Mn掺杂(K 0.5 Na 0.5 ) 0.96 Sr 0.02 NbO3无铅压电陶瓷的研究
Mn-modified (K 0.5 Na 0.5 ) 0.96 Sr 0.02 NbO3 Lead-free Piezoelectric Ceramics
Received date: 2006-07-05
Revised date: 2006-09-26
Online published: 2007-05-20
采用常压烧结方法制备了Mn掺杂的(K 0.5 Na 0.5) 0.96 Sr 0.02 Nb 1-x Mn x O 3无铅压电陶瓷. 研究了Mn含量对该体系材料的相组成、微观结构、介电、压电和热稳定性能的影响. XRD表明随着Mn含量的增加, 体系由正交相过渡到赝四方相; 而且, 富Na的第二相消失, 得到纯净的钙钛矿相结构. 在Mn含量为x=0.03和0.04时, 观察到了两个温度(200和390℃)处的介电反常, 这和晶格畸变引起的复晶胞结构有关. Mn含量为x=0.02时, 得到综合性能优良的压电超声换能器用材料: 介电常数εT33/ε0=479, 压电常数d33=121pC/N, 机电耦合系数 Kp=41%, 机械品质因子Qm=298, 介电损耗tanδ=1.6%, 居里温度Tc=391℃, 谐振频率fr和机电耦合系数Kp随温度的变化率αfr(80℃)和αKp (80℃)分别为-1.85%和1.19%.
刘涛 , 丁爱丽 , 何夕云 , 郑鑫森 , 仇萍荪 , 程文秀 . Mn掺杂(K 0.5 Na 0.5 ) 0.96 Sr 0.02 NbO3无铅压电陶瓷的研究[J]. 无机材料学报, 2007 , 22(3) : 469 -473 . DOI: 10.3724/SP.J.1077.2007.00469
Dense lead free ceramics of (K 0.5 Na 0.5 ) 0.96 Sr 0.02 Nb 1-x Mn x O 3 (x=0,0.01,0.02,0.03,0.04) were successfully prepared by a conventional mixed oxide method. The X-ray diffraction patterns revealed pure peroveskite structure after Mn doping as compared to the original composition. This was attributed to the inhibition of K+ volatility during sintering process. Dielectric anomaly was observed and explained by multiple-cell structure resulting from Mn-induced lattice distortion. Low loss tangent and relatively high planar electromechanical coupling factor were obtained at x=0.02. The main parameters for the composition of x=0.02 are: εT33/ε0=479, d33=121pC/N Kp=41%, Qm=298, tanδ=1.6%, Tc=391℃. The rates of resonant frequency variation, αfr, and planar coupling factor variation, αKp, with temperature are --1.85% and 1.19% at 80℃, respectively. This material may be suitable for applications in ultrasonic transducers.
Key words: lead free; piezoelectric ceramics; dielectric; transducer
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