Transparent thermal insulation structure

Abstract

Depositing a functional layer comprising silver and one or more alloying agents of copper, aluminum, and nickel in the presence of nitrogen can dramatically improve the corrosion resistance and bendability of low-emissivity solar-control structures. The enhancements are achieved by a two-stage process. In the first stage, a layer of core-shell like crystallites is formed during the deposition, wherein each crystalline silver grain is surrounded by an ultrathin shell of nitrogenated aluminum bronze segregated alongside the grain boundaries. Essentially no silver nitride is formed at this stage due to its exceptionally high enthalpy of formation. In a second stage, the nitrogenated bronze shell reacts with arriving environmental oxygen or oxygen deliberately introduced immediately after the formation of the functional layer. This leads to the formation of a permanently protective oxidized aluminum bronze which encapsulates the crystalline silver grains and arrests any further oxidation or attacks by other corrosive species, such as sulphur-inclusive agents. The method is also beneficial for enhanced flexibility of low-emissivity solar-control structures deposited on bendable substrates or subjected to a high-temperature bending process. This nitrogen-present sputter-deposition of silver-core bronze-shell paradigm can be adapted to render a manifold of compositional, structural, grain size-shape variations to achieve functional layers of silver that exhibit desired enhancements in electrical, optical-photonic-plasmonic, corrosion-resistance and mechanical-thermal properties, particularly within the framework of multi-layer dielectric-metal-dielectric stacks disposed on a variety of substrate materials of rigid and flexible form.

Description

[0001] TRANSPARENT THERMAL INSULATION STRUCTURE

[0002] FIELD

[0003] The present invention relates to low-emissivity (low-E) solar-control structures and, particularly, to low-E structures with infrared (IR) reflective silver (Ag) functional electrically conductive layers having enhanced corrosion resistance and bendability, as well as methods of fabrication of such structures thereof.

[0004] BACKGROUND

[0005] Low-emissivity solar-control (LESC) structures are known in art [US7339728B2] and are widely employed in various applications such as energy-efficient architectural and automotive glazing. The main characteristics of a LESC structure are its low emissivity (high mid-1 R reflectivity) and near-IR control. Emissivity is a unitless surface characteristic representing the total amount of radiant energy emitted by a surface in relation to that by an ideal black body surface, both surfaces being at the same temperature - and as such a critical property that can be utilized to minimize the transfer of ambient thermal energy through the glazing. Solar control characteristics of architectural and automotive glazing are represented by various parameters. The solar heat gain coefficient (SHGC), also known as the g-value or the total solar energy transmittance (TST, TSET or TTS), is the fraction of the impinging total solar radiation transmitted through the glazing (including re-radiation of the energy absorbed in the glazing). Another important characteristic of solar-control heatinsulating glazing is its visible light transmittance (Tvis or VLT). The Tvis to SHGC ratio is called light-to-solar heat gain (LSG) ratio. The higher the LSG, the more daylight a glazing can deliver while transferring less solar heat, thus impacting occupant comfort.

[0006] To maximize the LSG, large-area LESC coatings are typically deposited by magnetron sputtering and comprise at least one highly electrically conductive and optically transparent functional metal layer, such as silver, deposited in pure argon. Properly deposited silver offers optimal values of index of refraction (IOR) and extinction coefficient in the visible spectral range and in the infrared. To achieve the above-mentioned optical and electrical properties optimally, it is essential to deposit the Ag functional layer with a preferred <111 > crystal orientation, achieve a smooth interface with the underlying bottom layer, and realize a well-developed crystalline silver (c-Ag) grain structure to minimize scattering of free electrons. Additional important requirements include the high purity of the sputter-deposited silver. It was shown that highly crystalline <111 >- oriented silver grains are typically surrounded by a shell of more porous and amorphous-crystalline (a-Ag) silver [https: / / www.researchgate.net / publication / 308908203], which suggests the possibility of gettering impurities at the grain boundaries.

[0007] Besides the Ag functional layer, a traditional LESC sputtered stack processing comprises, starting with a transparent substrate, deposition of a barrier layer to prevent unwanted diffusion of alkaline elements; then having a so-called wetting layer disposed just below the silver functional layer to promote its proper crystalline orientation; then a so-called blocker layer deposited right above the silver to provide some protection against corrosion; and followed by a protection layer on top of the stack. In some applications, LESC structures are either laminated between two panes of glass, like in the case of automotive glazing, or exposed to an argon- filled interior of an insulating glass unit (IGU). In both cases, the coating is protected from the ingress of oxygen from the atmosphere. The situation is different when the coating is exposed to the air, like in secondary glazing window inserts which are added to existing windows as a cost-effective way to improve thermal insulation. In this case, the thin-film IR-reflective functional layer made from pure silver is known to be highly susceptible to corrosion, primarily caused by the electrochemical anodic reaction due to the ingress of atmospheric oxygen and moisture, as well as sulphur-inclusive species, such as hydrogen sulfide (H2S), which occurs through pinholes and other imperfections in protective sputtered layer.

[0008] It is noteworthy that the <111 > crystal orientation yields dense silver layers with closely packed large grains which result in a high specific conductivity of LESC functional layers, in turn enabling high IR reflectance. On the flip side, the close-packed structure makes the Ag layer susceptible to oxygen, moisture or sulphur-induced corrosion, which starts from the grain boundaries where oxygen, moisture or sulphur, after reaching the silver layer, initiate the oxidation or reduction reactions. Another drawback of the dense silver functional layer is its limited bendability, which often results in cracking when the LESC stack is processed on flexible substrates or subjected to high- temperature bending.

[0009] A number of methods have been suggested to make the functional Ag layer more air stable by quasi-uniform distribution of corrosion-resistant elements in silver or, in other words, by alloying the silver with other metals, such as gold (Au), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), or nickel (Ni). Examples include the use of a 5-30 nm thick functional layer made of a corrosion resistant alloy comprising 90-70 wt.% of Ag and 10-30 wt.% of copper [https: / / doi.Org / 10.1016 / j.solmat.2022.112033]; a Ag-AI alloy with an Al concentration ranging from 0.29 to 0.77 atomic % (at.%) [US 11 ,685,688 B2]; or an alloy from the following list: Ag-Cu-AI, Ag-Cu-Ni, or Ag-Cu-Pt [CN103802379] with respective content wt.% ratios of Ag: 80-95%, Cu: 2.5-10%, Al: 2.5-10%; Ag: 85-95%, Cu: 4-10%, Ni: 1-5%; and Ag: 90-98%, Cu: 1-5%, Pt: 1-5%. Alternative corrosion resistant measures include protecting a pure silver functional layer from the air side with a planar silver-inclusive alloy layer [A. Dirks, J. Van den Broek, P. Wierenga, Mechanical properties of thin alloy films: ultra-microhardness and internal stress, J. Appl. Phys. 55 (1984) 4248-4256]; [D.-Y. Song, R. Sprague, H.A. Macleod, M.R. Jacobson, Progress in the development of a durable silver-based high-reflectance coating for astronomical telescopes, Appl. Opt. 24 (1985) 1164-1170]; https: / / doi.org / 10.1016 / Q165- 1633(90)90040-8: https: / / doi.Org / 10.1016 / S0040-6090(98)01796-9 : https: / / doi.Org / 10.1016 / j.corsci.2009.06.044 . The use of protective layers of metals or metal alloys not comprising silver was also suggested for corrosion protection [R.J. Bussjager, H.A. Macleod, Using surface plasmon resonances to test the durability of silver-copper films, Appl. Opt. 35 (1996) 5044-5047]; [https: / / doi.Org / 10.1364 / ao.35.005044], [https: / / opg.optica.org / ao / abstract.cfm7URkao-24-8-1164],

[0010] Alloying the Ag functional layer with other metals or coupling it with a protective metal layer, unfortunately, results in a significant compromise of the Tvis and LSG since no other metals are favorably comparable to the silver in terms of being highly transparent in the visible and, at the same time, enabling a high reflectivity in the near-IR. Besides, there is no evidence found in prior art suggesting an improved bendability of LESC structures deposited on flexible substrates or subjected to post-deposition bending due to the use of such alloys or layer combinations.

[0011] With ever increasing demand for air-stable Ag-inclusive coatings, it would be desirable to provide a LESC structure enabling, in addition to the high optical and solar performance, superior protection against oxygen-, moisture- and sulphur-induced corrosion and improved bendability.

[0012] SUMMARY

[0013] In embodiments, the present invention discloses a method for making a corrosion resistant LESC structure by adding nitrogen to argon plasma during the sputter deposition of Ag-Cu-AI functional layer or layers. The role of nitrogen in this process is three-fold: i) to add some level of porosity to the silver, primarily by expanding the spacing between the closely packed <111 >-oriented c-Ag grains via increasing the number of <100>-oriented fine a-Ag crystallites at the grain boundaries. These steps create favorable conditions for segregation of alloy element(s) in steps ii and iii; ii) to preferentially bind the Cu and Al atoms by nitrogen and driving them to migrate outside the crystalline Ag grain and to the grain periphery due to the fulfilment of thermodynamic considerations and the system’s minimum energy requirements, thus forming a nitrogenated Cu-AI (denoted here as ‘Al bronze’) ultrathin layer cladding the essentially pure-Ag grain, and iii) to convert the nitrogenated Al bronze to a protective oxynitride I oxidized and highly transparent ultrathin Cu-AI alloy upon the arrival of environmental or intentionally introduced oxygen.

[0014] As discovered by the inventors of the present invention, the added localized porosity to the Ag layer due to the presence of nitrogen along with the tendency of nitrogen to react with Cu and Al, but not with Ag, advantageously creates the conditions for forming a core-shell structure wherein the primarily pure Ag core is eventually “cocooned” in a protective oxynitride I oxidized bronze shell which, analogous to a native superficial aluminum oxide formed on pure Al surface or a patina formed on the surface of bulk bronze, arrests any further oxidation and makes the silver grain highly resistant to corrosion. Unlike the use of indiscriminate alloying of the entire Ag functional layer, the nitrogenated Cu-AI alloy of the present invention is naturally segregated at the porous grain boundaries and, upon oxidation, does not noticeably compromise the Tvis and LSG of the LESC structure due to its high transparency.

[0015] Besides, the formation of an oxynitride I oxidized aluminum bronze protective grain encapsulant which is present in the spacing between the <111 >-oriented pure silver grains, the inventors found that the present invention advantageously enhances the resistance of the layer stack to oxygen-, moisture- and sulphur-induced corrosion in case of occasional microcracking or other localized damage, as well as improves its bendability. The former can be explained by the fact that cracking of the functional layer, such as due to a high intrinsic compressive stress or another type of mechanical damage, almost exclusively occurs between the grain boundaries. When the boundaries are filled with a Cu-AI oxynitride I oxide, the pure-Ag grains are “sealed off”, and no further corrosion caused by oxidation takes place. The explanation for the latter lies in the added flexibility to the otherwise rigid closely packed silver layer - typically having a high intrinsic compressive stress owing to metal-to-metal grain bonding - due to the introduction of oxides between / at the grain boundaries. The fine-grained oxide covering in this case plays the role of a soft glue between the silver grains due to the large electronegativity of oxygen. The enhanced flexibility of Ag functional layers can be beneficial during the deposition process and fabrication of window inserts on flexible substrates as well as in LESC structures disposed on glass and later subjected to postdeposition high-temperature processing, such as thermal bending.

[0016] Previously reported use of nitrogen during pure Ag deposition resulted in ultra-smooth sputtered functional layers with reduced plasmonic absorption but at the expense of a loss in Tvis and IR reflectance

[0017] [https: / / doi.org / 10.1063Z1 .50522611. The focus of that study did not include improving corrosion resistance of the stack by adding Cu or Al to the silver layer. In another study, a <100> crystal orientation of relatively thick (more than a micron) silver films used for optoelectronic applications was found to proportionally increase relative to the <111 > orientation with increasing nitrogen content in sputtering gas [https: / / doi.Org / 10.1155 / 2019 / 30793931. Again, the improved corrosion resistance of the silver was out of scope of that study, and the layer comprised pure silver.

[0018] In embodiments of the present invention, nitrogen is added to the argon working gas during sputter deposition of the Ag-Cu-AI functional layer of a LESC structure. There are no other Ag-inclusive layers in direct contact with the nitrogenated Ag-Cu-AI functional layer. In embodiments, the composition of the alloy of the functional layer sputter deposited in the atmosphere comprising nitrogen is limited to Ag-Cu or Ag-AI.

[0019] In embodiments, the alloyed layer is deposited on top of a pure silver layer or another nitrogenated Ag-Cu-AI, Ag-Cu, or Ag-AI layer with a composition different than the first alloyed layer, thus forming a functional bilayer.

[0020] In embodiments, the nitrogenated functional layer or bilayer is exposed to an oxygen-containing plasma immediately after the deposition to convert the nitrogenated alloy of the protective shell to an oxynitride I oxidized alloy shell. The exposure can be done in a defined oxygen plasma chamber, appropriately situated after the nitrogenated alloy sputter deposition chamber or chambers. The gas chemistry of the oxygen plasma chamber can comprise pure oxygen, oxygen-argon mixtures, oxygen-nitrogen-argon mixture, or a mixture of argon with nitrous oxide. Additionally, other inert gases such as helium can also be used to alter plasma conditions and thus influence the desired oxidation process of the functional layer. Other non-reactive or mildly-reacting gases can also be used at appropriate concentrations to achieve optimum reaction and alloy chemistry. The argon-to-nitrogen flow ratio in the sputtering chamber ranges between 100:1 to 70:30, with a preferred range between 96:4 to 90:10.

[0021] In embodiments, the oxidation is achieved during post-deposition high- temperature processing steps on a completed LESC structure.

[0022] In embodiments, the LESC structure comprises more than one functional layer or bilayer, separated from one another by a dielectric or a dielectric stack. In embodiments, the functional layer or bilayer is deposited on top of an aluminum nitride wetting (AIN) layer.

[0023] In embodiments, the functional layer is capped by an AIN layer.

[0024] In embodiments, the composition of the alloyed layer or layers is within the following ranges of atomic percentage: Ag: 90-96%; Cu: 3-9%; Al: 0.3-2%.

[0025] In embodiments, the atomic percentage of nitrogen in argon atmosphere ranges between 0.01 and 50%, with a preferred range of 0.5 to 20%.

[0026] In embodiments, the atomic percentage of nitrogen in the alloyed functional layer ranges between 0.01 and 7%, with a preferred range of 0.5 to 4%.

[0027] In embodiments, alloying elements other than Cu and Al can be utilized. For example, Ni could be utilized as an additional alloying element or a substitutional element. Other combinations of alloying elements could be utilized, for example, rare earths or misch metal.

[0028] In summary, the addition of nitrogen during sputtering of an alloyed Ag- Cu-AI functional layer promotes a selective nitrogenation of Cu and Al without significantly affecting the silver due to the inertness of silver to nitrogen. Due to the thermodynamic considerations and minimum energy requirements, copper, and aluminum (or other impurity / alloying elements), bound by nitrogen, are driven to migrate out of the silver grains to the grain periphery. As a result of such a 3D morphological process, an ultrathin nitrogenated aluminum bronze layer is preferentially formed along the grain boundaries primarily comprising low-density a-Ag crystallites, thus encapsulating the preferentially pure <111 >- oriented c-Ag core with a temporary / transitional protective shell of nitrogenated bronze. In a second phase of the process, oxygen atoms arrive at the sites either after diffusing through the top layers from the atmosphere or in form of reactive species intentionally introduced right after the alloy layer is deposited. Upon contact with oxygen, the nitrogenated alloy is converted to an oxidized bronze alloy. This arrests any further reaction with oxygen and sulphur of both the alloy and the Ag grain that it protects. The released small amount of nitrogen is safely and harmlessly distributed along the grain boundaries. The disclosed method of encapsulating silver grains with a protective barrier layer contrasts with the conventional protective planar layer and is in contrast with the 'quasi-uniform distribution' of protective alloying elements within silver grains used in prior art. The resultant unique silver functional layer comprising encapsulated silver grains can be integrated within a range of dielectric layers to create appropriate layer stacks and thus achieve spectrally selective coatings with desired properties. Potential dielectric layers include other nitrides (for example, silicon nitride), oxynitrides (for example, aluminum oxynitride, silicon oxynitride), and oxides. In addition to an enhanced resistance to oxygen-, moisture- and sulphur-induced corrosion, the method also assists with an improved bendability of the LESC structure as well as its survivability against corrosion in case of local cracking or other mechanical damage.

[0029] A further understanding of the functional and advantageous aspects of the disclosure can be realized by reference to the following detailed description and drawings.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention can be understood by considering the following drawings and the legend for the reference numerals presented further below: Fig. 1 schematically demonstrates a PRIOR ART LESC coating.

[0032] Fig. 2A is a schematic cross-sectional representation of a sputtered silver grain consisting of crystalline silver surrounded by amorphous silver naturally formed along the grain boundaries.

[0033] Fig. 2B is a schematic cross-sectional representation of the silver grain of Fig. 2A with depiction of Ag atoms.

[0034] Fig. 2C is a schematic cross-sectional representation of the silver grain of Fig. 2B alloyed with copper and aluminum agents in the presence of pure argon.

[0035] Fig. 3A is a schematic cross-sectional representation of the silver grain alloyed with copper and aluminum agents in the presence of nitrogen.

[0036] Fig. 3B is a schematic cross-sectional representation of the silver grain of Fig. 3A after nitrogen in Cu-AI-N is replaced with the arriving oxygen.

[0037] Fig. 3C is a schematic cross-sectional representation of the silver grain of Fig. 3B depicting the formation of oxidized aluminum bronze corrosion protective layer around the silver grain.

[0038] Fig. 4 schematically demonstrates a LESC coating comprising a bilayer functional layer.

[0039] Definition of the Reference Numerals used in the Drawings

[0040] 100, 400 Substrate (pane 1 )

[0041] 110, 410 LESC coating

[0042] 120, 420 Barrier layer

[0043] 130, 430 Optional AR layer

[0044] 140, 240, 340, 440 Wetting layer

[0045] 150, 450 Ag functional layer

[0046] 451 Top sublayer of a Ag functional bilayer 160, 460 Blocker layer

[0047] 170, 470 Optional color-control layer

[0048] 180, 480 Protection layer

[0049] 215, 315 Ag highly crystalline grain

[0050] 225 Grain boundary

[0051] 235 Layer of porous a-Ag

[0052] 245, 345 Silver atom

[0053] 255, 355 Copper atom

[0054] 265, 365 Aluminum atom

[0055] 375 Nitrogen atom

[0056] 385 Oxygen atom

[0057] 395 Oxidized protective aluminum bronze layer

[0058] DETAILED DESCRIPTION

[0059] A detailed description is provided below to facilitate a thorough understanding of the disclosed embodiments and connections thereof. The description is not limited to any particular example included herein.

[0060] Various embodiments and aspects of the disclosure will be described with reference to the details discussed below. The following description and drawings are illustrative of the disclosure and are not to be construed as limiting the disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. The Figures are not to scale. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure.

[0061] As used herein, the terms, “comprises” and “comprising” are to be construed as being inclusive and open ended, and not exclusive. Specifically, when used in the specification and claims, the terms, “comprises” and “comprising” and variations thereof mean the specified features, steps or components are included. These terms are not to be interpreted to exclude the presence of other features, steps or components.

[0062] As used herein, the term “exemplary” means “serving as an example, instance, or illustration,” and should not be construed as preferred or advantageous over other configurations disclosed herein.

[0063] As used herein, the terms “about” and “approximately”, when used in conjunction with ranges of dimensions of particles, compositions of mixtures or other physical properties or characteristics, are meant to cover slight variations that may exist in the upper and lower limits of the ranges of dimensions so as to not exclude embodiments where on average most of the dimensions are satisfied but where statistically dimensions may exist outside this region. It is not the intention to exclude embodiments such as these from the present disclosure. Unless otherwise specified, the terms “about” and “approximately” mean plus or minus 25 percent or less.

[0064] It is to be understood that unless otherwise specified, any specified range or group is as a shorthand way of referring to each and every member of a range or group individually, as well as each and every possible sub-range or sub-group encompassed therein and similarly with respect to any sub-ranges or sub-groups therein. Unless otherwise specified, the present disclosure relates to and explicitly incorporates each and every specific member and combination of sub-ranges or sub-groups. As used herein, the term "on the order of", when used in conjunction with a quantity or parameter, refers to a range spanning approximately one tenth to ten times the stated quantity or parameter.

[0065] In some embodiments, the present invention discloses methods of making a corrosion resistant LESC structure by adding nitrogen to argon plasma during the sputter deposition of at least one Ag-Cu-AI functional layer. In this process, nitrogen adds some level of porosity to the silver functional layer, primarily by increasing the spacing between the closely packed <111 >-oriented c-Ag grains via the introduction of <100>-oriented fine a-Ag crystallites at the grain boundaries. Additionally, nitrogen binds the Cu and Al atoms and forces them to segregate outside the crystalline Ag grain and to the porous grain periphery due to the fulfilment of thermodynamic considerations and the system’s minimum energy requirements. This process results in the formation of a nitrogenated aluminum bronze ultrathin film cladding the highly crystalline Ag grain. Upon the arrival of environmental or intentionally introduced oxygen, the nitrogenated Al bronze is converted to a protective oxidized and highly transparent ultrathin Cu-AI alloy which arrests any further oxidation of the bronze layer as well as the protected Ag grain.

[0066] The nitrogenated aluminum bronze layer, therefore, serves as a temporary sacrificial layer which converts into a permanent oxidized protective layer. The thickness of the oxidized aluminum bronze layer depends on the concentration of the alloying elements as well as the concentration of nitrogen in the mixture of argon and nitrogen. It may range between 0.1 and 3 nm with a preferred range of 0.3 - 2 nm. It is noteworthy that the thickness of the oxidized aluminum bronze layer is determined by the thickness of the nitrogenated sacrificial layer and will not significantly change after the process of oxidation. All of the above-mentioned considerations also apply to the Cu-Ni or Al-Ni.

[0067] The main phenomenon behind the disclosed method is selective reaction of nitrogen with copper and aluminum of the sputtered Ag-Cu-AI alloy, but not with silver. This can be understood by considering the standard enthalpy of formation, which represents enthalpy changes (measure of the energy released or consumed) resulting from the formation of one mole of a substance from its constituent elements in their standard states. For comparison, the standard enthalpies of formation of CusN, AIN, and AgsN are respectively -88, -318, and + 199 kJ / mol, indicating that energetically it is far more favorable for the system to form copper and aluminum nitrides but not silver nitride.

[0068] As a result of such selective nitrogenation of the constituents of the Ag- Cu-AI alloy along with the tendency of nitrogen to add to the porosity of the a- Ag peripheral layer at the grain boundaries, a core-shell like structure is formed wherein the primarily pure Ag highly crystalline core is surrounded by an interim shell of nitrogenated Cu-AI bronze.

[0069] In the next and final stage of the process, the shell comes in contact with the environmental oxygen diffused to the functional layer through the top layers of the thin-film stack or with the oxygen deliberately introduced immediately after the functional layer deposition through a process, such as the exposure to oxygen plasma. This process stage results in the oxidation of the nitrogenated bronze layer due to much higher negative values of the standard enthalpies of formation of Cu and Al oxides compared to those of respective nitrides. For comparison with the above-mentioned enthalpies of formation of the nitrides, the standard enthalpies of formation of CU2O, CuO, and AI2O3 are respectively - 309, - 155, and - 1676 kJ / mol. The formation of the oxidized bronze shell arrests any further reaction with oxygen and sulphur (enthalpy of formation of CuS is - 48.5 kJ / mol) of both the alloy and the Ag grain that it protects.

[0070] The released small amount of nitrogen uniformly and harmlessly occupies available spaces along the porous amorphous silver grain boundaries or diffuses outside the crystal lattice.

[0071] In an embodiment, the formation of said oxidized bronze protective layer also provides the benefit of resistance against oxygen- and sulphur-induced corrosion in case of occasional microcracking or other localized damage, as well as to improve bendability of the LESC structure. This can be explained by the fact that cracking of the functional layer, such as due to a high intrinsic compressive stress or another type of mechanical damage, almost exclusively occurs between the grain boundaries. When the boundaries are filled with a Cu- Al oxide, the pure-Ag grains are “sealed off”, and no further corrosion caused by oxidation takes place.

[0072] In an embodiment, the formation of said oxidized bronze protective layer has the benefit of added flexibility to the otherwise rigid closely packed silver layer - typically having a high intrinsic compressive stress owing to metal-to- metal grain bonding - due to the introduction of oxides between / at the grain boundaries. The fine-grained oxide covering in this case plays the role of a soft glue between the silver grains due to the large electronegativity of oxygen. The enhanced flexibility of Ag functional layers can be beneficial during the deposition process and fabrication of window inserts on flexible substrates as well as in LESC structures disposed on glass and later subjected to postdeposition high-temperature processing, such as thermal bending. In an embodiment, nitrogen tuning gas is added to the argon working gas during sputter deposition of the Ag-Cu-AI functional layer. There are no other Ag-inclusive layers in direct contact with the nitrogenated Ag-Cu-AI functional layer.

[0073] In an embodiment, the composition of the alloy of the functional layer sputter deposited in the atmosphere comprising nitrogen is limited to Ag-Cu.

[0074] In an embodiment, the composition of the alloy of the functional layer sputter deposited in the atmosphere comprising nitrogen is limited to Ag-AI.

[0075] In an embodiment, the composition of the alloy of the functional layer sputter deposited in the atmosphere comprising nitrogen is limited to Ag-Ni.

[0076] In an embodiment, the nitrogenated alloyed Ag-Cu-AI layer is deposited as a corrosion-protection layer on top of a pure silver functional layer, thus forming a functional bilayer.

[0077] In an embodiment, the nitrogenated alloyed Ag-Cu-AI layer is deposited as a protective layer on top of another nitrogenated Ag-Cu-AI functional layer having a different composition than the first nitrogenated alloyed layer.

[0078] In an embodiment, the nitrogenated alloyed Ag-Cu-AI functional layer is exposed to an oxygen-containing plasma immediately after the deposition to convert the nitrogenated alloy of the protective shell to an oxidized alloy shell. The exposure is done in a defined oxygen plasma chamber, appropriately situated after the nitrogenated alloy sputter deposition chamber or chambers. The gas chemistry of the oxygen plasma chamber can comprise pure oxygen, oxygen-argon mixtures, oxygen-nitrogen-argon mixture, or a mixture of argon with nitrous oxide. Additionally, other inert gases such as helium can also be used to alter plasma conditions and thus influence the desired oxidation process of the functional layer. Other non-reactive or mildly-reacting gases can also be used at appropriate concentrations to achieve optimum reaction and alloy chemistry.

[0079] In embodiments, the oxidation is achieved inline or offline during a postdeposition treatment of the completed LESC structure, hence the oxidation is facilitated due to the ingress of the environmental oxygen. Examples include the exposure to a source of convectional or radiative heat energy, radiofrequency, intense light, or another source of radiation, or a combination thereof. Such treatment methods are appropriate for coated glass but are also amenable where polymeric substrates are used; that is, where the thermal effects are appropriately controlled in relation to the transition temperature of the polymeric material.

[0080] The advantage of both methods of oxidizing the nitrogenated protective Al bronze during or after the stack deposition, as opposed to allowing it to naturally oxidize with environmental oxygen over a period of time, is owed to the immediate attainment by the LESC structure its final optical and IR performance.

[0081] In an embodiment, the LESC structure comprises more than one alloyed functional layer, separated from one another by a dielectric or a dielectric stack.

[0082] In an embodiment, at least one functional layer or bilayer is in direct contact with at least one aluminum nitride (AIN) layer.

[0083] In an embodiment, at least one functional layer is separated by a layer from at least one aluminum nitride (AIN) layer.

[0084] In an embodiment, the composition of the alloy in the at least one functional layer is within the following ranges: Ag: 90-96 at.%; Cu: 3-9 at.%; Al: 0.3-2 at.%.

[0085] In an embodiment, the percentage of nitrogen in argon atmosphere during the deposition ranges between 0.01 and 50%, with a preferred range of 0.5 to 20%.

[0086] In embodiments, the atomic percentage of nitrogen in the alloyed functional layer ranges between 0.01 and 7%, with a preferred range of 0.5 to 4%.

[0087] In an embodiment, the architecture of the structure is monolithic, i.e., the LESC layer stack is deposited on a substrate and is exposed to atmosphere, such as to the air in case of window inserts or to argon in case of encapsulated integrated-glass units. In case of window inserts, the use of a plastic substate is advantageous in lowering the total weight of the combined glazing while improving heat insulation. The use of a glass substrate, such as that made of soda-lime glass, may be preferred if, for instance, a tempered-glass structure is required for safety reasons. The substantially optically transparent substrate may be a glass window.

[0088] In embodiments, polymethyl methacrylate (PMMA), 1.0 to 13.0 mm and preferably 1 .5 -6.0 mm thick, is used as a substrate. The PMMA may be primed with an appropriate hard coating, such as siloxane disposed, e.g., by a gravitational flow or “doctor blade” process.

[0089] In embodiments, polycarbonate (PC), 1.0 to 13.0 mm and preferably 1.5 -6.0 mm thick, is used as a substrate. The PC may be primed with an appropriate hard coating, such as siloxane disposed, e.g., by a gravitational flow or “doctor blade” process. In embodiments, the substrate is made of glass, such as soda-lime, borosilicate, alumino-silicate, or any other type of glass with a thickness between 0.5 to 16.0 mm and preferably between 1 .5 and 5.0 mm.

[0090] In an embodiment, the structure is laminated to the second pane, such as a soda-lime glass, using a thermoplastic bonding layer, such as PVB. The coating can be used either as-deposited or heat activated. The use of a laminated structure may also provide the benefit of added safety in case of breakage.

[0091] In an embodiment, the LESC structure on a glass substrate is bent and laminated to another bent glass pane. Besides shaping the coated glass to a required form, high-temperature bending may provide additional improvement to optical and solar performance of the structure by activating the functional layer.

[0092] In embodiments, the ratio of the <111 > to <100 crystal orientation peaks of the functional layer, as measured by X-ray diffraction, is at least 50:1 , preferably between 20:1 and 10:1.

[0093] Fig. 1 demonstrates a generic LESC coated structure 110 deposited on a substantially transparent substrate 100 made from plastic or glass. The substrate is optionally coated with a silicon oxide (SiOx) or silicon-oxy-nitride (SiOxNy) barrier layer 120 intended to protect the functional layer from the unwanted diffusion of alkaline elements from glass or to serve as a foundation layer when the LESC structure is deposited on plastics. Above the barrier layer, an optional anti-reflection layer 130 is deposited to enhance the AR properties of the stack. The layer is made of a medium - high IOR material, such as TiOx, NbOx, SiOxNy, or TiSiOx and has a thickness between 5 and 50 nm, preferably 10-30 nm. Directly above the AR layer 130 is a wetting layer 140, about 5-30 nm thick, which serves to improve the crystal orientation, smoothness, and chemical adhesion of functional layer 150. Functional layer 150 is cladded with a blocker layer 160, about 0.5-5 nm thick, the main role of which is to provide an additional level of protection for the silver layer from corrosion, as well as to minimize the damage from energetic sputtering species during the deposition of the layer above the functional layer, such as optional color-control layer 170 made of ZnSnOx, TiOx, NbOx, ZrOx, or TiZrOx. Its thickness ranges between 10 and 80 nm, preferably between 30 and 70 nm. The physical phenomenon behind the functionality of the color-control layer is optical interference. The transmittance, reflectance, and color of the coating can be tuned (usually to a preferred neutral color) via the material selection and the layer thickness adjustment. The protection layer 180 is made of any material from the following list: SiOx, SiOxNy, ZrSiOx, TiOx, ZrTiOx, and its thickness ranges between 10 and 60 nm, preferably between 15 and 30 nm.

[0094] All layers of a LESC thin-film stack can be preferentially deposited using metal or ceramic sputtering targets. The targets can be planar, rotatable, or any combination thereof. Other apparatus and additions to the plasma process, such as collimators, electron-confining magnets, or high-power impulse magnetron sputtering, can also be used.

[0095] To summarize, the process of using sputtering to produce the low- emissivity solar-control structure; comprises producing at least one functional layer on substantially optically transparent substrate, by a process of sputtering Ag along with at least one alloying agent being any one of Cu, Al, and Ni, in the presence of Ar and N, and once sputtering is complete, exposing the as sputtered functional layer is exposed to oxygen. The at least one sputtered functional layer characterized in that the functional layer comprises a plurality of Ag grains with preferentially <111 > crystal orientation with the Ag grains enveloped in a peripheral protective bronze layer around each said grain having preferentially a <100 crystal orientation, wherein the detectable nitrogen content in the at least one functional layer ranges between 0.01 and 7%, and wherein a ratio of the <111 > to <100> crystal orientation peaks of the functional layer, as measured by X-ray diffraction, is at least 50:1. The low-emissivity solar-control structure is characterized by an integrated visible light transmittance of at least 25 %, as defined by IS09050 and has a sheet resistance of no greater than 9 Q / sq.

[0096] The sputtered produced functional layer is characterized in that the ratio of the <111 > to <100> crystal orientation peaks of the functional layer, as measured by X-ray diffraction is between about 20:1 and about 10:1.

[0097] The sputtered produced functional layer is characterized in that the detectable nitrogen content in the at least one functional layer ranges between about 0.5 and about 4 at.%.

[0098] The process of sputtering may be performed in which the at least one alloying agent being concurrently sputtered is any combination of Cu, Al, and Ni such that the protective bronze layer is comprised of any combination of Cu, Al, and Ni bound with oxygen.

[0099] The exposure to oxygen after deposition may include forming an oxygencontaining plasma immediately after deposition of the functional layer.

[0100] The sputtering may be performed using a single mixed metal target comprising Ag and the alloying agent(s). The sputtering may be co-sputtering performed using a Ag metal target and separate metal target(s)s for the alloying agent(s).

[0101] The argon-to-nitrogen flow ratio in the sputtering chamber may range between about 100:1 to about 70:30, and more preferably between about 96:4 to about 90:10.

[0102] The functional layer may have a thickness in a range from about 5 to about 30 nm.

[0103] The sputtering is performed with the substantially optically transparent substrate not being intentionally heated.

[0104] Alternative to sputtering, the layers of the stack can be deposited by any other deposition technique, including but not limited to: chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), ion-beam deposition, laser-ablation deposition, thermal evaporation, atomic-layer deposition (ALD), or a combination thereof. The at least one functional layer can be sputter deposited using at least one alloyed sputtering target comprising silver and at least one alloying element from the following list: Cu, Al, and Ni. Alternatively, the at least one functional layer can be sputter deposited using co-sputtering from at least two sputtering targets to achieve a desired composition of the functional layer. The combined atomic percentage range of the elements in the targets is as follows. Ag: 90-99%; Cu: 0-10%; Al: 0-5%; Ni: 0-2%. It should be appreciated, however, that the concentration range of the elements in the sputtering target or targets may not directly represent the concentration range of the elements in the deposited film.

[0105] Depicted in Fig. 2A is a schematic cross-sectional representation of a sputtered silver grain deposited on a wetting layer 240 and consisting of a c-Ag core 215 surrounded by grain boundaries 225, separated from the core by an ultrathin a-Ag layer 235, naturally formed along the boundaries.

[0106] Fig. 2B further explains the crystalline silver grain 215 as comprising Ag atoms 245. It should be appreciated that Ag atoms 245 as well as atoms of other elements depicted in subsequent figures of the present invention are only a stylistic representation of the respective elements and are used for illustrative purpose only and without any other limitations to demonstrate the migration and segregation of those elements. It is also noteworthy that in reality and, as mentioned earlier in the Detailed Description, the Ag atoms are organized in the grain as a close-packed crystal lattice structure surrounded by a less dense amorphous Ag shell.

[0107] Fig. 2C depicts a cross-section of a silver grain alloyed with atoms of aluminum 255 and copper 265. As shown in the figure, without any additional measures taken, the grain comprises a quasi-uniformly distributed network of Ag, Cu, and Al. Although having improved corrosion resistant properties, such a uniformly alloyed functional layer has a significant drawback of compromised LSG due to inferior optical performance of Cu and Al compared to that of Ag in the visible and IR spectral regions.

[0108] The situation is fundamentally different when silver 345 is alloyed with Al 355 and Cu 365 in the presence of nitrogen 375, as schematically depicted in a cross-sectional view of Fig. 3A. In this case, nitrogen binds Cu and Al and forces them to migrate towards the periphery of the growing c-Ag grain, thus forming a nitrogenated Cu-AI alloy within the expanded porous layer along the grain boundaries. Due to the high standard enthalpy of AgsN formation, there is little to no nitrogen bonding with silver atoms. Upon contact with the migrated environmental or intentionally introduced oxygen, the nitrogenated Al bronze segregated at the grain boundaries undergoes an oxidation reaction, during which nitrogen atoms 375 are permanently replaced with oxygen atoms 385, as depicted in a cross-sectional view of Fig. 3B.

[0109] Fig. 3C is a schematic cross-sectional representation of the core silver grain 345 with an oxidized Al bronze layer or sheath 395 formed around the silver grains 345. In a preferred embodiment, the oxidation takes place during the exposure of the Ag functional layer comprising nitrogenated Al bronze to an oxygen-containing plasma immediately after its deposition. The grain, therefore, becomes a core-shell like structure in which a preferentially highly crystalline pure-Ag core is surrounded by a preferentially porous layer filled with a protective oxidized Cu-AI alloy, so no further corrosion of the alloy or the grain that it protects can take place.

[0110] Fig. 4 is a schematic representation of a solar-control stack comprising an alloyed functional bilayer comprising silver-based sublayers 450 and 451.

[0111] In embodiments, the present invention discloses a LESC structure with a coating 110 comprising at least one functional layer 150 with improved corrosion resistance and having a visible light transmittance measured at 8 degrees greater than 70%.

[0112] Examples of the embodiments are presented below. The disclosed examples are illustrative and should not be considered as restrictive.

[0113] Example 1

[0114] Example 1 is a LESC structure comprising a 1.5 mm thick PMMA substrate primed with a siloxane hard coating and a sputtered coating having one functional layer comprising silver, copper, aluminum, oxygen, and nitrogen in the following proportions: 95 at.% Ag; 3 at.% Cu; 0.5 at.% Al; 1 at.% O; 0.5 at.% N. The thickness of the functional layer is 12 nm. The ratio of the <111 > to <100> crystal orientation peaks of the functional layer, as measured by X-ray diffraction, is 10:1. The coating also comprises an AIN layer, 35 nm thick, on each side of the functional layer. The structure is characterized by the following optical and solar values: U-factor = 1.4; SHGC = 0.66; Tvis = 78%.

[0115] Transmitted and film-side reflected colors (Cl ELAB chromaticity space) of the structure are as follows: T(8°): a*=0.6, b*=3.9; R(8°): a*=-0.2, b*=-9.0. Example 2

[0116] Example 2 similar to Example 1 but the substrate is a 3.0 mm thick PMMA, and the LESC sputtered coating comprises additional 7 nm thick ZnAIOx wetting layer just below the functional layer. The functional layer comprises silver, copper, aluminum, oxygen, and nitrogen in the following proportions: 92 at.% Ag; 4 at.% Cu; 1.5 at.% Al; 1.5 at.% O; 1 at.% N.

[0117] The coating additionally comprises an AR layer, 22 nm thick, made of NbOx. A NiCrOx blocker layer is disposed above the Ag functional layer for ever more enhanced corrosion protection.

[0118] Example 3

[0119] Example 3 is similar to Example 2 but the substrate is a 3.2 mm thick soda-lime glass, and the functional layer is a bilayer comprising two alloyed sublayers. The first sublayer (starting from the substrate side) of the bilayer functional layer comprises silver, copper, aluminum, oxygen, and nitrogen in the following proportions: 95 at.% Ag; 3 at.% Cu; 0.5 at.% Al; 1 at.% O; 0.5 at.% N. The second sublayer of the functional bilayer comprises silver, copper, aluminum, oxygen, and nitrogen in the following proportions: 90 at.% Ag; 5 at.% Cu; 0.5 at.% Al; 4 at.% O; 0.5 at.% N. The structure is post-deposition heat treated at 630 C for 10 minutes.

[0120] Example 4 Example 4 is similar to Example 3 but the glass substrate is 2.1 mm thick Clear soda-lime glass. The first sublayer (starting from the substrate side) of the functional bilayer comprises pure silver. The second sublayer of the functional bilayer comprises silver, copper, aluminum, oxygen, and nitrogen in the following proportions: 91 at.% Ag; 4 at.% Cu; 2 at.% Al; 2 at.% O; 1 at.% N. The coated LESC structure is subjected to post-deposition high-temperature gravitational bending at 630 C, followed by its lamination to a second protecting glass pane, 2.1 mm thick and bent to the same shape, with the help of a 0.76 mm thick polyvinyl butyral thermoplastic bonding layer.

[0121] List of References

[0122] NPL:

[0123] 1 ) W. Shamsuddin, et al., Environmentally robust Ag-Cu based low-e coatings, Solar Energy Materials and Solar Cells, 248 (2022) 112033, https: / / doi.org / 10.1016Zi.solmat.2022.112033

[0124] 2) A. Dirks, et al., Mechanical properties of thin alloy films: ultra-microhardness and internal stress, J. Appl. Phys. 55 (1984) 4248-4256, https: / / doi.Org / 10.1063 / 1.333027

[0125] 3) D.-Y. Song, et al., Progress in the development of a durable silver-based high- reflectance coating for astronomical telescopes, Appl. Opt. 24 (1985) 1164, https: / / doi.org / 10.1364 / AO.24.001164

[0126] 4) R.C. Ross, Observations on humidity-induced degradation of Ag-based low-emissivity films, Solar Energy Materials 21 (1990) 25, https: / / doi.org / 10.1016 / 0165- 1633(90)90040-81-1. Remy, et al., Ultrasmooth ultrathin Ag films by AIN seeding and Ar / N2 sputtering for transparent conductive and heating applications, APL Mater. 6 (2018) 121112, https: / / doi.orq / 10.1063 / 1.5052261

[0127] 5) K. Koike, et al., Aggregation in thin-film silver: Induced by chlorine and inhibited by alloying with two dopants, Corrosion Science 51 (2009) 2557, https: / / doi.Org / 10.1016 / i.corsci.2009.06.044

[0128] 6) E. Ando et al., Moisture degradation mechanism of silver-based low-emissivity coatings, Thin Solid Films 351 (1999) 308, https: / / doi.org / 10.1016 / 50040-6090(98)01796-9

[0129] 7) R.J. Bussjager, et al., Using surface plasmon resonances to test the durability of silvercopper films, Appl. Opt. 35 (1996) 5044, https: / / doi.org / 10.1364 / ao.35.005044

[0130] 8) Y. Hu., et al., Understanding the Preferred Crystal Orientation of Sputtered Silver in Ar / N2 Atmosphere: A Microstructure Investigation, Mat. Sci. and Eng., (2019), https: / / doi.Org / 10.1155 / 2019 / 3079393

[0131] 9) M. Zamani, et al., Optimization of heat treatment of AI-Cu-(Mg-Ag) cast alloys, J. Therm. Anal. Calorim. 139 (2020) 3427, https: / / doi.org / 10.1007 / s10973-019-08702-x

[0132] List of References for IDS

[0133] NPL:

[0134] 1 ) W. Shamsuddin, et al., Environmentally robust Ag-Cu based low-e coatings, Solar Energy Materials and Solar Cells, 248 (2022) 112033, https: / / doi.Org / 10.1016 / i.solmat.2022.112033

[0135] 2) A. Dirks, et al., Mechanical properties of thin alloy films: ultra-microhardness and internal stress, J. Appl. Phys. 55 (1984) 4248-4256, https: / / doi.Org / 10.1063 / 1.333027

[0136] 3) D.-Y. Song, et al., Progress in the development of a durable silver-based high- reflectance coating for astronomical telescopes, Appl. Opt. 24 (1985) 1164, https: / / doi.org / 10.1364 / AQ.24.001164

[0137] 4) R.C. Ross, Observations on humidity-induced degradation of Ag-based low-emissivity films, Solar Energy Materials 21 (1990) 25, https: / / doi.org / 10.1016 / 0165- 1633(90)90040-8 ) Y. Hu., et al., Understanding the Preferred Crystal Orientation of Sputtered Silver in Ar / N2 Atmosphere: A Microstructure Investigation, Mat. Sci. and Eng., (2019), https: / / doi.Org / 10.1155 / 2019 / 3079393 ) M. Zamani, et al., Optimization of heat treatment of AI-Cu-(Mg-Ag) cast alloys, J. Therm. Anal. Calorim. 139 (2020) 3427, https: / / doi.org / 10.1007 / s10973-019-08702-x

Claims

WHAT WE CLAIM IS:1 . A low-emissivity solar-control structure, comprising a substantially optically transparent substrate and at least one thin-film coating having at least one functional layer comprising Ag, nitrogen, and at least one alloying agent being any one of Cu, Al, and Ni, wherein the detectable nitrogen content in the at least one functional layer is at least 0.01 at.% (atomic percent), and wherein said low-emissivity solar-control structure is characterized by an integrated visible light transmittance of at least 25 %, as defined by IS09050 and has a sheet resistance of no greater than 9 Q / sq.

2. The low-emissivity solar-control structure according to claim 1 , wherein the detectable nitrogen content in the at least one functional layer ranges between about 0.5 and about 4 at.%.

3. The low-emissivity solar-control structure according to claims 1 or 2 wherein the protective bronze layer is comprised of any combination of Cu, Al, and Ni bound with oxygen.

4. The low-emissivity solar-control structure according to any one of claims 1 to 3, produced by sputtering the Ag and the alloying agent in the presence of Ar and N such that post sputtering the silver grains are substantially absent of the N and coated with a nitrogenated bronze layer, whereupon exposure tooxygen after deposition the N is replaced by O to form the protective bronze layer.

5. The low-emissivity solar-control structure according to claim 4, wherein the exposure to oxygen after deposition includes forming an oxygen-containing plasma immediately after deposition of said functional layer.

6. The low-emissivity solar-control structure according to claims 4 or 5, wherein the sputtering is performed using a single mixed metal target comprising Ag and the alloying agent(s).

7. The low-emissivity solar-control structure according to claims 4 or5, wherein the process of sputtering is co-sputtering performed using a Ag metal target and separate metal target(s) for the alloying agent(s).

8. The low-emissivity solar-control structure according to any one of claims 1 to 7, wherein the substantially optically transparent substrate is a window.

9. A glazing comprising the low-emissivity solar-control structure of any one of claims 1 to 7.

10. A low-emissivity solar-control structure; comprising; a substantially optically transparent substrate and at least one thin-film coating on a surface of the optically transparent substrate having at least one functional layer comprising a plurality of grains of Ag, a protective layer aroundeach said grain and comprised of at least one alloying agent being any one of Cu, Al, and Ni bound with oxygen and segregated in the peripheries of said grains, a detectable nitrogen content in the functional layer ranges between about 0.01 and about 7%;, and nitrogen replaced by oxygen with the nitrogen having segregated at grain boundaries after the oxidation process; and wherein said low-emissivity solar-control structure is characterized by an integrated visible light transmittance of at least 25 %, as defined by IS09050 and has a sheet resistance of no greater than 9 Q / sq.11 . The low-emissivity solar-control structure according to claim 10, wherein the plurality of grains of Ag generally have <111 > crystal orientation, and the peripheries having preferentially a <100> crystal orientation, wherein a ratio of the <111 > to <100> crystal orientation peaks of the functional layer, as measured by X-ray diffraction, is at least 50:1 .

12. The low-emissivity solar-control structure according to claim 11 , wherein the ratio of the <111 > to <100> crystal orientation peaks of the functional layer, as measured by X-ray diffraction is between about 20:1 and about 10:1.

13. The low-emissivity solar-control structure according to claim 10, 11 or 12, wherein the detectable nitrogen content in the at least one functional layer ranges between about 0.5 and about 4 at.%.

14. The low-emissivity solar-control structure according to any one of claims10 to 13, wherein the protective bronze layer is comprised of any combination of Cu, Al, and Ni bound with oxygen.

15. The low-emissivity solar-control structure according to any one of claims 10 to 14, produced by sputtering the Ag and the alloying agent in the presence of Ar and N such that post sputtering the silver grains are substantially absent of the N and coated with a nitrogenated bronze layer, whereupon exposure to oxygen after deposition the N is replaced by O to form the protective bronze layer.

16. The low-emissivity solar-control structure according to claim 15, wherein the exposure to oxygen after deposition includes forming an oxygen-containing plasma immediately after deposition of said functional layer.

17. The low-emissivity solar-control structure according to claims 15 or 16, wherein the sputtering is performed using a single mixed metal target comprising Ag and the alloying agent(s).

18. The low-emissivity solar-control structure according to claims 15 or 16, wherein the sputtering process is co-sputtering performed using a Ag metal target and separate metal target(s) for the alloying agent(s).

19. The low-emissivity solar-control structure according to any one of claims 10 to 18, wherein the at least one functional layer has a thickness in a range from about 5 to about 30 nm.

20. The low-emissivity solar-control structure according to any one of claims 1 to 19, wherein the substantially transparent substrate is a window.21 . A glazing comprising the low-emissivity solar-control structure of any one of claims 10 to 19.

22. A method of producing a low-emissivity solar-control structure; comprising: producing at least one functional layer on substantially optically transparent substrate, by a process of sputtering Ag along with at least one alloying agent being any one of Cu, Al, and Ni, in the presence of Ar and N, and once sputtering is complete, exposing the as sputtered functional layer is exposed to oxygen; the at least one sputtered functional layer characterized in that the functional layer comprises a plurality of Ag grains with preferentially <111 > crystal orientation with the Ag grains enveloped in a peripheral protective bronze layer around each said grain having preferentially a <100 crystal orientation, wherein the detectable nitrogen content in the at least one functional layer ranges between 0.01 and 7%, and wherein a ratio of the <111 > to <100> crystal orientation peaks of the functional layer, as measured by X-ray diffraction, is at least 50:1 , andwherein said low-emissivity solar-control structure is characterized by an integrated visible light transmittance of at least 25 %, as defined by IS09050 and has a sheet resistance of no greater than 9 Q / sq.

23. The method according to claim 22, characterized in that the ratio of the <111 > to <100 crystal orientation peaks of the functional layer, as measured by X-ray diffraction is between about 20: 1 and about 10:1.

24. The method according to claims 22 or 23, characterized in that the detectable nitrogen content in the at least one functional layer ranges between about 0.5 and about 4 at.%.

25. The method according to any one of claims 22 to 24, wherein the process of sputtering is performed in which the at least one alloying agent being concurrently sputtered is any combination of Cu, Al, and Ni such that the protective bronze layer is comprised of any combination of Cu, Al, and Ni bound with oxygen.

26. The method according to claims 22 to 25, wherein the exposure to oxygen after deposition includes forming an oxygen-containing plasma immediately after deposition of said functional layer.

27. The method according to any one of claims 22 to 26, wherein the sputtering is performed using a single mixed metal target comprising Ag and the alloying agent(s).

28. The method according to any one of claims 22 to 26, wherein the sputtering is co-sputtering performed using a Ag metal target and separate metal target(s)s for the alloying agent(s).

29. The method according to any one of claims 22 to 28, wherein an argon- to-nitrogen flow ratio in the sputtering chamber ranges between about 100:1 to about 70:30.

30. The method according to any one of claims 22 to 28, wherein an argon- to-nitrogen flow ratio in the sputtering chamber ranges between about 96:4 to about 90:10.31 . The method according to any one of claims 22 to 30, wherein the at least one functional layer has a thickness in a range from about 5 to about 30 nm.

32. The method according to any one of claims 22 to 31 , wherein the sputtering is performed with the substantially optically transparent substrate not being intentionally heated.

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