Methods for synthesiziing nitrogen-containing materials via decomposotion of a lithiated nitrogen-containing precursor

Abstract

A method for synthesizing a nitrogen-containing material includes mixing a nitrogen-containing lithiated precursor with at least one element other than lithium and nitrogen to yield a mixed composition, placing the mixed composition in an apparatus, supplying nitrogen gas into the apparatus, and heating the apparatus to an elevated temperature at an elevated pressure for a predetermined period of time to yield the nitrogen-containing material.

Description

METHODS FOR SYNTHESIZIING NITROGEN-CONTAINING MATERIALS VIA DECOMPOSOTION OF A LITHIATED NITROGEN-CONTAINING PRECURSOR CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application is a continuation of United States Provisional Patent Application Serial No. 63 / 497,027, filed April 19, 2023, the entirety of which is hereby incorporated by reference herein as though fully set forth herein. FIELD OF DISCLOSURE

[0002] The present disclosure relates to methods for synthesizing nitrogen-containing materials, and more particularly to methods for growing nitrogen-containing single crystals via decomposition of lithiated nitrogen-containing precursors. BACKGROUND

[0003] Semiconductor materials are useful in many electric device applications for their exceptional material properties. Challenges arise regarding synthesis of these materials at large volumes due to equipment requirements and associated expenses.

[0004] Accordingly, those skilled in the art continue research and development in the field of synthesizing nitrogen-containing materials, such as semiconductor materials. BRIEF SUMMARY

[0005] This summary is intended merely to introduce a simplified summary of some aspects of one or more implementations of the present disclosure. Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. This summary is not an extensive overview, nor is it intended to identify key or critical elements of the present teachings, nor to delineate the scope of the disclosure. Rather, its purpose is merely to present one or more concepts in simplified form as a prelude to the detailed description below.

[0006] Presently, growth of single crystal GaN, AlN, and BN materials is limited to smaller sizes due to various material constraints. There is a need to grow larger size boules of those material to address industry needs of those materials. Accordingly, the present disclosure provides an affordable solution by offering a method for synthesizing those materials in boules on a larger scale while maintaining desired material properties.

[0007] The present disclosure is directed to methods for synthesizing a nitrogen-containing material.

[0008] A method for synthesizing a nitrogen-containing material includes mixing a nitrogen- containing lithiated precursor with at least one element other than lithium and nitrogen to yield a mixed composition, placing the mixed composition in an apparatus, supplying nitrogen gas into the apparatus, and heating the apparatus to an elevated temperature at an elevated pressure for a predetermined period of time to yield the nitrogen-containing material.

[0009] In one example, the lithiated precursor includes a binary nitride. In one example, the lithiated precursor includes a ternary nitride. In one example, the mixed composition includes at least one ternary or higher order lithium nitride compound. In one example, the lithiated precursor includes one or more of Li3N, Li3BN2, Li3GaN2, or Li3AlN2. In one example, the mixed composition includes one or more of Li3BN2, Li3GaN2, or Li3AlN2.

[0010] In one example, the at least one element other than lithium and nitrogen includes gallium, aluminum, or boron. In one example, the at least one element other than lithium and nitrogen includes an element or material that is dissolved in the flux or is in the liquid state under processing condition, that may include at least one flux modifier selected from hydrogen, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, lead, tin, antimony, indium, and bismuth. In one example, the mixed composition includes a nitride.

[0011] In one example, the method includes adding an impurity or dopant to the mixed composition, wherein the impurity or dopant includes one or more of carbon, sulfur, silicon, germanium, oxygen, beryllium, zinc, or magnesium. In one example, the nitrogen-containing material includes GaN. In one example, the nitrogen-containing material includes BN. In one example, the nitrogen-containing material includes AlN.

[0012] In one example, the mixed composition includes a nitrogen content greater than 1 at%N, greater than 5 at%N, or greater than 10 at%N. In one example, the nitrogen-containing material includes AlGaN, AlBN, BGaN, or BAlGaN at arbitrary ratios of Al to Ga to B. In one example, the nitrogen-containing material includes AlxGa1-xN, AlxB1-xN, BxGa1-xN, or BxAlyGa1-x-yN, wherein x or y are greater than or equal to 0 and less than or equal to 1. In one example, the nitrogen-containing material includes a controlled amount of a dopant or impurity. In one example, the nitrogen-containing material is a single crystal. In one example, nitrogen-containing materialis a single crystal boule having a diameter or width of at least 1 cm, at least 5 cm, or at least 10 cm.

[0013] In one example, the apparatus is an autoclave. In one example, the elevated temperature ranges from about 800 C to about 1600 °C. In one example, the elevated pressure ranges from about 0.1 MPa to about 100 MPa.

[0014] In one example, the method includes positioning the mixed composition in a crucible and positioning the crucible into an autoclave prior to heating. In one example, the crucible is positioned near a heating apparatus in the apparatus. In one example, the crucible includes one or more of B, C, N, O, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, or Re.

[0015] In one example, the method includes pressurizing the apparatus with nitrogen gas at room temperature for a predetermined period of time to a pressure ranging from 0.1 MPa to 100 MPa and reducing the pressure to a pressure ranging from 0.1 MPa to 10 MPa prior or shortly after heating. In one example, the apparatus is pressurized for a predetermined time ranging from about 20 minutes to about 24 hours.

[0016] In one example, the method includes adding at least one flux modifier to the mixed composition. In one example, the method includes separating the nitrogen-containing material from a byproduct material.

[0017] A method for synthesizing a nitrogen-containing material includes providing a molten material in an apparatus and transporting a nitrogen-containing lithiated precursor through the molten material for a predetermined period of time to yield the nitrogen-containing material.

[0018] In one example, the apparatus is pressurized at 1 atm N2. In one example, the molten material includes one or more of aluminum, gallium, boron, sodium, potassium, cesium, lead, tin, antimony, and indium. In one example, the apparatus is heated to a temperature ranging from about 800 °C to about 1600 °C. In one example, the lithiated precursor includes a binary nitride. In one example, the lithiated precursor includes one or more ternary nitride. In one example, the lithiated precursor includes one or more of Li3N, Li3BN2, Li3GaN2, or Li3AlN2. In one example, the nitrogen-containing material includes GaN. In one example, the nitrogen-containing material includes BN. In one example, the nitrogen-containing material includes AlN.

[0019] In one example, the nitrogen-containing material includes AlxGa1-xNI, AlxB1-xN, BxGa1-xN, or BxAlyGa1-x-yN for which x or y are greater than or equal to 0, yet less than or equal to 1. In one example, the nitrogen-containing material contains a controlled amount of a dopant or impurity.In one example, the nitrogen-containing material is a single crystal. In one example, the nitrogen- containing material is a single crystal boule having a diameter or width of at least 1 cm, at least 5 cm, or at least 10 cm. In one example, the apparatus is an autoclave.

[0020] A method for synthesizing a nitrogen-containing material incudes providing a nitrogen- containing lithiated material and a non-lithiated material in an apparatus and heating the apparatus to a temperature greater than the decomposition temperature of the nitrogen-containing lithiated material for a predetermined period of time at at least 1 atm of N2to yield the nitrogen-containing material.

[0021] In one example, the lithiated precursor includes a binary nitride. In one example, the lithiated precursor includes a ternary or higher order nitride. In one example, the lithiated precursor includes Li3N, Li3BN2, Li3GaN2, or Li3AlN2. In one example, the nitrogen-containing material includes AlxGa1-xNI, AlxB1-xN, BxGa1-xN, or BxAlyGa1-x-yN, wherein x or y are greater than or equal to 0 and less than or equal to 1. In one example, the nitrogen-containing material contains a controlled amount of a dopant or impurity. In one example, the non-lithiated material includes a dissolved element. In one example, the non-lithiated material includes a reactive material.

[0022] In one example, the nitrogen-containing material includes GaN. In one example, the nitrogen-containing material includes BN. In one example, the nitrogen-containing material includes AlN. In one example, the nitrogen-containing material is a single crystal. In one example, the nitrogen-containing material is a single crystal boule having a diameter or width of at least 1 cm, at least 5 cm, or at least 10 cm. In one example, the apparatus is an autoclave.

[0023] A nitrogen-containing single crystal includes GaN, a diameter or width of at least 50 mm, and a length to diameter ratio of at least 1:1. In one example, the since crystal includes a lattice curvature of greater than 100 m and a diameter or width greater than 1 cm. In one example, the single crystal material is a boule. In one example, the single crystal is synthesized via a nitrogen- containing lithiated material. In one example, the single crystal includes a controlled amount of a dopant or impurity.

[0024] A nitrogen-containing single crystal including AlN, a diameter or width of at least 50 mm, and a length to diameter ratio of at least 2:1.

[0025] In one example, the single crystal has a lattice curvature of greater than 100 m and a diameter greater than 1 cm. In one example, the single crystal material is a boule. In one example,the single crystal is synthesized via a nitrogen-containing lithiated material. In one example, the single crystal includes a controlled amount of a dopant or impurity.

[0026] A nitrogen-containing single crystal includes BN, a diameter or width of at least 10 mm, and a length to diameter ratio of at least 1:2.

[0027] In one example, the single crystal includes a lattice curvature of greater than 100 m and a diameter or width greater than 1 cm. In one example, the single crystal material is a boule. In one example, the single crystal is synthesized via a nitrogen-containing lithiated material. In one example, the single crystal includes a controlled amount of a dopant or impurity. In one example, the nitrogen-containing single crystal has at least 100%, at least 99%, or at least 95% of a hexagonal, wurtzite, cubic, or rhombohedral phase. DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a graph illustrating decomposition pressure of Li3N as a function of temperature;

[0029] Figure 2 is a schematic of a system for synthesizing a nitrogen-containing material;

[0030] Figure 3 is graph illustrating equilibrium vapor pressure of Li over pure Li;

[0031] Figure 4 is a schematic of an autoclave used for the disclosed method;

[0032] Figure 5 is a scanning electron micrograph of a hBN crystal grown by the disclosed method;

[0033] Figure 6 is a scanning electron micrograph of a portion of the hBN crystal of Figure 5;

[0034] Figure 7 is a series of boron and nitrogen energy-dispersive X-ray spectroscopy images of the hBN crystal of Figure 5;

[0035] Figure 8 is an X-ray diffraction scan of the hBN crystal of Figure 5;

[0036] Figure 9 is a Raman scattering spectra of the hBN crystal of Figure 5; and

[0037] Figure 10 is an X-ray diffraction scan of a GaN crystal.

[0038] The detailed description of the disclosure will be better understood when read in conjunction with the appended drawings. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities of the examples shown in the drawings.DETAILED DESCRIPTION

[0039] For illustrative purposes, the principles of the present disclosure are described by referencing various examples thereof. Although certain examples of the disclosure are specifically described herein, one of ordinary skill in the art will readily recognize that the same principles are equally applicable to, and can be employed in other applications and methods. It is to be understood that the disclosure is not limited in its application to the details of any particular example shown. The terminology used herein is for the purpose of description and not to limit the disclosure, its application, or uses.

[0040] As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context dictates otherwise. The singular form of any class of the ingredients refers not only to one chemical species within that class, but also to a mixture of those chemical species. The terms “a” (or “an”), “one or more” and “at least one” may be used interchangeably herein. The terms “comprising”, “including”, “containing”, and “having” may be used interchangeably. The term “include” should be interpreted as “include, but are not limited to”. The term “including” should be interpreted as “including, but are not limited to”.

[0041] As used throughout, ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. Thus, any range of values disclosed herein is merely exemplary and includes all values and sub-ranges there-between

[0042] Unless otherwise specified, all percentages and amounts expressed herein and elsewhere in the specification should be understood to refer to percentages by weight of the total composition. Unless otherwise specified, reference to a molecule, or to molecules, being present at a “wt. %” refers to the amount of that molecule, or molecules, present in the composition based on the total dry-weight of the composition. Unless otherwise specified, reference to a molecule, or to molecules, being present “based on the dry weight of the composition” refers to that molecule, or molecules, being present in the composition based on the total dry-weight of the composition in a dry state. The “dry state” refers to solvent being present in the composition at an amount less than 5.0 wt. %, less than about 3.0 wt. %, less than about 1.0 wt. %; preferably less than about 0.5 wt. %, and more preferably less than about 0.25 wt. % of the composition. For example, a composition in the dry state may refer to a composition having about 95% solids, about 98% solids, preferably about 99% solids, or more preferably about 100% solids. By contrast, unless otherwise specified,reference to a molecule, or to molecules, being present “based on the wet weight of the composition” refers to that molecule, or molecules, being present in the composition based on the total dry-weight of the composition which includes at least 5 wt. % of solvent.

[0043] According to the present application, use of the term “about” in conjunction with a numeral value refers to a value that may be + / - 5% of that numeral. As used herein, the term “substantially free” is intended to mean an amount less than about 5.0 wt. %, less than 3.0 wt. %, less than 1.0 wt. %; preferably less than about 0.5 wt. %, and more preferably less than about 0.25 wt. % of the composition.

[0044] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this disclosure belongs. All patents, patent applications, publications, and other references cited or referred to herein are incorporated by reference in their entireties for all purposes. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure Comparatives.

[0045] In the description of examples disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present disclosure. Relative terms such as "lower," "upper," “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing (if applicable) under discussion. These relative terms are for convenience of description only and, unless specified otherwise, do not require that the apparatus be constructed or operated in a particular orientation.

[0046] As used herein, terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and the like refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. Accordingly, the disclosure is not limited to such examples illustrating certain combinations of features that may exist alone or in combination with other features.

[0047] Disclosed herein is a method for synthesizing nitrogen-containing materials. The method uses a lithiated precursor material for growing nitrogen-containing single crystals, such as gallium nitride (GaN), boron nitride (BN), and aluminum nitride (AlN). The method utilizes controlleddecomposition of a nitrogen-containing, lithiated precursor to yield the synthesis for a nitrogen- containing material.

[0048] Nitrogen-containing materials, including nitrides, oxynitrides, carbonitrides, etc. may be useful for forming materials with advantageous material properties. For example, GaN, a wide band gap semiconductor, is used for the production of blue (white) LEDs and lasers, as well as during operation of power electronic / RF devices. AlN may be useful for UV optoelectronic devices (disinfection, curing, etc.). BN may be useful, particularly in the hexagonal polymorph, for development of 2D device technologies and, in the cubic polymorph, as a super hard material having exceptional thermal conductivity and uses in power electronics / RF devices due to its intrinsic material properties.

[0049] Challenges with synthesizing the above-mentioned materials in large volumes arise due to expenses required as well as ease with which those materials decompose at temperature prior to them melting (e.g. GaN to Ga metal + N2 gas). Furthermore, synthesis of ternary alloys, such as AlGaN, in formats larger than thin film or in powder form faces complications with commercial viability.

[0050] The nitride (N3-) anion imparts unique electronic and bonding characteristics in nitride materials that are difficult to achieve in other chemical spaces making nitrides an exciting materials design space. These properties lead to useful (opto-)electronic and defect-tolerant properties along with strong metal- nitrogen bonds for structural stability and mechanical stiffness. Proper materials selection and design has led to important advances and breakthroughs in: solid-state lighting (e.g. InxGa1-xN, Sr[LiAl3N4]:Eu2+), superconductors (e.g. CaTaN2), ammonia-synthesis catalysts (e.g. Fe3Mo3N, Co3Mo3N, Ni2Mo3N), and topological materials (e.g. MgTa2-xNbxN3), amongst manyothers. Computationally, many new andexciting nitrides and associated material systems withintriguing materials properties have been predicted. These include, for example, thermodynamically stable, pure-nitride perovskites for which computationpredicts: LaWN3tohave ferroelectric polarizations similar, if not superior, to toxic lead titanate, LaMoN3 to exhibitdegenerate p-type doping via Sr doping which is uncommon for nitride semiconductors, and NdReN3or DyReN3to have magnetizations comparable, if not superior to, state-of-the-art Nd-based hard- magnets (i.e. Nd2Fe14B).As all these materials are perovskites, considerable latitude is anticipated in their tuning of properties via cation substitutions as is the case for oxides.

[0051] The disclosed method provides a suitable synthesis process. Typical processes require the addition of nitrogen to the system in a reactive form (plasma, ammonia or precursors such as azides (NaN3), amides (NaNH2), or nitrides (Ca3N2)). By applying heat (and in some cases pressure),nitrogen is transferred to the desired elements thereby forming a nitride. This typically occurs in the solid- state or from the gas phase. While these techniques have been successfully applied to nitrides today, there are two critical shortcomings if the nitride can be synthesized at all: materials are typically defective polycrystalline solids with a significant quantity of grain boundaries negatively impacting intrinsic material properties or they are thin films applied onto a substrate leading to strained, polycrystalline or defected films. High-quality, free-standing single crystal materials sufficient for proper materials characterization are commonly limited in size to a few millimeters due to constraints of their synthesis tool.

[0052] With the advent of wide-band gap GaN in the early 1990s, increased attention led to the development and refinement of synthesis routes for large volume, single crystal growth methods of nitrides to take full advantage of their intrinsic properties. The most promising commercialized methods follow two different strategies: gas-phase delivery of a metal-halide and ammonia in large concentrations leading to > 1 cm per day grow rates (e.g. hydride vapor phase epitaxy (HVPE)) or use of a nitrogen-rich solvent (supercritical ammonia) enabling the dissolution of elements and crystallization of their respective nitrides (e.g. ammonothermal method). While of both these methods have exhibited success, they may be constrained in their thermodynamic or kinetic flexibility to provide significantly new synthesis opportunities for crystalline multinary nitrides.

[0053] One approach to nitride growth is the use of sodium as a flux. Sodium will not form a nitride at elevated temperatures (T) and as such acts as a mediating agent for nitrogen, thereby allowing for growth of nitrides. Nevertheless, synthesis of large single crystals (> 1 mm3) requires continuous dissolution and transport of nitrogen in the melt, which is exceedingly challenging as it is typically many orders of magnitude below 1 at%N (e.g.10-11at%N in pure Na), in effect choking off the nitrogen supply and negating any significant growth. A notable exception to this behavior found thus far is GaN, which forms from a unique Na-Ga liquid with anomalously large voids allowing nitrogen to more readily dissolve, leading to increased solubility by almost six order of magnitudes (0.01 at%N). This has led to the synthesis of large size crystals of GaN of high purity and outstanding quality-a feat clearly demonstrating large-diameter growth of high purity, single crystal nitrides can occur from a flux-based system.

[0054] Another approach to nitride synthesis, while retaining the simplicity and flexibility of a flux- based approach, includes a new flux which has substantially higher nitrogen solubility and is independent of the constituents present in the flux. Lithium (Li)readily nitrides and forms Li3N,even under ambient conditions, leading to a flux with 25 at%N. Furthermore, Li is known to form ternary nitrides with over 32 elements (including B, Al, Ga, In) with additional nitrides being computationally predicted suggesting at last finite solubility for a wide range of elements in this flux-system.

[0055] Critical to the successful synthesis of materials is the ability to liquify the Li-flux while retaining a stoichiometric mixture of Li:N as 3:1 to avoid existence of potentially undesired,reactive, non-nitrided compounds in the melt. Previous work on using Li3N as a flux typicallyentailed the use of either a sealed, isothermally held ampoule or a nitrogen (sub-)atmospheric Czochralski puller. Pure Li3N melts at 813 °C and it is estimated that a nitrogen pressure of at least 0.6 atm is needed to prevent decomposition: 2 Li3N(l)➔6 Li(l)+ N2(g). Experimentally measureddecomposition pressures for Li3N can beassuming insignificant changes to the enthalpy (166 kJ / molLi3N) and entropy (120.6 J / mol-K) of formation of Li3Nand is provided inFigure 1. This extrapolation illustrates a pure Li3N melt can be stabilized up to ~ 1000 °C if 100 atm of N2, or 1060 °C for 1000 atm N2. As the boiling temperature of pure lithium is ~ 1330 °C at 1 atm N2, its vapor pressure contribution to the total system pressure can be neglected from a pressure-design perspective. Thus, it has been discovered that using Li3N as a nitriding agent as a liquid at super-atmospheric pressure to eliminate its decomposition and forming of an undesired N-deficient Li3N-Li melt is useful for synthesizing nitrogen-containing materials. It is noted that while Figure 1 shows up to 100 C, growth is possible at temperature of above 1200 °C and pressures above 100 atm. For example, pressure up to 4000 atm may be utilized within the disclosed method.

[0056] The disclosed method may be implemented in a suitable, corrosion-resistant crucible 200,see Figure 4,capable of containing the melt. In one example, the method is performed in a crucible 200 that includes tungsten (W). Tungsten’s dissolution kinetics and resulting formation of LiWN2 may be accelerated by oxygen contamination of the system, suggesting high-purity systems are beneficial.

[0057] In another example, the disclosed method is performed in a crucible 200 that includes one or more of Mo, Nb, Ta, Fe, Re, TiC, ZrC, BN, Ti, Zr, ZrN, ZrBN, and Cr3C2.Materials which havebeen successfully used with Li or Li3XN2(X = B, Al, Ga) at high temperature (> 800 °C) include Mo, Nb, Ta, Fe, Re, TiC, ZrC, BN, and Cr3C2with BN and Wshowing stability for all threeproposed ternary systems. Large scale growth of nitrides from an alkali metal-flux containing an insufficient reservoir of solid- source nitrogen (in the form of a compound) necessitates addition of nitrogen from the gaseous phase. This requires an open system to allow for continuous nitrogen supply while simultaneously a closed system to prevent alkali metal vapors from escaping and hence rapidly depleting the alkali metal-flux. All these processes are performed in a pressurized chamber (< 100 atm) with a crucible temperature up to~1000 °C.

[0058] Accordingly, the present disclosure provides methodology for synthesizing nitrogen- containing materials from a molten bath of lithiated nitrogen-containing precursors under industrially accessible and scalable conditions. The disclosed methodology is performed at pressures around or below 100 atm and at temperatures in excess of 800 °C. In one aspect, the disclosure provides a means for growing nitride single crystals via controlled decomposition of a N-containing precursor on a submerged, preferentially heated surface in the melt.

[0059] In one or more examples, the disclosed method includes providing a lithiated nitriding flux. In one example, the lithiated nitriding flux includes Li3N. The Li3N requires temperatures above approximately 813 °C and pressure above approximately 0.6 atm of nitrogen gas to stabilize and prevent decomposition required for use within an apparatus, such as an autoclave.

[0060] In one or more examples, the method includes mixing the lithiated nitriding flux with a soluble element, such as a metal or metalloid material. In one example, the method includes mixing the lithiated nitriding flux with gallium. Upon mixing the lithiated nitriding flux with a soluble element such as gallium, a lithiated precursor is formed. For example, upon mixing with gallium, the lithiated precursor Li3GaN2 is formed. The resulting lithiated precursor can then be destabilized via increasing the temperature to a temperature above the decomposition / stability temperature of the compound. Increasing the temperature to a temperature above the decomposition / stability temperature of the compound reduces the lithium and / or nitrogen partial pressures to destabilize the resulting compound.

[0061] In one or more examples, the method includes subjecting the nitrogen-containing lithiated precursor to a suitable combination of temperature and partial pressures to decompose the nitrogen-containing lithiated precursor into a nitride material, such as GaN, and a nitrogen- containing lithium compound, such as Li3N. It has been observed that providing higher nitrogengas levels within the autoclave advantageously stabilizes the desired nitride material (GaN, AlN, BN). It has further been observed that lower lithium vapor pressure promotes destabilization of the lithiated precursor material.

[0062] In one example, the method includes mixing the nitrogen-containing lithiated precursor with at least one element other than lithium and nitrogen, such as a metal or metalloid, to yield a mixed composition. In one example, the nitrogen-containing lithiated precursor includes a binary nitride. In another example, the nitrogen-containing lithiated precursor includes a ternary nitride. The lithiated precursor may include Li3N, Li3BN2, Li3GaN2, or Li3AlN2.

[0063] The amount of lithium needed for the method may be a function of the amount of nitrogen present within the system and may be further based upon the present of a binary or ternary or higher nitride. For example, the lithium may be present at 1 at%Li or 10 at%Li. In another example, when using ternary compounds, lithium may be present at a ratio of 25at%Li or 33at% Li. In yet another example, lithium may be present at ratios of 75at% Li and 50at%Li respectively.

[0064] In one or more examples, the method includes adding one or more dopants to the mixed composition. The dopant may include one or more of C, S, Si, O, Be, Zn, and Mg. Upon adding the dopant, a new compound may form. For example, when utilizing a mixed composition with gallium, adding magnesium to the mix may yield in the formation of LiMgN, which can then be used to synthesize magnesium-doped GaN.

[0065] In one or more examples, the at least one element other than lithium and nitrogen includes at least one flux modifier selected from materials that are liquid under operating conditions and for example can include, though not limited to, one or more of hydrogen, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, lead, tin, antimony, indium, and bismuth.

[0066] In one or more examples, the at least one element other than lithium and nitrogen includes gallium, aluminum, or boron. The method further includes placing the mixed composition in an apparatus. In one example, the apparatus is an autoclave. In one example, the method includes placing the mixed composition in an upper portion of the apparatus for top seed crystal growth.

[0067] The method further includes supplying nitrogen gas into the apparatus and heating the apparatus to an elevated temperature at an elevated pressure for a predetermined period of time to yield the nitrogen-containing material. In one example, the apparatus is heated to an elevatedtemperature for a predetermined period of time ranging from about 24 hours to about 10000 hours. In another example, the elevated temperature ranges from about 1000 °C to about 1400 °C, from about 1100 °C to about 1350 °C, or at a temperature ranging from about 1200 °C to about 1300 °C. In another example, the elevated pressure ranges from about 0.1 MPa to about 0.5 MPa.

[0068] In one example, the method includes pressurizing the apparatus with nitrogen gas at room temperature for a predetermined period of time to a pressure ranging from 0.8 MPa to 1.6 MPa and reducing the pressure to a pressure ranging from 0.1 MPa to 0.5 MPa prior to heating. In another example, the method includes adding a catalyst to the mixed composition. In one example, the apparatus is pressurized for a predetermined time ranging from about 20 minutes to about 2 hours.

[0069] In one example, the method includes positioning the mixed composition in a crucible 200, such as in a mesh 220 within a crucible 200, and positioning the crucible 200 into the autoclave prior to heating, see Figure 4. The crucible 200 may be positioned near a heating apparatus in the apparatus 100 or autoclave to promote crystal growth. The heater 230 may be located at a bottom end or a top end of the apparatus 100 or autoclave such that the crystal grows near the heater. Growing from the top advantageously allows for larger crystal growth, such as boules having a diameter, or width, and length greater than 1 cm, 5 cm, or 10 cm. For example, the method may include gradually raising the mechanism used to position a surface of the growing crystal on the melt / gas interface 210 and then slowly move this device 210 upward retaining the position of the crystal / melt interface, or moving the crucible 200 down via an actuating device to approximately match the growth rate of the growing crystal to ensure a suitable crystal growth conditions.

[0070] To aid in the growth of these crystal boules, the growing crystal may be preferentially heated using proper design of heating system 230. In one example, the crucible 200 includes one or more of the crucible 200 includes one or more of Mo, Nb, Ta, Fe, Re, Ti, BN, Ti, Zr, or Cr. In another example, the crucible 200 includes one or more of Mo, Nb, Ta, Fe, Re, TiC, ZrC, BN, Ti, Zr, ZrN, ZrBN, and Cr3C2.

[0071] In one example, the method includes cooling the apparatus 100 to room temperature to yield the nitrogen-containing material. In one example, the method further includes separating the nitrogen-containing material from a byproduct material.

[0072] In one example, the resulting nitrogen-containing material includes GaN. In another example, the resulting nitrogen-containing material includes BN, such as hexagonal BN. In another example, the resulting nitrogen-containing material includes AlN. In yet another example, the nitrogen-containing material is a single crystal. The single crystal may have a length and a width of at least 1 cm, at least 5 cm, or at least 10 cm. The single crystal may further be a boule having a lattice curvature of greater than 100 m and a diameter or width of at least 1 cm.

[0073] Also disclosed is a nitrogen-containing single crystal having a lattice curvature of greater than 100 m and a diameter or width greater than 1 cm. In one example, the single crystal material is a boule. The single crystal material is synthesized via a nitrogen-containing lithiated material as described by the method herein.

[0074] The nitrogen-containing single crystal may be a GaN boule having a length to diameter ratio of at least 2:1. The nitrogen-containing, GaN, single crystal may further have a diameter or width greater than 10 cm.

[0075] The nitrogen-containing single crystal may be an AlN boule having a length to diameter ratio of at least 2:1.The nitrogen-containing, AlN, single crystal may further have a diameter or width greater than 5 cm.

[0076] The nitrogen-containing single crystal may be a BN, either hexagonal, wurtzite, rhombohedral, or cubic BN, boule having a length to diameter ratio of at least 0.5:1. The nitrogen- containing, BN, single crystal may further have a diameter or width greater than 1 cm.

[0077] It is understood that while the term “diameter” is used above, it is not limited to round crystals. Rather, diameter is used to define the size, or width, or the crystal relative to the length of the crystal. Thus, the terms may be used interchangeably to define the dimensions along that plane of the crystal.

[0078] The nitrogen-containing single crystal may have 100% phase purity such that it has a 100% of a hexagonal, wurtzite, cubic, or rhombohedral phase. In another example, the single crystal includes at least 99% of a hexagonal, wurtzite, cubic, or rhombohedral phase, with about 1% impurity of another phase. In another example, the single crystal includes at least 95% of a hexagonal, cubic, or rhombohedral phase, with about 5% impurity of one or more other phases. In yet another example, the single crystal includes at least 90% of a hexagonal, wurtzite, cubic, or rhombohedral phase, with about 10% impurity of one or more other phases. The nitrogen-containing single crystal may further have lattice curvature greater than 100 m and at least 1 cm, at least 5 cm, or at least 10 in diameter.

[0079] In one or more examples, a method for synthesizing a nitrogen-containing material includes providing a molten material in an apparatus 100 and transporting a nitrogen-containing lithiated precursor through the molten metallic material for a predetermined period of time to yield the nitrogen-containing material. In one example, the molten material includes one or more of aluminum, gallium, boron, and / or one or more of sodium, potassium, lead, tin, antimony, indium, which may act as flux modifiers. The use of flux modifying material is useful to modify the properties of the flux and control the properties of the growing crystal.

[0080] In one example, the apparatus 100 is an autoclave and is pressurized at 1atm N2. In another example, the apparatus 100 is heated to a temperature ranging from about 1000 °C to about 1500 °C, from about 1100 °C to about 1350 °C, or at a temperature ranging from about 1200 °C to about 1300 °C.

[0081] In one example, the molten metallic material and nitrogen-containing lithiated precursor are provided at a ratio of approximately 4:1. In one example, the flux in the apparatus 100 is N- deficient relative to the thermodynamic stable / desired condition. A reduction in N2 pressure in the system results in a reduction in N in the melt. The lithiated precursor may include a binary nitride or a ternary nitride. In one example, the lithiated precursor includes Li3N, Li3BN2, Li3GaN2, or Li3AlN2.

[0082] In one example, the resulting nitrogen-containing material includes GaN. In another example, the resulting nitrogen-containing material includes BN. In another example, the resulting nitrogen-containing material includes AlN. In yet another example, the nitrogen- containing material is a single crystal. The single crystal may have a length and a width of at least 1 cm, at least 5 cm, or at least 10 cm. The single crystal may further be a boule having a lattice curvature of greater than 100 m and a diameter of at least 1 cm.

[0083] In one or more examples, a method for synthesizing a nitrogen-containing material includes providing a nitrogen-containing lithiated material and an additional material in an apparatus 100, such as an autoclave, and heating the apparatus 100 to a temperature greater than the decomposition temperature of the nitrogen-containing lithiated material for a predetermined period of time at 1 atm N2to yield the nitrogen-containing material. In one example, the methodincludes placing the nitrogen-containing lithiated material and a metallic material in an upper portion of the apparatus for top seed crystal growth.

[0084] In one example, the additional material is a reactive material. In another example, the additional material is a dissolved material. One result of using a nitrogen-containing lithiated material with the additional material includes yielding ternary or higher compounds.

[0085] The lithiated precursor may include a binary nitride or a ternary nitride. In one example, the lithiated precursor includes Li3N, Li3BN2, Li3GaN2, or Li3AlN2.

[0086] In one or more examples, the mixed composition comprises at least one ternary or higher order lithium nitride compound. In another example, the mixed composition comprises one or more of Li3BN2, Li3GaN2, or Li3AlN2. In one or more examples, the mixed composition comprises a nitrogen solubility or content greater than 1 at%, greater than 5 at%, or greater than 10 at%.

[0087] In one example, the resulting nitrogen-containing material includes GaN. In another example, the resulting nitrogen-containing material includes BN. In another example, the resulting nitrogen-containing material includes AlN. In yet another example, the nitrogen- containing material is a single crystal. The single crystal may have a length and a width of at least 1 cm, at least 5 cm, or at least 10 cm. The single crystal may further be a boule having a lattice curvature of greater than 100 m and a diameter of at least 1 cm.

[0088] The lithium vapor resulting from the disclosed methodology is controllable via a cooler zone within the apparatus 100, or autoclave. In one example, lithium vapor is transported to the autoclave. Upon exposure to elevated temperature and pressure, the lithium vapor condenses on the walls forming solid Li or Li3N. The Li or Li3N may then be removed from the melt (flux), leaving the desired nitride material behind. The lithium vapor pressure above the melt remains below equilibrium, therefore driving the continued removal. Continuous removal of the Li thus leads to a continuous deposition of the nitrogen-containing byproduct of the decomposition of the lithiated precursor material.

[0089] In one or more examples, the disclosed method may be implemented for synthesizing ternary or higher-order alloys via mixing of precursors. For example, AlGaN may be synthesized by the disclosed method via mixing of Li3GaN and Li3AlN in the melt. In this example, AlGaN is precipitated, and changing the ratio of Ga:Al in the melt, along with adjusting the temperature and partial pressures, allows for optimal conditions for synthesizing AlGaN, or other ternary alloys. Itis understood that AlGaN does not mean a material with one aluminum, one gallium and one nitrogen element, rather it is shorthand for AlxGa1-xN, for which x takes on a value between 0 and 1. For x = 0 the materials is a binary GaN, while x = 1 is AlN, while values in between have a ratio of Al to Ga atoms in the nitride. The sum of the Al and Ga atoms is equal to one.

[0090] In one or more examples, the disclosed method may be implemented for synthesizing a nitrogen-containing material including AlBN, BGaN, or BAlGaN at arbitrary ratios of Al to Ga to B. In a further example, the nitrogen-containing material may include AlxGa1-xN, AlxB1-xN, BxGa1-xN, or BxAlyGa1-x-yN, wherein x or y are greater than or equal to 0 and less than or equal to 1.

[0091] The disclosed method advantageously provides a solution for growing single crystal boules on a larger scale than presently available while achieving phase purity and a lattice curvature of greater than 100 m at a diameter greater than 1 cm. For example, the disclosed method may be used to grow single crystal BN boules larger than 1 cm in diameter and length. The disclosed method may also be used to grow single crystal AlN boules having a diameter of at least 5 cm and a length to diameter ratio of greater than 2:1. The disclosed method may also be used to grow single crystal GaN boules having a diameter of at least 10 cm and a length to diameter ratio of greater than 2:1.

[0092] The disclosed method uniquely utilizes a flux having higher nitrogen solubility (25 at%N). Further, using a lithiated precursor material allows for high solubility of a wide range of elements across the periodic table, as almost all elements for a lithiated nitride. The method advantageously provides for a controllable crystal grown rate via lithium vapor pressure and transport in the vapor phase. Removal of the flux post-run is achievable via decomposition (solvent burn-off) without the need for etching or other cumbersome methods to extract material.

[0093] The disclosed method advantageously utilizes a lithiated flux (Li3N) that is completely reusable and can be recycled as it recrystallizes in a different zone of the apparatus 100, or autoclave. All that is needed for recycling is additional nitrogen gas and any elements needed to form the lithiated nitride-containing desired materials.

[0094] Other advantages to the disclosed method include adaptability. Changes to melt-height are inconsequential as no diffusion of nitrogen through the melt must occur for synthesis. Rather, only the diffusion of lithium away from the interface is required. Crystal growth is not N-arrival limited, rather, it is temperature limited in that crystal growth can be controlled via thermal energy and / or lithium / nitrogen pressures.

[0095] Additionally, the disclosed method advantageously does not result in surface crusting. Typically, a gas is driven into solution to grow a submerged crystal. The surface layer sees the highest concentration of nitrogen, hence leading to crusting, or formation of a solid nitride on the gas / liquid interface, which in turn chokes off the flow of gas, and nitrogen will not readily diffuse through a solid nitride layer. This limits growth rates, only giving a small opportunity to drive growth of a nitride.

[0096] Further advantages to the disclosed method include the material of interest to be synthesized is already present in the melt in the form of a precursor. By controlling the precursor and additional elements in the flux, other than the lithiated nitride precursor, the polymorph of the crystal can be controlled. For example, the formation of cubic BN vs hexagonal BN is controllable.

[0097] Further, the disclosed method can be operated in a closed fashion. For example, no additional materials are required to be added or removed from the system to continue formation of the desired materials. This advantageously minimizes the risk of contamination.

[0098] In one or more examples, the disclosed method utilizes Li as a liquid, nitriding solvent stable under mild conditions. Controlled removal of Li under enhanced N-activity (via pressurization) will lead to controlled nitride synthesis. The precursor materials (LixXyNz compounds) are used to achieve nitride growth.

[0099] In accordance with the above disclosure, the methodology allows for an Element X to be reacted to form a ternary nitride with lithium, e.g., Li3XN2, which is dissolved into a flux or simply molten (self-fluxing). It then thermally decomposes over a slightly hotter surface (the crystal held at Thot+ ΔT), resulting in the formation of liquid Li3N and deposition of solid XN. Thotin Figure 2 is below the decomposition temperature. Two independent parameters can be used to tune the system during growth beyond temperature: nitrogen and lithium pressure. The nitrogen pressure is used to tune the stability of nitrides in the melt (i.e., Li3N and XN), e.g., GaN is thermodynamically stabilized from 837 °C (1 atm N2) to 1040 °C with 100 atm of N2 pressure. While Figure 2 illustrates a system designed to go to 1000 °C at 100 atm, it is noted that higher temperatures and pressures are achievable within the disclosed method.

[0100] Stability of Li-containing compounds is controlled via vapor pressure of the Li in the system, see Figure 3. Lithium melts at 181 °C and boils at 1330 °C (1 atm), hence Li vapor can condense on surfaces which are cooler than the Li-containing melt. The vapor pressure of Li3N is found to be composed primarily of Li and N2with the Li vapor pressure to be within a factor of 2to that of pure Li. Via deliberate control of the temperature and effective area ratio of exposed melt to cold-wall surfaces, the Li-vapor pressure can be reduced and maintained at a non-equilibrium value. This will induce Li to vaporize and further destabilize lithium compounds in the melt, such as lithiated nitride precursors (Li3XN2). Depending on the kinetics, Li may deposit as a liquid and drip into a dedicated container, or it may react with ambient N2 to form solid Li3N.

[0101] Therefore, growth of Li3N and XN can occur concurrently while the flux is consumed. For self-fluxing melts (melt composed entirely of LiXN ) it is possible to completely utilize all the precursor material leaving behind only XN which can be removed post-run without any of the traditional problems associated with removal of submerged crystals from fluxes which solidify upon cooling-a significant advantage.

[0102] Two separate approaches can be pursued for continuous growth of nitrides: use of a X-richmelt suchthat Li3N may react with X in the melt using N2as the nitrogen source forming LixXyNz(requiring an open system and N2supply)or use of a flux containing the desired amount of Li3XN2and evaporating Li3N to completion (closed system adequate). The latter approach critically does not require continuous N2 diffusion or dissolution in the melt, which can be a limitation in growth of nitrides from melts.

[0103] Unlike other growth approaches, the disclosed approach critically and uniquely already has the nitrided product present within the compound and just needs to be encouraged to release it. This removes another challenging aspect of nitride growth namely overcoming kinetic barriers to react element X with N at sufficiently low temperatures without decomposing the nitride.

[0104] Another significant benefit of the disclosed method is that the crystal is thermodynamically driven to grow within the melt due to decomposition and not due to development of a super- saturation of N in the melt driven by excessive N2pressure. The latter results in the formation of nitrides on the surface of the melt which rapidly crusts over and prevents any further growth. Thisapproach uses the surface to evaporate Lior to have Li react with N2to form liquid Li3N. In bothscenarios, conditions are unfavorable for (solid)nitride synthesis on the surface, even at thetypically most favored site for spontaneous, heterogenous nucleation: the rim encompassing the liquid-gas-crucible interface. The lack of surface crusting is a significant advantage and overcomes yet another potential hurdle in flux-based crystal growth approaches.

[0105] The closed-system approach requires the compound to have the same stoichiometric ratio of Li3N to the growing nitride. Further, via this methodology, a closed system approach is viable.Binary and ternary nitrides (BN, AlN, GaN, AlxGayN) are thermodynamically stable under the disclosed synthesis conditions. The melting temperatures are estimated at 916 °C for Li3BN2 and 1170 °C for Li3AlN2, while decomposition temperatures are estimated to be 838 °C, 1000 °C, and 900 °C, for Li3N, Li3AlN2, and Li3GaN2, respectively.

[0106] Critical to the successful growth of these nitrides, is a strong foundational understanding of the thermodynamics, specifically, the relationship and interplay between compound stability and associated activities of Li and N in the system.

[0107] The disclosed method may also be conducted under the following conditions. An autoclave can be used under the conditions based on the schematic of Figure 2. A cartridge heater or air / liquid cooled finger can be used to control lithium vapor pressure. To control the mass-flow rate of Li vapor, a two-chamber design can be connected with an opening (orifice or mesh) with fixed open area choking overall flow of Li through it and providing finer control for evaporation rate and hence crystal growth rate. Utilizing growth from stoichiometric melts (Li:X:N = 3:1:2), an open growthsystem can beused to dynamically change the N2pressure and hence stability of N-containing compounds during growth.

[0108] Growth can be controlled via multiple independentparameters: PN2, PLi(via temperatureof the cold-finger), orifice size (mass-transport), Tmelt, Tcrystal(Tmelt+ΔT), and melt composition.In situ data including system pressure, temperature and RGA- determined gas compositions can be collected.

[0109] Analysis of the high-pressure phase diagram of Li3N- BN illustrates a single two-phase region between a Li-B-N melt and solid BN just above the melting temperature ofLi3BN2.Continued removal of Li under the disclosed conditions leads to formation and growth of BN.

[0110] Self-nucleation of hBN is favored over cBN while growth kinetics typically favors hBN as well. Purity is also considered important as high pressure, high temperature anvil growth of BN suggests minor traces of oxygen promotes hBN growth. It has been demonstrated cBN growth under mild conditions (907 °C and 1 atm) on a diamond seed (1.4% latticemismatch).

[0111] For ternary nitride synthesis using the disclosed method, ternary nitrides can besynthesized from a melt composed of two or more lithiated ternary nitrides. Specifically, control of the alloy composition can be achieved by changing the activity of the species in the melt via changing their relative concentrations. EXAMPLES

[0112] The examples and other implementations described herein are exemplary and not intended to be limiting in describing the full scope of compositions and methods of this disclosure. Equivalent changes, modifications and variations of specific implementations, materials, compositions, and methods may be made within the scope of the present disclosure, with substantially similar results.

[0113] The provided example provides methos steps and materials used to grow a hBN crystal via the disclosed methodology. A high-pressure autoclave containing a heated metal crucible in which a hexagonal BN (hBN) crucible was placed was used for the experiment. The following materials were positioned in the crucible: TABLE 1 Composition Mass (mg)

[0114] The experim . Feedstock of BN and Li3BN2were measured in a glove box with a nitrogen environment and low trace oxygen / water concentrations. The BN and Li3BN2were mixed and then positioned into a pyrolytic crucible of hBN. Once filled, the hBN crucible was placed inside a metal crucible which was placed inside the autoclave. The autoclave was then sealed inside and removed from the glove box.

[0115] The system was placed in a heater assembly which preferentially heated the zone in which the crucible was placed. To check the seals of the autoclave, the system was pressurized with 99.9999% pure N2 gas at room temperature to 1.2 MPa and held for at least 30 min to verify no pressure drop. The system was then reduced in pressure to 0.2 MPa. The autoclave was then heated at a rate of 4 °C / min up to 1200 °C and held for 34 hours.

[0116] Upon completion, power to the heaters was then shut off and it was allowed to cool naturally to room temperature. The autoclave was removed from the heater assembly and brought back into the glovebox for disassembly and sample retrieval. All crystalline material was separated from the remaining solid material in the crucible and was then characterized.

[0117] Sample 1, a hBN crystal, was verified to exist via structural analysis (XRD), optical analysis (Raman, optical microscopy), chemical analysis (EDS), and based on morphology assessment (SEM).Figure 5 illustrates an overview of the grown polycrystalline agglomeration ofhBN crystals taken on SEM. Figure 6 illustrates a close-up view of a faceted region of hBN flake taken on SEM. Figure 7 illustrates the presence of B and N EDS maps of a selected hBN region.

[0118] Figure 8 is an XRD scan of hBN sample (top) and hBN reference peaks from powder diffraction file (PDF) (bottom). The PDF card used for the XRD scan was 00-045-0893. Figure 9 is a Raman scattering spectra for selected hBN region (shown in inset in a). Overall spectra is shown in a. Narrower selected region shows two peaks in b. Diamond is an unknown peak (likely an oxide compound) and the star is hBN. Focus on the star in c shows the peak is at 1368.8 cm-1. hBN Raman peak is at 1364 cm-1.

[0119] Figure 10 illustrates an XRD scan for Sample 2, a wurtzite GaN material synthesized using the disclosed method. For growth of this material, a crucible was filled with metallic Ga and Li3N in a molar ration of 3:2. The crucible was positioned in the middle of an autoclave, which was then sealed. The autoclave was then positioned within a heater system providing a uniform temperature to the region in which the crucible was positioned. The system was then pressurized with nitrogen gas to about 10 MPa and then reduced to about 4 MPa. The system was then heated to about 850 °C. The system was subsequently cooled from 850 °C to 835 °C over the course of about 54 hours. Pressure in the system was held at about 4 MPa during this process. At the end of the trial, the system was cooled.

[0120] While the foregoing description and drawings represent exemplary embodiments of the present disclosure, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope and range of equivalents of the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, sizes, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. In addition, numerous variations in the methods / processes described herein may be made within the scope of the present disclosure. One skilled in the art will further appreciate that the embodiments may be used with many modifications of structure, arrangement, proportions, sizes, materials, and components and otherwise, used in the practice of the disclosure, which are particularly adapted to specific environments and operative requirements without departing from the principles described herein. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive. The appended claims should be construed broadly, to include other variants and embodiments of the disclosure, which may bemade by those skilled in the art without departing from the scope and range of equivalents. In addition, all combinations of any and all of the features described in the disclosure, in any combination, are part of the invention.

Claims

What is claimed is:

1. A method for synthesizing a nitrogen-containing material comprising: mixing a nitrogen-containing lithiated precursor with at least one element other than lithium and nitrogen to yield a mixed composition; placing the mixed composition in an apparatus; supplying nitrogen gas into the apparatus; and heating the apparatus to an elevated temperature at an elevated pressure for a predetermined period of time to yield the nitrogen-containing material.

2. The method according to claim 1, wherein the lithiated precursor comprises a binary nitride.

3. The method according to claim 1, wherein the lithiated precursor comprises a ternary nitride.

4. The method according to any one of claims 1 to 3, wherein the mixed composition comprises at least one ternary or higher order lithium nitride compound.

5. The method according to any one of claims 1 to 4, wherein the lithiated precursor comprises one or more of Li3N, Li3BN2, Li3GaN2, or Li3AlN2.

6. The method according to any one of claims 1 to 5, wherein the mixed composition comprises one or more of Li3BN2, Li3GaN2, or Li3AlN2.

7. The method according to any one of claims 1 to 6, wherein the at least one element other than lithium and nitrogen comprises gallium, aluminum, or boron.

8. The method according to any one of claims 1 to 7, wherein the at least one element other than lithium and nitrogen comprises an element or material that is dissolved in the flux or is in the liquid state under processing condition, that may include at least one flux modifier selected fromhydrogen, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, lead, tin, antimony, indium, and bismuth.

9. The method according to any one of claims 1 to 8, wherein the mixed composition comprises a nitride.

10. The method according to any one of claims 1 to 9 , further comprising adding an impurity or dopant to the mixed composition, wherein the impurity or dopant comprises one or more of carbon, sulfur, silicon, germanium, oxygen, beryllium, zinc, or magnesium.

11. The method according to any one of claims 1 to10, wherein the nitrogen-containing material comprises GaN.

12. The method according to any one of claims 1 to 10, wherein the nitrogen-containing material comprises BN.

13. The method according to any one of claims 1 to 10, wherein the nitrogen-containing material comprises AlN.

14. The method according to any one of claims 1 to 13, wherein the mixed composition comprises a nitrogen content greater than 1 at%N, greater than 5 at%N, or greater than 10 at%N.

15. The method according to any one of claims 1 to 14, wherein the nitrogen-containing material comprises AlGaN, AlBN, BGaN, or BAlGaN at arbitrary ratios of Al to Ga to B.

16. The method according to any one of claims 1 to 15, wherein the nitrogen-containing material comprises AlxGa1-xN, AlxB1-xN, BxGa1-xN, or BxAlyGa1-x-yN, wherein x or y are greater than or equal to 0 and less than or equal to 1.

17. The method according to any one of claims 1 to 16, wherein the nitrogen-containing material comprises a controlled amount of a dopant or impurity.

18. The method according to any one of claims 1 to 17, wherein the nitrogen-containing material is a single crystal.

19. The method according to any one of claims 1 to 18, wherein the nitrogen-containing material is a single crystal boule having a diameter of at least 1 cm, at least 5 cm, or at least 10 cm.

20. The method according to any one of claims 1 to 19, wherein the apparatus is an autoclave.

21. The method according to any one of claims 1 to 20, wherein the elevated temperature ranges from about 800 C to about 1600 °C.

22. The method according to any one of claims 1 to 21, wherein the elevated pressure ranges from about 0.1 MPa to about 100 MPa.

23. The method according to any one of claims 1 to 22, further comprising: positioning the mixed composition in a crucible; and positioning the crucible into an autoclave prior to heating.

24. The method according to claim 23, wherein the crucible is positioned near a heating apparatus in the apparatus.

25. The method according to claim 23 or 24, wherein the crucible comprises one or more of B, C, N, O, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, or Re.

26. The method according to any one of claims 1 to 25, further comprising:pressurizing the apparatus with nitrogen gas at room temperature for a predetermined period of time to a pressure ranging from 0.1 MPa to 100 MPa; and reducing the pressure to a pressure ranging from 0.1 MPa to 10 MPa prior or shortly after heating.

27. The method according to claim 26, wherein the apparatus is pressurized for a predetermined time ranging from about 20 minutes to about 24 hours.

28. The method according to any one of claims 1 to 27, further comprising adding at least one flux modifier to the mixed composition.

29. The method according to any one of claims 1 to 28, further comprising separating the nitrogen-containing material from a byproduct material.

30. A method for synthesizing a nitrogen-containing material comprising: providing a molten material in an apparatus; and transporting a nitrogen-containing lithiated precursor through the molten material for a predetermined period of time to yield the nitrogen-containing material.

31. The method according to claim 30, wherein the apparatus is pressurized at 1 atm N2.

32. The method according to claim 30 or 31, wherein the molten material comprises one or more of aluminum, gallium, boron, sodium, potassium, cesium, lead, tin, antimony, and indium.

33. The method according to any one of claims 30 to 32, wherein the apparatus is heated to a temperature ranging from about 800 °C to about 1600 °C.

34. The method according to any one of claims 30 to 33, wherein the lithiated precursor comprises a binary nitride.

35. The method according to any one of claims 30 to 33, wherein the lithiated precursor comprises one or more ternary nitride.

36. The method according to any one of claims 30 to 35, wherein the lithiated precursor comprises one or more of Li3N, Li3BN2, Li3GaN2, or Li3AlN2.

37. The method according to any one of claims 30 to 36, wherein the nitrogen-containing material comprises GaN.

38. The method according to any one of claims 30 to 36, wherein the nitrogen-containing material comprises BN.

39. The method according to any one of claims 30 to 36, wherein the nitrogen-containing material comprises AlN.

40. The method according to any one of claims 30 to 39, wherein the nitrogen-containing material comprises AlxGa1-xNI, AlxB1-xN, BxGa1-xN, or BxAlyGa1-x-yN for which x or y are greater than or equal to 0, yet less than or equal to 1.

41. The method according to any one of claims 30 to 40, wherein the nitrogen-containing material contains a controlled amount of a dopant or impurity.

42. The method according to any one of claims 30 to 41, wherein the nitrogen-containing material is a single crystal.

43. The method according to any one of claims 30 to 42, wherein the nitrogen-containing materialis a single crystal boule having a diameter of at least 1 cm, at least 5 cm, or at least 10 cm.

44. The method according to any one of claims 30 to 43, wherein the apparatus is an autoclave.

45. A method for synthesizing a nitrogen-containing material comprising: providing a nitrogen-containing lithiated material and a non-lithiated material in an apparatus; and heating the apparatus to a temperature greater than the decomposition temperature of the nitrogen-containing lithiated material for a predetermined period of time at at least 1 atm of N2 to yield the nitrogen-containing material.

46. The method according to claim 45, wherein the lithiated precursor comprises a binary nitride.

47. The method according to claim 45, wherein the lithiated precursor comprises a ternary or higher order nitride.

48. The method according to any one of claims 45 to 47, wherein the lithiated precursor comprises Li3N, Li3BN2, Li3GaN2, or Li3AlN2.

49. The method according to any one of claims 45 to 48, wherein the nitrogen-containing material comprises AlxGa1-xNI, AlxB1-xN, BxGa1-xN, or BxAlyGa1-x-yN, wherein x or y are greater than or equal to 0 and less than or equal to 1.

50. The method according to any one of claims 45 to 49, wherein the nitrogen-containing material contains a controlled amount of a dopant or impurity.

51. The method according to any one of claims 45 to 50, wherein the non-lithiated material comprises a dissolved element.

52. The method according to any one of claims 45 to 51, wherein the non-lithiated material comprises a reactive material.

53. The method according to any one of claims 45 to 52, wherein the nitrogen-containing material comprises GaN.

54. The method according to any one of claims 45 to 52, wherein the nitrogen-containing material comprises BN.

55. The method according to any one of claims 45 to 52, wherein the nitrogen-containing material comprises AlN.

56. The method according to any one of claims 45 to 55, wherein the nitrogen-containing material is a single crystal.

57. The method according to any one of claims 45 to 56, wherein the nitrogen-containing material is a single crystal boule having a diameter of at least 1 cm, at least 5 cm, or at least 10 cm.

58. The method according to any one of claims 45 to 57, wherein the apparatus is an autoclave.

59. A nitrogen-containing single crystal comprising: GaN; a diameter of at least 50 mm; and a length to diameter ratio of at least 1:1.

60. The single crystal according to claim 59 comprising a lattice curvature of greater than 100 m and a diameter greater than 1 cm.

61. The single crystal according to claim 59 or 60, wherein the single crystal material is a boule.

62. The single crystal according to any one of claims 59 to 61 synthesized via a nitrogen- containing lithiated material.

62. The single crystal according to any one of claims 59 to 62 comprising a controlled amount of a dopant or impurity.

63. A nitrogen-containing single crystal comprising: AlN; a diameter of at least 50 mm; and a length to diameter ratio of at least 2:

1.

64. The single crystal according to claim 63 comprising a lattice curvature of greater than 100 m and a diameter greater than 1 cm.

65. The single crystal according to claim 63 or 64, wherein the single crystal material is a boule.

66. The single crystal according to any one of claims 63 to 65 synthesized via a nitrogen-containing lithiated material.

67. The single crystal according to any one of claims 63 to 66 comprising a controlled amount of a dopant or impurity.

68. A nitrogen-containing single crystal comprising: BN; a diameter of at least 10 mm; and a length to diameter ratio of at least 1:

2.

69. The single crystal according to claim 68 comprising a lattice curvature of greater than 100 m and a diameter greater than 1 cm.

70. The single crystal according to claim 68 or 69, wherein the single crystal material is a boule.

71. The single crystal according to any one of claims 68 to 70 synthesized via a nitrogen-containing lithiated material.

72. The single crystal according to any one of claims 68 to 71 comprising a controlled amount of a dopant or impurity.

73. The single crystal according to any one of claims 59 to 72 having at least 100%, at least 99%, or at least 95% of a hexagonal, wurtzite, cubic, or rhombohedral phase.

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