Springer Science and Business Media LLC

The hyperfine quadrupole interaction at Hf sites in films and powders of 14 mol% CaO–HfO2 and 20 mol% CaO–HfO2 has been determined as a function of temperature. Results indicate the formation of a cubic solid solution and other microstructures assigned to the ϕ1 (CaHf4O9) and ϕ2 (Ca6Hf19O44) phases. Dynamical effects on the electric field gradient reveal the existence of oxygen vacancies movements in the solid solution. The thermal behavior of the relaxation constant observed in films allowed the determination of activation energies of 0.54 eV and 0.70 eV for the 14 mol% and 20 mol% CaO doped hafnias, respectively. The influence of the microdomains and the stability of the cubic solid solution are discussed.

Nickel loaded with hydrogen electrolytically or under high pressure was studied by57Fe Mössbauer spectroscopy on dilute substitutional iron solutes. Experiments in external magnetic fields at 4.2 K show that Fe species in nickel hydride have magnetic moments between about 4.7 and 2.5 μB and saturation hyperfine fields between 24 and 17 T, depending on the number of nearest hydrogen neighbours. By quenching hydride samples from ambient to liquid nitrogen temperature, non-equilibrium hydrogen distributions in the vicinity of the iron can be frozen in. They relax towards equilibrium between 130 and 150 K within hours, permitting information on hydrogen jump rates to be obtained.

Zinc phosphating of Armco iron and a medium carbon steel with different solutions led to coatings that differed in morphology and phase composition. Not only the steel, but also the iron underwent a differential attack from the solutions, with a considerable increase in surface roughness. For the steel, particularly deep etching on ferrite areas caused a considerable reduction in the fatigue limit to rotating bending.

57Fe Mössbauer spectroscopic results on the alternatively prepared spin crossover coordination polymer Fe(3-Clpy)2Pd(CN)4 sample I agree with those of SQUID data. Mössbauer specrum at RT shows two diffrent doublets which correspond to the HS1(inner doublet) and HS2(outer doublet). The intensity of the HS1 doublet decreases on cooling to 78 K at the expense of a new one featuring the LS singlet. Almost 100 % of HS1 change to LS singlet due to iron(II) ions coordinated by four N atoms of cyano groups and two N atoms of 3-Clpy ligand in the sample I. The SQUID data of the sample I prepared by a new direct contact method are different from those of the already reported Fe(3-Clpy)2Pd(CN)4 sample. The differences of the SQUID data are associated with particle size effects in molecule spin crossover samples.

The pressure dependence of the muon Knight shift in antimony has been measured at 30K using polycrystalline samples and at 10K using single crystals. A considerably stronger pressure dependence is observed with the field parallel to the c-axis than perpendicular. The deduced linear parts of the isotropic and axial pressure dependence are dKiso/dP=−0.19(3)%/kbar and dKax/dP−0.24 (5)%/kbar. First principle molecular-cluster calculations show the origin, of the huge Knight shift and its pressure dependence.

Using111In as a probe, TDPAC measurements have been performed on the 173–247 keV γ-γ cascade in111Cd. Information on nuclear quadrupole interaction parameters is reported for α-In Cl, In Cl2 and In Cl3.

It is shown that in57Fe-doped LaCuO3−x , low temperature magnetic ordering probably proceeds through the very gradual freezing of copper clusters (perhaps composed of ordered Cu2+-Cu2+ pairs).

Ảnh hưởng của nhiệt độ sulfid hóa lên các tính chất xúc tác và cấu trúc của các chất xúc tác Co-Mo/Al2O3 được nghiên cứu bằng cách xem xét các tác động sau phát sinh từ 57-Co trong alumina. Hoạt tính xúc tác thể hiện sự tương quan với cả các pha MoS2 hoặc CoMoS và Co9S8.