Nanotechnology for photonic and optical components

#The invention relates to non-stoichiometric substances and more particularly to nanostructured non-stoichiometric substances and products incorporating such substances.

#Most compounds are prepared as stoichiometric compositions, and numerous methods of preparing substances for commercial use are motivated in objective to create stoichiometric compounds. For example, producers of titania fillers, copper oxide catalysts, titanate dielectrics, ferrite magnetics, carbide tooling products, tin oxide sensors, zinc sulfide phosphors, and gallium nitride electronics all seek stoichiometric compositions (TiO2, CuO, BaTiO3, NiFe2O4, TiC, SnO2, ZnS, and GaN, respectively).

#Those skilled in the art will note that conventional powders of oxides and other compounds, when exposed to reducing atmospheres (e.g. hydrogen, forming gas, ammonia, and others) over a period of time, are transformed to non-stoichiometric materials. However, the time and cost of doing this is very high because the inherent diffusion coefficients and gas-solid transport phenomena are slow. This has made it difficult and uneconomical to prepare and commercially apply stable non-stoichiometric forms of materials to useful applications.

#The invention is described with reference to the several figures of the drawing, in which,

#FIG. 1: UV-Vis absorption spectra of stoichiometric indium tin oxide (yellow) and non-stoichiometric indium tin oxide (blue).

#FIG. 2. Resistance of stoichiometric (1) and non-stoichiometric (2) nickel zinc ferrites as a function of frequency.

#Non-stoichiometric substances in this invention are envisioned as substances that bridge between the artificial classification of substances—i.e. metals, alloys, oxides, carbides, nitrides, borides, sulfides, chalcogenides, suicides, etc. For example, while tin (Sn) is a metal, tin oxide (SnO2) is an oxide ceramic. Non-stoichiometric tin oxide is then a form of a substance that transitions the properties of metallic tin to ceramic tin oxide. For example, non-stoichiometric tin oxides can be prepared with composition such as SnO0.04, SnO0.14, SnO0.24, SnO0.34, SnO0.44, SnO0.54, SnO0.64, SnO0.74, SnO0.84, and SnO0.94. The physical, thermal, chemical, and other properties of tin and tin oxide are very different, and the properties of non-stoichiometric tin oxide are anticipated to be very different and unique when compared with both metallic tin and ceramic tin oxide. The presence of vacancies in SnOx is anticipated to lead to higher conductivities, novel catalytic properties, novel structural properties, novel magnetic properties, faster sintering, and other desirable commercial performance. A preferred embodiment is to use a submicron non-stoichiometric form. A more preferred embodiment is to use a nanoscale non-stoichiometric form. It is important to note that the non-stoichiometric form can be converted to a stoichiometric form if and when desired. Thus, the beneficial properties of non-stoichiometric forms can be utilized in some applications during processing, while leaving the flexibility for use of either a stoichiometric or a non-stoichiometric form in the final product.

#Another illustration, without limiting the scope of this invention, is the non-metal boron and the ceramic boron nitride. In stoichiometric form, boron is B, and the ceramic boron nitride is BN. These two materials have very different molecular orbitals and different physical, thermal, chemical, optical, catalytic, structural, and other properties. Additionally, it is easier to process boron than boron nitride. Illustrative but not limiting forms of non-stoichiometric boron nitride include BN0.025, BN0.125, BN0.225, BN0.325, BN0.425, BN0.525, BN0.625, BN0.725, BN0.825, BN0.925. It is anticipated that nanoscale forms of these non-stoichiometric BNx will yield novel electrical and electronic properties, novel catalytic properties, novel structural properties, novel magnetic properties, faster sintering, and other desirable commercial performance. Once again, a preferred embodiment is to use a submicron non-stoichiometric form. A more preferred embodiment is to use a nanoscale non-stoichiometric form. Once again, it is important to note that the non-stoichiometric form can be converted to a stoichiometric form if and when desired. Thus, the beneficial properties of non-stoichiometric forms can be utilized in some applications during processing, while leaving the flexibility for use of either a stoichiometric or a non-stoichiometric form in the final product.

#Yet another illustration, without limiting the scope of this invention, is metallic titanium and the ceramic titanium carbide. In stoichiometric form, metallic titanium is Ti, and ceramic titanium carbide is TiC. These two materials have very different molecular orbitals and different physical, thermal, chemical, optical, catalytic, structural, and other properties. It is easier to process metals than ceramics, and the ductilities of metals are very different than those of ceramics. Illustrative but not limiting forms of non-stoichiometric titanium carbide include TiC0.05, TiC0.15, TiC0.25, TiC0.35, TiC0.45, TiC0.55, TiC0.65, TiC0.75, TiC0.85, TiC0.95. It is anticipated that nanoscale forms of nonstoichiometric TiCx will yield novel electrical and electronic properties, novel catalytic properties, novel structural properties, novel magnetic properties, faster sintering, and other desirable commercial performance. Once again, a preferred embodiment is to use a submicron non-stoichiometric form. A more preferred embodiment is to use a nanoscale non-stoichiometric form. Once again, it is important to note that the non-stoichiometric form can be converted to a stoichiometric form if and when desired. Thus, the beneficial properties of non-stoichiometric forms can be utilized in some applications during processing, while leaving the flexibility for use of either a stoichiometric or a non-stoichiometric form in the final product.