【作者】 陈浩；

【导师】 朱建国； 包绍明；

【作者基本信息】 四川大学 ， 材料工程（专业学位）， 2021， 硕士

【摘要】 锆钛酸铅（PZT）基压电陶瓷因其具有优异的电学性能,以及较低的生产成本,已被广泛应用于制备传感器、受话器、滤波器、超声换能器等。但PZT基陶瓷的烧结温度通常大于1200℃,烧结过程中会有严重的铅挥发,会污染环境,对人体健康造成危害。如果能将陶瓷的烧结温度降低至1000℃以下,那将会大大减少铅挥发造成的危害。因此,为了在较低烧结温度（小于1000℃）下制备得到有着优异电学性能的PZT基压电陶瓷。本文选用了0.2Pb(Ni_1/3Nb_2/3)O₃–0.1Pb(Zn_1/3Nb_2/3)O₃–0.7Pb(Zr_0.46Ti_0.54)O₃（简写为PNN-PZN-PZT）和0.09Pb(Ni_1/3Nb_2/3)O₃–0.03Pb(Mg_1/2W_1/2)O₃–0.88Pb(Zr_1/2Ti_1/2)O₃（简写为PNN-PMW-PZT）体系作为研究对象,采用固相反应法制备陶瓷样品。研究了Li₂CO₃作为烧结助剂,同时也作为A位的不等价离子取代,对PNN-PZN-PZT陶瓷性能的影响规律。研究了Sr²⁺作为等价离子取代A位的Pb²⁺,对PNN-PMW-PZT陶瓷相组成和电学性能的影响;也研究了Ta⁵⁺作为不等价离子取代PNN-PMW-PZT陶瓷的B位离子后,其晶体结构、相组成与电学性能的关系。通过以上研究工作,得到以下结果:（1）研究结果表明,Li₂CO₃助熔剂可以优化PNN-PZN-PZT陶瓷的电学性能,同时将降低烧结温度至1020℃。随着Li₂CO₃含量的增加,大尺寸晶粒逐渐增多,平均晶粒尺寸增加,分布也更为均匀,提高了陶瓷的致密度。当Li₂CO₃的含量为0.6 wt%时,陶瓷的平均晶粒尺寸最大为6.54μm,并且得到最优的电学性能:压电常数(d₃₃)=680 p C/N,机电耦合系数（k_p）=0.674,居里温度（T_c）=269℃,相对介电常数（ε_r）=3728。（2）将一定量的SrCO₃加入PNN-PMW-PZT陶瓷中,经960℃烧结4小时,发现随着SrCO₃含量的增加,陶瓷中的四方相含量随之增加。在SrCO₃的含量为0.6 mol%时陶瓷的四方相含量最高(C_TP=81.23%),通过压电力显微镜（PFM）观察到陶瓷表面有很多纳米畴,在电场作用下更容易翻转,从而产生更大的压电响应,提高了陶瓷的电学性能(d₃₃=623 p C/N,d₃₃^*=783 pm/V,T_c=289℃)。（3）用一定量的Ta₂O₅掺入PNN-PMW-PZT陶瓷,经过940℃烧结4小时后发现,Ta₂O₅的加入会引起陶瓷的晶格畸变、晶格常数增加、晶胞体积变大、B-O键的力常数减小,导致[BO₆]八面体扩大。在Ta₂O₅的掺杂量为0.70 wt%时陶瓷有最优的电学性能(d₃₃=640 p C/N,d₃₃^*=676 pm/V,T_c=303℃),该组分的陶瓷有最高的四方相含量(C_TP=68.43%),以及最低的畴壁翻转激活能（E_a=0.025e V）。通过PFM观测到陶瓷有很多纳米畴。表明该体系陶瓷四方相含量越高、畴的激活能越低、越有利于生成纳米畴,从而产生更高的压电性能。更多还原

【Abstract】 PZT-based piezoelectric ceramics（PZT）are widely used in sensors,receivers,filters,ultrasonic transducers and other fields because of their excellent electrical properties and low production costs.However,the sintering temperature of PZT-based ceramics is usually more than 1200℃,and there will be serious lead volatilization in the sintering process,so it will cause harm to human body and environment in the preparation process and use process.If the sintering temperature can be reduced below1000℃,the harm of lead will be greatly reduced.Therefore,PZT based piezoelectric ceramics with excellent electrical properties were prepared at low sintering temperature（<1000℃）.0.2Pb(Ni_1/3Nb_2/3)O₃–0.1Pb(Zn_1/3Nb_2/3)O₃–0.7Pb(Zr_0.46Ti_0.54)O₃（abbreviated as PNN-PZN-PZT）and0.09Pb(Ni_1/3Nb_2/3)O₃–0.03Pb(Mg_1/2W_1/2)O₃–0.88Pb(Zr_1/2Ti_1/2)O₃（abbreviated as PNN-PMW-PZT）systems were selected as research objects in this paper,and the ceramic samples were prepared by traditional solid-phase reaction method.The effect of Li₂CO₃ on PNN-PZN-PZT ceramics as sintering aids and as a non-equivalent ion substitution at A site was studied.The effect of Sr₂CO₃ on the phase composition and electrical properties of PNN-PMW-PZT ceramics as equivalent ion substituted Pb²⁺was studied.The relationship between the crystal structure,phase composition and the electrical properties of PNN-PMW-PZT ceramics was also studied after Ta₂O₅replaced the B site ions of PNN-PMW-PZT ceramics.Through the above research works,the following results can be obtained:（1）The research shows that Li₂CO₃ sintering aids can improve the electrical properties of PNN-PZN-PZT ceramics while reducing the sintering temperature to1020℃.With the increase of Li₂CO₃ doping amount,the grain size of the ceramics increases gradualy and the grain arrangement becomes more compact.The content of the Li₂CO₃ is 0.6 wt%,the average grain size of the ceramic is the largest,and the high electrical properties are obtained:d₃₃=680 p C/N,k_p=0.674,T_c=267℃,ε_r=3798.（2）When a certain amount of SrCO₃ is added to PNN-PMW-PZT ceramics sintered at 960℃for 4 hours.It is found that with the increase of SrCO₃ content,the tetragonal phase content of the ceramic increases,and the electrical properties of the samples have the same change trend as the tetragonal phase content.When the content of SrCO₃ is 0.6mol%,the content of tetragonal phase is the highest(C_TP=81.23%).It is observed by piezoresponse force microscopy（PFM）that there are many nanoscale domains on the surface of the ceramic,which are more easily reversed under the action of electric field,thus generating greater piezoelectric response and improving the electrical properties of the ceramics(d₃₃=623 p C/N,d₃₃^*=783 pm/V,T_c=289℃).（3）When a certain amount of Ta₂O₅ is added into PNN-PMW-PZT ceramics sintered at 940℃for 4 hours,it is found that the addition of Ta₂O₅ will cause lattice distortion,crystal cell volume increase,the force constant of B-O bond decreases,and result in the[BO₆]octahedron enlargement.When the doping amount of Ta₂O₅ is 0.70wt%,the ceramic has the optimal electrical performances(d₃₃=640 p C/N,d₃₃^*=676pm/V,T_c=303℃).This component has the highest content of tetragonal phase(C_TP=68.43%)and the lowest activation energy of domain wall movement（E_a=0.025e V）,and many nanoscale domains are observed by PFM.It is shown that the higher the content of tetragonal phase is,the lower the activation energy of domain wall movement is,and the more advantageous it is to generate nanoscale domains,thus producing higher piezoelectric properties.更多还原