添加表面活性剂对Bi_2O_3-ZnO-Nb_2O_5系陶瓷温度系数的影响

OPTIMIZATION OF DIELECTRIC CONSTANT TEMPERATURE COEFFICIENT OF Bi_2O_3-ZnO-Nb_2O_5-BASED CERAMICS BY ADDING SURFACE ACTIVE AGENT

研究了原料混合球磨研磨时 ,加入表面活性剂对Bi2 O3-ZnO -Nb2 O5(BZN )系复相区陶瓷的相组成及性能的影响 .依据最佳的(Bi3xZn2 - 3x) (ZnxNb2 -x)O7陶瓷配方 ,采用固相反应法制备BZN陶瓷试样 .在原料混合球磨研磨时 ,加入具有醇和胺双重性质的两性表面活性剂 ,借助XRD ,DTA ,SEM和HP42 74A阻抗分析仪等研究手段 ,研究实验制备的BZN陶瓷试样的相结构与介电性能 .结果表明 :试样的相结构仍为焦绿石立方结构α相和单斜结构β相的 (α +β)复相焦绿石结构 ;在制备过程中加入表面活性剂 ,可降低Bi2 O3,ZnO ,Nb2 O5原料固液界面表面张力 ,破坏原料的团聚状态 ,达到各种原料的充分混合 ,从而促进了在较低温度下形成相对较多的立方焦绿石α相 ,提高了相组成的稳定性 .大大扩大了符合零温度系数 [( 0± 30 )× 10 - 6 /℃ ]要求的烧成范围 ,且此BZN陶瓷介电常数高 (ε≥ 10 5 )、介电损耗小 (tgδ <10 - 4 )

Bi 2O 3-ZnO-Nb 2O 5 (BZN) ceramic samples were prepared according to the optimum composition of (Bi 3 x Zn 2-3 x )·(Zn x Nb 2- x )O 7 by solid state reaction. The amphoteric surface active agent with alcohol amine double nature and the equilibrium value (hydrophilic lipohilic balance, HLB) of 9.4 was introduced when the raw materials were mixed and ground. The BZN ceramic structure and dielectric properties were explored by XRD, SEM, DTA, grain size analysis and HP4274A impedance analyzer. The results reveal that the phase composition is still the coexisting phases of cubic pyrochlore ( α -phase) and monoclinic pyrochlore ( β -phase ). The surface tension of the solid-liquid interface of the raw materials is reduced and the raw materials are well mixed as a result of the surface active agent. It is found that more cubic pyrochlore are produced and the phase composition stability is also increased. High dielectric constants ( ε ≥105 ), very low dielectric loss (tg δ <10 -4 ) and the zero temperature coefficient(0±30×10 -6 /℃)of BZN ceramics are obtained in a wide sintering temperature range of 1 000-1 040 ℃ .