In one embodiment, a method of producing an sp3 bonded C.sub.3N.sub.4 product includes contacting a starting material with a catalyst solvent in a reaction vessel, heating the reaction vessel to a temperature of 900? to 2000? C. under a pressure of 4 to 8 GPa, melting at least some of the catalyst solvent, and transforming at least some of the sp2 bonded C.sub.3N.sub.4 into sp3 hybridized C.sub.3N.sub.4. The starting material may include sp2 bonded C.sub.3N.sub.4. The catalyst solvent may be a solid at room temperature. In one example, the catalyst solvent is a carbo-nitride based catalyst solvent including a first compound having the chemical formula A.sub.xB.sub.yN.sub.z and a second compound having the chemical formula D.sub.qE.sub.rC.sub.s. In a second example, the catalyst solvent is a metal alloy based catalyst solvent including a compound having the chemical formula G.sub.xH.sub.y.