ZIB

1

Digitale Medien

Magnetic-field distributions in zinc-nickel ferrite : 35TH ANNUAL CONFERENCE ON MAGNETISM AND MAGNETIC MATERIALS San Diego, California (USA) 29 Oct−1 Nov 1990 (1991)

Dooling, T. A. ; Cook, D. C.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 69 (1991), S. 5352-5354

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The Mössbauer effect has been used to study the microscopic magnetic properties of the cubic microwave ferrite (Zn0.41Ni0.59)Fe2O4 at 300 K. The magnetically split spectrum is broad and unresolved due to the overlap of the hyperfine magnetic fields at the tetrahedral and octahedral sites. This is caused by a distribution of magnetic fields at each site. The distribution is especially large and asymmetric at the octahedral site and is due to the fact that the iron atoms at this site are influenced by the presence of both iron and zinc at the tetrahedral site. The octahedral site is more sensitive to changes in the number of zinc neighbors than is the tetrahedral site. Assuming a random distribution of the zinc at the tetrahedral site, and knowing the fraction of zinc in the ferrite, the binomial distribution has been used to calculate the expected magnetic-field distribution at the octahedral site as a function of the number of zinc neighbors. These figures have been compared with the magnetic-field distribution profile determined from the fit to the Mössbauer spectrum. Sufficiently good agreement has been found to allow us to isolate the magnetic-field contribution due to most of the different numbers, between zero and six, of neighboring zinc atoms.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.348026

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

2

Digitale Medien

Phase changes in plasma-sprayed zinc-nickel ferrite : 35TH ANNUAL CONFERENCE ON MAGNETISM AND MAGNETIC MATERIALS San Diego, California (USA) 29 Oct−1 Nov 1990 (1991)

Dooling, T. A. ; Cook, D. C.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 69 (1991), S. 5355-5357

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The magnetic and crystalline properties of a plasma-sprayed coating of the microwave absorbing zinc-nickel ferrite, (Zn0.41Ni0.59 )Fe2O4 have been studied at 300 K using the Mössbauer effect and x-ray diffraction (XRD). Both techniques indicate that the plasma-sprayed material separated into two phases. The first is a nickel-rich phase with magnetic fields of 47.5 and 44.5 T at the tetrahedral and octahedral sites, respectively. The second is a zinc-rich phase, zinc meta-ferrite, having a small magnetic field of 4.2 T. The quadrupole splitting of this second phase is ΔE=0.34 mm s−1, which is the same as in pure nonmagnetic zinc ferrite. XRD analysis shows that the zinc-rich phase remains cubic with a0= 8.389 A(ring) and the zinc meta-ferrite phase is tetragonal with the same lattice parameters as the cubic phase except for one elongated axis given by c0 =8.488 A(ring). This is much larger than the spacing for any of the series of zinc-nickel ferrites. The isomer shift of the zinc meta-ferrite is 0.710 mm s−1, which indicates that a large fraction of Fe3+ was reduced during the spraying process. Annealing the sprayed coating at temperatures less than 400 °C converted the zinc meta-ferrite into a magnetic phase that now exhibits magnetic fields close to those in the nickel-rich phase. However, the large isomer shift remains, indicating that the ferrous iron is still present. XRD shows that the phase is now cubic. Annealing up to 650 °C gradually oxidized all of the Fe2+ in the material and restored the magnetic and crystalline properties of the plasma-sprayed coating to very close to those of the unsprayed ferrite.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.348027

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

3

Digitale Medien

Mössbauer effect determination of relative recoilless fractions for iron oxides (1999)

Oh, Sei J. ; Cook, D. C.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 85 (1999), S. 329-332

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The relative recoilless fraction (F-value) of each of six iron oxides, defined as the ratio of the recoil-free fractions of two different materials, was experimentally determined relative to hematite at 300 K and 77 K by Mössbauer spectroscopy. Using the relative recoil-free fractions compared to that of hematite, the relative recoilless fractions between all pairs of the seven iron oxides were determined. The F-values can allow conversion of Mössbauer subspectral areas to the relative atomic, molecular, or weight fractions of each iron oxide present in a mixed oxide phase sample. © 1999 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.369451

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

4

Digitale Medien

Palaeopathology: An American Account (1980)

Buikstra, J E ; Cook, D C

Palo Alto, Calif. : Annual Reviews

Annual Review of Anthropology 9 (1980), S. 433-470

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 0084-6570

Quelle: Annual Reviews Electronic Back Volume Collection 1932-2001ff

Thema: Ethnologie , Biologie

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1146/annurev.an.09.100180.002245

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

5

Digitale Medien

A gas flow proportional counter for the Mössbauer study of surfaces between 100 K and 400 K (1986)

Cook, D. C.

Springer

Hyperfine interactions 29 (1986), S. 1463-1466

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1572-9540

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract A gas flow proportional counter has been constructed for operation between 100K and 400K without the need for an evacuated cryostat. The detector is temperature controlled and may be used for detecting conversion electrons or X-rays. Six different gases, pure He, He/1%CH4, He/5%CH4, He/10%CH4, He/5%Co, and Ar/5%CH4 have been investigated in order to obtain maximum efficiency and reliability of operation. At room temperature and above, all gases are suitable. At low temperatures, He/5%Co is the most suitable for electron detection, For X-ray detection, Ar/5%CH4 is suitable over the entire temperature range.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02399510

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

6

Digitale Medien

The microstructural properties of highly nitrogenated iron and iron-aluminum powders (1994)

Cook, D. C. ; Rawers, J. C.

Springer

Hyperfine interactions 92 (1994), S. 959-964

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1572-9540

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract A study has been made of highly nitrogenated pure iron and iron-aluminum alloy powder containing 2 wt.% Al (Fe-2Al) using Mössbauer spectroscopy and X-ray diffraction. The samples were prepared by high-temperature, high-pressure diffusion of nitrogen. They were prepared in a hot-isostatic-pressure (HIP) furnace at 1000 °C at nitrogen pressures up to 200 MPa. The alloy powders contained up to 8 at.% nitrogen as determined by vacuum fusion analysis. XRD analysis indicates that for the pure iron powders, the lattice spacing remained independent of nitrogen concentration, but that for the Fe-2Al powders, it decreased with increasing nitrogen concentration. Mössbauer analysis showed that for the pure iron powders, most of the nitrogen was associated with the formation of the iron nitride Fe4N. For the alloy powders containing less than 5 at.% nitrogen, all of the nitrogen was contained interstitially. The presence of nitrogen completely eliminated the conduction-electron spin-density oscillations observed in many ferromagnetic alloys.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02065719

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

7

Digitale Medien

Study of the surface structure of tempered carbon steel (1988)

Cook, D. C.

Springer

Hyperfine interactions 41 (1988), S. 625-628

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1572-9540

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract A CEMS and XMS study of carbon steel has shown that the microstructure of the bulk material as well as the surface depends on the temperature at which the steel was tempered. Ion milling of the surface results in no change to the surface microstructure which corresponds closely to the bulk properties. However, after polishing the surface with 3μm diamond, the surface composition is changed to a large extent. Polishing decreases the amount of retained austenite and also the fraction of interstitial carbon within the austenite on the surface of the non-tempered steel. A related increase in the amount of surface martensite is observed. The effects of polishing extends to depths of over 1000 Å. Both X- and θ-carbides are present in each of the tempered steels and only the amount of θ-carbide is seen to increase as the samples are tempered to decrease hardness. Tempering to higher temperatures decreases the martensite content and a corresponding increase is seen in the θ-carbide only. Polishing also removes a large feaction of the carbide from the surface and this may account for the anomalously high wear resistance previously determined for the steel.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02400468

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

8

Digitale Medien

Environmental influence on the formation of α-FeOOH on the surface of weathering steel (1988)

Rezaie-Serej, S. ; Cook, D. C.

Springer

Hyperfine interactions 41 (1988), S. 701-704

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1572-9540

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract A CEMS and XMS study of the surface oxidation of weathering steel, ASTM A242 Type 1, has shown that after exposure times of 5 1/2 years in a marine or industrial environment, the steel has not yet reached a stage at which the surface is fully protecting the substrate from further corrosion. The formation of α-FeOOH, an intermediate stage of protection, occurs mainly in the form of small particles, the properties of which exhibit an appreciable amount of superparamagnetic relaxation. For the steel exposed to a more moist marine environment, α-FeOOH exists only in the form of small particles. However for the steel exposed to a much dryer and corrosive industrial environment, more α-FeOOH is present. The formation of bulk α-FeOOH is more complete. The temperature dependence of the superparamagnetic hyperfine field and also the field distributions indicate that, in a marine environment, the clusters of α-FeOOH are both smaller in size and have a larger distribution of particle size. The XMS results indicate that α-FeOOH is present below a layer of γ-FeOOH and ferrihydrite which are generally accepted to constitute the early oxidation phases observed on steels.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02400487

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

9

Digitale Medien

Determination of the nuclear parameters of155Gd excited states using the Mössbauer effect (1977)

Cook, D. C. ; Cashion, J. D.

Springer

Hyperfine interactions 5 (1977), S. 479-486

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1572-9540

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract From Mössbauer spectra of GdAlO3 and GdVO4 above and below the Néel temperature and fitted using a transmission integral, we have determined the following parameters of the 86.5 keV and 105 keV levels:g(86)/g(0)=+1.217±0.005,Q(86)/Q(0)= +0.10±0.02,g(105)/g(0)=−0.55±0.02,Q(105)/Q(0)=+0.74±0.02, Δ〈r 2〉105/ Δ〈r 2〉86=+1.30±0.05. The linewidth observed for the 105 keV transition is less than the calculated natural linewidth.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01021716

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

10

Digitale Medien

A high temperature Mössbauer effect study of iron-doped YBa2Cu3O7 superconductor (1994)

Ford, D. J. ; Cook, D. C. ; Gardner, J. A. ; [weitere]

Springer

Hyperfine interactions 93 (1994), S. 1627-1633

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1572-9540

Quelle: Springer Online Journal Archives 1860-2000

Thema: Physik

Notizen: Abstract Superconducting YBa2Cu2.955Fe0.045O7 has been studied at temperatures between 300 and 1000 K. Spectra were recorded on a sample which was sealed as a pellet pressed with boron nitride. An atmosphere of oxygen was maintained in the sample region at all times. At temperatures up to 900 K, we observed the four iron sites A, (Cu(1) chain-site; square planar oxygen coordination with O(5) vacancy on thea-axis), B, (Cu(2) plane-site; square pyramidal oxygen coordination), C, (Cu(1) chain-site; square pyramidal oxygen coordination with O(5) site occupied) and D, (Cu(1) chain-site; quasi-tetrahedral oxygen coordination with O(4) vacancy along theb-axis). At temperatures up to 700 K, the relative area of the B and C sites remained nearly constant as the temperature was increased. However, the area of the A site decreased while, the D site area increased with increasing temperature. At all times, the total area of sites A and D remained constant, thereby indicating the possibility of oxygen atom hopping in thea-b plane. The quadrupole splitting of each site, except the B site, decreased linearly with increasing temperature.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02072919

Permalink

Bibliothek	Standort	Signatur	Band/Heft/Jahr	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext