SE469029B - PROCEDURE CONCERNING THE formation of a high-purity material consisting mainly of silicon, nitrogen and wet matter and the product produced by the process - Google Patents

Description

.O_ \ 10 15 20 25 30 vb CD xD 2 Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol. VI, New York: Wiley, 1961, p. 163. He discovered that ammonia reacts with silicon in bright red heat, forming nitride while releasing hydrogen. High temperature nitriding of silicon is also described in detail in U.S. Patent 4,235,857 and is otherwise well known. However, ultra-high-grade silicon is extremely difficult to nitrate at high temperatures due to the formation of protective nitride layers (exactly of the type used on semiconductors for passivation). According to S.S. Lin in an article entitled "Mass Spectrometric Studies on High Temperature Reaction Between Hydrogen Chloride and Silica / Silicon" in the Journal Electrochem. Society, vol. 123, 1976, p. 512-514 and another article entitled "Comparative Studies of Metal Additives on the Nitridation of Silicon" in the Journal Am. Ceram. Soc., Vol. 60 (1-2), p. 78-81; halide, iron or other cation catalysts are required in such nitration processes. D.

Campos-Loriz et al. developed in an article entitled "The Effects of Hydrogen on the Nitridation of Silicon" in the Journal Mat. Sci., Vol. 14, 1979, p. 1007-1008 and H.

Dervisbegovic et al. in an article entitled "The Role of Hydrogen in the Nitridation of Silicon Powder Compacts" in the Journal Mat. Sci, vol. 16, 1979, p. 1945-55 further the catalytic effects of hydrogen and water vapor on the nitration of silicon with the intention of overcoming the inertia and high cost of the process.

In Between p. 163 stated that E. Vigouroux did not succeed in his attempts to react silicon with liquid ammonia at low temperatures. These results made it apparent to those skilled in the art that more reactive silicon derivatives, such as silicon chloride, silane, etc., would need to be used to produce Si3N4 at temperatures below 100 ° C, the preferred temperature range for industrial processing. Silicon nitride is therefore now produced industrially on a large scale by low temperature reaction between silicon tetrachloride and liquid ammonia as described in U.S. Pat. No. 4,196,178. The intermediate product of amorphous silicon diimide can be brought to crystallize to alpha-silicon nitride during heat treatment in a nitrogen atmosphere. However, the product formed tends to retain chloride on the particle surfaces, thereby not exhibiting the required purity required for the desired applications described above. Prolonged extractions with liquid ammonia or vacuum treatments to remove the halide from the finished product entail additional process costs. Oxygen contamination can occur during this purification process due to the air and moisture sensitivity of the diimide intermediate. Even in the gas phase reaction between silicon tetrachloride and ammonia at temperatures above 700 ° C, chloride and oxygen contamination can reasonably be ruled out as described by M. Rahaman et al. in an article entitled "Surface Characterization of Silicon Nitride and Silicon Carbide Powders" in the Am. Ceram.

SOC. Bull., V01. 65 (8), 1986, p. 1171-76.

The use of silicon halides as a source of silicon for reaction with a nitrogen-containing material to form silicon nitride is well known, and such reactions are described in a number of U.S. patents, such as 3,959,446, 4,073,845, 4,113,830, 4,122,220, 4. 145 224, 4 208 215, 4 368 180, 4 376 652 0Ch 4 399 115.

Formation of silicon nitride using a silane as the silicon source for reaction with a nitrogen compound has also been proposed. U.S. Patents 4,122,155, 4,346,068, 4,387,079 and 4,612,297 disclose the use of a silane as a silicon source in such a reaction. Use of silane (SiH4), a highly reactive gas at temperatures above -112 ° C, can be problematic due to its explosive nature, prolonged product deposition times, insufficient control of the product stoichiometry and morphology of the product and the total high cost of the process. Reactions with halogen-substituted silanes, as set forth in the latter two patents, can lead to contamination problems which require additional purification costs.

Synthesis of silica nitride can be achieved at elevated temperatures (from 1000 to 1700 ° C) by carbothermal nitration of silica. This process is described in U.S. Pat. Nos. 4,122,152, 4,428,916 and 4,590,053.

Processes for producing silicon nitride from mono- and disulfides of silicon and ammonia have been disclosed at high temperature in U.S. Pat. Nos. 3,211,527 and 4,552,740.

These synthetic pathways are more attractive than the above-mentioned high-temperature processes as high reactivity and varying morphologies can be achieved through steam transfer and VLS mechanisms. In addition, sulfur evaporates cleaner from the product.

It would be convenient to have a process in which elemental silicon, which is an available high-purity starting material, could be reacted at a temperature, corresponding to atmospheric pressure, up to below 200 ° C and preferably below 100 ° C, with a nitrogen solution. hydrogen reactant in its liquid state to form a highly pure intermediate consisting mainly of silicon, nitrogen and hydrogen, from which highly pure silicon nitride can be formed by a heat treatment.

It is therefore an object of the present invention to provide a process for the formation of highly pure silicon nitride from elemental silicon and a reactive nitrogen-hydrogen compound which is in its liquid state at temperatures suitable for industrial purposes. It is another object of the present invention to provide a process for forming highly pure silicon nitride from an initial reaction of elemental silicon and a reactive nitrogen-hydrogen liquid at a low temperature. , i.e. below 200 ° C and preferably below 100 ° C.

It is a further object of the invention to provide a process for the formation of highly pure silicon nitride from a reaction intermediate consisting essentially of silicon, nitrogen and hydrogen, which in turn is produced at a temperature below 200 ° C and preferably below 100 ° C, from a reaction between highly pure elemental particulate silicon and a highly pure nitrogen-hydrogen reactant in its liquid state.

It is still another object of the invention to provide a process for producing an intermediate product at a temperature below 100 ° C, which consists essentially of silicon, nitrogen and hydrogen.

The invention thus relates to a process for the formation of a highly pure material, which consists mainly of silicon, nitrogen and hydrogen, wherein elemental particulate silicon is reacted with a nitrogen-hydrogen reactant in its liquid state at a low temperature. which is characterized by a) removing coatings on the elemental silicon particles to promote reaction between the silicon and the hydrogen-hydrogen reactant and b) causing the elemental silicon particles to react with a nitrogen-hydrogen reactant of the formula: NnH (n + m) vari: n = 1-4; and m = 2 when the nitrogen-hydrogen reactant is straight chain and 0 when the nitrogen-hydrogen reactant is cyclic, at a temperature corresponding to atmospheric pressure, up to below about 200 ° C, after which it is optionally heated the reaction product to a temperature of about 1200-1700 ° C in a non-reactive atmosphere to convert the reaction product to a crystalline material, mainly consisting of alpha-silicon nitride.

The invention also relates to the highly pure material, mainly consisting of silicon, nitrogen and hydrogen, which has been obtained according to this process.

The invention is further illustrated by the following description.

The only figure is a flow chart illustrating the method according to the invention. High-purity silicon nitride is formed according to the invention by a first formation of a high-purity intermediate, which is formed by reacting high-purity elemental, particulate silicon with a highly pure nitrogen-hydrogen reactant in its liquid state at a temperature corresponding to atmospheric pressure up to below 200 ° C. ° C, and preferably below 100 ° C, as shown in the following reaction: Si + [NnH (Si, N, H) intermediate (n + m)] 1 wherein: n = 1-4; and m = 2 when the nitrogen-hydrogen reactant is straight chain and 0 when the nitrogen-hydrogen reactant is cyclic.

The highly pure reactive liquid hydrogen-hydrogen compound, hereinafter referred to as [NnH (n + m)] 1 reactant, consists mainly of liquid ammonia (NH3) when n = 1 or a hydrazine compound (NnHn + m) when n = 2 or more. The preferred hydrazine compound is NZH4. However, the use of higher molecular weight hydrazines such as reactive nitrogen-hydrogen liquid, e.g. triazane (N3H5), tetrazine (N4H6) and isotetrazine (N4H6), as well as cyclic hydrazines, such as cyclotriazane (N3H3), within the scope of the invention. The purity of the highly pure [NnH (n + m)] 1 reactant should be at least 99.9% by weight, preferably 99.995% by weight, to obtain the desired high-purity intermediate. Liquid ammonia is readily available in such purity, for example by condensing it from the corresponding gas, while liquid anhydrous hydrazine (NZH4) at such purity level is available commercially (in Mil Spec. Grade) as a component for rocket fuel.

The second reactant comprises elemental silicon in particulate form.

The product obtained by reaction between elemental silicon and liquid ammonia is a solid imide which cannot be easily purified. Surprisingly, however, the reaction with liquid hydrazine gives a clear liquid, which immediately indicates that chemical purification procedures are possible in this case. Consequently, the need for high purity silicon feedstock can be avoided when a liquid hydrazine is used and the use of lower purity silicon, e.g. 95% by weight or higher, may even be economically preferable. The well-known purification procedures for liquids could be applied in such a case: distillation, solvent extraction, crystallization, etc.

Thus, the requirement for the purity of the silicon varies depending on whether n = 1 or greater than 1 for the reactant [NnH (n + m)] 1. When n = 2-4 (see the following Example II), the use of high-purity silicon is not required and a silicon with a purity of 95% by weight or higher can be used for this reaction. However, since the product formed when n = 1 (see the following Example I) cannot be easily purified, the use of high purity silicon is required when liquid ammonia is used as the second reactant. By high-purity silicon is meant a silicon with a purity of 99.9% by weight or better, preferably a purity of 99.999% by weight.

The particle size range of the elemental silicon reactant is preferably about 100 mesh (Tyler) or less, i.e. less than about 150 micrometers. Although larger silicon particles can be used 46 10 15 20 25 30 35 Ü 9 / L 8 _ p for reaction with the [NnH (n + m)] 1 reactant, it should be understood that for an accurate and efficient reaction it is important that the silicon surface area in contact with the reactive nitrogen-hydrogen liquid is large.

Larger silicon particles, even lumps (ie a diameter v of 2.5 cm) with reduced surface area will react more slowly.

The use of such large particles could be desirable in a continuous stream of reactants in an industrial process application of the present invention. The lower limit for the silicon particle size will be determined by the availability of smaller particles as well as safety limitations with regard to the extent of pyrophoric properties for the fine particles. A particle size range from about 0.01 micrometers (colloidal) up to about 150 micrometers gives particles that react rapidly and thoroughly with the [NnH (n + m)] 1 reactant without giving unnecessary safety risks.

If silicon with larger particle size was used, e.g. greater than 150 μm, such particles can be ground before the reaction or in situ during the reaction, as discussed below, under conditions which do not destroy the desired purity. For example, larger silicon particles can be ground using large lumps of silicon as a grinding agent.

Since it is known that silicon is technically a non-metal and not a metal, the term "elemental" is used herein with respect to the silicon reactant to show that elemental silicon, i.e. reduced silicon and not a silicon compound, is what is meant by the highly pure reactant.

In accordance with the invention, the [NnH (n + m)] 1 reactant and the elemental silicon particulate reactant are reacted with each other at low temperature, comprising a temperature below the boiling point of the [NnH (n + m)] 1 reactant at the use the pressure, and preferably at a temperature from about 15 ° C to about 100 ° C below the corresponding boiling point at the pressure used. For example, when the reactive nitrogen-hydrogen liquid is ammonia, the reaction temperature, at atmospheric pressure, will be below -33 ° C. When hydrazine is used as the liquid reactant, the reaction temperature, at atmospheric pressure, will be below 113 ° C and preferably below about 98 ° C.

The term "low temperature" is used herein to refer to a temperature corresponding to atmospheric pressure of below 200 ° C, preferably below 100 ° C, to distinguish this process from prior art processes where temperatures above 1000 ° C are used. in the initial reaction between the silicon-containing reactant and the nitrogen-containing reactant.

The preferred reaction temperature range, when reacting ammonia, is a temperature range, corresponding to atmospheric pressure, from about -33 ° C to about -78 ° C. The preferred reaction temperature range, when hydrazine (NZH 4) is reacted, is a temperature range, corresponding to atmospheric pressure, from about 0 ° C to about 75 ° C, preferably about 15 ° C to 50 ° C.

It should be noted that the above discussion with respect to the reaction temperature range has been expressed in a language which shows temperatures corresponding to the indicated temperatures at atmospheric pressure when it is possible that the reaction may be carried out at a pressure other than atmospheric pressure. For example, when liquid ammonia is used as the [NnH (n + m)] 1 reactant, it may be more advantageous to react liquid ammonia with particulate silicon at a temperature higher than -33 ° C by increasing the pressure, t. ex. to carry out the reaction at room temperature under a pressure of 12 atmospheres. Thus, it is understood that the reaction temperature ranges discussed are not absolute, but are related to the pressure used.

The reaction time of the reactants (or residence time of a continuous reaction) will vary depending on the reactants, the temperature / pressure, at which the reaction is carried out, and other reaction conditions, as discussed below. The reaction time for a batch reaction comprising specified amounts of reactant (eg 50 ml [NnH (n + m)] 1 and 5 g of silicon 1 micrometer in size) can vary from less than 1 hour to as much as 100 hours. , preferably from about 30 minutes to about 50 hours. Longer reaction times are possible with larger particle sizes for silicon and increase of the SiO 2 layer on the surface.

For example, batch reaction between hydrazine and particulate elemental silicon at 25 ° C (atmospheric pressure) can be carried out completely in a few hours, while the batch reaction between liquid ammonia and particulate elemental silicon at -78 ° C (atmospheric pressure) can be carried out in 48 hours.

The reaction time can be accelerated according to a preferred embodiment of the invention by performing a grinding during the reaction. This is believed to accelerate the reaction by constantly exposing new unreacted silicon surfaces and coming into contact with [NnH (n + m)] 1 silicon particles having a particle size of 150 μm and liquid ammonia at -78 ° C at atmospheric pressure shortened from 48 hours or more down to 1 hour or less by grinding the silicon particles during the reaction with the liquid ammonia reactant. For example, a reaction between the reactant may.

Such grinding or crushing of the elemental silicon serves to remove any coatings on its surface (ie.

SiO2), which, if not removed, could interfere with the reaction between the silicon and the [NnH (n + m)] 1 reactant. Such coatings may also optionally be removed prior to the reaction by chemically treating the particulate silicon with coating removers such as hydrofluoric acid or ammonium bifluoride and / or heat treating to at least 1300 ° C in a reducing atmosphere, such as an argon / hydrogen atmosphere, for to significantly improve the reaction time, e.g. to less than 0.5 hour.

It should be noted that when such crushing or grinding is performed as part of the reaction, elementary silicon particles of larger size may be used, e.g. particles larger than 150 μm, which are ground down in situ during the course of the reaction. It should further be noted that the reaction can be carried out continuously, the product being removed as soon as it is prepared, or batchwise, and that the use of large size elemental silicon particles, which are ground in situ during the course of the reaction, may be of particular value when the process is carried out continuously. liquid containing the intermediate formed by the reaction is continuously removed from the reaction zone, leaving the large particles of elemental silicon to be further ground and reacted with new [NnH (n + m)] 1 reactant, which is continuously fed into the reaction zone.

When the reaction is carried out batchwise, the [NnH (n + m)] 1 reactant can be used in stoichiometric excess, which then enables recovery of the reaction product by solvent evaporation of the remaining [NnH (n + m)] 1 reactant. When a continuous process is used, liquid can be continuously removed from the reaction zone, which contains both the intermediate and the [NnH (n + m)] 1 reactant, which can then be separated from the intermediate and returned to the reaction zone, if desired.

The intermediate solution formed by this reaction comprises a solution or dispersion consisting of silicon, nitrogen and hydrogen with less than about 5-10 ppm of impurities. This intermediate can be used in applications which require one or more elements in liquid form, e.g. for polymer processing into fibers. The intermediate formed in accordance with the invention could also be used as a reactant in a wide range of chemistry for the synthesis of complex molecules containing silicon, nitrogen and hydrogen and optionally other elements. In this case, this intermediate can also be used for the production of ceramic silicon materials (eg silicon nitride or silicon carbide) by suitable reaction routes. For example, the intermediate could be heated to 800 ° C in an argon atmosphere to produce silicon nitride with ammonia and hydrogen.

As indicated above, the recovery of the reaction intermediate can be carried out by solvent evaporation of the remaining [NnH (n + m)] 1 reactant. When the [NnH (n + m)] 1 reactant is hydrazine, the product is a clear stable solution, which deposits a white residue on evaporation. Infrared analysis of the solution shows a peak splitting of the NN stretch (normally centered at about 1098 cm -1) to two peaks of equal intensity at 1050 and 1120 cm -1, which may occur through the Si-N junction in solution and do not indicate presence of some other elements are silicon, nitrogen and hydrogen in amounts above 0.05% by weight, which indicates that the solution has a high purity.

After evaporation of the solvent, high purity kistallin alpha-silicon nitride (Si3N4), ie an alpha-silicon nitride product having a purity of at least 99.9% by weight, preferably 99.995% by weight, is formed from the amorphous powdery intermediate residue by heating the residue up to a temperature range of about 1200-1700 ° C in a non-reactive atmosphere, such as argon , 'followed by keeping the residue at this temperature for at least about 15 minutes up to about 2 hours. Longer time periods can be used, but are believed to be unnecessary to achieve complete conversion of the residue to alpha-Si3N4 with a particle size range of about 0.01-0.5 micrometers. It should be noted that the detection of the final product as alpha-silicon nitride is another sign of the cationic purity of the material, as it is known that lower purity amorphous silicon nitride generally forms both beta-silicon nitride and the alpha form in high temperature heat treatment. On the other hand, if beta-silicon nitride is a desired product, this can be achieved by the addition of agents known in the art to promote the formation of the beta form.

The following examples serve to better illustrate the process of the invention.

Example I Ammonia gas was condensed over a six hour period in a polyethylene bottle using dry ice at about -78 ° C to give 50 ml of liquid ammonia, which was then contacted with 5 g of particulate silicon having a particle size of 1 micrometer. or less and a purity of 99.9% by weight. The reactants were ground in the reaction vessel for 3 hours at a temperature of -78 ° C for 48 hours. The intermediate was recovered by evaporation of the remaining NH 3 as a tan residue.

This residue was found to be amorphous on X-ray diffraction examination with some unreacted silicon, of which the brown color follows. Infrared spectroscopy of the residue showed peaks, which differed from an IR reference pattern for silicon.

Sharp absorption peaks were found at 1180 cm -1, 1210 cm -1 and 5000 cm -1, which is associated with the presence of NH and NH 2 groups, and an elevated threshold between 960 and 1050 cm -1 depending on the wide Si-N range. Examination by scanning electron microscopy (SEM) of the residue showed non-crystalline material distributed among the silicon particles. The residue was heated to a temperature of 1300 ° C in argon for 2 hours. Possible oxygen contamination was avoided with a double enclosed crucible arrangement, whereby silicon nitride powder surrounds the walls of the inner crucible. The product obtained gave an X-ray pattern indicating alpha-silicon nitride at 1400 ° C and unreacted silicon. Formation of alpha-silicon nitride only at 1400 ° C, as well as SEM EDS analysis, whereby only silicon was found (nitrogen can not be detected), confirms the high purity of the reaction product.

Example II To 50 ml of liquid hydrazine was added 0.05 g of particulate silicon having an average particle size of about or less than 10 microns and a purity greater than 99.9% by weight, and the mixture was reacted in a reaction vessel under an inert argon atmosphere for 3 hours at a temperature of 25 ° C. The resulting reaction product was a clear solution containing silicon, which was confirmed by inductively coupled plasma atom absorption.

Solvent evaporation in vacuo of the hydrazine left a polymer residue which showed an IR absorption band at 950 cm -1 depending on the Si-N range, a wide NN range between 1100-1220 cm -1 and the oscillations and the anti-symmetrical ranges due to NH, NH groups within 1250-1600 cm-1 - the area respectively the wide 2800-3500 cm_1 it. The product produced a broadband Raman top, which had a center at 800 cm_1 and which is flattened when the product is exposed to air. Heating of the residue in air caused the disappearance of the Si-N-, NH- and NH2 groups, these being replaced by SiO at 1150 cm-1. The Si / NZH4 intermediate complex also absorbs within the ultraviolet range at 240, 288 and has a wide threshold at 278 nm. The conversion in the near-ultraviolet range at 288 nm may indicate some double-bonded nitrogen atoms, ie. -N = N-, depending on an electron transition from the pi-orbital state to an anti-binding pi-orbital state. The electron transition from the ground state to an anti-binding sigma orbital state, which is normally seen at 220 nm in silanyl-hydrazine complexes, is redshifted to 240 nm, whereby re-donation from nitrogen to silicon can be inhibited depending on the nitrogen-nitrogen multiple bond. Thermal gravimetric analysis in argon of the residue showed a loss of 79% by weight. This corresponds to approximately six N H4 molecules for each silicon atom. X-ray stretching range 2 diffraction analysis of the intermediate showed that it was amorphous. SEM examination indicated that the intermediate residue after evaporation is a fine colloidal powder. The residue was then heated to a temperature of 140 DEG C. for 3 hours in an argon atmosphere under a nitrogen buffer as described in Example 1. Finely divided crystals were recovered, which on X-ray diffraction were found to be alpha-Si3 N4.

Example III To further characterize the intermediate formed by the reaction between elemental silicon and the [NnH + m)] 1 reactant, the local silicon region was analyzed by silicon NMR to determine the type of bond present in the intermediate in a hydrazine solution. Peaks were found at -73.1 ppm and -82.06 ppm, which is typical of a silicon-nitrogen bond.

No other peaks of appreciable size were noted, indicating that the silicon-nitrogen-hydrogen bond predominates in the intermediate.

In particular, no silicon-hydrogen bonding was detected using INEPT Cross Polarization Techniques, as described by David T. Pegg and M. Robin Bendall in "Polarization Transfer Between Two Scalar-Coupled Systems of Arbitrary Numbers of Nuclei of Arbitrary Spins", Journal of Magnetic Resonance , vol. 55 (1983), p. 51-63.

The sample was also analyzed by proton NM. The chemical proton shift was similar to that typically known in silyl amines. This shows that the hydrogen is bound by nitrogen to silicon, ie. not simply as a nitrogen-hydrogen bond as in the hydrazine solvent. This confirms the reaction between the elemental silicon and the [NnH (n + m)] 1 reactant. Furthermore, as the silicon NM analyzes did not indicate any direct silicon-hydrogen bonding, the intermediate must comprise a compound having silicon-hydrogen-hydrogen bonding. 42 :.

While a particular embodiment of the process for forming high purity Si N and its starting materials has been illustrated and described: in accordance with the present invention, modifications and alterations of apparatus and processes are comprehensive parameters. and materials, etc., will be apparent to one skilled in the art and all such modifications and changes are within the scope of the appended claims and are within the scope of the invention.

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Claims (18)

10 15 20 25 30 17 Patent claims A process for forming a highly pure material, consisting essentially of silicon, nitrogen and hydrogen, wherein elemental particulate silicon is reacted with a nitrogen-hydrogen reactant in its liquid state at a low temperature, characterized in by a) removing coatings on the elemental silicon particles to promote reaction between the silicon and the hydrogen-hydrogen reactant and b) causing the elemental silicon particles to react with a nitrogen-hydrogen reactant of the formula: NnH (n + m) gvari : n = 1-4; and m = 2 when the nitrogen-hydrogen reactant is row chain and 0 when the nitrogen-hydrogen reactant is cyclic, at a temperature corresponding to atmospheric pressure, up to below about 200 ° C, after which the reaction product is optionally heated to a temperature of about 1200-1700 ° C in a non-reactive atmosphere to convert the reaction product to a crystalline material, mainly consisting of alpha-silicon nitride. 2. A method according to claim 1, characterized in that the surface coating on the elemental silicon particles is removed by chemical treatment of the silicon with a reactant which can remove the coating. 3. A method according to claim 1, characterized in that the coating on the elemental silicon particles is removed by heating the particulate material to a temperature of at least 1300 ° C in a reducing atmosphere. C] \ 10 15 20 25 30 v fl CD M3 vD 18 4. A method according to claim 1, characterized in that the surface layer of the elemental silicon particles is removed by grinding the silicon particles during the reaction between the particulate silicon material and the N -reactant. f nH (n + m) a t of that or higher k n n e t e c k n Vi The method of claim 1, the elemental silicon having a purity of 99.9% by weight when n = 1 and of 95% by weight or higher when n = 2-4. a t of that 99.9% by weight. 6. A method according to claim 1, characterized in that the elemental silicon has a purity of at least a t of 99.999% by weight. 7. A method according to claim 6, characterized in that the elemental silicon has a purity of at least A process according to claim 1, characterized in that the particulate elemental silicon used in the reaction has a particle size range from about 0.01 micrometers to about 150 micrometers. 9. A process according to claim 1, characterized in that the N H -reactant comprises a compound with a boiling point, n (n + m) corresponding to atmospheric pressure, of below 200 ° C. 10. A process according to claim 9, characterized in that the NnH (n + m) reactant is selected from the group consisting of ammonia; a hydrazine compound of the formula NnH (n + 2), wherein n = 2-4; a cyclic hydrazine compound of the formula NnHn, wherein n = 3-4; and mixtures thereof. Process according to Claim 10, characterized in that the NnH (n + m) reactant consists mainly of ammonia and in that the reaction temperature range is a temperature which at atmospheric pressure corresponds to from about -40 ° C to about -125 °. C. 10 15 20 25 30 35 19 A process according to claim 10, characterized in that the NnH (n + m) reactant consists mainly of hydrazine (NZH4) and that the reaction temperature range is a temperature, corresponding to atmospheric pressure, from about 0 ° C to about 100 ° C. 13. The process of claim 1, wherein the low temperature ranges from about 15 ° C to about 100 ° C below the boiling point of the NnH (n + m) reactant. 14. A process according to claim 1, characterized in that the NnH (n + m) reactant is present in stoichiometric excess relative to the elemental silicon reactant. A process according to claim 1, characterized in that the elemental silicon is reacted with the NnH (n + m) reactant for a time of from less than 1 hour up to about 100 hours. 16. A process according to claim 15, characterized in that the reaction time is from about 30 minutes up to about 50 hours. 17. A process according to claim 1, characterized in that the process is carried out in a continuous manner and that the reactants have a contact time together from from 1 hour up to about 100 hours. 18. A product consisting essentially of silicon, nitrogen and hydrogen, characterized in that it is prepared by a) removing coatings on elemental silicon particles b) causing the elemental silicon particles to react with a nitrogen-hydrogen reactant of the formula NnH (n + m) vari: n = 1-4; and m = 2 when the nitrogen-hydrogen reactant is row chain and 0 u-.n I xO c: m ~ o 20 when the nitrogen-hydrogen reactant is cyclic, at a temperature, corresponding to atmospheric pressure, up to below about 200 ° C.