Solvothermal Metal Nitride Chemistry

Our current research is examining precursor reactions in superheated organic solvents aimed at the synthesis of metastable and nanoscale metal nitride structures.  Metal nitrides exhibit a wide range of practically useful properties, for example, GaN and InN are semiconductors that serve as components of visible light lasers and LEDs, ZrN and NbN are metallic refractory materials that become superconducting at low temperatures, and TiN and Si₃N₄ are metallic and insulating hard ceramics, respectively.  The mid- or late-transition metal nitrides are generally thermally unstable systems, such as Mo₂N, Fe₃N, and Cu₃N, making them particularly amenable to mild reactions that may encourage metastable phase formation.

 

One major challenge with low-temperature routes to metal nitrides involves finding an appropriate source of nitrogen that does not contain thermally stable extraneous bonds.  A major focus of our research involves an examination of energetically unstable metal azide intermediates to metal nitrides, e.g., [Ga(N₃)₃]_n polymeric intermediates.  In transition-metal systems, metal azides decompose to sub-micron metal particles or serve as reactive intermediates to metal sulfides.

 

Several links to one-page executive summaries of recent papers are listed below.  Links to the complete papers are available on the full publications page (see left side bar).

 

Solvothermal synthesis of InN from reactive metal azides

 

Solvothermal synthesis of metastable cubic Cu₃N and analysis of intermediates

 

Synchrotron analysis of local structure in nanocrystalline GaN powders

 

Solvothermal metal azide decomposition route to GaN nanostructures

 

Solvent-free low-temperature synthesis of GaN nanoparticles

 

Azide intermediates in solvothermal routes to Ag and Ag₂S particles

 

Several routes to novel single-source molecular precursors to main group nitrides are also being investigated.  One system resulted in an unusually air-stable gallium hydride.