Ferroelectric phase transition and crystal asymmetry monitoring of SrTiO3 using quasi TE m,1,1 and quasi TM m,1,1 modes

M. A. Hosain, J. M. Le Floch, J. F. Bourhill, Jerzy Krupka, M. E. Tobar

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Dielectric spectroscopy of a SrTiO 3 single crystal over a broad range of microwave frequency using quasi T E m, 1, 1 and quasi T M m, 1, 1 modes reveals crystal asymmetry from typical measurement of Q-factor, transmission, or frequency characteristics in continuous cooling down to a few Kelvin. The properties of the modes due to the crystal asymmetry are validated by implementing a quasiharmonic phonon approximation. The observed ferroelectric phase transition temperature is around 51 K, and quantum-mechanical stabilization of the paraelectric phase arises below 5 K with very high permittivity. Also, an antiferrodistortive transition was indicated at 105 K. Landau's theory of correlation length supports the observation of an extra-loss term so the transition may be identified near the Q-factor maxima or transmission maxima depending on the other loss terms present in the cavity. Thus, the ferroelectric phase transition with respect to temperature is identified when its extra-loss term causes a discontinuity or deviation in the derivative of the temperature characteristic near the minimum of total cavity loss (maximum Q-factor or maximum transmission temperature characteristic). This temperature is confirmed by transmission amplitude variation of quasi T E 2, 1, 1 under 200 V dc electric field showing the existence of the soft-mode. These measurements support a typical polarization model and explicit temperature dependency of the soft-mode incorporating an imaginary frequency.

Original languageEnglish
Article number104102
JournalJournal of Applied Physics
Issue number10
Publication statusPublished - 14 Sept 2019


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