In Situ Single-phase Formation of LaCl(CN 2 ) Mixed-Anion Compound Via Controlled Pyrolysis of La 3+ Modified Melamine Precursor.

Nitride (N ^3- ) or cyanamide (CN ₂ ^2- ) based mixed-anion compounds stand as attractive materials due to their unique properties derived from the binary or multiple anions, although their synthesis remains challenging in incorporating the N ^3- or CN ₂ ^2- anions safely. This work highlights the first demonstration of in situ single phase formation of a LaCl(CN ₂ ) mixed-anion compound from a stable single source precursor, melamine modified with LaCl ₃ preparable under aqueous conditions. The in situ formation of LaCl(CN ₂ ) involves the chemical modification of melamine with LaCl ₃ to form a complex. Upon heating of the precursor under N ₂ flowing, this complex generates cyanamide species around 400 °C, which react with LaCl ₃ and nonsublimated melamine to afford a binary LaCl(CN ₂ )/g-C ₃ N ₄ composite. Further pyrolysis at 800 °C decomposes the g-C ₃ N ₄ counterpart, resulting in the LaCl(CN ₂ ) single-phase formation. The electronic properties of the precursor-derived single phase LaCl(CN ₂ ) were studied by the density functional theory calculation and UV-vis spectroscopy combined with X-ray photoelectron spectroscopy analyses and characterized by measuring 4.7, 1.8, and -2.9 eV for the band gap energy, the valence band maximum, and the conduction band minimum relative to Fermi energy, respectively. This study paves the way for exploring various cyanamide-based mixed anion compounds, advancing their potential applications in various fields.