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Electrical, Electromechanical and Piezoelectric Properties of Ca₃TaGa₃Si₂O₁₄ Resonators at Elevated Temperatures

100%

Suhak Y., Schulz M., Sotnikov A., Schmidt H., Fritze H.

Acta Physica Polonica A

2018

vol. 133

issue 4

1069-1073

The electrical conductivity, resonance frequency and piezoelectric strain constants are determined for ordered piezoelectric Ca₃TaGa₃Si₂O₁₄ (CTGS) single crystals from room temperature to 900°C. The latter result from three independent methods, namely resonant, ultrasonic pulse-echo, and laser Doppler vibrometry techniques, which allows validating the results. Further, the long-term behaviour of fundamental materials properties including electrical conductivity and resonance frequency are examined at 1000°C for CTGS crystals, grown by different manufacturers. After an initial period of about 500 h, the conductivity is found to remain nearly constant for at least 1500 h. In a period of 2000-5000 h a decrease of conductivity by only 20% is observed. The resonance frequency is found to decrease almost linearly in a period of 500-5000 h for all investigated samples.

Thermal Behaviour of PrCo_{1-x}Fe_xO₃ Probed by X-ray Synchrotron Powder Diffraction and Impedance Spectroscopy Measurements

86%

Pekinchak O., Sugak D., Ubizskii S., Suhak Y., Fritze H., Vasylechko L.

Acta Physica Polonica A

2018

vol. 133

issue 4

798-801

Crystal structure and transport properties of the mixed praseodymium cobaltites-ferrites PrCo_{1-x}Fe_xO₃ have been studied in the temperature range of 298-1173 K by a combination of in situ X-ray synchrotron powder diffraction and temperature dependent impedance spectroscopy measurements. In situ high temperature powder diffraction examination of PrCo_{1-x}Fe_xO₃ series revealed considerable anomalies in the lattice expansion which are especially pronounced for the cobalt-rich specimens. These anomalies, which are reflected in a sigmoidal dependence of the unit cell dimensions and in the considerable increase of the thermal expansion coefficients, are obviously associated with transitions of Co^{3+} ions from low spin to the higher spin states and the coupled metal-insulator transitions, occurring in in rare earth cobaltites at the elevated temperatures. Indeed, the temperature-dependent impedance measurements clearly prove the change of conductivity type from dielectric to the metallic behaviour in the mixed cobaltite-ferrites PrCo_{1-x}Fe_xO₃ at the elevated temperatures.

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2 Acta Physica Polonica A

2 2018

2 Fritze H.

2 Suhak Y.

1 Pekinchak O.

1 Schmidt H.

1 Schulz M.

1 Sotnikov A.

1 Sugak D.

1 Ubizskii S.

1 Vasylechko L.

Search results

Electrical, Electromechanical and Piezoelectric Properties of Ca₃TaGa₃Si₂O₁₄ Resonators at Elevated Temperatures

Thermal Behaviour of PrCo_{1-x}Fe_xO₃ Probed by X-ray Synchrotron Powder Diffraction and Impedance Spectroscopy Measurements