13586-84-0Relevant articles and documents
Room Temperature Blocked Magnetic Nanoparticles Based on Ferrite Promoted by a Three-Step Thermal Decomposition Process
Sartori, Kevin,Choueikani, Fadi,Gloter, Alexandre,Begin-Colin, Sylvie,Taverna, Dario,Pichon, Benoit P.
supporting information, p. 9783 - 9787 (2019/07/04)
Exchange coupled nanoparticles that combine hard and soft magnetic phases are very promising to enhance the effective magnetic anisotropy while preserving sizes below 20 nm. However, the core-shell structure is usually insufficient to produce rare earth-free ferro(i)magnetic blocked nanoparticles at room temperature. We report on onion-type magnetic nanoparticles prepared by a three-step seed mediated growth based on the thermal decomposition method. The core@shell@shell structure consists of a core and an external shell of Fe3-?O4 separated by an intermediate Co-doped ferrite shell. The double exchange coupling at both core@shell and shell@shell interfaces results in such an increased of the magnetic anisotropy energy, that onion-type nanoparticles of 16 nm mainly based on iron oxide are blocked at room temperature. We envision that these results are very appealing for potential applications based on permanent magnets.
Wet-chemical catalyst deposition for scalable synthesis of vertical aligned carbon nanotubes on metal substrates
Doerfler,Meier,Thieme,Nemeth,Althues,Kaskel
, p. 288 - 293 (2011/10/06)
A scalable process for carbon nanotube (CNT) growth on metallic substrates has been developed including dip-coating steps for the wet-chemical catalyst and co-catalyst layer deposition and a subsequent chemical vapor deposition step. Organic metal salt/2-propanol solutions were applied as precursors for alumina co-catalyst thin films and the actual Fe (Co, Mo) catalyst layer. Vertical aligned carbon nanotube forests were obtained on catalyst-coated nickel foil in a thermal CVD process at atmospheric pressure and 730 °C using ethene as carbon source. The influence of the catalyst composition on growth rate, density and structure of resulting CNT films was investigated.
FATTY ACID METAL SALT FOR FORMING ULTRAFINE METAL PARTICLE
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Page/Page column 11, (2010/11/19)
A fatty acid metal salt used for forming ultrafine metal particles satisfying at least one of that: (i) the water content is 200 ppm or less; (ii) the volume-cumulative particle diameter D90 is 80 μm or smaller as measured by the particle size distribution measuring method of the laser diffraction/scattering type; or (iii) a metal of an atomic weight of 50 to 200 is contained, and the amount of the unreacted substance or the by-product is 4.0 mol% or less when the fatty acid metal salt is formed. The fatty acid metal salt can be favorably used for forming ultrafine metal particles in a resin, or for forming a resin composition, a coating, a dispersion solution or a molded article containing the ultrafine metal particles.
Relating structure with morphology: A comparative study of perfect Langmuir-Blodgett multilayers
Mukherjee, Smita,Datta, Alokmay,Giglia, Angelo,Mahne, Nichole,Nannarone, Stefano
, p. 80 - 87 (2008/09/20)
Atomic force microscopy and X-ray reflectivity of metal-stearate (MSt) Langmuir-Blodgett films on hydrophilic Silicon (1 0 0), show dramatic reduction in 'pinhole' defects when metal M is changed from Cd to Co, along with excellent periodicity in multilayer, with hydrocarbon tails tilted 9.6° from vertical for CoSt (untilted for CdSt). Near edge X-ray absorption fine structure (NEXAFS) and Fourier transform infra-red (FTIR) spectroscopies indicate bidentate bridging metal-carboxylate coordination in CoSt (unidentate in CdSt), underscoring role of headgroup structure in determining morphology. FTIR studies also show increased packing density in CoSt, consistent with increased coverage.
Catalytic oxidative cleavage of terminal olefins by chromium(III) stearate
Jarupinthusophon, Suekanya,Thong-In, Uthumporn,Chavasiri, Warinthorn
, p. 289 - 294 (2008/10/09)
A new synthetic methodology for the preparation of carbonyl compounds from the oxidative cleavage of terminal olefins has been developed. With the use of TBHP in combination with chromium(III) stearate, selective oxidation of double bonds conjugated with aromatic ring or carbonyl group could be achieved at ambient temperature in moderate to excellent yield. The oxidative cleavage of electron rich α-methylstyrene derivatives proceeded in good to excellent yield whereas lower yields were observed in α-methylstyrene derivatives containing an electron withdrawing group. This developed oxidation reaction was believed to undergo via free radical process and high valent chromium oxo species.
Synthesis of biodiesel via homogeneous Lewis acid catalyst
Di Serio,Tesser,Dimiccoli,Cammarota,Nastasi,Santacesaria
, p. 111 - 115 (2008/10/09)
Nowadays, most biodiesel (fatty acids methyl esters, FAME) is produced by the transesterification of triglycerides (TG) of refined/edible type oils using methanol and an homogeneous alkaline catalyst. However, production costs are still rather high compared with the ones of petroleum-based diesel fuel. To lower costs and make biodiesel competitive less-expensive feedstocks such as waste fats or non-edible type oils could be used. The use of homogeneous alkaline catalysts in the transesterification of such types of fats and oils poses great difficulties due to the presence of large amounts of free fatty acids (FFA). This paper studies the use of carboxylic salts as a possible alternative, because these catalysts are active also in the presence of high FFA concentrations. The most active catalyst (Cd, Mn, Pb, Zn carboxylic salts) have been individuated and a correlation of the activities with the cation acidity has been found.
Spin-glass behavior in CoSt2 Langmuir-Blodgett multilayer films
Hatta,Maekawa,Mukasa,Shimoyama
, p. 14561 - 14564 (2008/10/09)
The de susceptibilities have been measured on cobalt stearate (CoSt2) Langmuir-Blodgett (LB) multilayer films. Two successive peaks and irreversibility are observed clearly in both parallel and perpendicular directions to the c axis. These behaviors are consistent with the mean-field theory for the Heisenberg-type spin-glass system having a weak single-ion anisotropy. The above behavior has never been observed in small CoSt2 particles. so it is considered to be an inherent characteristic in the LB film structure. The magnetic behaviors between CoSt2 LB films and other related compounds are compared and discussed.
A water-bridged dinuclear complex of cobalt(II), pyridine and stearic acid
Corkery, Robert W.,Hockless, David C. R.
, p. 840 - 843 (2007/10/03)
In the crystal structure of μ-aqua-1:2κ2O-tetrapyridine-1κ 2N,2κ2N-bis(μ-stearato)-1κ 2O:2κ 2O′-bis(stearato)-1κO,2κO-dicobalt(II), [Co2(C18H35O2)4(C 5H5N)4-(H2O)], hydrogen bonding [with an O...O distance of 2.564 (5) A] between the H atoms of the bridging water and the non-metal-bonding O atoms of the monodentate stearic acid molecules, stabilizes the dimeric core complex and consequently limits chain packing and conformation options. The structure is a member of a rare class of compounds, the well crystallized metallic salts of long-chain fatty acids. The structure also bears a remarkable similarity to built-up Langmuir-Blodgett films of metal carboxylates.
