In this research the effect of sintering methods has been investigated on the preparation of high entropy rare earth oxides (HEROs) of Ho 2 Er 2 Tm 2 Yb 2 Lu 2 O 15 including microwave and spark plasma sintering. Both techniques successfully produced a single-phase C-type cubic structure (space group Ia3), as confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) showed better elemental homogeneity in spark plasma-sintered (SPS) samples, which was credited to pressure-assisted densification and localized spark generation that promoted atomic diffusion and relieved lattice strain. Microwave-sintered samples showed minimal compositional inhomogeneities as a result of volumetric heating mechanisms and thermal gradients. HRTEM and XPS also confirmed the structural homogeneity of SPS-processed HEROs with refined electronic states and homogeneous cation distribution. While microwave sintering showed energy efficiency and aptness for complicated geometries, SPS proved to be the best technique for applications requiring high compositional control and densification. This comparative investigation highlights the key role of sintering methods for microstructure and property tailoring of high-entropy rare earth oxides with relevance to optimal material design for catalysis, electronics, and energy storage.
Ghasali et al. (Sun,) studied this question.