Effect of Borohydride Addition Rate on Chemically Prepared Amorphous Fe–B Particles

1990 ◽  
Vol 206 ◽  
Author(s):  
C. Bender Koch ◽  
S. Mørup ◽  
S. Linderoth
Keyword(s):  
Chemical Composition ◽  
Aqueous Solutions ◽  
Hyperfine Field ◽  
Isomer Shift ◽  
Amorphous Alloys ◽  
Chemical Reduction ◽  
Magnetic Hyperfine Field ◽  
Hyperfine Parameters ◽  
Addition Rate ◽  
Identical Composition

ABSTRACTAmorphous Fe-B alloys can be prepared by reacting aqueous solutions of Fe salts and NaBH4. In this work the effect of the addition rate of the NaBH4 solution to the FeSO4 solution on the precipitate is investigated. The chemical composition of the amorphous alloys formed varies between Fe79B21 and Fe68B32. The hyperfine parameters of the alloys, derived from Mössbauer spectra, show a decrease from 29 to 25 T of the magnetic hyperfine field and an increase from 0.19 to 0.28 mms−1 of the isomer shift with increasing NaBH4 addition rate. The results suggest that alloys with different structures but identical composition may be produced by chemical reduction.

Preparation of Fe–Zr–B amorphous alloys by chemical reduction

1999 ◽  
Vol 92-93 ◽  
pp. 525-528 ◽  
Author(s):  
Glyn D. Forster ◽  
Luis Fernández Barquı́n ◽  
Neil S. Cohen ◽  
Quentin A. Pankhurst ◽  
Ivan P. Parkin
Keyword(s):  
Amorphous Alloys ◽  
Chemical Reduction

scholarly journals Orange opals from Buriti dos Montes, Piauí: solid inclusions as genetic guides

2015 ◽  
Vol 68 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Gisele Tavares Marques ◽  
Marcondes Lima da Costa ◽  
Érico Rodrigues Gomes
Keyword(s):  
Chemical Composition ◽  
Aqueous Solutions ◽  
High Stability ◽  
Hydrothermal Fluids ◽  
Northeastern Brazil ◽  
Quartz Crystals ◽  
Hydrothermal Processes ◽  
Hydrothermal Environment

Orange opals from Buriti dos Montes (Piauí, northeastern Brazil) have gemological properties that favor their use as jewelry; these characteristics include their colors, transparency, relatively high stability and hardness. The exotic content of solid inclusions provides greater beauty to the opals of this region. These opals originated from hydrothermal processes and are found mainly as veinlets and veins in the sandstones of the Serra Grande Group, sectioned by diabase dikes and sills of the Sardinha Formation. Solid inclusions, such as bubbles, botryoidal aggregates, dendrites, and nodules, among others, consist mainly of kaolinite, hematite/goethite and quartz and influence the chemical composition of opals. Intense zoning of quartz crystals and high values of Ba and Fe suggest that opal deposits were formed in a hydrothermal environment. Diabase dykes could have been responsible for heating the hydrothermal fluids. Sandstones, rich in aqueous solutions, also contributed to the available silica for the saturation of these solutions, and fractures enabled the migration and entrapment of hydrothermal fluids, resulting in the mineralized veins.

Controlled Formation of Quantum Size Metal and Semiconductor Particles from Aqueous Solutions

1990 ◽  
Vol 206 ◽  
Author(s):  
Ramesh C. Patel ◽  
Jovan Nedeljkovic ◽  
Olga Micic
Keyword(s):  
Aqueous Solutions ◽  
Chemical Reduction ◽  
Deposition Process ◽  
Metallic Silver ◽  
Uniform Size ◽  
Quantum Size ◽  
Spherical Silica ◽  
Reduction Methods ◽  
Spherical Silica Particles ◽  
Excimer Laser Irradiation

ABSTRACTPhotochemical and chemical reduction methods are described for the controlled formation of metallic silver in aqueous solutions. The former approach is capable of generally depositing a number of metals. When spherical silver bromide particles are the substrates, the resulting silver coated composite particles exhibit optical absorption spectra which vary with the coat thickness as theoretically predicted. In the case of spherical silica particles of uniform size, it was possible to produce both quantum size silver particles supported on silica, as well as a silver coat of variable thickness, depending on the rate of the deposition process. In addition to silica, substrates such as latex and chromium hydroxide could be used.CdS particles with two different particle diameters (50–200 Å and < 30 Å) were subjected to 308 nm excimer laser irradiation at 77 K, and the subsequent charge carrier processes studied by ESR. Dramatic differences in the ESR signals as a function of decreasing particle size could be observed, consistent with the localization of charge carriers on numerous surface sites.

Magnetic hyperfine field for zinc in nickel

1974 ◽  
Vol 267 (4) ◽  
pp. 299-304 ◽  
Author(s):  
H. Bertschat ◽  
H. Haas ◽  
F. Pleiter ◽  
E. Recknagel ◽  
E. Schlodder ◽  
...  
Keyword(s):  
Hyperfine Field ◽  
Magnetic Hyperfine Field ◽  
Magnetic Hyperfine

197Au MÖssbauer Study of Au/Fe, Au/Co and Au/Ni Magnetic Multilayers

1995 ◽  
Vol 384 ◽  
Author(s):  
Saburo Nasu ◽  
Yasuhiro Kobayashi
Keyword(s):  
Hyperfine Field ◽  
Magnetic Hyperfine Field ◽  
Ferromagnetic Layer ◽  
Magnetic Multilayers ◽  
Electron Spin Polarization ◽  
Hyperfine Fields ◽  
Mössbauer Study ◽  
Mössbauer Measurements ◽  
Local Environments ◽  
Ferromagnetic Layers

ABSTRACT197Au Mössbauer measurements have been performed for Au/Fe, Au/Co and Au/Ni magnetic multilayers. 197Au Mössbauer spectra observed from multilayers consist of at least 4 components having different magnitude of hyperfine fields and isomer shift values those depend on the local environments of the Au probe-atoms in multilayers. Rather large electron spin polarization at Au atoms has been observed in the interface with adjacent ferromagnetic layers, but nearly no magnetic hyperfine field has been observed to the interior of Au layer. It implies that the largest hyperfine field observed is not due to the conduction-electron polarization but induced by the hybridization in the interface with ferromagnetic layer.

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