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Sintering and Electrical Properties of Lead‐Free Na 0.5 K 0.5 NbO 3 Piezoelectric Ceramics
Author(s) -
Zuo Ruzhong,
Rödel Jürgen,
Chen Renzheng,
Li Longtu
Publication year - 2006
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2006.00991.x
Subject(s) - materials science , piezoelectricity , sintering , dielectric , curie temperature , ferroelectricity , ceramic , relative permittivity , relative density , composite material , mineralogy , dielectric loss , permittivity , analytical chemistry (journal) , condensed matter physics , chemistry , optoelectronics , physics , chromatography , ferromagnetism
Lead‐free Na 0.5 K 0.5 NbO 3 (NKN) piezoelectric ceramics were fairly well densified at a relatively low temperature under atmospheric conditions. A relative density of 96%–99% can be achieved by either using high‐energy attrition milling or adding 1 mol% oxide additives. It is suggested that ultra‐fine starting powders by active milling or oxygen vacancies and even liquid phases from B‐site oxide additives mainly lead to improved sintering. Not only were dielectric properties influenced by oxide additives, such as the Curie temperature ( T c ) and dielectric loss ( D ), but also the ferroelectricity was modified. A relatively large remanent polarization was produced, ranging from 16 μC/cm 2 for pure NKN to 23 μC/cm 2 for ZnO‐added NKN samples. The following dielectric and piezoelectric properties were obtained: relative permittivity ɛ T 33 /ɛ 0 =570–650, planar mode electromechanical coupling factor, k p =32%–44%, and piezoelectric strain constant, d 33 =92–117 pC/N.