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Effect of carbon black on properties of 0–3 piezoelectric ceramic/cement composites
Huang Shifeng,Li Xue,Liu Futian,Chang Jun,Xu Dongyu,Cheng Xin 한국물리학회 2009 Current Applied Physics Vol.9 No.6
0–3 cement-based piezoelectric composites were fabricated using sulphoaluminate cement and piezoelectric ceramic [0.08Pb(Li1/4Nb3/4)O3 . 0.47PbTiO3 . 0.45PbZrO3] [P(LN)ZT] as raw materials by compressing technique. The influences of carbon black content on the piezoelectric and dielectric properties, electric conductivity and impedance were investigated. The results indicate that the piezoelectric strain constant d33 and piezoelectric voltage constant g33 of the composites increase gradually with a suitable carbon black addition. When the carbon black content is 0.3 wt%, both of the piezoelectric strain constant d33 and piezoelectric voltage constant g33 of the composite exist the maximum value, which are 17.45 pC N-1 and 36.3 mV m N-1, respectively. As the carbon black content increases, the dielectric constant εr, dielectric loss tanδ and electric conductivity σ of the composites all increase, while the impedance decreases. In the frequency range tested, the more the carbon black content, the higher the εr value. The planar electromechanical coupling coefficient Kp, the thickness electromechanical coupling coefficient Kt and the mechanical quality factor Qm are almost unaffected by the carbon black content.
Clean and facile synthesis of triuret from urea and dimethyl carbonate (DMC) under mild conditions
Jianchao Chen,Peihua Zhao,Hua Liu,Futian Zhu,Yaqing Liu 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.3
Triuret has been successfully synthesized by the reaction of urea with dimethyl carbonate (DMC) under mild conditions in the presence of potassium methoxide as a catalyst. It has been fully characterized by FT-IR, 1H-NMR,13C-NMR, and MS. Effects of the catalyst, the molar ratio of starting materials, and the reaction time on the obtained product were examined in detail. It was found that when n (urea) : n (DMC)=1.2 : 1, 6 h, and 0.8% catalyst, the yield of triuret can reach 98.1%. Especially, this novel procedure is reported for the first time and has many significant advantages such as easy and clean synthesis, simple work up, and high yields.