Homo- and heterometallic terbium alkoxides - Synthesis, characterization and conversion to luminescent oxide nanostructures

摘要

Terbium alkoxides in homometallic - [Tb_3(μ_3-OtBu) _2(μ_2-OtBu)_3(OtBu)_4 (HOtBu) _2] (1), [Tb{OC(tBu)_3}_3(THF)] (2) - and heterometallic configurations - [TbAl(μ_2-OiPr)_3(OiPr) _3(iPrOH)]_2 (3), [TbAl_3(μ_2-OiPr) _6(OiPr)6] (4) - were synthesized and characterized by single-crystal X-ray diffraction. Decomposition of 1 and 2 under solvothermal conditions produced Tb(OH)_3 nanorods, whereby the material formation and crystallization were influenced by the steric profile of the organic ligand, which controlled the hydrolysis and condensation reactions of the precursor molecules. Monophasic terbium aluminate in the perovskite phase (TbAlO _3) was obtained by the sol-gel processing of 3. Heterometallic frameworks present in 3 and 4 were, however, unstable under solvothermal conditions and resulted in hydroxide-oxide composites [Tb(OH) _3/Al_2O_3/Al(OH)_3]. Compound 4 exhibited sufficient vapour pressure to be used in the chemical vapour deposition (CVD) process to grow Tb-O-Al thin films. Crystalline compositions obtained on MgAl_2O_4 and SiO_2 (quartz) substrates were garnet and perovskite phases, and were ascribed to the crystallographic relationship between the substrate and CVD deposits. The optical properties of the powders obtained were studied by photoluminescence spectroscopy.