Analysis of dislocation pipe diffusion in deformed alpha-phase PdHX using a synthesized QENS approach

Dislocation pipe diffusion;Hydrogen;Palladium;QENS;neutron scattering

Serio, Joseph Anthony ; Zhang, Yang ; Heuser ; Brent

关键词: Dislocation pipe diffusion;    Hydrogen;    Palladium;    QENS;    neutron scattering;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/99282/SERIO-THESIS-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Using quasielastic neutron scattering results from multiple spectrometers, material considerations are made for annealed and deformed PdH_x with sufficiently low [H] as to encourage the process of dislocation pipe diffusion (DPD) below a critical temperature. The results of this analysis indicate that the simultaneous comparison of QENS results from instrument with different instrumental resolution and energy transfer window can provide a more comprehensive picture of the diffusive modes seen within a system than using the instruments independently. A method is developed for accurately comparing the dynamic structure factor S_inc(Q,E) data of multiple instruments, using an inverse Fourier transform in order to obtain the intermediate scattering function F_inc(Q,t) for each instrument and simultaneously analyzing the output from three QENS spectrometers. An array of models are approached to describe the combined F_inc(Q,t), with the best description of F_inc(Q,t) for the deformed PdH_x found to be a summed KWW/single exponential fit. The results show that the DPD contribution to the F_inc(Q,t) can be well described using a stretched exponential (KWW) mode, which is qualitatively correlated to the heterogeneity of the diffusive modes expected for the near-core and inner core region of heavily deformed Pd.