过量Na~＋对(K_(0.5)Na_(0.5))NbO_3-LiNbO_3无铅压电陶瓷相组成及结构的影响

Influences of excess Na^+ on phase composition and microstructure of (K_(0.5)Na_(0.5))NbO_3-LiNbO_3 lead-free piezoceramics

通过固相反应法预合成0.94(K0.5Na0.5)NbO3-0.06LiNbO3(KNLN6)无铅压电陶瓷粉体。采用X线衍射仪(XRD)、扫描电子显微镜/能谱仪(SEM/EDS)和高分辨透射电子显微镜(HRTEM)对KNLN6试样进行性能表征。结果表明:按化学计量配比合成的KNLN6粉体中含有K3Li2Nb5O15(KLN)第二相;Na2CO3摩尔分数过量5%时,可有效地消除第二相KLN,从而获得单一钙钛矿结构的KNLN6粉体,同时,粉体的预烧温度降低了50℃;在1070℃下烧结2 h制备的Na2CO3过量5%的无铅压电陶瓷中,KNLN6晶体具有A位无序的单一正交钙钛矿结构,晶粒呈立方体状,平均尺寸约为10μm。

Lithium sodium potassium niobate 0.94（K0.5Na0.5）NbO3-0.06LiNbO3（KNLN6） lead-free piezoelectric ceramic powders were prepared by solid state reaction technique.X-ray diffractometer（XRD）,scanning electron microscope/energy-dispersive spectrometer（SEM/EDS） and high resolution transmission electron microscope（HRTEM） were used as property characteristic for KNLN6 samples.Results showed that the second phase K3Li2Nb5O15（KLN） was detected in stoichiometric KNLN6 powders.After introducing 5% excess Na2CO3 into the starting mixture,the second phase KLN was eliminated,and powders with a single perovskite structure were obtained,and the calcination temperature was also decreased by 50 ℃.KNLN6 crystals in lead-free piezoelectric ceramics with 5% excess of Na2CO3 sintered at 1 070 ℃ for 2 h had an A-site disordered orthorhombic perovskite structure,and grains were cuboid with an average size of about 10 μm.