FAULTS: a program for refinement of structures with extended defects

Abstract

The FAULTS program is a powerful tool for the refinement of diffraction patterns of materials with planar defects. A new release of the FAULTS program is herein presented, together with a number of new capabilities, aimed at improving the refinement process and evolving towards a more user‐friendly approach. These include the possibility to refine multiple sets of single‐crystal profiles of diffuse streaks, the visualization of the model structures, the possibility to add the diffracted intensities from secondary phases as background and the new DIFFaX2FAULTS converter, among others. Three examples related to battery materials are shown to illustrate the capabilities of the program.

Nature of the “Z”-phase in layered Na-ion battery cathodes

“…Simulation of intergrowth structures was carried out with FAULTS profile refinement program (based on the DIFFaX simulation program). 23,24 Structural parameters were taken from the operando XRD data. P-type layers were defined to have a Na content of 1/3 Na per formula unit and an interlayer distance equal to that of P2-Na , were assumed to have equal probability to achieve O-type stacking.…”

A routine for the determination of the microstructure of stacking-faulted nickel cobalt aluminium hydroxide precursors for lithium nickel cobalt aluminium oxide battery materials

“…The complex diffraction line shapes of stacking-faulted samples can be modelled by anisotropic microstrain broadening models (Stephens, 1999;Leineweber, 2006) that are used to refine strongly idealized and averaged structure models of stacking-faulted substances (Todorova et al, 2011), but information on the degree of faulting cannot be extracted from these approaches. The FAULTS routine (Casas-Cabanas et al, 2016) connects recursive DIFFaX simulations with a Rietveld refinement (Rietveld, 1969) of the atomic parameters and thus enables further insights into the ideal faultless structure of stacking-faulted solids such as the layered Li(Ni 1ÀxÀy Co x Mn y )O 2 material (Reynaud & Casas-Cabanas, 2017). By comparing the simulated with the measured diffraction patterns, some information on the degree and type of faulting, i.e.…”

“…This procedure, however, does not enable any refinement of a microstructural model against the measured data. The FAULTS routine (Casas-Cabanas et al, 2016) connects recursive DIFFaX simulations with a Rietveld refinement (Rietveld, 1969) of the atomic parameters and thus enables further insights into the ideal faultless structure of stacking-faulted solids such as the layered Li(Ni 1ÀxÀy Co x Mn y )O 2 material (Reynaud & Casas-Cabanas, 2017). The degree of faulting, however, cannot be directly refined from the measured data.…”

Synthetic Pathway Determines the Non-equilibrium Crystallography of Li- and Mn-rich Layered Oxides

“…Refinement (Rietveld 28,29 ) of the LMNCO structures against X-ray and neutron diffraction data were carried out with FAULTS 30 and TOPAS, respectively. FAULTS facilitates the refinement of stacking faulted structures, thereby enabling an investigation of the degree of faulting within the structure in addition to other structural parameters.…”