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Volatilization of alkali ions and effects of molecular weight of polyvinylpyrrolidone introduced in solution-derived ferroelectric K0.5Na0.5NbO3 films

Published online by Cambridge University Press:  31 January 2011

Lingyan Wang
Affiliation:
Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China; and Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 117602
Kui Yao*
Affiliation:
Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China; and Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 117602
Phoi Chin Goh
Affiliation:
Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 117602
Wei Ren
Affiliation:
Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
*
a) Address all correspondence to this author. e-mail: [email protected]
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Abstract

Ferroelectric K0.5Na0.5NbO3 (KNN) thin films were prepared by a chemical solution deposition approach with polyvinylpyrrolidone (PVP) of different molecular weights introduced in the precursor solutions. The volatilization of the alkali ions and the effects of the molecular weight of PVP were examined with x-ray diffraction (XRD), thermal analysis, mass spectrometry, and x-ray photoelectron spectroscopy (XPS). The results clearly showed that the volatilization of the alkali ions mainly happened at moderate temperatures before the crystallization of the KNN perovskite phase. Loss of Na was more significant than K ions during the heating process of KNN. The introduction of PVP with the appropriate molecular weight could effectively promote the crystallization of the KNN perovskite phase at reduced temperature and substantially suppress the loss of the alkali ions before crystallization. Therefore, a high dielectric constant, piezoelectric coefficient, and well saturated ferroelectric hysteresis loops were obtained in the KNN films in which PVP of the right molecular weight were introduced.

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Articles
Copyright
Copyright © Materials Research Society 2009

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