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  • 1
    Electronic Resource
    Electronic Resource
    The positive muon in the intermetallic hydride ZrV2Hx: A muon tracer study supplemented by differential thermoanalysis, neutron vibrational spectroscopy, and quasielastic neutron scattering (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 1935-1949 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: ZrV2 is an intermetallic compound with energetically different interstitial sites, which upon hydrogenation are successively filled with hydrogen (thermodynamic distribution). When a positive muon is added as a microscopic probe, it is thermalized at random and thus at low temperatures statistically distributed over the available (unblocked) interstices. By varying the preloading we scan the accessible hydrogen sites and find that at high hydrogen content three kinds of interstices are occupied, in contradiction to literature diffraction data. This surprising result is confirmed by a detailed neutron vibrational spectroscopy study on ZrV2Hx which is presented as well. The temperature dependence of the μ+ relaxation rate is textbook-like in empty ZrV2: static muon at T〈50 K, complete motional narrowing at T〉200 K. In ZrV2Hx, however, the relaxation rate exhibits an intermediate plateau which we attribute to a relocation of the muon. The motion of the muon above 150 K is interpreted as being directly related to the hydrogen diffusion which we have separately measured by means of quasielastic neutron scattering. In addition, we investigated the ZrV2/H phase diagram by differential thermoanalysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456672
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  • 2
    Electronic Resource
    Electronic Resource
    Mössbauer studies and nuclear quadrupole moments of186, 188, 189, 190 Os (1972)
    Springer
    The European physical journal 254 (1972), S. 112-126 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Mössbauer transmission experiments with the 137, 155, 69 and 187 keV gamma rays of186, 188, 189, 190Os, respectively, yielded the electric quadrupole splitting of these gamma resonance lines in OsO2 and OsP2. From the results the following ratios of quadrupole moments were derived:Q 2 +(186Os, 137 keV):Q 2 +(188Os, 155keV):Q 2 +(190Os, 187 keV):Q 3/2 −(189Os, g.s.)=(+1.100±0.020): 1.0:(+0.863±0.051): (−0.586±0.011) andQ 5/2 −(189Os, 69 keV)/Q 3/2 −(189Os, g.s.)=−0.735 ±0.012. The ratios for180, 188, 190Os are, within their limits of error, in agreement with the expectation of the rotational model, indicating that the pairing-plusquadrupole model calculations of Kumar and Baranger predict too rapid a transition form rotational to vibrational nuclei. Applying this argument to186Os in particular and using the measured ratios, one obtains a set of values for the quadrupole moments themselves, namelyQ 2 + (186Os)=−(1.50 ± 0.10)b,Q 2 +(188Os)=−(1.36± 0.09) b,Q 2 + (190Os)=−(1.18 ± 0.08) b,Q 3/2 −(189Os)=+ (0.80 ± 0.06) b, andQ 5/2 − (189Os)=− (0.59 ± 0.05) b. For the electric field gradient at Os nuclei in Re metal a value ofV zz=−(3.3 ± 0.6) · 1017 V/cm2 was found. A measurement with a magnetically split source yielded δ=+ 0.685 ± 0.025 for theE2/M1 mixing parameter of the 69 keV transition of189Os,g 5/2 −/g 3/2 −=0.895 ± 0.006 for the ratio of theg-factors of the 69 keV state and the groundstate, andH i=−(1135 ± 20) kOe for the hyperfine field at Os nuclei in an iron matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01380060
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  • 3
    Electronic Resource
    Electronic Resource
    μSR studies of magnetic properties of CeRhSb and La0.1Ce0.9RhSb (1997)
    Springer
    Hyperfine interactions 104 (1997), S. 193-198 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Zero, longitudinal, and transverse field μSR data are reported for CeRhSband La0.1Ce0.9RhSbdown to 45 mK. The muon spin relaxation at temperatures above a few Kelvin is caused by nuclear dipoles. Only at lower temperatures the additional depolarizing effect of electronic moments is observable, signalizing the onset of magnetic correlations in the 4f moment system. These findings are compared to the corresponding data on CeNiSn, showing that the ground state properties are basically alike in the two materials, that is, magnetic correlations develop, but remain weakly dynamic and long range antiferromagnetic order does not set in. The results for La0.1Ce0.9RhSbdiffer little from those of pure CeRhSb, indicating that the magnetic ground state properties as seen by μSR have not been altered significantly. The muonic Knight shift in CeRhSb exhibits similar features as the bulk susceptibility in the temperature range between 20 and 2 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012631927522
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  • 4
    Electronic Resource
    Electronic Resource
    High pressure μSR studies on single crystalline gadolinium (1997)
    Springer
    Hyperfine interactions 104 (1997), S. 311-317 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Muon spin rotation data on a single crystalline gadolinium sample have been obtained as function of temperature and hydrostatic external pressure up to 0.6 GPa. In the ferromagnetic state the application of pressure has a strong influence on the whole spin‐turning‐process of the spontaneous magnetization: The onset of the spin‐turning is shifted towards lower temperatures with a rate of approximately dTst/ dp\approx -50 K/GPa. Higher values of the turning angle up to \varthetaext=90\circ can be reached and stabilized over a wider temperature range. At low temperatures the magnetization turns back again. In the paramagnetic regime the data show a similar behaviour as under ambient pressure: both the Knight‐shift and the muon spin relaxation show deviations from their high temperature behaviour in the critical regime below (T-TC) 〈 10 K. So there is no indication of pressure induced effects in this temperature range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012668902931
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  • 5
    Electronic Resource
    Electronic Resource
    Muon spin relaxation in different samples of DyAl2 (1986)
    Springer
    Hyperfine interactions 31 (1986), S. 337-338 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Two samples of DyAl2 were studied by longitudial μSR in the paramagnetic and ferromagnetic regime. In a region Tc±40 K the samples give different signals although X-ray analysis can not detect any impurity phase in either of them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401578
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  • 6
    Electronic Resource
    Electronic Resource
    Spin dynamics in crystalline and amorphous DyAg (1986)
    Springer
    Hyperfine interactions 31 (1986), S. 303-308 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Crystalline (cr-) Dyag [CsC] structure] orders antiferro-magnetically with TN≅60K; amorphous (am-) DyAg ferro-magnetically with TC≈-18K. We measured the longitudinal field (LF) μ+SR relaxation functions GZZ(t) for 5K〈T〈300K using surface muons. In the paramagnetic state. cr-DyAg gives an exponential GZZ (t) in the relaxation rate rising first slowly then more rapidlynear TN; no decoupling is observed in LF up to 0.4T. In the ordered state we see a Lorentzian Kubo-Toyabe GZZ(t), becoming nearly static at the lowest temperatures. Its static width is very narrow (Δ≈-7 MHz), and full dceoupling is achieved here in 0.1 T. On approaching TN, the fluctuation rate and the static width increase mootonically bt the field distribution remains Loratzian. A LF of 0.4T is then insufficient to quench the fast exponential relaxation. In paramagnetic am-DyAg, the μ+ depolarization is always much faster then in cr-DyAg. At lower temperatures it is better described by a root-exponential than an exponential GZZ(t). Below TC an exponentially relaxing signal with 1/3 amplitude is seen. The decoupling effect of LF up to 0.4T was negligible at all temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401572
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  • 7
    Electronic Resource
    Electronic Resource
    Knight shifts and relaxation in gadolinium above the curie temperature (1986)
    Springer
    Hyperfine interactions 31 (1986), S. 325-330 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have studied the transverse μSR signal in Gd metal in the temperature region 1–2 TC, and it is demonstrated that measurements in the paramagnetic range can be used to obtain the hyperfine field at the muon site, as well as to give information on the fluctuations of the Gd spins. The critical exponent for slowing down of Gd spin fluctuations is 0.56(5) above 1.05 TC but decreases to 0.15(5) below 1.05 TC. Comparisons with results from PAC and Mössbauer measurements are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401576
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  • 8
    Electronic Resource
    Electronic Resource
    Muon diffusion in Nb−H systems (1986)
    Springer
    Hyperfine interactions 31 (1986), S. 241-245 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have studied the muon diffusion in various Nb−HX systems with 0.75〈x〈0.95, with special attention to the concentrations x〈0.9. For x〉0.9 the muon linewidth as function of temperature has a smooth behaviour and the muon mobility is strongly correlated to the hydrogen diffusion in the beta phase. The activation energy for the μ+ diffusion is 160 meV, which is lower than that for protons. At hydrogen concentrations below 0.9, the muon diffusion behaviour is more complicated, and the influence of Nb−H phase transitions is evident. The implications for the local environment of the muon are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02401566
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  • 9
    Electronic Resource
    Electronic Resource
    Ion beam induced reactions in Fe-PVC thin film structures (1989)
    Springer
    Hyperfine interactions 46 (1989), S. 549-556 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Films of57Fe, 50–100 Å thick, were evaporated onto PVC substrates. Samples were irradiated with 48 McV Br8+ ions. Recoiling target atoms, ejected from the sample, were collected in a time of flight-energy detector telescope to monitor effects induced by the impinging Br ions. Conversion electron Mössbauer spectra were recorded before and after ion irradiation. Substantial radiation induced alterations were observed both in recoil and Mössbauer spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02398242
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  • 10
    Electronic Resource
    Electronic Resource
    Muon diffusion in β-V2H (1991)
    Springer
    Hyperfine interactions 64 (1991), S. 649-656 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Hydrogen diffusion in the ordered hydride β-V2H is mainly brought about by a minority fraction of interstitial atoms on antistructural sites. Recently, this mechanism was elucidated in a single crystal QNS study at temperatures close to the critical point (390 K≤T≤440 K) where already an appreciable amount of antistructural sites is occupied. Here we use the positive muon as a radioactive hydrogen tracer in order to show that the same diffusion mechanism is also valid at low temperatures (80 K≤T≤320 K) where the different jump processes are very slow and where the fraction of antistructural atoms is tiny but nevertheless dominates the long range diffusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02396200
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