Unlocking the structure of mixed amorphous-crystalline ceramic oxide films synthesized under low temperature electromagnetic excitation

Abstract

The effect of electromagnetic fields on nanoscale atomic structure was determined using synchrotron X-ray pair distribution function (PDF) analysis.

Towards quantitative treatment of electron pair distribution function

“…This approach is called 'small box modeling', and it has an obvious benefit of having only a few parameters rather than hundreds, otherwise needed for amorphous materials. This strategy is often used in X-ray and neutron PDF refinement (Petkov et al, 1999;Nakamura et al, 2017;Transue et al, 2019), and will certainly be efficient for ePDF analysis.…”

Synchrotron X-ray characterization of materials synthesized under microwave irradiation

“…Two such recent reports will be reviewed in this section, covering MWRassisted synthesis of TiNiSn and TiCoSb half-Heusler compounds 33 and titanium dioxide (TiO 2 ) thin films. 5 Birkel et al used a domestic microwave oven (LG Goldstar, Seoul, South Korea) operating at 700 W to synthesize TiNiSn and TiCoSb half-Heusler compounds at significantly reduced reaction times. 33 The reaction time was reduced from more than a week (conventional) to 1 min (microwave).…”

“…By using synchrotron X-ray pair distribution function (PDF) analysis, our work (Nakamura et al), also reported differences in phase composition relative to conventional processes in TiO 2 films synthesized by MWR-assisted synthesis. 5 Unlike XRD, which uses Bragg reflections and characterizes only long-range atomic order (crystalline phases), PDF analysis is capable of quantitatively characterizing both local and long-range atomic order, thus giving information on crystalline and amorphous or locally disordered components in the material. 34 By incorporating both Bragg and diffuse scattering information, PDF analysis provides a powerful new tool to study deviations from the symmetry (e.g., changes in shortrange atomic ordering) that is frequently observed when external fields like MWR are applied.…”

“…34 By incorporating both Bragg and diffuse scattering information, PDF analysis provides a powerful new tool to study deviations from the symmetry (e.g., changes in shortrange atomic ordering) that is frequently observed when external fields like MWR are applied. 5 35 For more details regarding PDF data collection and analysis, the reader is directed to the textbook by Egami and Billinge. 34 In the study by Nakamura et al, TiO 2 thin films were synthesized on electrically conducting layers using MWR-assisted synthesis.…”

“…Application of electromagnetic (EM) fields with frequency between 0.3 and 300 GHz, or microwave radiation (MWR), can generate surprising phenomena, which are not observed during conventional materials synthesis. Field-assisted methods have been shown to induce rapid phase transformations, [1][2][3][4] influence local atomic structure, 5 and affect microstructure [6][7][8][9] at significantly lower temperatures compared with conventional techniques. Indeed, field-assisted processes have been applied to a range of material systems, including ceramics, 1,10,11 metal-organic frameworks, 12 polymers, 13,14 and pharmaceuticals.…”