(福州大學(xué) 材料科學(xué)與工程學(xué)院，福州 350108)
摘 要: 針對(duì)CaCu3Ti4O12 (CCTO)陶瓷的巨介電性起源存在較大爭(zhēng)議的情況，以少量MnO2取代CCTO中CuO或TiO2、采用固相反應(yīng)法燒結(jié)制備名義成分為CaCu3−xMnxTi4O12 (x=0~0.3)和CaCu3Ti4−yMnyO12 (y=0~0.1)的陶瓷。通過(guò)微結(jié)構(gòu)和電性能的演變討論CCTO陶瓷的巨介電響應(yīng)機(jī)理。結(jié)果表明：加入少量MnO2后，所有陶瓷均為體心立方(BCC)類鈣鈦礦結(jié)構(gòu)的CCTO單相；但是，CCTO陶瓷顯微結(jié)構(gòu)從異常長(zhǎng)大的晶粒轉(zhuǎn)變成均勻的細(xì)小晶粒；同時(shí)，CCTO陶瓷的電阻率從107Ω·cm顯著提高到109 Ω·cm；介電常數(shù)從104顯著下降到102；介電損耗從10−1急劇降低到10−3；CCTO陶瓷的巨介電響應(yīng)是由半導(dǎo)體化的晶界/亞晶界和相對(duì)絕緣的晶粒/亞晶粒組成的內(nèi)部阻擋層電容器(IBLC)所致。在較低溫度下(＜1 100 ℃)燒結(jié)獲得高介電常數(shù)、低損耗和溫度穩(wěn)定的CCTO基陶瓷，找到一種降低CCTO陶瓷介電損耗的有效方法。
關(guān)鍵字: CaCu3Ti4O12陶瓷；巨介電常數(shù)；內(nèi)部阻擋層電容器(IBLC)；低介電損耗
（College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China）
Abstract:According to the debate on the origin of the giant permittivity of CaCu3Ti4O12 (CCTO) ceramics, a small amount of MnO2 substitution for CuO or TiO2 was adopted to prepare the ceramics with nominal composition of CaCu3−xMnxTi4O12 (x=0−0.3) or CaCu3Ti4−yMnyO12 (y=0−0.1) by solid-state reaction method. The mechanism of giant dielectric response in CCTO ceramics was discussed in view of microstructure evolution and variation of electric properties. The results show that CCTO ceramics with a small amount of MnO2 substitution exhibit BCC perovskite single phase, but the abnormal growth grain gradually disappears and grains become obviously uniform and fine. Meantime, resistivity significantly increases from 107 to 109 Ω·cm, dielectric constant is abruptly suppressed from 104 to 102, and dielectric loss is greatly reduced from 10−1 to 10−3. An internal barrier layer capacitor (IBLC) is associated with relative insulating grains/subgrains and semiconducting grain boundaries/subgrain boundaries. CCTO ceramics with high dielectric constant, low dielectric loss and good temperature stability are achieved at lower sintering temperature (<1 100 ℃). An effective method is found to decrease the dielectric loss of CCTO ceramics.
Key words: CaCu3Ti4O12 ceramics; giant dielectric constant; internal barrier layer capacitor (IBLC); low dielectric loss
