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CoGa 2 O 4 Nanoparticles and Films Using a Single Molecular Source
Author(s) -
Mathur Sanjay,
Cavelius Christian,
Shen Hao
Publication year - 2009
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200900167
Subject(s) - spinel , materials science , amorphous solid , nanoparticle , chemical vapor deposition , analytical chemistry (journal) , decomposition , microstructure , crystallography , chemical engineering , nanotechnology , metallurgy , chemistry , chromatography , engineering , organic chemistry
Mixed‐metal tert ‐butoxide, [CoGa 2 (O t Bu) 8 ], was employed in the chemical vapor deposition (CVD) and sol‐gel processes to obtain thin films and nanoparticles of spinel CoGa 2 O 4 phase, respectively. The appropriate Co:Ga ratio and intact vaporization (115–120 °C / 10 –2 Torr) of the molecular source produced crystalline deposits of CoGa 2 O 4 at relatively low temperatures (~ 500 °C). A clean transformation of the heterometal precursor in spinel oxide of definite composition was supported by TG/DTA analysis that showed no weight loss above 470 °C. The SEM images of CoGa 2 O 4 films showed homogeneous morphology and dense microstructure constituted by nanometric grains (< d >, ~ 35 nm). Hydrolytic decomposition of the precursor produced gels that upon heat‐treatment (400–1200 °C) formed nanoscaled spinel. For comparison, CoGa 2 O 4 was also prepared by complexing Co 2+ and Ga 3+ ions with glycolate ligands, significant agglomeration effect, broader size dispersion and amorphous domains were observed indicating that low‐temperature synthesis of monophasic materials following conventional chemical approaches is hampered by thermodynamic impediments. The UV/Vis spectra of CoGa 2 O 4 particles exhibit characteristic peaks corresponding to 4 A 2 (F) → 4 T 1 (P) transition in the divalent cobalt cation. The magnetization data of the CoGa 2 O 4 nanoparticles showed as expected an antiferromagentic behavior.