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Publisher: Melville, NY : American Inst. of Physics × Subject: Piezoelectricity ×

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Now showing 1 - 2 of 2
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    High-temperature electromechanical loss in piezoelectric langasite and catangasite crystals
    (Melville, NY : American Inst. of Physics, 2021) Suhak, Yuriy; Fritze, Holger; Sotnikov, Andrei; Schmidt, Hagen; Johnson, Ward L.
    Temperature-dependent acoustic loss Q−1 is studied in partially disordered langasite (LGS, La3Ga5SiO14) and ordered catangasite (CTGS, Ca3TaGa3Si2O14) crystals and compared with previously reported CTGS and langatate (LGT, La3Ga5.5Ta0.5O14) data. Two independent techniques, a contactless tone-burst excitation technique and contacting resonant piezoelectric spectroscopy, are used in this study. Contributions to the measured Q−1(T) are determined through fitting to physics-based functions, and the extracted fit parameters, including the activation energies of the processes, are discussed. It is shown that losses in LGS and CTGS are caused by a superposition of several mechanisms, including intrinsic phonon–phonon loss, point-defect relaxations, and conductivity-related relaxations.
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    Huge impact of compressive strain on phase transition temperatures in epitaxial ferroelectric KxNa1-xNbO3 thin films
    (Melville, NY : American Inst. of Physics, 2019) Von Helden, L.; Bogula, L.; Janolin, P.-E.; Hanke, M.; Breuer, T.; Schmidbauer, M.; Ganschow, S.; Schwarzkopf, J.
    We present a study in which ferroelectric phase transition temperatures in epitaxial KxNa1-xNbO3 films are altered systematically by choosing different (110)-oriented rare-earth scandate substrates and by variation of the potassium to sodium ratio. Our results prove the capability to continuously shift the ferroelectric-to-ferroelectric transition from the monoclinic MC to orthorhombic c-phase by about 400 °C via the application of anisotropic compressive strain. The phase transition was investigated in detail by monitoring the temperature dependence of ferroelectric domain patterns using piezoresponse force microscopy and upon analyzing structural changes by means of high resolution X-ray diffraction including X-ray reciprocal space mapping. Moreover, the temperature evolution of the effective piezoelectric coefficient d33,f was determined using double beam laser interferometry, which exhibits a significant dependence on the particular ferroelectric phase. © 2019 Author(s).