China
Africa
Explore chapters and articles related to this topic
Crystal Structures and Properties of Nanomagnetic Materials
Published in Ram K. Gupta, Sanjay R. Mishra, Tuan Anh Nguyen, Fundamentals of Low Dimensional Magnets, 2023
Mirza H. K. Rubel, M. Khalid Hossain
Since the material is paramagnetic at high temperatures, under a definite characteristic temperature, the magnetic dipoles are organized in an ordered antiparallel direction. The transition temperature Tn is also acquainted with the Néel temperature, after the discovery and explanation by French physicist Louis-Eugène-Félix Néel in 1936. Néel temperatures are usually observed for compounds, and the several typical antiferromagnetic kinds of stuff are chromium (311 K), manganese fluoride (67 K), nickel fluoride (73 K), manganese oxide (116 K), and ferrous oxide (198 K). However, the ordered antiferromagnetic phase is a more complex state compared to that of the ferromagnetic phase because a minimum of two sets of dipoles point oppositely. No net spontaneous magnetization is observed on a macroscopic measurement while the identical figure of dipoles of the equivalent dimension on each kit is considered. Most of the insulating chemical compounds exhibit an antiferromagnetic nature via exchanging forces between the magnetic ions. Figure 10.7 shows the spin alignments of a ferromagnet where A is spin alignments for a lattice of one substance and B is that for another. It is seen that the magnetic moments of these components expel each other and produce net a magnetic moment of zero owing to the spin matching of sublattices between A and B. The material is regarded as ferromagnetic while the spin of the lattice is either only A or B type.
Surfaces
Published in Gerald L. Schneberger, Adhesives in Manufacturing, 2018
In Fig. 26 the PTFE film thickness is observed to increase with increased rubbing speed. X-ray photoemission spectroscopy analysis of the PTFE film transferred to the nickel surface revealed that the PTFE adhered to the nickel as a film and that the film was of the same composition as the bulk PTFE polymer. A small amount (< 1%) of nickel fluoride (NiF2) was present on the surface of the nickel, reflecting a chemical reaction to a limited extent of the PTFE with the nickel surface.
Preparation of Bulk and Supported Perovskites
Published in L.G. Tejuca, J.L.G. Fierro, Properties and Appbications of Peroushite-Type Oxides, 1992
Fujita, T., Y. Aoki, Y. Maeno, J. Sakurai, H. Fukuba, H. Fujil, crystallographic, magnetic and superconductive transition in lanthanum barium copper oxide, La1-xBax2CuO4-y ), Jpn. J. Appl. Phys., 26:202 (1987). 4. Nguyen, N. J J. Choisnet, M. Hervieu and B. Raveau, Oxygen defect potassium nickel fluoride K2NiF2-type oxides: the compounds lanthanum strontium copper oxide La2-xSrxCu4x/2+δ, J. Solid State Chem., 39:20 (1981).
EUROCORR 2018: applied science with constant awareness
Published in Corrosion Engineering, Science and Technology, 2019
M. Kocabas (Selçuk University, Konya, Turkey) described ‘The effect of anodic oxidation conditions on the structure of dual pre-treatment electroless nickel coating on AA1050 surface’. Specimens were subjected to a sequence of: electropolishing, anodic oxidation, surface activation (immersion in 5 g L−1 nickel fluoride solution at 30 ± 1°C and pH 6 ± 0.2 for 60, 120 and 240 s) and electroless Ni-P coating deposition from acidic solution (pH 4.4–4.8) at 85 ± 2°C for 60, 300, 600 s and 1 h. The coatings were examined by SEM, XRD, EDX and confocal laser microscopy. By considering the nucleation time and deposition rate of the electroless Ni-P coating, the optimum nickel fluoride surface activation time before coating was found to be 120 s for 15 V after 300 s of anodic oxidation.