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Title: Compositional inhomogeneityand segregation in (K 0.5Na 0.5)NbO 3 ceramics

The effects of the calcination temperature of (K 0.5Na 0.5)NbO 3 (KNN) powder on the sintering and piezoelectric properties of KNN ceramics have been investigated in this report. KNN powders are synthesized via the solid-state approach. Scanning electron microscopy and X-ray diffraction characterizations indicate that the incomplete reaction at 700 °C and 750 °C calcination results in the compositional inhomogeneity of the K-rich and Na-rich phases while the orthorhombic single phase is obtained after calcination at 900 °C. During the sintering, the presence of the liquid K-rich phase due to the lower melting point has a significant impact on the densification, the abnormal grain growth and the deteriorated piezoelectric properties. From the standpoint of piezoelectric properties, the optimal calcination temperature obtained for KNN ceramics calcined at this temperature is determined to be 800 °C, with piezoelectric constant d 33=128.3 pC/N, planar electromechanical coupling coefficient k p=32.2%, mechanical quality factor Q m=88, and dielectric loss tan δ=2.1%.
 [1] ;  [1] ;  [2]
  1. North China Electric Power Univ., Beijing (China)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Ceramics International
Additional Journal Information:
Journal Volume: 42; Journal Issue: 8; Journal ID: ISSN 0272-8842
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; Lead-free piezoelectric; Compositional inhomogeneity; Compositional segregation; Liquid phase sintering; Potassium–sodium niobate; Calcination temperature
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1323960