Comparison of Methods for Measurement of Curie Temperature

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The paper is focused on practical determination of piezoelectric materials’ behaviour at high temperatures near the Curie point. Temperature dependence of piezoelectric, elastic and dielectric coefficients near the Curie point is important yet hardly measurable material property of piezoelectric ceramics. Various methods can be used for measurement of temperature dependence of piezoelectric parameters and for the determination of the Curie point. Three methods have mostly been used for that purpose - a frequency method, X-ray diffraction spectroscopy (XRD) method and a thermal differential scanning calorimetry (DSC) analysis. These methods were also selected in this study, described in more detail and their results were compared with respect to achievable accuracy and requirements on instrumentation and preparation of samples. Cylinders of hard NCE41 and soft NCE55, NCE51 and PCM51 ceramics obtained from the company Noliac Ceramics were used for material coefficients temperature dependencies determination. Real crystallographic structure and chemical composition of the samples were confirmed by X-ray diffraction spectroscopy and energy dispersive spectroscopy (EDS), respectively [1, 2, 3]. Special laboratory temperature chamber Gemini 700LRI was utilized for measuring temperature dependences using frequency method. It was used as a reference method due to its ability to determine all coefficients. Maximal temperature of this furnace is 700 °C and air was used as a filling in its inner space. It was necessary to design and manufacture special measuring clamp, so-called “tweezers“, for measuring at high temperatures. These tweezers were connected to a Agilent 4294A analyser for measurement of complex impedance of samples. The Curie temperatures determined for all samples by frequency method were compared with results of X-ray diffraction spectrometry using Empyrean spectrometer from PANalytical which includes temperature chamber HTK16 from Anton Paar, and measurements using differential scanning calorimeter Discovery from TA Instruments. Finally, an optimized measurement methodology facilitating accurate determination of the Curie temperature, representing a phase transition to the cubic crystallographic structure, using several methods, was obtained. [1]S. Sherrit, T.J. Masys, H.D. Wiederick and B.K. Mukherjee, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 58, 9 (2011). [2]R.G. Sabat, B.K. Mukherjee, W. Ren and G. Yang, Journal of applied Physics: Dielectric end Ferroelectricity, 101, 6 (2007). [3]B. Noheda, J.A. Gonzalo, L.E. CroSS, R. GuO, S.-E. Park, D.E. Cox and G. Shirane, Physical Review B, 61, 13 (2000).

Curie temperature, X-ray diffraction spectroscopy, Frequency method

FIALKA, J.; BENEŠ, P.; HAVRÁNEK, Z.

21. 5. 2018

Fyzikální ústav AV ČR, v. v. i.

Printed in the Czech Republic (Powerprint s.r.o., Prague)

978-80-905962-7-6

Structural and ferroelectric phase transitions: Book of abstracts - XXIII Czech - Polish seminar

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