Synthesis and thermal decomposition of a novel zirconium acetato-propionate cluster: [Zr12]

Abstract

International audienceThis work reports a novel Zirconium acetato-propionate complex herein called [Zr12] obtained by reaction of zirconium acetylacetonate Zr(acac)4 with propionic acid. The molecular structure has been determined by X-ray diffraction on single crystals and proposed to be [Zr12(m3-O)16(CH3CH2CO2)12(CH3CO2)8(m2- CH3CH2CO2)4]. This cluster involves oxo/hydroxo bonds in the direct surrounding of the metallic center. The decomposition of [Zr12] has been studied by thermal analysis and compared to Zr(acac)4. Its temperature of decomposition is much lower than for acetylacetonate derivative. In consequence, the formation of ZrO2 is easier from [Zr12] than from Zr(acac)4. This phenomenon highlights the influence of the molecular structure on the process of decomposition. The local surrounding of Zr in [Zr12] and in ZrO2 are very close, while it is markedly different in Zr(acac)4.This difference of environment of the metallic ions is at the origin of the huge difference of thermal behavior of both compounds

Alternative route for the preparation of Zr-doped TiO2 layers for energy and environmental applications

“…After 400 1C no additional weight losses are observed, even if broad endothermic and exothermic peaks are clearly visible. These transitions could be related to the crystallization of ZrO 2 , at around 600 1C, and to the formation of a metastable monoclinic phase [24][25][26]. This result indicates that the temperature considered for the sintering of the deposited films (450 1C) will ensure the complete burnout of the organic part of the precursor, therefore it is completely suitable for the development of the doping process.…”

Synthesis, crystal structure and thermal decomposition of Zr6O4(OH)4(CH3CH2COO)12

“…This explains the interest in the study of their structure, stability and thermal decomposition [6]. Metal acetylacetonates show a very low solubility in simple alcohols (methanol, ethanol, propanol and butanol) or organic solvents like toluene, hexane, acetylacetone, but easily dissolve in carboxylic acids up to high concentrations.…”

Effect of oxygen partial pressure on the crystallization of CeO2 and La2Zr2O7 bi-axially textured thin films

“…It results in a transparent and yellow solution, which is very stable when it is preserved from sun light and heat. Precursor for La 2 Zr 2 O 7 is prepared according to a procedure already described elsewhere [25,29] and composed of a clean solution of lanthanum and zirconium propionate (0.5 M) stable for months, this solution is called herein LaZr(prop) 7 .…”

“…Such reducing condition is compatible with the formation of oxides if the oxygen chemical potential is higher than the chemical potential of reduction of the oxide and if oxygen is already present in the metal-ligands of the metal-organic precursor as in the case of carboxylates [28,29]. However the crystallization in these conditions is inhibited by carbon deposition [23,30] resulting in a poor or inexistent texture at the surface, which impedes further growth of a new epitaxial layer.…”

“…However the crystallization in these conditions is inhibited by carbon deposition [23,30] resulting in a poor or inexistent texture at the surface, which impedes further growth of a new epitaxial layer. Attempts have been made to improve the crystallinity by oxidizing [29,31] the surface by post annealing. However depending on the conditions, random crystallization could appear and controlled atmosphere is recommended to tune a slow recrystallization [31].…”