Nanometer-sized zinc aluminate (ZnAl 2 O 4 ) particles were synthesized from heterometal alkoxides, [ZnAl 2 (OR) 8 ], possessing an ideal cation stoichiometry for the ZnAl 2 O 4 spinel. ZnAl 2 O 4 is formed at 400°C, which is the lowest temperature reported for the formation of monophasic ZnAl 2 O 4 . 27 Al magic-angle spinning nuclear magnetic resonance spectroscopy revealed that ZnAl 2 O 4 possesses an inverse structure at <900°C, while the normal spinel phase is observed at higher temperatures. The homogeneity of the in-depth composition and Zn:Al stoichiometry (1:2) was confirmed by electron spectroscopy for chemical analysis. Evaluation of the valence-band spectra of ZnAl 2 O 4 and ZnS suggested that the hybridization of O 2p and Zn 3d orbitals is responsible for lowering the bandgap in the latter. The average crystallite size showed an exponential relationship to the calcination temperature (X-ray diffractometry and transmission electron microscopy data). The optical spectra of different spinel powders (average particle sizes, 20 -250 nm) showed that the absorption edge exhibits a blue shift as particle size decreases.

A single‐step hydrolytic decomposition of a mixed‐metal precursor (see Figure) results in the size‐controlled synthesis of nanocrystalline GdFeO3 particles with high compositional and morphological homogeneity. Owing to the molecular level mixing of the cations and the preformed Gd–O–Fe linkage, the temperature required for the formation of this crystalline orthoferrite phase is much lower than that for a solid‐state synthesis.

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The relationship between poly(1-trimethylgermyl-1-propyne) (PTMGP) microstructure and gas permeability property is reported. Controlling the synthesis conditions via TaCl5 and NbCl5 catalyst systems, tailor-made polyacetylenes in a wide range of cis/trans ratio (trans content from 35 to ∼100%) were obtained. According to the cis and trans ratio in the polymeric chain, a two-phase structure was found characterized by the presence of regions with enhanced level of macrochains ordering and with amorphous regions. The polymer microstructure has been related with free-volume, gas permeability, and polymer resistance toward liquid hydrocarbons. PTMGP membranes with high trans content (80−90%) exhibited higher gas permeability than samples with low trans content. Gas permeability of PTMGP membranes decreased with the density of polymer films, i.e., with the free-volume fraction in polymers with different microstructures. Furthermore, it was demonstrated that gas permeability and resistance toward solvents of the PTMGPs are directly defined by their cis/trans microstructure and supramolecular ordering. PTMGP with well-defined microstructure (trans content between 80 and 90%) can be considered as potential membrane material for gas separation, e.g., separation of higher hydrocarbons from natural gas. PTMGP/TiO2 nanocomposite membranes were also studied for exploring the gas permeability properties and stability of polyacetylene membranes. Gas transport properties were affected slightly by TiO2 presence; however, the long-term stability was enhanced.

Using a Ni−Sn heterometal alkoxide, [Ni2Sn2(OtBu)8], in a chemical vapor deposition (CVD) process, thin films of biphasic composite, Ni3Sn4/SnO2, have been obtained. Due to the presence of two metal atoms in a single molecule, the decomposition occurs at a molecular level resulting in homogeneous incorporation of intermetallic Ni3Sn4 in an SnO2 matrix. The CVD experiments performed at different temperatures (450−550 °C) show that the obtained composite results from two chemical processes:  (i) disproportionation of Sn(II) species and (ii) the redox reactions ocurring between Sn(II) and Ni(II) species. Fragmentation of the precursor and disproportionation of the tin(II) component dominate up to 500 °C, resulting in the formation of NiO, Sn(0), and SnO2. Redox reactions are favored at higher temperature (550 °C) which lead to the formation of the Ni3Sn4 alloy. This alloy−metal oxide composite has been deposited on different substrates (steel, copper, silicon wafer), and no heterogeneity was observed on a micrometer level (energy-dispersive X-ray analysis). Powder X-ray diffraction patterns of the deposits obtained at 550 °C show Ni3Sn4 and SnO2 as the only crystalline phases. The scanning electron micrograph images reveal a microstructured surface with a fibrous morphology. High-resolution transmission electron microscope investigations show a bimodal mixture where the Ni3Sn4 crystallites (ca. 60−80 nm) are uniformly dispersed in a SnO2 matrix (30−45 nm). Well-developed lattice fringes, for both particle types, corroborate the crystalline nature of the two phases. The isomeric shift in the Mössbauer spectrum of the CVD deposit, when compared with the Ni3Sn4 and SnO2 standards, confirms the biphasic nature of the obtained material and shows the composition to be Ni3Sn4/SnO2. Electron spectroscopy for chemical analysis (ESCA) studies performed on both (i) as obtained and (ii) argon sputtered samples established the elemental composition, the oxidation states of the Ni and Sn atoms, and the effect of atmospheric oxidation on the metal atoms located on the surface of the layers. Further characterization of the Ni−Sn intermetallic phase was achieved by detailed ESCA and high-resolution transmission electron microscopy (HR-TEM) studies.