ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Selected studies of magnetism at high pressure (1996)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 18 (1996), S. 145-161 
    Details
    ISSN: 0392-6737
    Keywords: Metal-insulator transitions ; High-pressure and shock-wave effects in solids ; Mössbauer effect ; other γ-ray spectroscopy ; Transition-metal compounds ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Most previous studies of magnetism in various compounds under extreme conditions have been conducted over a wide pressure range at room temperature or over a wide range of cryogenic temperatures at pressures below 20 GPa (200 kbar). We present some of the most recent studies of magnetism over an extended range of temperatures and pressures far beyond 20 GPa,i.e. in regions of pressure-temperature (P-T) space where magnetism has been largely unexplored. Recent techniques have permitted investigations of magnetism in selected 3d transition metal compounds in regions ofP-T where physical properties may be drastically modified; related effects have often been seen in selected doping studies at ambient pressures. We present57Fe and129I Mössbauer isotope studies covering the range 300–4 K to sub-megabar pressures in compounds such as Sr2FeO4, LaFeO3 and FeI2, representative of a broad class of 3d transition metal compounds. At ambient pressure the electronic structure of the transition metal atom in these antiferromagnetic insulators extends from 3d 4 to 3d 6 and has a distinct influence on the pressure evolution of their magnetic properties. Mössbauer studies of these compounds are considered in conjunction with available structural and electrical transport data at pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02458889
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Pressure-induced Mott transition in transition-metal iodides (invited) : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5956-5960 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Many of the transition-metal (TM) compounds, because of exchange and correlation interactions within the narrow and poorly overlapping d bands, become antiferromagnetic insulators, the Mott insulators (MI). The properties of the MI and their gradual transition into the noncorrelated metallic state (the Mott transition) are of crucial importance for the elucidation of high-temperature superconducting materials features in particular and to magnetism in general. The transition of the MI into a metal can be achieved either by doping or by high pressure. The first method is definitely inappropriate for studying the nature of the Mott transition; for the narrow-band materials the electronic and structural disorder inherent in doping has a strongly perturbing effect. To yield the definitive data on the Mott transition, high-pressure work on well-characterized materials should be sought. The present studies provide for the first time extensive information on the Mott–Hubbard gap closure induced by high pressure. High-pressure studies using diamond anvil cells were conducted with several (TM)I2 compounds. They all have layered structures and order antiferromagnetically at ambient pressure. 129I Mössbauer spectroscopy (MS) was used to study the properties of the (TM)2+ sublattice magnetization as a function of pressure and temperature, and x-ray diffraction was used to look for possible crystallographic transitions and to obtain the equation of state. Results show that the high-pressure transition at Pc from a magnetic to a nonmagnetic state is not accompanied by crystallographic changes. Previous studies [M. P. Pasternak et al., Phys. Rev. Lett. 65, 790 (1990)] with NiI2 have confirmed the presence of a metallic state at P (approximately-greater-than) Pc. Inherent to the pressure behavior of the magnetic state is the gradual increase of TN in all cases and a slight increase in the TM2+ moments with pressure increase. The collapse of the magnetic state is abrupt for some cases (NiI2) and gradual for others (CoI2), indicative of different band-overlap mechanisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350089
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Hysteresis in the high pressure transformation of bcc- to hcp-iron : 35th annual conference on magnetism and magnetic materials (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 6126-6128 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The α-Fe/ε-Fe phase transformation has been studied by the Mössbauer effect of 57Fe in a diamond anvil cell at hydrostatic pressures up to 24 GPa. The α/ε composition is easily derived as a function of intermediate pressure. For rising pressures the transition onset is about 9 GPa and half of the α-Fe is converted to ε-Fe by 15 GPa; for lowering pressures half of the ε-Fe is converted to α-Fe by 9 GPa. The transition pressures, widths, and hysteresis widths are compared to those obtained by other techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348779
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    A multipurpose miniature diamond anvil cell (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 1117-1119 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new multipurpose miniature diamond anvil high-pressure cell (DAC) has been constructed. The circular DAC has an overall 22-mm diam. and 15-mm height and is comprised of a gasket, opposing diamond anvils each mounted on backing plates, and force rings (platens). The pressure is generated by six Allen-type screws. Pressures up to 38 GPa were achieved with this miniature cell. Design features, mode of operation, and performance are described. A particular application to cryogenic and room temperature 119Sn Mössbauer spectroscopy is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141433
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    57Fe Mössbauer spectroscopy in a diamond-anvil cell at variable high pressures and cryogenic temperatures (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3787-3792 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A detailed description is given of a new facility for transmission 57Fe Mössbauer spectroscopy (MS) studies on absorbers in a miniature diamond-anvil cell in the temperature range 10–300 K and pressure range 0–45 GPa. Spectra with an adequate signal-to-noise ratio for a reliable analysis to be made have each been measured in 20–30 h of data accumulation time. This has been accomplished in spite of the severe constraints imposed by both the minute sample area and the high attenuation of the 14.4 keV probing radiation by the diamond anvils compared with the experimental conditions of conventional MS experiments. A custom-made Rh(57Co) "point'' source with a high specific activity has been used in conjunction with absorbers that have an optimal enrichment (10%–20%) of 57Fe. The successful implementation of 57Fe Mössbauer spectroscopy at very high pressures and variable cryogenic temperatures has been accomplished by making relatively simple refinements to existing elements of high-pressure MS methodology. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144508
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    A multipurpose miniature piston-cylinder diamond-anvil cell for pressures beyond 100 GPa (1998)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 1423-1425 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A miniature piston-cylinder diamond-anvil cell (DAC) was constructed and tested for pressure operation at and beyond 100 GPa. Its advantages compared to other piston-cylinder DACs are its compactness (22-mm diam by 21-mm high), self-contained force generator, and simple way of operation. Tungsten carbide backing plates are used for supporting the anvils; one with a hemispherical shape allowing for parallelism alignment, and one with a flat circular shape allowing for lateral alignment of the anvils' culets. The force is generated by six M3 Allen screws and is conveyed to the piston via force rings. Pressures to 130 GPa were achieved with beveled culets having 300-μm flats and Re gaskets. Design features, mode of operation, and performance are described. The latter has been demonstrated for the particular case of Mössbauer spectroscopy in La57FeO3. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148775
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Applications of perforated diamond anvils for very high-pressure research (2001)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 2633-2637 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: To reduce the large absorption effect in diamond anvil pressure cells for soft x rays, perforated anvils employed as diamond-backing plates (DBPs) used in conjunction with miniature anvils (MAs) made of 1/100 carat diamonds were tested for high-pressure efficacy. Static pressures beyond 100 GPa were generated using a piston/cylinder cell having 0.2 mm culets. Tests were carried out in 0.1 mm cavities drilled in a Re gasket, using Ar samples and ruby chips for manometry. Except for a single failure of a 0.3 mm culet MA, no damage was detected in the DBPs drilled with truncated conical holes tapering from 0.3 mm to 1, 1.5, and 2 mm diameter. Another arrangement in which one anvil was partially drilled leaving a 0.5 mm thick wall behind the culet achieved 100 GPa. Detailed discussions are given concerning the benefits of the DBP/MA cells for high-pressure studies with soft x rays and for background reduction in Raman, IR, UV, and 57Fe Mössbauer spectroscopies. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1370561
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    High-pressure metallization and electronic-magnetic propertiesof hexagonal cubanite (CuFe2S3) (1997)
    Springer
    Physics and chemistry of minerals 24 (1997), S. 569-573 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  57Fe Mössbauer studies at room temperature and temperature-dependent resistance studies have been performed on a natural specimen of cubanite (CuFe2S3) in a diamond-anvil cell at pressures up to ∼10 GPa. An insulator-metal phase transition occurs in the range 3.4–5.8 GPa coinciding with a previously observed structural transition from an orthorhombic to a hexagonal NiAs (B8) structure. The room temperature data shows that the metallization process concurs with a gradual transition from a magnetically ordered phase at low pressure to a nonmagnetic or paramagnetic phase at high-pressure. The change in magnetic behaviour at the structural transition may be attributed to a reduction of the Fe-S-Fe superexchange angle formed by edge-sharing octahedra occurring in the high-pressure phase. The non-magnetic or paramagnetic metallic phase at high pressure is retained upon decompression to ambient pressure-temperature conditions, indicative of substantial hysteresis associated with the pressure driven orthorhombic→hexagonal structural transition. The pressure evolution of both the 57Fe Mössbauer hyperfine interaction parameters and resistance behaviour is consistent with the transition from mixed-valence character in the low pressure orthorhombic structure to that of extended-electron delocalization in the hexagonal phase at high-pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690050074
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Sub-megabar Mössbauer studies using diamond anvil cells (1990)
    Springer
    Hyperfine interactions 53 (1990), S. 159-174 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The development and the use of the diamond anvil cell for Mössbauer Spectroscopy (MS) to pressures nearing 100 GPa are discussed. Three types of cells and their typical performance are given. Pressure calibration, hydrostatic media, gasketing, collimation, γ-ray absorption, and sample size for MS are reviewed. New MS results showing hysteresis in the room temperature high pressure transition in iron and showing the rapid rise ofT N in NiI2 with pressure are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02101045
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    High pressure129I Mössbauer studies of GeI4 molecular crystals (1990)
    Springer
    Hyperfine interactions 53 (1990), S. 385-390 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Mössbauer effect in129I in conjunction with Diamond-Anvil-Cell high pressure techniques was applied to investigate the high pressure phase(s) of the molecular crystal GeI4. The129IQuadrupole Interaction was the main probe for characterizing theintermolecular structural transformation with pressure. With increasing pressure, at about 15 GPa, the onset of a partial molecular-association phase (HP1) is first observed. In HP1 two out of the four iodines strongly overlap to form linear chains of GeI4. The HP1 phase coexists with the low pressure (LP) molecular phase, but its population increases with increasing pressure. AtP=20 GPa a second high pressure phase (HP2) is identified where all four iodines strongly overlap to form a three dimensional, fully molecular-associated structure. With increasing pressure and atP〉20 GPa, HP2 is the only phase up toP=34 GPa, the highest pressure used. A significant hysteresis of the relative abundances with pressure is observed. The isomer shift of the HP2 and HP1 structures is considerably larger than that of the LP one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02101071
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...