15 research outputs found
The influence of modifying ligands on the structure, stability and material science application of zirconium and hafnium precursors
Synthesis and characterization of diethanolamine modified heterometallic zirconium and titanium precursors and their application in synthesis of new dielectrics
Design of molecular structure and synthetic approaches to single-source precursors in the sol-gel technology
Zirconium and hafnium tert-butoxides and tert-butoxo-beta-diketonate complexes – Isolation, structrural characterization and application in the one-step synthesis of 3D metal oxide nanostructrures
Long term storage of the pure commercial Zr(OtBu)4 in a sealed ampoule results in crystallization of a new high symmetry phase of Zr3O(OtBu)10 (1). Modification of Zr(OtBu)4 and Hf(OtBu)4 with 2,2,6,6,-tetramethyl-3,5-heptanedione (Hthd) produces dependent on the stoichiometry two types of derivatives, M(OtBu)2(thd)2 (2, 3) and M(OtBu)(thd)3 (4, 5) M = Zr(2, 4), Hf(3, 5), which have all been characterized by NMR and mass-spectral studies and for 4 and 5 also by complete X-ray single crystal studies. The latter failed for 2 and 3 in the view of their poor X-ray reflectivity. Addition of minor amounts of n-C5H11OH to 3 resulted in isolation of an unusual heteroleptic complex Hf2(OH)(OnC5H11)(OtBu)2(thd)4 (6). Thermal decomposition of compounds 1 and 3 in nitrogen atmosphere was studied for different thermal regimes by TGA-FTIR approach, revealing in all cases the formation of tetragonal ZrO2 and monoclinic HfO2 respectively, along with iso-butene, butanol and water for 1 and the same mixture including also Hthd for 3. Decomposition of 3 occurred always through intermediate melting, while higher heating rate for 1 permitted to achieve decomposition on in situ evaporation resulting in 3D hedgehog nanostructures according to SEM
Synthesis and characterization of diethanolamine modified zirconium precursors and their application for the preparation of highly ordered mesoporous zirconia
El libro de los deberes
Reseña de: ESTÉVEZ ARAUJO, José Antonio (ed.). (2013). El libro de los deberes. Las debilidades e insuficiencias de la estrategia de los derechos. Madrid: Trotta. 264 pp