Facile synthesis of high-entropy zirconate nanopowders and their sintering behaviors

Abstract

The challenge in synthesizing high-entropy ceramic (HEC) nanopowders is to suppress severe grain coarsening and particle agglomeration, which occur at elevated temperatures. This challenge could be addressed by the polyacrylamide gel method. In this work, single-phase high-entropy (La 0.2 Nd 0.2 Sm 0.2 Gd 0.2 Yb 0.2 ) 2 Zr 2 O 7 and (La 0.2 Nd 0.2 Y 0.2 Eu 0.2 Gd 0.2 ) 2 Zr 2 O 7 nanopowders without agglomeration were successfully synthesized using the polyacrylamide gel method for the first time. The results showed that phase composition, particle size, and agglomeration degree of the nanopowders were greatly influenced by the molar ratio of acrylamide (AM)/Zr and calcination temperature. These as-synthesized high-entropy zirconate (HEZ) nanopowders could be sintered into fully dense ceramics at 1500 ℃ for 2 h. These HEZ nanopowders showed a phase transformation from a defect-fluorite phase to a pyrochlore phase with the increase of sintering temperature. Additionally, two-step sintering of these nanopowders was conducted, and the HEZ ceramics with fine grains were prepared. The polyacrylamide gel method is simple and easily operated, which is a facile approach of producing the HEC nanopowders with excellent sinterability.

A Novel Strategy for Rapid Synthesis of Nanostructured High-Entropy Metal Oxides through Thermal Plasma for Supercapacitor Applications

“…3 Since then, HEOs with a variety of crystal structures including rock-salt structure, 6 spinel structure, 23 perovskite structure, 24 pyrochlore structure, 25 and fluorite structure 26 have been synthesized. Several methods have been employed to synthesize HEOs, which include sol−gel method, 19 solvothermal method, 27 polyacrylamide gel method, 28 coprecipitations, 14 solid-state synthesis, flame spray pyrolysis, 29 hydrothermal synthesis, 30 and nebulized spray pyrolysis. 31 Each technique has unique characteristics and advantages, but most methods are fairly complex, requiring extended treatment times for controlling the phase and size of HEO particles.…”

Grain growth behavior and properties of high-entropy pseudobrookite (Mg,Co,Ni,Zn)Ti 2O 5ceramics

“…Inspired by it, Zhou et al [6,7] successfully prepared high-entropy (TiZrNbTaMo)C and (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2Zr2O7 with fine grains. Then Su et al [8] used polyacrylamide gel technology to successfully solve the problems of grain coarsening and particle aggregation of highentropy ceramics during sintering. By using a plasma-assisted ball milling technique, Wang et al [9] enhance the sintering characteristics and prepare high-entropy fluorite oxide ceramics with little AGG and good density and mechanical qualities.…”

Recent Progress in MOF-Based Electrochemical Sensors for Non-Enzymatic Glucose Detection

“…Notable examples of such conductive materials encompass carbon materials, metal/metal oxide nanoparticles, conductive polymers, and graphene materials [ 26 , 27 , 28 ]. Particularly, graphene aerogels (GAs) have gained significant attention in recent years as a novel and versatile porous material widely explored by researchers [ 29 , 30 , 31 ]. GAs exhibit a high porosity, substantial surface area, tunable electrical conductivity, and low density.…”