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

Abstract

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 °C. The results indicate that using SPS sintering method can significantly reduce the sintering temperature (1100 °C) and time (3 min) of garnet ceramics. (Y, Gd, Sm, Eu, Dy)3Fe5O12 (1.6 × 10−6 K−1) exhibits superior thermal expansion stability compared to Y1.2Nd1.8Fe5O12 (5.4 × 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.