Effect of nano- and micron-sized K0.5Na0.5NbO3 fillers on the dielectric and piezoelectric properties of PVDF composites

Ponraj, Bharathi and Bhimireddi, Rajasekhar and Varma, K B R (2016) Effect of nano- and micron-sized K0.5Na0.5NbO3 fillers on the dielectric and piezoelectric properties of PVDF composites. In: JOURNAL OF ADVANCED CERAMICS, 5 (4). pp. 308-320.

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Abstract

Polymer nanocrystal composites were fabricated by embedding polyvinylidene fluoride (PVDF) with K0.5Na0.5NbO3 (KNN) nanocrystallites of different volume fraction using the hot-pressing technique. For comparison, PVDF-KNN microcrystal composites of the same compositions were also fabricated which facilitated the studies of the crystallite size (wide range) effect on the dielectric and piezoelectric properties. The structural, morphological, dielectric, and piezoelectric properties of these nano and micro crystal composites were investigated. The incorporation of KNN fillers in PVDF at both nanometer and micron scales above 10 vol% resulted in the formation of polar beta-form of PVDF. The room temperature dielectric constant as high as 3273 at 100 Hz was obtained for the PVDF comprising 40 vol% KNN nanocrystallites due to dipole-dipole interactions (as the presence of beta-PVDF is prominent), whereas it was only 236 for the PVDF containing the same amount (40 vol%) of micron-sized crystallites of KNN at the same frequency. Various theoretical models were employed to predict the dielectric constants of the PVDF-KNN nano and micro crystal composites. The PVDF comprising 70 vol% micron-sized crystallites of KNN exhibited a d (33) value of 35 pC/N, while the nanocrystal composites of PVDF-KNN did not exhibit any piezoelectric response perhaps due to the unrelieved internal stress within each grain, besides the fact that they have less domain walls.

Item Type:	Journal Article
Publication:	JOURNAL OF ADVANCED CERAMICS
Publisher:	TSINGHUA UNIV PRESS, TSINGHUA UNIV, RM A703, XUEYAN BLDG, BEIJING, 100084, PEOPLES R CHINA
Additional Information:	Copy right for this article belongs to the TSINGHUA UNIV PRESS, TSINGHUA UNIV, RM A703, XUEYAN BLDG, BEIJING, 100084, PEOPLES R CHINA
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	08 Mar 2017 10:10
Last Modified:	08 Mar 2017 10:10
URI:	http://eprints.iisc.ac.in/id/eprint/56308

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