Rapid preparation of traditional and high-entropy garnet ceramics by SPS at low temperature with ultrafast densification

Spark plasma sintering (SPS) is a fast and efficient method for preparing functional ceramics. This article investigates the phase evolution, thermal expansion and chemical stability of traditional (Y1.2Nd1.8Fe5O12) and high-entropy ((Y, Gd, Sm, Eu, Dy)3Fe5O12) garnet ceramics. Prepared under conventional SPS (50 MPa) conditions at 900-1100 degrees C. The results indicate that using SPS sintering method can significantly reduce the sintering temperature (1100 degrees C) and time (3 min) of garnet ceramics. (Y, Gd, Sm, Eu, Dy)3Fe5O12 (1.6 x 10-6 K-1) exhibits superior thermal expansion stability compared to Y1.2Nd1.8Fe5O12 (5.4 x 10-6 K-1). The strong REE-O bond energy and severe lattice distortion of high entropy garnet ceramics hinder the migration and diffusion of cations, resulting in higher leaching resistance of high-entropy garnet ceramics (-10-7 g m- 2 d-1-10-8 g m- 2 d-1) compared to traditional garnet ceramics (-10-5 g m- 2 d-1-10-6 g m- 2 d-1). Therefore, SPS has broad application prospects in the low-temperature preparation of high-entropy garnet ceramics for immobilization of actinide elements.