(福州大學(xué) 材料學(xué)院，福州 350108)
摘 要: 采用傳統(tǒng)固相反應(yīng)法，將ZnO-B2O3(ZB)與1 100 ℃預(yù)燒的CaCu3Ti4O12(CCTO)粉末混合燒結(jié)成陶瓷。探討ZB對CCTO陶瓷顯微結(jié)構(gòu)和介電性能的影響，并進(jìn)一步分析CCTO陶瓷的巨介電機(jī)理。結(jié)果表明：當(dāng)添加少量ZB(w≤2%，質(zhì)量分?jǐn)?shù))時(shí)，形成體心立方BCC類鈣鈦礦結(jié)構(gòu)的CCTO單相；當(dāng)w＞2%時(shí)，生成Zn2TiO4雜相；當(dāng)ZB的添加量為0.5%和10%時(shí)，CCTO陶瓷的介電常數(shù)明顯增大，介電損耗也較高；而當(dāng)ZB的添加量為1.0%~5.0%時(shí)，介電常數(shù)的變化很小，同時(shí)具有較低的損耗和良好的溫度穩(wěn)定性。其中，w=2%時(shí)CCTO基陶瓷具有優(yōu)異的介電性能(100 kHz)，即相對介電常數(shù)εr=336，介電損耗tan δ=0.018，介電常數(shù)溫度系數(shù)τε=−1.5×10−5 ℃−1。ZB摻雜CCTO基陶瓷的阻抗譜表明：CCTO陶瓷由半導(dǎo)體化晶界和相對絕緣的晶粒構(gòu)成，因此，其具有巨介電常數(shù)。
關(guān)鍵字: CaCu3Ti4O12陶瓷；ZnO；B2O3；巨介電常數(shù)；溫度系數(shù)
structure and dielectric properties of CaCu3Ti4O12 ceramics
（College of Materials Science and Engineering, Fuzhou University, Fuzhou 350108, China）
Abstract:ZnO-B2O3 (ZB) doped CaCu3Ti4O12 (CCTO) ceramics were prepared by solid-state reaction, from the mixture of ZB and CCTO powder calcined at 1 100 ℃. The effects of ZB on the microstructure and dielectric properties of CCTO ceramics were investigated. And the dielectric mechanism with giant dielectric constant was also analyzed. The results show that CCTO ceramics with a small amount of ZB additive (w≤2%, mass fraction) is of single CCTO phase with BCC perovskite structure. Zn2TiO4 phase is detected when w is above 2%. For the CCTO ceramics with w=0.5% and 10%, the dielectric constant is enhanced obviously, while the dielectric loss is higher than that of CCTO. On the other hand, for the CCTO ceramics with 1%−5% ZB additions, the dielectric constant is nearly independent of ZB content and frequency. And they exhibit low dielectric loss and good thermal stability. Especially, CCTO ceramics with 2% ZB exhibit the excellent dielectric properties: relative dielectric constant εr=336，dielectric loss tan δ=0.018，temperature coefficient of dielectric constant τε=−1.5×10−5 ℃−1. The impedance spectra of the ZB-doped CCTO ceramics indicate that CCTO ceramics consist of semiconducting grain boundaries and insulating grains, which results in the giant dielectric constant of CCTO ceramics.
Key words: CaCu3Ti4O12 ceramics; ZnO; B2O3; giant dielectric constant; temperature coefficient
