The nonstoichiometric β-SIC powders were synthesized via combustion reaction of Si and C system in a 0.1 MPa nitrogen atmosphere, using Teflon as the chemical activator. The prepared powders were invistigated by XRD ...The nonstoichiometric β-SIC powders were synthesized via combustion reaction of Si and C system in a 0.1 MPa nitrogen atmosphere, using Teflon as the chemical activator. The prepared powders were invistigated by XRD and Raman spectra. The results indicates that the cell parameters of all the prepared β-SIC powder are smaller than the standard value of β-SIC because of generation of CSi defects. The complex permittivity of prepared products was carried out in the frequency range of 8.2-12.4 GHz. It shows that the dielectric property of prepared β-SiC powder decrease with increasing PTFE content. The effect of CSi defects on dielectric property of β-SiC powder has been discussed.展开更多
Lead-free 0.98(K_(0.5)Na_(0.5))NbO_3-0.02LaFeO_3(abbreviated as 0.98KNN-0.02LF) ceramics were prepared by a conventional solid-state sintering method at various sintering temperatures of 1140,1145,1150,1155 and 1160 ...Lead-free 0.98(K_(0.5)Na_(0.5))NbO_3-0.02LaFeO_3(abbreviated as 0.98KNN-0.02LF) ceramics were prepared by a conventional solid-state sintering method at various sintering temperatures of 1140,1145,1150,1155 and 1160 ℃ and dwell time for 2 h.The samples were characterized by X-ray diffraction and scanning electron microscopy,respectively.The dielectric properties of the 0.98KNN-0.02 LF ceramics were also investigated.The results show that all the ceramics sintered at different sintering temperatures are a pure pseudo-cubic perovskite phase,and it is effective to improve the density and dielectric properties when the sintering temperature increases.However,the properties of the ceramics can be deteriorated when the sintering temperature exceeds the optimum value.The 0.98KNN-0.02 LF ceramics sintered at1150 ℃ for 2 h show the optimum dielectric properties,i.e.,the high dielectric permittivity(near 2000) and low dielectric loss(<5%) in the temperature range of 100-400 ℃ and the capacitance variation(AC/C_(150℃)) of ±15%,indicating a potential application in high-temperature ceramics capacitors.展开更多
基金supported by the National Natural Science Foundation of China under grant No. 50572090the fund of the Slate Key Laboratory of Solidification Processing in NWPU, No. KP200901
文摘The nonstoichiometric β-SIC powders were synthesized via combustion reaction of Si and C system in a 0.1 MPa nitrogen atmosphere, using Teflon as the chemical activator. The prepared powders were invistigated by XRD and Raman spectra. The results indicates that the cell parameters of all the prepared β-SIC powder are smaller than the standard value of β-SIC because of generation of CSi defects. The complex permittivity of prepared products was carried out in the frequency range of 8.2-12.4 GHz. It shows that the dielectric property of prepared β-SiC powder decrease with increasing PTFE content. The effect of CSi defects on dielectric property of β-SiC powder has been discussed.
基金supported by the National Natural Science Foundation of China(51072165)the fund of State Key Laboratory of Solidification Processing in NWPU(KP201307)+1 种基金Doctor Start fund of Baoji University of Arts.&Sci.(ZK15044)the fund of Shaanxi Key Laboratory of Phytochemistry(13JS006)
文摘Lead-free 0.98(K_(0.5)Na_(0.5))NbO_3-0.02LaFeO_3(abbreviated as 0.98KNN-0.02LF) ceramics were prepared by a conventional solid-state sintering method at various sintering temperatures of 1140,1145,1150,1155 and 1160 ℃ and dwell time for 2 h.The samples were characterized by X-ray diffraction and scanning electron microscopy,respectively.The dielectric properties of the 0.98KNN-0.02 LF ceramics were also investigated.The results show that all the ceramics sintered at different sintering temperatures are a pure pseudo-cubic perovskite phase,and it is effective to improve the density and dielectric properties when the sintering temperature increases.However,the properties of the ceramics can be deteriorated when the sintering temperature exceeds the optimum value.The 0.98KNN-0.02 LF ceramics sintered at1150 ℃ for 2 h show the optimum dielectric properties,i.e.,the high dielectric permittivity(near 2000) and low dielectric loss(<5%) in the temperature range of 100-400 ℃ and the capacitance variation(AC/C_(150℃)) of ±15%,indicating a potential application in high-temperature ceramics capacitors.
