Showing papers by "Peter Rogl published in 2001"
TL;DR: The ternary compounds Yb2T2In (T=Cu, Pd and Au) have been synthesized as discussed by the authors, and the indides of these compounds are shown to crystallize in the Mo2FeB2 structure type.
28 citations
TL;DR: Rietveld analysis was performed for the intermetallics Yb3Co4.3Sn12.7 as mentioned in this paper, which showed both an overall decrease of the absolute resistivity values, as well as a decrease of Tc, which vanishes for a critical pressure below 10 kbar.
Abstract: Rietveld analysis was performed for the intermetallics Yb3Co4.3Sn12.7 and Yb3Co4Ge13 crystallizing with the closely related structure types, Yb3Rh4Sn13 and Yb3Co4Ge13. Below Tc = 3.4 K Yb3Co4.3Sn12.7 crosses over into a type-II superconducting ground state with Hc2(0)~2.5 T. Yb3Co4Ge13 stays in the normal state down to 300 mK. The γ value of 2.3(2) mJ gat-1 K-2 and the Debye temperature ΘD = 207(5) K deduced from the specific heat as well as Tc correspond to that of elementary Sn, thus indicating conventional BCS superconductivity. Hydrostatic pressure applied to Yb3Co4.3Sn12.7 reveals both an overall decrease of the absolute resistivity values, as well as a decrease of Tc, which vanishes for a critical pressure below 10 kbar. The magnetoresistance of both Yb-based compounds is positive at low temperature but does not exceed 8% in fields of 12 T. The Seebeck coefficient has a maximum value of about 18 µV K-1 at T~250 K. LIII and magnetic susceptibility measurements reveal intermediate valence: 2.66(3) and 2.18(3) for Yb3Co4Ge13 and Yb3Co4.3Sn12.7, respectively.
25 citations
TL;DR: In this paper, a brief review on the state of the art of the materials science of ternary metal boron nitrides, comprising the stability of binary Boron Nitride BN, their crystal structure(s) and the phase relations in ternanary systems M-B-N, is presented.
22 citations
TL;DR: In this article, phase equilibria in the system Mo-Si-U were established at 1400°C for the region less than 60 at% U and at 850°C with a small field of existence around U(Mo 068 Si 032 ) 2 and U 4 Mo(Mo x Si 1−x ) 1− x ) 1 Si 2 (ordered structure variant of W 5 Si 3 -type).
20 citations
TL;DR: In this article, phase relations in the Al-rich corner of the Ti-Ni-Al system were determined for three partial isothermal sections at 900, 800 and 600°C by diffusion couples and 14 bulk alloy samples employing X-ray powder diffraction, optical microscopy and electron probe microanalysis (EPMA).
19 citations
TL;DR: In this article, phase relations have been established for the Ce-Ag-Ge system at 850°C by means of X-ray diffraction, light optical microscopy, and quantitative electron probe microanalysis.
14 citations
TL;DR: In this article, a detailed study of magnetization, electrical resistivity, magnetoresistivity, and heat capacity performed on the novel family of intermetallic compounds U3M2M′3, (M=Al, Ga, and M′=Si, Ge).
8 citations
TL;DR: In this paper, a series of structural, magnetic, and thermodynamic measurements, a study of transport properties and x-ray absorption edge spectroscopy, were reported on the properties of antiferromagnetic structures for concentrations of 0.1l~xl~0.35%.
Abstract: We report on a series of structural, magnetic, and thermodynamic measurements, a study of transport properties and x-ray absorption edge spectroscopy on $\mathrm{Ce}({\mathrm{Rh}}_{1\ensuremath{-}x}{\mathrm{Ru}}_{x}{)}_{3}{\mathrm{B}}_{2}.$ These investigations evidence that in addition to the already established ferromagnetic range for $xl~0.06,$ a complex antiferromagnetic structure exists for concentrations $0.1l~xl~0.35.$ The behavior in the latter regime is dominated by an extraordinary strong intersite coupling; however, the magnetic moments involved appear to be very small. At the phase boundary to the paramagnetic regime $(x\ensuremath{\approx}0.4),$ significant deviations from a Fermi-liquid behavior occur.
7 citations
TL;DR: In this article, the authors present results of magnetisation, resistivity, thermopower and thermal conductivity measurements on the compound Eu 0.83 Fe 4 Sb 12, which orders magnetically below 84 K.
4 citations
08 Jun 2001
TL;DR: In this paper, the Eu-content of the two solid solutions Eu/sub y/Fe/sub 4-x/Co/sub x/Sb/sub 12/ was determined by Rietveld refinements and electron microprobe measurements EMPA confirming a gradual decrease of the maximum Eu content from y=0.83 to y.44.
Abstract: Alloys from the two solid solutions Eu/sub y/Fe/sub 4-x/Co/sub x/Sb/sub 12/ and Eu/sub y/Fe/sub 4-x/Ni/sub x/Sb/sub 12/ were synthesised by argon arc-melting and isotypism was established with the skutterudite-type structure LaFe/sub 4/P/sub 12/. The Eu-content of the samples was determined by Rietveld refinements and electron microprobe measurements EMPA confirming a gradual decrease of the maximum Eu-content from y=0.83 in Eu/sub y/Fe/sub 4/Sb/sub 12/ to y=0.44 in Eu/sub y/Co/sub 4/Sb/sub 12/ and to y=0.56 in Eu/sub y/Fe/sub 2/Ni/sub 2/Sb/sub 12/. Eo/sub 0.83/Fe/sub 4/Sb/sub 12/ orders magnetically around 84 K and the transition temperature decreases as a function of the Fe/Co and Fe/Ni substitution. X-ray absorption edge and magnetic susceptibility measurements served to define the electronic configuration of Eu and the magnetic state of the polyanions [Fe/sub 4-x/Co/sub x/Sb/sub 12/]. To evaluate the figure of merit, thermopower, thermal conductivity and electrical resistivity measurements were performed. Due to the Fe/Co-substitution the hole number is reduced and further compensated by the electropositive element. This influences the Seebeck coefficients significantly, which has a great impact on the figure of merit.
3 citations
TL;DR: Magnetization and 57 Fe high field Mossbauer measurements on RE 6 Fe 13 X (RE=Nd,Pr; X=Pd, Sn) point towards a tilting of the moments in the antiferromagnetic ordered individual Fe layers.
TL;DR: In this paper, a systematic trend for the Eu-occupancy y in the parent lattice, revealing a gradual decrease of the maximum Eu content from practically full occupancy, y = 0.83, in Eu 0.5 Fe 2 Ni 2 Sb 12 to y ∼ 0.
Abstract: Quantitative X-ray powder Rietveld refinements for a series of alloys from the solid solution EuyFe 4−x Ni x Sb 12 , synthesized by argon arc-melting followed by long term annealing, established in all cases isotypism with the partially filled skutterudite-type structure, LaFe 4 P 12 . The Eucontent of the samples was determined from the combined data obtained results of Rietveld refinements and electron microprobe measurements. These investigations confirmed a systematic trend for the Eu-occupancy y in the parent lattice, revealing a gradual decrease of the maximum Eu-content from practically full occupancy, y = 0.83, in Eu 0.83 Fe 4 Sb 12 to y ∼ 0.5 for Eu∼ 0.5 Fe 2 Ni 2 Sb 12 . Eu 0.83 Fe 4 Sb 12 orders magnetically below 84 K and the transition temperature decreases as a function of Fe/Ni substitution. As a further consequence of the Fe/Ni substitution electronic transport crosses over from a hole conductivity regime into electron dominated behaviour. Concomitantly, the transition metal exchange increases the Seebeck coefficient significantly, hence the figure of merit enhances.
TL;DR: In this paper, it was shown that no ferromagnetic order exists in the Ce 2 Ni 22 C 2.75 sample down to 1.7 K. This agreement together with X-ray absorption spectroscopy data obtained at two fixed temperatures, 10 and 300 K, clearly give evidence for a non-integral valence state of Ce in Ce 2Ni 22 C2.75.
TL;DR: In this paper, phase relations have been established for the Ce-Ag-Ge system at 850°C by means of X-ray diffraction, light optical microscopy, and quantitative electron probe microanalysis.
Abstract: Phase relations have been established for the Ce-Ag-Ge system at 850°C by means of X-ray diffraction, light optical microscopy, and quantitative electron probe microanalysis. Phase equilibria are characterized by the existence of extended solid solutions of Ce(Ag x Ge1−x )2−y (ThSi2 type), Ce(Ag1−x Ge x )1−y , and Ce(Ag1−x Ge x )2−y (unknown structure type). New ternary compounds were found to exist: Ce∼7Ag∼8Ge∼5 (unknown structure), Ce∼6Ag∼5Ge∼9 (unknown structure), Ce3Ag4Ge4 (Gd3Cu4Si4 type), and Ce(Ag x Ge1−x )2 (AlB2 type). Ge/Si substitution was investigated for the alloy systems CeAg-Si x Ge1−x (CaIn2 type for x<0.67 and LiGaGe type for x≥0.67) and CeAg x (Si y Ge1−y )2−x (AlB2 type). Magnetic behavior was studied from susceptibility and magnetization measurements down to 1.7 K and employing magnetic fields up to 5 T. In contrast to earlier descriptions of CeAgGe to order antiferromagnetically below 4.8 K, the authors’ susceptibility and magnetization measurements revealed rather a soft ferromagnetic nature below 6.8 K. Substitution of Ge by Si, x Si=0.1, 0.33, 0.5, 0.67, and 0.75, enhances the ferromagnetic interactions. The AlB2-type alloys, CeAg0.67Ge1.33 and CeAgGe0.84Si0.16, showed soft ferromagnetism with Curie temperature (T C)=7.5 and 8.3 K, respectively. Starting from ferromagnetic binary CeGe2 (ThSi2−y type, T C=7.2 K) replacement of Ge by Ag retains the ferromagnetism below 8 K for x Ag=0.08, but changes to antiferromagnetism with ordering (Neel) temperature T N=9 K for x Ag=0.13. For CeAg2Ge2 (ThCr2Sr2 type) the antiferromagnetic type of order is confirmed, but with lower ordering temperature, (T N=4.5 K) than derived earlier. Ce3Ag4Ge4 (Gd3Cu4Ge4 type) exhibits spin-glass behavior below 7 K. Complex magnetic properties were encountered for Ce∼6Ag∼5Ge∼9 (Ce∼6Ag∼5Ge∼9 type) with two subsequent phase transitions at T N=8.5 K followed by T C=6.9 K.