The Investigation On The Preparation And Property Improvement Of Potassium Niobate-based Ternary Lead-free Ceramic System

Piezoelectric ceramic is a kind of functional material that can allow the conversion between electric energy and mechanical energy.Since 1950s,lead-based piezoelectric ceramics,for example,Pb?Zr,Ti?O₃?PZT?,have been dominating the market of piezoelectric materials and devices due for their excellent electrical properties.However,the high toxicity of lead element inevitably causes serious harm to people's health and the environment.In order to maintain the sustainable development of our society,seeking suitable lead-free piezoelectric system as substitution of lead-based piezo-ceramics has become an important topic in material science research.Due to higher piezoelectric properties,higher Curie temperature,?K,Na?Nb O₃-based?KNN?piezoelectric ceramics have become extensively investigated lead-free piezoelectric system in recent years.Similar as other piezoelectric systems,the piezoelectric coefficient d₃₃of KNN based ceramics enhances at the expense of T_C,that is,the high d₃₃value is often accompanied by a poor T_C,which greatly limits the application of KNN lead-free ceramics in practice.Meanwhile,the change of temperature has an obvious influence on properties of KNN ceramics,how to maintain higher properties of KNN ceramics in a relatively wider temperature range is also a meaningful issue for their future application.For the purpose of designing new KNN-based ceramic system with good comprehensive properties,we chose several suitable additives to design the ferroelectric phase boundary and optimize KNN components.Finally,we obtained four new KNN ceramic systems satisfied our demand,as follows:1.?0.98-x?K_0.525Na_0.475Nb_0.965Sb_0.035O₃-x(Bi_0.5Na_0.5)Zr O₃-0.02Ba Zr_0.5Hf_0.5O₃ceramics?0?x?0.05??abbreviated as KNNS-x BNZ-BZH?.2.?1-x?K_0.48Na_0.52Nb_0.965Sb_0.035O₃-x(0.9Bi_0.5Na_0.5Zr O₃-0.1Ba Sn O₃)ceramics?0.000?x?0.050?[abbreviated as KNNS-x?BNZ-BS?].3.?0.995-x?K_0.55Na_0.45Nb_0.965Sb_0.035O₃-0.005Bi Sc O₃-x(Bi_0.5K_0.5)Zr O₃ceramics?0.00?x?0.06?[abbreviated as?0.995-x?KNNS-BS-x BKZ)].4.?1-x?K_0.48Na_0.52Nb_0.965Sb_0.035O₃-x(0.995Bi_0.5Na_0.5Zr O₃-0.005Bi_0.5Li_0.5Ce O₃)ceramics?0.000?x?0.050?[abbreviated as?1-x?KNNS-x?BNZ-BLC?].