We report the synthesis of alloyed quaternary and quinary nanocrystals based on copper chalcogenides, namely, copper zinc selenide–sulfide (CZSeS), copper tin selenide–sulfide (CTSeS), and copper zinc tin selenide–sulfide (CZTSeS) nanoplatelets (NPLs) (∼20 nm wide) with tunable chemical composition. Our synthesis scheme consisted of two facile steps: i.e., the preparation of copper selenide–sulfide (Cu2–xSeyS1–y) platelet shaped nanocrystals via the colloidal route, followed by an in situ cation exchange reaction. During the latter step, the cation exchange proceeded through a partial replacement of copper ions by zinc or/and tin cations, yielding homogeneously alloyed nanocrystals with platelet shape. Overall, the chemical composition of the alloyed nanocrystals can easily be controlled by the amount of precursors that contain cations of interest (e.g., Zn, Sn) to be incorporated/alloyed. We have also optimized the reaction conditions that allow a complete preservation of the size, morphology, and crystal structure as that of the starting Cu2–xSeyS1–y NPLs. The alloyed NPLs were characterized by optical spectroscopy (UV–vis–NIR) and cyclic voltammetry (CV), which demonstrated tunability of their light absorption characteristics as well as their electrochemical band gaps.

Nanoparticles of Ag, Au, Pd, and Cu have been prepared by the reduction of their salts by ethyl alcohol under refluxing conditions in the presence of polyvinylpyrrolidone (PVP). In the case of Au and Cu, it was necessary to use magnesium metal as a catalyst during the reduction. The nanoparticles are in the 5-35 nm range in the case of Ag, Au, and Pd, but there is considerable agglomeration in the case of Cu even in the presence of PVP.

Cobalt ferrite nanoparticles of different sizes are prepared by varying the concentration of Co2+ metal ions using precipitation approach. The average crystallite size, coercivity (H C), and saturation magnetization (M S) increases from 11 to 16 nm, 0.12 to 0.8 kOe, and 28 to 52 emu/g, respectively, as Co2+ ion concentration is reduced from 0.4 to 0.025 M. High resolution transmission electron microscopy and X-ray diffraction analysis confirms that CoFe2O4 nanoparticles are crystalline in nature with cubic structure. Raman spectroscopic investigation shows traces of paramagnetic ferrihydrite in samples prepared with Co2+ ion concentration greater than 0.1 M. These experimental results suggest that metal ion concentration plays an important role in the size, magnetic property and purity of precipitated cobalt ferrite nanoparticles. The variation in the average crystalline size with Co2+ ion concentration is in good agreement with the nucleation theory. Our approach is useful in tuning the size and magnetic properties of cobalt ferrite nanoparticles.

The hydrothermal synthesis and single crystal XRD characterization of a three-dimensional open-framework lead(II) carboxyethylphosphonate, Pb 3 (O 2 CCH 2 CH 2 PO 3 ) 2 , is described; the structure contains PbO 3 , PbO 4 and PbO 5 polyhedra, each with stereochemically active lone pairs of electrons, and exhibits several types of channels.

We study the effects of surfactant monolayer coating on the reduction of Fe 3 O 4 nanoparticles under vacuum thermal annealing. Oleic acid coated and uncoated Fe 3 O 4 nanoparticles were synthesized by a simple coprecipitation technique. In the temperature range of 300-700 °C, the particle size and lattice constant of uncoated Fe 3 O 4 nanoparticles increased from 9 to 18 nm and from 8.357 to 8.446 Å, respectively. On further heating (above 700 °C), Fe 3 O 4 decomposed into γ-Fe 2 O 3 and FeO phases. In the range of 800-1000 °C, the FeO phase was predominant, and its size grew significantly from 30 to 44 nm. Conversion of oleic acid coated Fe 3 O 4 phase to metallic R-Fe commenced at 500 °C and continued up to 800 °C. After vacuum annealing at 800 °C, the magnetic behavior of the sample changed from ferrimagnetic to ferromagnetic. The activation energies for the phase transitions of uncoated and oleic acid coated nanoparticles were estimated to be 30.304 and 17.349 kJ/mol, respectively. Thermogravimetric analysis (TGA) coupled with mass spectrometry revealed that, for coated nanoparticles, effluents such as H 2 , CO, and CO 2 from oleic acid facilitate the reduction of Fe 3 O 4 into R-Fe and FeO during vacuum thermal annealing. The interaction between the headgroup of the oleic acid and the oxygen in Fe 3 O 4 is expected to lead to weakened bonding, which could result in a lower activation energy for the reduction of the surfactant-coated nanoparticles. This is a plausible reason for the precipitatation of R-Fe at lower temperature (at 500 °C) in the surfactant-coated system.