FIGS. 3 and 5 are concerned: plan(s) C of the sapphire material samples has (have) been treated.

(22) In following data, ion doses (further called dose) are expressed in 10.sup.16 ions/cm.sup.2, and acceleration voltages (further called voltage) are expressed in kV.

(23) In FIG. 2, curve 20 relates to an untreated sapphire material sample; curve 21 to a sapphire material sample treated with a dose=11 and a voltage=17.5; curve 22 to a sapphire material sample treated with a dose=12.5 and a voltage=25; curve 23 to a sapphire material sample treated with a dose=15 and a voltage=32.5.

(24) In FIG. 3, curve 30 relates to an untreated sapphire material sample; curve 31 to a sapphire material sample treated with a dose=11 and a voltage=17.5; curve 32 to a sapphire material sample treated with a dose=12.5 and a voltage=25; curve 33 to a sapphire material sample treated with a dose=15 and a voltage=32.5.

(25) In FIG. 4, curve 40 relates to an untreated sapphire material sample; curve 41 to a sapphire material sample treated with a dose=11 and a voltage=17.5; curve 42 to a sapphire material sample treated with a dose=12.5 and a voltage=25; curve 43 to a sapphire material sample treated with a dose=15 and a voltage=32.5.

(26) In FIG. 5, curve 50 relates to an untreated sapphire material sample; curve 51 to a sapphire material sample treated with a dose=11 and a voltage=17.5; curve 52 to a sapphire material sample treated with a dose=12.5 and a voltage=25; curve 53 to a sapphire material sample treated with a dose=15 and a voltage=32.5.

(27) Thanks to these figures, one can consider the influence of a plurality of process parameters.

(28) FIGS. 2 and 3 can be respectively compared to FIGS. 4 and 5 to demonstrate the influence of single face versus double faces treatments.

(29) Measured results reported in FIGS. 2 to 5 demonstrate that bombardment of a surface of the sapphire material according to the present invention modifies the reflected colour of a sapphire material surface.

(30) The reflected colour of a sapphire material surface of samples corresponding to curves 21, 31, 41 and 51, where the voltage is 17.5 kV, is substantially orange;

(31) The reflected colour of a sapphire material surface of samples corresponding to curves 22, 32, 42 and 52, where the voltage is 25 kV, is substantially purple;

(32) The reflected colour of a sapphire material surface of samples corresponding to curves 23, 33, 43 and 53, where the voltage is 32.5 kV, is substantially dark blue.

(33) One can accordingly make a reflected colour choice for a sapphire material surface and choose relevant treatment method parameters that permit obtaining the desired colour.

(34) Based on such type of experiments, one can gather data and handle them so as to provide further guidelines of colour variation of a sapphire surface according to an element (here Oxygen) of the single- and/or multi-charged ions beam, the acceleration voltage and the ion dose per unit of surface area.

(35) Measured results reported in FIGS. 2 to 5 demonstrate that bombardment of a surface of the sapphire material, said surface facing a medium different from the sapphire material, by a single- and/or multi-charged gas ion beam is also suitable to produce an ion implanted layer in the sapphire material that provides an anti-glare treatment in the visible range.

(36) Surprisingly, very high transmissions have been achieved in the visible range.

(37) Synthetic sapphire material comprising at least one surface with implanted ions have been obtained where the reflection of an incident wave in the visible range on said surface is equal or less to 2%, as for example equal or less to 1%, when measured at a 560 nm wavelength.

(38) Thanks to results reported in FIGS. 2 to 5, one can determine preferred ranges to implement the method according to the present invention.

(39) Determining said preferred ranges is a way to provide additional choice rules to choose ions of an element, an acceleration voltage and a dose of implanted single- and/or multi-charged gas ions according to needs.

(40) FIGS. 6 to 10 illustrate data that can be useful for choosing parameters when using Oxygen as single- and/or multi-charged ions.

(41) Transmission diagrams of sapphire material samples treated by the method of the present invention can be analyzed on the basis of FIG. 6; one determinate three parameters on the basis of transmission diagram (60), where P is the transmission peak position (in nm), D is a variability parameter (in transmission unit), L is the width (in nm) of the transmission diagram corresponding to the D variability.

(42) FIGS. 7 and 8 illustrate the variation of the transmission peak position (respectively, curves 70 and 80) according to the acceleration voltage for respectively plans A and C of a sapphire material.

(43) Thanks to such diagram, one can choose an acceleration voltage for obtaining a desired colour.

(44) FIG. 9 shows the variation of the width of the transmission diagram (L) as a function of the variability parameter (D) for a sapphire material treated according to a A plane.

(45) FIG. 10 shows the variation of the width of the transmission diagram (L) as a function of the variability parameter (D) for a sapphire material treated according to a C plane.

(46) Numerous other data presentations can be used to provide additional choice rules for obtaining a desired colour.

(47) As shown by here above results, the treatment method of the invention may be used so as to produce an ion implanted layer on a single surface of the sapphire material or may be used so as to produce a plurality of ion implanted layers on a first and a second sapphire material surface of the sapphire material, where the first and the second sapphire material surface are substantially parallel surfaces and separated by a transparent medium.

(48) FIGS. 11 to 14 illustrate examples of modifying the reflected colour of sapphire material surfaces thanks to the method of the present invention when using a plurality of single- and/or multi-charged gas ion beams so as to produce an ion implanted layer in the sapphire material; similar results would be obtained when using a plurality of ion implanted layers on a first and a second sapphire material surface of the sapphire material, where the first and the second sapphire material surface are substantially parallel surfaces separated by a transparent medium.

(49) FIG. 11 shows sketches indicating the incidence of a first, 110, and a second, 111, Oxygen multi-charged gas ion beams on transmission within the visible range where the acceleration voltage differ from a gas ion beam to another gas ion beam as far as is concerned. A peak difference P can be seen between the two curves 110, 111. The acceleration voltages are, for example, in the range of 10 to 50 kV, as for example in the range of 15 to 35 kV, and the acceleration voltage difference between to neighbouring is comprised between 5 and 50 kV, between 10 and 20 kV. The inventors have determined the colorimetric properties resulting from the combination of such curves and corresponding data are shown in FIG. 12.

(50) FIG. 12 presents the results in the CIE 1931 colour spaces on the basis of a CIE xy chromaticity diagram. The outer curved boundary 120 is the spectral locus, with wavelengths shown in nanometers. The diagram represents all of the chromaticities visible to the average person. Such diagrams are commonly used in the field of colour information presentation and interpretation of such diagrams is well known from a person skilled in the art. Point 121 corresponds at the chromaticity of a sapphire material surface treated with 15 kV and 25 kV Oxygen multi-charged gas ion beams; corresponding colour is pink. Point 122 corresponds at the chromaticity of a sapphire material surface treated with 20 kV and 30 kV Oxygen multi-charged gas ion beams; corresponding colour is purplish pink. Point 123 corresponds at the chromaticity of a sapphire material surface treated with 25 kV and 35 kV Oxygen multi-charged gas ion beams; corresponding colour is violet/blue.

(51) FIG. 13 shows sketches indicating the incidence of a first (131), a second (132) and a third (133) Oxygen multi-charged gas ion beams on transmission within the visible where the acceleration voltage differ from a gas ion beam to another gas ion beam as far as visible range transmission is concerned. A peak difference P can be seen between the two extreme curves 131, 133. The acceleration voltages are defined in the same ranges than those of FIG. 11.

(52) FIG. 14 presents the results in the CIE 1931 colour spaces on the basis of a CIE xy chromaticity diagram. The outer curved boundary 140 is the spectral locus, with wavelengths shown in nanometers. Point 141 corresponds at the chromaticity of a sapphire material surface treated with 10 kV, 20 kV and 30 kV Oxygen multi-charged gas ion beams; corresponding colour is lightly yellowish pink. Point 142 corresponds at the chromaticity of a sapphire material surface treated with 12.5 kV, 22.5 kV and 32.5 kV Oxygen multi-charged gas ion beams; corresponding colour is neutral. Point 143 corresponds at the chromaticity of a sapphire material surface treated with 15 kV, 25 kV and 35 kV Oxygen multi-charged gas ion beams; corresponding colour is light blue.

(53) In CIE xy chromaticity diagram of FIG. 14, one has represented a neutral colour box defined by rectangle 146 adjacent to the neutral point 145. Point 142 is situated within said neutral colour box.

(54) Combination of a plurality of Oxygen multi-charged gas ion beams according to the present invention allows finely tuning the reflected colour of the surface of a sapphire material. As here above demonstrated, the method of the invention also allows providing a neutral reflected colour of the surface of a sapphire material with an ion implanted layer. Accordingly one can obtain a neutral coloured antiglare surface.

(55) Obtaining a neutral reflected colour of the surface of a sapphire material with an ion implanted layer can be achieved by combining a plurality transmission profiles corresponding to different acceleration voltages so as to obtain a flat and constant transmission profile.

(56) According to an embodiment and in order to obtain a flat and constant transmission profile between 96 and 97%, situated between blue (400 nm) and red (800 nm), the inventors also give the following ion bombardment treatment example conducted in two steps: A first ion bombardment treatment with an extraction voltage approximately 10% less than the reference extraction voltage (suitable for obtaining yellow glare at 45) and a dose corresponding to half the reference dose (used to obtain the same yellow glare at an angle of 45), in other words, a voltage approximately equal to 20 KV and a dose equal to 0.7510.sup.17 ions/cm.sup.2; A second ion bombardment treatment with an extraction voltage approximately 10% greater than the reference extraction voltage (suitable for obtaining yellow glare at 45) and a dose corresponding to half the reference dose (used to obtain the same yellow glare at an angle of 45), in other words, a voltage approximately equal to 25 KV and a

(57) This two-step treatment makes it possible to advantageously create a flat and constant transmission profile between blue (400 nm) and red (800 nm) while retaining substantially the high transmission for the yellow colour (560 nm).

(58) FIGS. 15 to 19 show transmission diagrams of sapphire material samples treated by the method of the present invention that have been measured after treating sapphire material samples according to following experimental conditions:

(59) As far as FIGS. 15 to 18 are concerned: the single- and/or multi-charged gas ion beam is a single- and multi-charged nitrogen ion, N+, N.sup.2+, N.sup.3+, beam; estimated distribution of N ions is following: 57% of N.sup.+, 32% of N.sup.2+, 11% of N.sup.3+; only one face of the sapphire material samples has been treated.

(60) As far as FIGS. 15 and 16 are concerned: plan A of the sapphire material samples has been treated.

(61) As far as FIGS. 17 and 18 are concerned: plan C of the sapphire material samples has been treated.

(62) In following data, ion doses (further called dose) are expressed in 10.sup.16 ions/cm.sup.2, and acceleration voltages (further called voltage) are expressed in kV.

(63) As far as FIGS. 15 and 17 are concerned, the voltage=20;

(64) As far as FIGS. 16 and 18 are concerned, the voltage=25;

(65) In FIG. 15, curve 150 relates to an untreated sapphire material sample; curve 151 to a sapphire material sample treated with a dose=2.5; curve 152 to a sapphire material sample treated with a dose=5; curve 153 to a sapphire material sample treated with a dose=7.5; curve 154 to a sapphire material sample treated with a dose=10; curve 155 to a sapphire material sample treated with a dose=12.5; curve 156 to a sapphire material sample treated with a dose=15.

(66) In FIG. 16, curve 160 relates to an untreated sapphire material sample; curve 161 to a sapphire material sample treated with a dose=2.5; curve 162 to a sapphire material sample treated with a dose=5; curve 163 to a sapphire material sample treated with a dose=7.5; curve 164 to a sapphire material sample treated with a dose=10; curve 165 to a sapphire material sample treated with a dose=12.5; curve 166 to a sapphire material sample treated with a dose=15; curve 167 to a sapphire material sample treated with a dose=17.5.

(67) In FIG. 17, curve 170 relates to an untreated sapphire material sample; curve 171 to a sapphire material sample treated with a dose=2.5; curve 172 to a sapphire material sample treated with a dose=5; curve 173 to a sapphire material sample treated with a dose=7.5; curve 174 to a sapphire material sample treated with a dose=10; curve 175 to a sapphire material sample treated with a dose=12.5; curve 176 to a sapphire material sample treated with a dose=15; curve 177 to a sapphire material sample treated with a dose=17.5.

(68) In FIG. 18, curve 180 relates to an untreated sapphire material sample; curve 181 to a sapphire material sample treated with a dose=2.5; curve 182 to a sapphire material sample treated with a dose=5; curve 183 to a sapphire material sample treated with a dose=7.5; curve 184 to a sapphire material sample treated with a dose=10; curve 185 to a sapphire material sample treated with a dose=12.5; curve 186 to a sapphire material sample treated with a dose=15; curve 187 to a sapphire material sample treated with a dose=17.5.

(69) Samples that have treated with a 20 kV acceleration voltage are royal blue; samples that have treated with a 15 kV acceleration voltage are mauve.

(70) Modification of the reflected colour of a sapphire material surface can thus be achieved thanks to the method of the invention when using Nitrogen ions. Anti-glare properties can be also achieved thanks to the method of the invention when using Nitrogen ions.

(71) FIG. 19 shows transmission diagrams of sapphire material samples treated by the method of the present invention that have been measured after treating sapphire material samples according to following experimental conditions:

(72) the single- and/or multi-charged gas ion beam is a single- and multi-charged Argon ion, Ark, Ar.sup.2+, Ar.sup.3+, beam; estimated distribution of Ar ions is following: 71% of Ark, 23% of Ar.sup.2+, 6% of Ar.sup.3+; the two faces of the sapphire material samples have been treated. The treated is plan A of the sapphire material. The acceleration voltage is 35 kV. In following data, ion doses (further called dose) are expressed in 10.sup.16 ions/cm.sup.2:

(73) Curve 190 relates to an untreated sapphire material sample; curve 191 to a sapphire material sample treated with a dose=2.5; curve 192 to a sapphire material sample treated with a dose=7.5; curve 193 to a sapphire material sample treated with a dose=10.

(74) Modification of the reflected colour of a sapphire material surface can thus be achieved thanks to the method of the invention when using Argon ions. Anti-glare properties can be also achieved thanks to the method of the invention when using Argon ions.

(75) Based on the data that have been gathered, one can estimate with a high level of confidence that other ions should be suitable to implement the method of the invention and are relevant to modify the reflected colour of a sapphire material surface.

(76) It has been here above demonstrated that argon (Ar) ions are suitable to implement the method of the invention; accordingly, other noble gas ions appears to be also suitable to implement the method of the invention, such as helium (He), neon (Ne), krypton (Kr) and xenon (Xe).

(77) It has been here above demonstrated that nitrogen (N) and oxygen (O) ions are suitable to implement the method of the invention; accordingly, other Periodic Table surrounding ions appears to be also suitable to implement the method of the invention, such as boron (B), carbon (C), fluorine (F), silicon (Si), phosphorus (P) and sulphur (S).

(78) Based on here above results and comments, a person skilled in the art can use the teaching of the present invention and implement the treatment method by using a plurality of beams where the element of the ions beams differ from a gas ion beam to another gas ion beam. Said beams may be used so as to produce an ion implanted layer on a single surface of the sapphire material or may be used so as to produce a plurality of ion implanted layers on a first and a second sapphire material surface of the sapphire material, where the first and the second sapphire material surface are substantially parallel surfaces and separated by a transparent medium.

(79) According to an embodiment, the ion bombardment anti-reflective treatment of the sapphire material used in the present invention does not require long treatment times (a few seconds per cm.sup.2 and per micro-accelerator).

(80) The modification of the reflected colour of a sapphire material surface used in the present invention may enable the use thereof in an industrial context, where the cost thereof should not be redhibitory in relation to the costs of the sapphire substrate (for example one cm.sup.2 of sapphire for touch panels costs approximately 4 Euro, one cm.sup.2 treated within the scope of the invention costs a few cents).

(81) Thanks to the present invention, one can obtain a part made of synthetic sapphire material comprising at least one surface treated according to the method of any of preceding claims, wherein the dominant wavelength, .sub.DT, of the reflected colour of the treated surface is shifted from at least +50 nm or at least 50 nm from the dominant wavelength, .sub.DU, of the reflected colour of the untreated sapphire material surface, as for example shifted from at least +100 nm or at least 100 nm.

(82) The treatment method of the present invention can be used for treating a solid part made of sapphire material chosen for example from, but not limited to, the list consisting of a screen, such as for example a touch screen, a window, a watch glass, a lighting device part, such as a light emitting device (LED) part, an optical component, such as for example device lens.

(83) The invention has been described above with the aid of embodiments without limitation of the general inventive concept; in particular the parameters are not limited to the examples discussed.