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This content will become publicly available on March 11, 2017

Title: Compositional inhomogeneityand segregation in (K0.5Na0.5)NbO3 ceramics

The effects of the calcination temperature of (K0.5Na0.5)NbO3 (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 d33=128.3 pC/N, planar electromechanical coupling coefficient kp=32.2%, mechanical quality factor Qm=88, and dielectric loss tan δ=2.1%.
Authors:
 [1] ;  [1] ;  [2]
  1. North China Electric Power Univ., Beijing (China)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
1261357
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Ceramics International
Additional Journal Information:
Journal Volume: 42; Journal Issue: 8; Journal ID: ISSN 0272-8842
Publisher:
Elsevier
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE Lead-free piezoelectric; Compositional inhomogeneity; Compositional segregation; Liquid phase sintering; Potassium–sodium niobate; Calcination temperature