Journal of Electroceramics, 15, 119–122, 2005 C  2005 Springer Science + Business Media, Inc. Manufactured in The Netherlands. Piezoelectric Properties of 0.2[Pb(Mg 1/3 Nb 2/3 )]-0.8[PbTiO 3 -PbZrO 3 ] Ceramics Sintered at a Low Temperature with the Aid of Li 2 O BYUNG MOON JIN 1, ∗ , ILL WON KIM, 2 JIN SOO KIM, 2 DAE SU LEE, 2 CHANG WON AHN, 2 JEONG HO KWON, 3 JAE SHIN LEE, 3 JAE SUNG SONG, 4 & SOON JONG JEONG 4 1 Department of Physics, Dong Eui University, Busan, Korea 2 Department of Physics, University of Ulsan, Ulsan, Korea 3 School of Materials Science and Engineering, University of Ulsan, Ulsan, Korea 4 Electric & Magnetic Devices Group, KERI, Korea Submitted August 1, 2003; Revised August 1, 2003 Abstract. The dielectric and piezoelectric properties of 0.2Pb(Mg 1/3 Nb 2/3 )O 3 -0.8Pb(Zr 0.475 Ti 0.525 )O 3 (abbr. as PMNZT) ceramics were measured. Extremely low sintering temperatures of 950 ◦ C using liquid-phase sintering aid of Li 2 O is achieved which was very useful for multi-layered applications. X-ray study shows the splitting of rhombohedral (200) in pure PMNZT to (002) and (200) peaks in Li 2 O doped samples. 10 times higher dielectric constant was achieved in Li 2 O doped samples to compare to pure ones although the Curie temperature (T c = 322 ◦ C) of Li 2 O doped PMNZT ceramics was not changed. The value of k p and k 33 increased up to 0.1 wt% of Li 2 O and saturating thereafter. Keywords: PMN-PZT, dielectric & piezoelectric, low sintering temperature 1. Introduction Lead-containing perovskite is known to have excel- lent piezoelectric properties. PbMg 1/3 Nb 2/3 -PbTiO 3 - PbZrO 3 (PMN-PZT) ceramic is an attractive material for many applications, such as multi-layered ceramic actuator, ultrasonic motors and piezoelectric trans- formers. To make a multi-layered actuator for con- trolling a generating frequency, it is very important to reduce the sintering temperature given the relatively low melting point of the electrodes inter-electrodes. A number of studies have reported efforts to reduce the sintering temperature to fit this requirement although the matrix materials are not the same [1–5]. Among them, a few reports are very interesting. He et al. [6] reported that PZT ceramics modi- fied with multiple substitutions, that is, Cr 2 O 3 doped PbZr x Ti y (Mg 1/3 Nb 2/3 ) 1−x −y O 3 ceramics have been ∗ To whom all correspondence should be addressed. E-mail: bmjin@ dongeui.ac.kr fabricated at 1200–1320 ◦ C and exhibited excellent piezoelectricity with an electromechanical coupling factor, k p , of 68%. The sintering temperature about 1200 ◦ C is too high for multi-layered ceramic actua- tor application although this material can improve the piezoelectric properties a lot. At such a high temper- ature, Ag-rich inner electrodes cannot be used, be- cause Ag diffusion from Ag/Pd inner electrodes de- teriorated the reliability of piezoelectric properties. To solve this problem, low temperature sintering is necessary. Low sintering temperature has been attempted us- ing various methods: (a) sol-gel method [7], (b) hot- pressing in oxygen [8, 9], (c) fine powders prepared by chemical routes [10, 11], (d) by adding low-melting substances [12, 13]. In this paper, the results of dielectric and piezo- electric properties of 0.2Pb(Mg 1/3 Nb 2/3 )O 3 -0.8Pb (Zr 0.475 Ti 0.525 )O 3 (abbr. as PMNZT) ceramics that were fabricated at low sintering temperatures of 950 ◦ C using sintering aid of Li 2 O are presented.