Magnetic structure of beta-ErD2: Long-range and short-range order from powder neutron diffraction

Two parallel neutron powder diffraction investigations were performed on different specimens of ErD2 at the LLB (CEN Saclay) and at NIST for the determination of its magnetic structure. It comprises, below Tn=2.23 K, two coexisting sinusoidally modulated antiferromagnetic (AF) configurations, M' and M'', with the respective incommensurate propagation vectors, k'=(0.275,0.275,0.750), together with its third harmonic 3k', and k''=(0.120,0.120,0.750). Contrary to other heavy rare-earth dideuterides, no commensurate AF configuration could be detected down to 120 mK. On the other hand, similar to earlier observations on HoD2 and TbD2, magnetic short range order (SRO shows up near 1.5 K in ErD2 after the disappearance of certain M'' lines. This SRO seems to correlate with the hexagonal gamma-phase of the trideuterite and suggests an electronic phase separation with memory effect

Magnetic structure of beta-ErD2: Long-range and short-range order from powder neutron diffraction

Two parallel neutron powder diffraction investigations were performed on different specimens of ErD2 at the LLB (CEN Saclay) and at NIST for the determination of its magnetic structure. It comprises, below Tn=2.23 K, two coexisting sinusoidally modulated antiferromagnetic (AF) configurations, M' and M'', with the respective incommensurate propagation vectors, k'=(0.275,0.275,0.750), together with its third harmonic 3k', and k''=(0.120,0.120,0.750). Contrary to other heavy rare-earth dideuterides, no commensurate AF configuration could be detected down to 120 mK. On the other hand, similar to earlier observations on HoD2 and TbD2, magnetic short range order (SRO shows up near 1.5 K in ErD2 after the disappearance of certain M'' lines. This SRO seems to correlate with the hexagonal gamma-phase of the trideuterite and suggests an electronic phase separation with memory effect

Hydrogen dynamics in the hexagonal Ho 2 Fe 17 H 4 and Y 2 Fe 17 H 4.2 : Inelastic and quasielastic neutron scattering studies

International audienc

Quantitative analysis of UH3 in U metal and UO2 matrices by neutron vibrational spectroscopy

The ignition of UH3 has resulted in uranium fires. Neutron spectroscopy is proposed to quantify UH3 in fuel at risk. Spectra of UH3 in UO2 and U metal were obtained using two instruments at Argonne National Laboratory and two instruments at the National Institute of Standards and Technology. Analytical standards were prepared with powders of UH3, UO2 and U metal. Linear relationships were found between the mass of UH3 and the integrated intensity of the inelastic scattering associated with hydrogen motions. We discuss the relative merits of the different spectrometers for this type of measurement

Crystal structure and lattice dynamics of hydrogen-loaded austenitic steel

We investigated the crystal structure and hydrogen vibrations in a hydrogen-loaded AISI 310 type austenitic steel (Fe-25Cr-20Ni) by neutron diffraction and inelastic neutron scattering. The samples with hydrogen content ofH/Me = 0.43 and 0.92 were prepared in a hydrogen gas atmosphere at pressures up to 7.0 GPa. This doping procedure yields a more homogeneous hydrogen distribution within the sample than cathodic charging and allows clarifying the role of the concentration gradients and stresses on the phase transformation. Only fcc phase with increased lattice parameter was observed in both samples, however frequency spectra show a modification of the broad peak into two components at higher H content

Nuclear magnetic resonance study of anion and cation dynamics in CsSiH3

International audienc