Session Chair: Shujun Zhang, University of Wollongong
4:00pm - 4:30pm Invited
Development of KNN-based Lead-free Piezoceramics with Enhanced Piezoelectricity and Improved Thermal Stability
Jing-Feng LI, Qing LIU, Lei ZHAO, Wei SUN, Ke WANG, Longtu LI
Tsinghua University, China
Developing high-performance lead-free piezoelectric ceramics has been one of the most active materials research topics in the last decades. Extensive studies have been concentrated on sodium potassium niobate (K,Na)NbO3 (KNN), most of which to date have been devoted to enhancing the piezoelectric coefficient d33 by utilizing the two- or multi-phase coexisting effect. This talk will introduce a system based on (K,Na,Li)(Nb,Sb)O3-BaZrO3-(Bi,Na)HfO3, which showed excellent piezoelectric properties of d33 ~450 pC/N , converse d33* ~680 pm/V ( E=1 kV/mm ), kp ~0.53 and a relatively high Tc ~235 oC. Besides, the in-situ small signal d33* (E= 0kV/mm) and converse d33* (E= 1kV/mm) could be maintained above 370 pm/V and 500pm/V from room temperature to 100 oC, respectively. The domain morphology was analyzed by PFM to understand the mechanisms for property enhancement with enhanced thermal stability.
4:30pm - 5:00pm Invited
Development of Lead-Free (K,Na)NbO3 Piezoelectric Films
Piezoelectric films are widely used in angular rate sensors and inkjet printer heads. Most films are lead-based PZT films, but lead-free materials are now desired for environmental reasons. We have therefore focused on potassium sodium niobate ((K,Na)NbO3; (KNN)) as a possible alternative piezoelectric material; KNN has a high Curie temperature and high piezoelectric coefficient). We have developed technologies for forming KNN films by sputtering and successfully deposited high-quality KNN films on 6inch-Pt/Ti/SiO2/Si substrates. The films have excellent piezoelectric properties (d31>100pm/V). Moreover, we have succeeded in developing three-axis angular rate sensor devices using KNN films that are capable of precise detection of all three-axis angular rates at a level suitable for practical use. Temperature dependency and reliability are the key aspects for commercializing the material. Through extensive tests and experiments, promising results are being obtained. We will present some of such results as temperature dependency of PE-hysteresis loops, CV-loops, IV-curves, d31 values, and dielectric constants. Various reliability test results such as breakdown voltage, piezoelectric displacement fatigue, HALT (highly accelerated lifetime measurement), and humidity resistant will also be presented.
5:00pm - 5:15pm Oral
Role of BaZrO3 in Enhancement of Piezoelectric Property of 0.5BCT-0.5BZT
Atal Bihari SWAIN, Murugavel P
Indian institute of Technology, Madras India
Lead free ferroelectric ceramic 0.5(Ba0.7Ca0.3) TiO3-0.5 Ba (Ti0.9Zr0.1) O3 (0.5BCT-0.5BZT) is attracts research community due to its high piezoelectric coefficient reported by W.Liu et. al. Most of the reports showing usage of ZrO2 as Zr-ion dopant precursor. Here we have been synthesized 0.5BCT-0.5BZT by conventional solid state reaction first with ZrO2 as precursor for the Zr ion dopant then we used BaZrO3 as Zr-ion dopant. The effect of ZrO2 and BaZrO3 studied detail. The small trace of secondary phase BaCaTiO4 found in ZrO2 precursor which reduces the piezoelectric properties of the material drastically. Whereas the sample synthesized using BaZrO3 reduces the formation of secondary phase which lead to enhancement of the piezoelectricity. The sample prepared using BaZrO3 gives high piezoelectric coefficient d33=390pC/N and Pr=10µC/cm2 compared to sample prepared using ZrO2 which shows d33=180pC/N with Pr=3µC/cm2.