Microstructural evolution of ZnO via hybrid cold sintering/spark plasma sintering |
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| Affiliation: | 1. State Key Laboratory for Mechanical Behavior of Materials & School of Materials Science and Engineering, Xi''an Jiaotong University, Xi''an 710049, China;2. School of Electronic and Information Engineering, Xi''an Jiaotong University, Xi''an 710049, China;3. State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Shapingba District, Chongqing 400044, PR China;4. Department of Materials Science and Engineering & Shenzhen Engineering Research Center for Novel Electronic Information Materials and Devices, Southern University of Science and Technology, Shenzhen, China;5. Materials Research Institute and Department of Materials Science & Engineering, The Pennsylvania State University, University Park, PA 16802 United States |
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| Abstract: | In this work, we demonstrate a hybrid cold sintering/spark plasma sintering (CSP-SPS) process to densify ZnO ceramic with controlled grain growth. The densification of ZnO is initially activated at 85 °C, and high densities (>98%) are achieved at 200–300 °C in only 5 min with a low assisted pressure of 3.8–50 MPa. The microstructure of ZnO grains experiences a mild coarsening from ~205–680 nm during the CSP-SPS. In comparison, a much higher temperature (>770 °C) is required to sinter ZnO ceramic via SPS, and the grain size exhibits an obvious overgrowth to ~10 µm. The calculated apparent activation energy of grain growth using CSP-SPS is 69.3 ± 6 kJ/mol, which is much lower than that of SPS samples with 296.8 ± 59 kJ/mol. In addition, the conduction mechanism of the CSP-SPS and SPS samples is investigated using impedance spectroscopy. Overall, CSP-SPS is promising for the fabrication of fine ceramics with mild sintering conditions. |
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| Keywords: | Cold sintering Spark plasma sintering Zinc oxide Ceramics Grain growth |
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