Synthesis of Nanocrystalline Gd 2 O 2 NCN from a Versatile Single‐source Precursor

Nanocrystalline Gd 2 O 2 NCN ( P 3 m 1, crystallite size 30–40 nm) was synthesized upon ammonolysis of bis[ [(N ‐carboxymethyl,N‐carboxy‐κO‐methyl)amino‐κN]‐ethyl]‐glycinato(3‐)‐κN,κO]gadolinium(III) (diethylenetriamine pentaacetic acid gadolinium(III) dihydrogen salt or gadopentetic acid, Gd‐H 2 DTPA hereafter) at 900 °C. The conversion of Gd‐H 2 DTPA into Gd 2 O 2 NCN takes place in several steps, probably via transient formation of iminodiacetate‐, glycinate‐, and carbamate‐containing complexes of Gd. Thermal treatment in air of Gd‐H 2 DTPA at 750 and 1300 °C delivers nanocrystalline bixbyite‐type Gd 2 O 3 ( Ia 3 , crystallite size 30–70 nm); in an argon or nitrogen atmosphere the formation of monoclinic Gd 2 O 3 ( C 2/ m ) was observed at 1300 °C. The synthesized Gd 2 O 2 NCN converts upon thermal treatment in air, nitrogen, or argon atmosphere into monoclinic Gd 2 O 3 ( C2/m ). In ammonia atmosphere, Gd 2 O 2 NCN seems to be stable against decomposition, even upon prolonged exposure to 1000 °C. This study indicates that Gd‐H 2 DTPA may be a robust, low‐cost, and flexible precursor for nanoscaled Gd‐based nanopowders. Moreover, precursor approaches based on metal complexes using H 5 DTPA as a ligand are suggested as promising access pathways towards nanocrystalline materials in the M /O/C/N system.