Novel non-equimolar SrLa(Al0.25Zn0.125Mg0.125Ga0.25Ti0.25)O-4 high-entropy ceramics with excellent mechanical and microwave dielectric properties

Novel non-equimolar high-entropy SrLa(Al0.25Zn0.125Mg0.125Ga0.25Ti0.25)O-4 (SLAZMTG) ceramics with a layered perovskite structure have been prepared via the standard solid-state reaction method. The high-entropy composition belongs to the tetrahedral structure with a space group of I4/mmm, which is confirmed by the XRD and TEM analyses. Excellent microwave dielectric properties with a suitable dielectric constant (epsilon(r) = 22.5), high quality factor (Qf = 83,003 GHz), and near-zero iota(f) value of 1.7 ppm/degrees C are obtained in SLAZMTG ceramics sintered at 1400 degrees C. Meanwhile, a significant enhancement in compressive strength was achieved due to the improvement of configuration entropy, 912 MPa for SLAZMTG compared to 578 MPa in the pure SrLaAlO4 composition. Additionally, the high-entropy engineering in the present work suggests great potential in achieving low thermal conductivities. SLAZMTG ceramics exhibit low thermal conductivities ranging from 2.86 W/m center dot K at 323 K to 1.99 W/m center dot K at 673 K, much lower than those of SrLaAlO4 and other perovskite ceramics.

Automated summary

Novel non-equimolar high-entropy ceramics with a layered perovskite structure, SLAZMTG, were prepared via solid-state reaction method. The ceramics exhibited excellent microwave dielectric properties, high compressive strength, and significantly lower thermal conductivities compared to pure SrLaAlO4 and other perovskite ceramics.