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Dielectric spectroscopy study of Ba0.98Na0.02Ti0.98Nb0.02O3 ceramics

Author(s): W. Bąk | M. Gabryś | C. Kajtoch | K. Stanuch | F. Starzyk

Journal: Archives of Materials Science and Engineering
ISSN 1897-2764

Volume: 39;
Issue: 2;
Start page: 107;
Date: 2009;
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Keywords: Ceramics | Phase transitions | Ferroelectrics | Dielectric spectroscopy

Purpose: The purpose of this work was to investigate dielectric properties of new ceramic solid solution Ba0.98Na0.02Ti0.98Nb0.02O3 (BNTN2) within the temperature range 153 K - 473 K.Design/methodology/approach: The dielectric spectroscopy method was applied to measure frequency and temperature dependence of complex dielectric permittivity, complex admittance, phase angle. The frequency dependence of ac conductivity at constant temperature was analysed as well as reciprocal permittivity and dielectric modulus as functions of temperature and frequency were compared. The Curie-Weiss rule and its generalized formula were applied in outcomes analysis.Findings: The ferroelectric - paraelectric (FE - PE) phase transition occurring in BNTN2 was found as having diffusive nature. In the paraelectric phase at about 400 K the diffusivity of transition step is correlated with the same kind of transition in BaTiO3 (BT) (transition of FE - PE type) and with structural transition occurring in NaNbO3 (NN). Within the temperature range below Tm = 308 K, dependences of dielectric properties of BNTN2 ceramic on temperature and frequency was found as having relaxor type of behaviour.Research limitations/implications: The confirmations of achieved findings will be possible by more precise BNTN2 structure determination by means X-ray diffraction. Also closer explanation of FE - PE phase transition can be performed by dielectric measurements within broader frequency range up to 1.8 GHz ( diffusive versus relaxor character of transition).Originality/value: The new solid solution of BNTN2 was prepared. The structure of this material was characterized as dielectrically active and having FE - PE phase transition which was described.

Tango Jona
Tangokurs Rapperswil-Jona

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