A model for out-of-phase boundary induced X-ray diffraction peak profile changes in Aurivillius oxide thin films

Area of Science:

• Materials Science
• Solid State Physics
• Crystallography

Background:

• Layered crystal structures, including Ruddlesden-Popper and Aurivillius perovskites, exhibit diverse functionalities.
• Aurivillius family materials are recognized for ferroelectric properties and potential in multiferroic memory applications.

Purpose of the Study:

• To develop and validate an analytical model explaining the effect of out-of-phase boundaries (OPBs) on X-ray diffraction (XRD) peak profiles in epitaxial thin films.
• To provide a predictive framework for understanding defect structures in layered materials.

Main Methods:

• Development of a new analytical model to predict XRD peak splitting caused by OPBs.
• The model correlates peak splitting with OPB nanostructure parameters: displacement, interface angle, and periodicity.
• Application and validation of the model using epitaxial thin films of SrBi2(Ta,Nb)O9 (SBTN) and Bi4Ti3O12 (BiT).

Main Results:

• The model accurately predicts which diffraction peaks split and the extent of splitting based on OPB characteristics.
• Experimental XRD data for SBTN and BiT thin films showed good agreement with the model's predictions regarding peak splitting and OPB periodicity.
• Demonstrated the model's validity and accuracy in characterizing OPBs in layered systems.

Conclusions:

• The developed analytical model offers a robust method for analyzing and characterizing out-of-phase boundaries in layered thin films.
• This work provides a new framework for understanding defect-induced peak broadening and splitting in X-ray diffraction analysis.
• The findings are crucial for materials scientists and physicists studying layered perovskites and other thin-film materials with complex defect structures.