The Electric Field Gradients in (Zr/Hf)Al3 and (Zr/Hf)2Al3 Intermetallic Compounds Studied by 181Ta- and 111Cd-PAC Spectroscopy

The electric quadrupole hyperfine interactions for ¹⁸¹Hf/¹⁸¹Ta and for ¹¹¹In/¹¹¹Cd probes in polycrystalline ZrAl₃ and Zr₂Al₃ compounds were measured in the temperature range 30–1100 K and compared with the results for isostructural hafnium aluminides. On the basis of the similarities of the numbers, sizes and asymmetries of electric field gradients, lattice site allocations were made. In all matrices, ¹⁸¹Hf/¹⁸¹Ta was found to substitute the Hf/Zr site. The ¹¹¹In/¹¹¹Cd impurities were also assigned to the Hf/Zr site in the compounds (Zr/Hf)Al₃, but appear to substitute the two non-equivalent Al sites in the Zr₂Al₃ and Hf₂Al₃ phases. This revised version was published online in September 2006 with corrections to the Cover Date.     

Lattice Location of 181Ta and 111Cd Probes in Hafnium and Zirconium Aluminides Studied by Perturbed Angular Correlation

The perturbed angular correlation technique was applied to study the lattice location of the ¹¹¹In/¹¹¹Cd and ¹⁸¹Hf/¹⁸¹Ta probe atoms in hafnium and zirconium aluminides. Compounds of different stoichiometries and crystallographic structures were the subject of investigation. According to the expectation, in all investigated compounds ¹⁸¹Hf/¹⁸¹Ta probes occupy the Hf(Zr) crystallographic sites. The ¹¹¹In/¹¹¹Cd probes are placed at the sites of all constituent metals—aluminum, hafnium and zirconium, depending on the crystallographic structure of compound, concentration of the constituent metals and temperature of the sample.     

Hf3Al2 and Zr3Al2 Isostructural Aluminides Studied by PAC with 181Ta and 111Cd Probes

The electric quadrupole hyperfine interactions for ¹⁸¹Hf/¹⁸¹Ta and for ¹¹¹In/¹¹¹Cd probes in polycrystalline Zr₃Al₂ and Hf₃Al₂ compounds were measured in the temperature range 24–1100 K. The hyperfine quadrupole interaction parameters were determined after different doping techniques and heat treatments of the samples.¹⁸¹Hf/¹⁸¹Ta was found to substitute the Hf/Zr sites and the ¹¹¹In/¹¹¹Cd impurities appear to substitute both the 8(j) Al sites and the three nonequivalent Hf/Zr sites.     

Au/In bilayers studied with 111In deposited at the interface

Au/In bilayer samples of different stoichiometries were studied using the time-differential perturbed angular correlation technique. The ¹¹¹In probe atoms were deposited at the gold/indium interface to follow the formation of the intermetallic compounds at an early stage. Au-In phases of different composition (AuIn₂, AuIn, Au₇In₃, Au₃In) were created at the interfaces upon annealing. In addition a metastable Au₇In₃(m) phase, observed only after quenching in the bulk Au_0.7In_0.3 alloy, was found. This revised version was published online in August 2006 with corrections to the Cover Date.     

Solution of 111In impurities in the Hf(Zr)3Al2 minority phases of Hf(Zr)4Al3 samples

The hyperfine quadrupole interactions of ¹¹¹In/¹¹¹Cd probes in the polycrystalline isostructural Zr₄Al₃ and Hf₄Al₃ compounds were studied. Strong preference of ¹¹¹In solute for the Zr₃Al₂ and Hf₃Al₂ phases occurring as contaminant fractions in the measured samples was observed.     

Time-differential perturbed angular correlation study of the electric field gradient in Ti2Rh MoSi2-type compound

At KVI the technical structures for the TRIμP facility are nearly all in place. The aim of the project is to use radioactive ions to study fundamental interactions and symmetries. We will measure β-recoil correlations in nuclear β decay. There the V,A structure of the Weak interaction may be violated. The second line of research is the search for a permanent electric dipole moment in Ra, with a magnitude forbidden by the Standard Model. By trapping these radioactive nuclei in atom traps a pure sample that can be manipulated facilitates these searches. The TRIμP facility consists of a production target and magnetic separator on the high energy side and a Radio-Frequency Quadrupole (RFQ) cooler and buncher on the low energy side. An ion catcher stops the fast product nuclides and transport them into the RFQ cooler. New technological approaches were implemented for several of these devices.     

Hyperfine interaction of111Cd in In-Pd intermetallic compounds

Perturbed - angular correlation (PAC) spectroscopy was applied to study the hyperfine parameters for¹¹¹In probes in In-Pd intermetallic compounds. The PAC spectra measured in In₃Pd, In₃Pd₂ and InPd₂ compounds reflect the number, population and symmetry of nonequivalent indium probe sites predicted by the crystallographic data. The temperature dependence of the observed electric field gradients was measured in the temperature range 80–873 K.     

PAC measurements of In-Pt intermetallic compounds

The quadrupole interaction parameters for¹¹¹Cd in In₇Pt₃ and In₃Pt₂ compounds were measured by TDPAC in the temperature range 80–1000 K. The EFG temperature behavior follows theT ^3/2 relation.     

Electric quadrupole interaction at181Ta in tetragonal C16 intermetallic compounds

The TDPAC technique was employed for studies of the hyperfine interaction of¹⁸¹Ta in the Hf₂Ni and Zr₂Ni compounds with Al₂Cu-type structure. A linear temperature dependence of the quadrupole frequencies was measured in the temperature region 300–1100 K.