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Rapid Laser Reactive Sintering Synthesis of Colossal Dielectric CCTO Ceramics
oleh: Jiayang He, Yanwei Huang, Guang Feng, Si Shen, Ming Yan, Heping Zeng
Format: | Article |
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Diterbitkan: | MDPI AG 2020-05-01 |
Deskripsi
Calcium copper titanate (CCTO) ceramics were successfully synthesized using a rapid laser reactive sintering method without conventional long heat treatment times. The microstructure, dielectric properties, and impedance spectroscopy results for CCTO sintered at laser power rates of 25–85 W were investigated in detail. The X-ray diffractometry results showed that prepared CCTO is polycrystalline in a cubic structure with high purity. Scanning electron microscopy showed that CCTO sintered at 85 W has a dense microstructure with an average grain size of 30 nm. The dielectric permittivity of CCTO ceramics increased with increasing laser power over the entire frequency range and achieved a value of almost 10<sup>5</sup> in the low-frequency region. The dielectric permittivity maintained almost constant values from 10<sup>2</sup> Hz to 10<sup>7</sup> Hz, with lower dielectric loss (~0.1) from 10<sup>3</sup> Hz to 10<sup>6</sup> Hz, demonstrating good frequency stability. The impedance spectroscopy study showed that grain and grain boundary resistance decreased with rising laser power based on two parallel Resistor-Capacitance (RC) equivalent circuits in series. The activation energies for the grain boundaries were calculated from the impedance using the slope of ln<inline-formula> <math display="inline"> <semantics> <mi>σ</mi> </semantics> </math> </inline-formula> versus 1/T and were found to be in the range of 0.53–0.63 eV. CCTO synthesized by rapid laser reactive sintering is competitive for practical applications.