微波水热辅助法制备铌酸钾钠基无铅压电陶瓷

Preparation of(K,Na)NbO_3-based Lead-free Piezoelectric Ceramic by Microwavehydrothermal Method

以Nb2O5、NaOH和KOH为原料,采用微波辅助水热法,在起始摩尔比n(NaOH):n(KOH)=1.4:4.6、200℃反应30min,制备(K0.45Na0.55)NbO3(KNN)粉体,系统研究烧成温度对KNN陶瓷性能的影响。研究表明,在1 090℃保温2 h获得的纯KNN陶瓷具有较好的性能:体积密度ρV=4.235 g/cm3,压电常数d33=142 pC/N,机电耦合系数kp=0.376,介电常数εT33/ε0=426,机械品质因数Qm=82,Curie温度θC=410℃,剩余极化强度Pr=17.45μC/cm2,矫顽场Ec=1.41kV/mm,综合性能高于由水热法、固相法和熔盐法合成粉体制备的KNN陶瓷的性能。

Using Nb2O5 , NaOH, and KOH as raw materials, powders of （K0.45Na0.55 ）NbO 3 （KNN） were synthesized at 200 ℃ for 30 min by microwave-hydrothermal method when NaOH and KOH mole ratio was 1.4：4.6. Ceramics of KNN were prepared using KNN powders. Effects of sintering temperature on structure and piezoelectric properties of KNN ceramics were investigated. Results show that pure KNN ceramics have excellent properties which can be successfully obtained by sintering at 1090 ℃ for 2 h. Bulk density ρ V=4.235g/cm3 , piezoelectric constant d33=142 pC/N, electromechanical coupling coefficient kp=37.6%, dielectric constant ε T 33 /ε 0=426, mechanical quality factor Qm=82, Curie temperature θ C=410 ℃, remant polarization P r=17.45 μC/cm 2 , and coercive field E c=1.41 kV/mm. Its comprehensive performance is obviously better than other methods such as hydrothermal method, solid state method, and molten salt method.