We studied the kinetics of the formation of iron oxide nanocrystals obtained from the solution-phase thermal decomposition of iron−oleate complex via the “heating-up” process. To obtain detailed information on the thermal decomposition process and the formation of iron oxide nanocrystals in the solution, we performed a thermogravimetric-mass spectrometric analysis (TG-MS) and in-situ magnetic measurements using SQUID. The TG-MS results showed that iron−oleate complex was decomposed at around 320 °C. The in-situ SQUID data revealed that the thermal decomposition of iron−oleate complex generates intermediate species, which seem to act as monomers for the iron oxide nanocrystals. Extensive studies on the nucleation and growth process using size exclusion chromatography, the crystallization yield data, and TEM showed that the sudden increase in the number concentration of the nanocrystals (burst of nucleation) is followed by the rapid narrowing of the size distribution (size focusing). We constructed a theore...

Kinetics of Monodisperse Iron Oxide Nanocrystal Formation by “Heating-Up” Process

Quasi-monodisperse hydrophobic transition-metal ferrite MFe2O4 (M = Mn, Fe, Co, Ni, Zn) nanocrystals were synthesized by the thermolysis of transition-metal acetates in oleyl alcohol solutions under aerobic conditions. The proposed reaction protocol is simple, rapid, and highly versatile because it takes advantage of the multiple roles of the oleyl alcohol molecules, namely, solvent for the precursors, reaction medium, and capping ligand for the metal oxide nanoparticles. A systematic FT-IR spectroscopy study has indicated that the transition-metal ferrite nanoparticles are precipitated in oleyl alcohol solutions via a thermal decomposition process with no evidence about a potential esterification reaction, involving the long-chain alcohol and the metal acetate salt. A detailed characterization of the oleyl alcohol capped ferrite nanoparticles was performed by XRD, TEM, SAED, EXAFS, FT-IR, and SQUID measurements. The as-prepared transition-metal ferrite nanocrystals are spherically shaped, and their avera...

Size-Controlled Synthesis of Quasi-Monodisperse Transition-Metal Ferrite Nanocrystals in Fatty Alcohol Solutions

Volatilization interference is the first prerequisite to be eliminated for the quantitative thermal analysis of low-melting material. The volatilization processes of three low-melting organic nitro compounds, TNT, DNAN and DNTF, were measured by isothermal thermogravimetry. The thermal decomposition behaviors and kinetics were studied by dynamic pressure measuring thermal analysis. The interference of the vapor pressure on the gas pressure of thermal decomposition at specified temperatures was deducted quantitatively. DNAN is the most stable, though three compounds all match the standard of good thermal stability. DNTF has the highest activity and is the most sensitive to heating under specified conditions. The surface changes caused by melting and thermal decomposition stimulate the reaction activity and affect the reaction kinetics and thermal stability. The reaction activity of the nitro compounds is directly related to the number of the nitro group/nitrogen atom.

Volatilization interference in thermal analysis and kinetics of low-melting organic nitro compounds

A procedure has been proposed for the preparation of copper/polymer composites through Cu(C4H4O4) · H2O succinate thermolysis. Three types of copper nanoparticles have been incorporated into a fibrous carbon-polymer matrix of the composite: cubic (350 × 350 nm) and needle-like (40–80 nm in diameter and 4.5–5.5 μm in length) crystals and spherical copper particles (5 to 45 nm). We have compared copper succinate and copper maleate decomposition processes. The composites obtained through thermolysis have been shown to differ drastically.

Preparation of a copper-polymer composite through the thermolysis of copper(II) succinate

A systematic study of the thermal decomposition of hybrid perovskites of formula [AH][M(HCOO)3] under inert atmosphere was performed by means of thermogravimetry and simultaneous infrared spectroscopy of the evolved gases. The influence of: (i) the metal ion of the [M(HCOO)3]- framework and (ii) the guest [AH]+ cation, in the composition of the final residue was evaluated. In this work, it has been demonstrated that these materials can be used as precursors of metal or metal-oxide compounds—obtained free of carbon—, and that the composition of the final residue is determined by the standard reduction potential of the metal cation of the framework.

https://www.mdpi.com/2673-6497/2/2/11/pdf

Thermal Decomposition of [AH][M(HCOO)3] Perovskite-Like Formates

Thermal solid-phase decomposition of anhydrous copper(ii) formate has been studied at 120–180 ° The rate of gas evolution during the decomposition depends on the depth of conversion and can be presented as the sum of first-order reaction rates and the rate of the autocatalytic process (a second-order reaction). The evolution of the solid phase during thermolysis has been observed by optical microscopy. The decomposition of copper formate is a complex topochemical process, a combination of homogeneous and heterogeneous transformations and dispersion of large crystals.

A. S. Rozenberg

Papers

Thermal decomposition of transition metal carboxylates: I. Decomposition of anhydrous copper(II) formate. Morphology and regularities of gas evolution