Structures and properties of Li-Ta-Modified KNN lead-free piezoelectric ceramics

Zhenqi Deng, Feng Gao, Liangliang Liu, Le Yang, Changsheng Tian

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Abstract

Lead-free piezoelectric ceramics (1-x)K0.48Na0.52NbO3-x Li(Ta0.5Nb0.5)O3 have been fabricated by the conventional solid phase reaction method. The effects of Li(Ta0.5Nb0.5)O3 (LTN) on crystal structure and piezoelectric properties were investigated. The results showed that the perovskite structures of material transformed from the orthorhombic phase to the tetragonal phase as LTN content increased. The morphotropic phase boundary was formed at 0.06<x<0.08 and the second phase K3Li2Nb5O15 with tungsten bronze structure appeared at x>0.08 at beginning and then became dominant with the content of LTN increasing. The ferroelectric phase transitional point of "orthorhombic to tetragonal" ceramic TO-T shifted to the lower temperature while the Curie temperature (Tc) shifted to the higher temperature because of LTN content increasing. The dielectric constant (εr), the piezoelectric constant (d33), the electromechanical coupling coefficient (kp) increased at beginning and then decreased with the LTN content increasing. For the ceramic with x=0.07, the ceramic material had good piezoelectric properties with εr= 856(1 kHz), d33=140 pC/N and kp=0.33. The mechanical quality factor (Qm) was 161 and the Curie temperature (Tc) was 440°C.

Original languageEnglish
Pages (from-to)1021-1023+1026
JournalYadian Yu Shengguang/Piezoelectrics and Acoustooptics
Volume32
Issue number6
StatePublished - Dec 2010

Keywords

  • Crystal structure
  • Lead-free ceramics
  • Morphotropic phase boundary
  • Piezoelectric properties

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