Formation of nanoparticles of a new metastable copper compound in the copper acetate hydrate/poly(acrylonitrile) heterogeneous system

We use X-ray powder diffraction to study heterogeneous solid-phase reactions induced by IR radiation in the system Cu(OOCCH₃)₂·H₂O/PAN and intermediate copper compounds in the synthesis of copper nanoparticles. The composite Cu(OOCCH₃)₂ · H₂O/PAN after annealing contains crystallites of copper (l _Cu = 16 nm), a new metastable compound Cu _x>2O ( $ l_{Cu_{x > 2} O} We use X-ray powder diffraction to study heterogeneous solid-phase reactions induced by IR radiation in the system Cu(OOCCH₃)₂·H₂O/PAN and intermediate copper compounds in the synthesis of copper nanoparticles. The composite Cu(OOCCH₃)₂ · H₂O/PAN after annealing contains crystallites of copper (l _Cu = 16 nm), a new metastable compound Cu _x>2O ( = 20 nm), and Cu₂O ( = 20 nm). After 45 days of air exposure, the intensity of Cu _x>2O reflections in the composite decreases dramatically, whereas that of copper reflections increases. Cu _x>2O has a monoclinic unit cell with the parameters a = 5.424, b = 3.196, c = 3.072 ?, β = 119.51°. Original Russian Text ? V.M. Novotortsev, V.V. Kozlov, Yu.M. Korolev, G.P. Karpacheva, L.V. Kozhitov, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 7, pp. 1087–1089.     

Polyacrylonitrile-based FeCo/C nanocomposites: Preparation and magnetic properties

Metal–carbon nanocomposites that represent FeCo alloy nanoparticles uniformly distributed over the carbon matrix, were prepared by the IR pyrolysis of precursors comprising polyacrylonitrile (PAN), iron acetylacetonate, and cobalt acetate (the metal ratio in the precursors was Fe: Co = 1: 1, 3: 1). The composition of FeCo alloy nanoparticles satisfies the tailored ratio Fe: Co. The FeCo phase is formed at synthesis temperatures in the range 500–600°С; at T ≤ 500°С only FCC-Co-base solid solutions are observed. The nanocomposites prepared at T ≥ 600°С simultaneously contain FeCo intermetallic nanoparticles and an insignificant amount of a FCC-Co phase or a cobalt-base solid solution phase. The saturation magnetization of FeCo/C metal–carbon nanocomposites is determined by the mean nanoparticle size and the alloy composition, and ranges from 36 to 64 (A m²)/kg (when Fe: Co = 1: 1) and from 35 to 52 (A m²)/kg (when Fe: Co = 3: 1) at synthesis temperatures in the range 600–800°С.     

Radar Absorbing NiCo Nanoparticles in Carbon Matrix of Nanocomposites in the Microwave Range

Russian Physics Journal - The paper focuses on the synthesis of NiCo/C nanocomposites comprising the Ni–Co alloy nanoparticles uniformly distributed and stabilized in a carbon matrix. The...     

A novel functional material based on carbon nanotubes modified by copper nanoparticles

A novel functional material is obtained on the basis of multiwall carbon nanotubes (CNT) modified by copper nanoparticles, which are distributed in the interlayer space and inside the CNT channel. Transformations induced by IR heating in a Cu(OOCH₃)₂ · H₂O-CNT system are studied by powder X-ray diffraction analysis and transmission electron microscopy. The CuO, Cu₂O, and Cu nanparticles penetrate into graphite-like layers of the CNT and form intercalated CNT. The intercalation of the CNT by Cu(OOCCH₃)₂ · H₂O can be used for their purification from impurity nanoparticles of amorphous carbon and polyaromatic compounds.     

Metal-Polymer Nanocomposites Based on Pyrolyzed Polyacrylonitrile with Fe–Ni–Co Inclusions

Russian Physics Journal - The paper presents the results of the computational modeling and quantum-chemical investigations of metal-polymer composites based on pyrolyzed polyacrylonitrile (PAN)...     

On synthesis of BaFe<Subscript>12</Subscript>O<Subscript>19</Subscript>, SrFe<Subscript>12</Subscript>O<Subscript>19</Subscript>, and PbFe<Subscript>12</Subscript>O<Subscript>19</Subscript> hexagonal ferrite ceramics with multiferroid properties

We analyze the possibility of obtaining M-type hexagonal ferrites of barium, strontium, and lead with multiferroid properties with the help of ceramic technology. Using the modified ceramic technology (especially pure initial raw materials, admixture of B₂O₃, and sintering in the oxygen atmosphere), we obtained for the first time the BaFe₁₂O₁₉ and SrFe₁₂O₁₉ samples with intense multiferroid properties at room temperature. At the same time, the employed technology does not make it possible to obtain PbFe₁₂O₁₉ samples exhibiting ferroelectricity. The multiferroid characteristics of experimental samples are compared with the characteristics of classical high-temperature multiferroic BiFeO₃ and with the characteristics of BaFe₁₂O₁₉, SrFe₁₂O₁₉, and PbFe₁₂O₁₉ ferrite ceramics obtained in accordance with polymer precursor technology. We propose a mechanism explaining multiferroid properties of the hexagonal ferrite ceramic samples and note the importance of our results for applications.     

FeCo/C nanocomposites: Synthesis,magnetic and electromagnetic properties

FeCo alloy nanoparticles encapsulated in the carbon matrix of metal–carbon nanocomposites have been manufactured under IR heating. The size of FeCo nanoparticles have been found to be tailored by varying synthesis temperature and metal concentration. The saturation magnetization has been shown to increase as the synthesis temperature or metal concentration rises, with an attendant decrease in coercive force. The electromagnetic properties of FeCo/C nanocomposites have been studied. Complex magnetic permittivity measurements have shown that variation of the synthesis temperature or metal concentration can appreciably increase magnetic loss, which leads to a shift of the band of minimum electromagnetic reflectivity in the frequency range 3–12 GHz.     

Synthesis,Structure and Electromagnetic Properties of Nanocomposites with Three-component FeCoNi Nanoparticles

Russian Physics Journal - Infrared heating was used to synthesize FeCoNi/С nanocomposites, where nanoparticles of FeCoNi ternary alloy are stabilized and uniformly distributed in the carbon...