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  • 1.
    Wojcik, Natalia A.
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET). Gdansk Univ Technol, Poland.
    Kupracz, P.
    Gdansk Univ Technol, Poland.
    Barczynski, R. J.
    Gdansk Univ Technol, Poland.
    Nonlinear electrical properties of glass-ceramics nanocomposites containing ferroelectric nanocrystallites of Bi2VO5.52018Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 317, s. 7-14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nonlinear A.C. impedance measurements were conducted in the 50BiV-50SrBAlO nanocomposite as a function of frequency, temperature and A.C. voltage. This material is ferroelectric below temperature of 730 K, and above 730 K is a good ion-conductor. For this nanocomposite a low A.C. voltage of 1 V-rms, is enough to observe high nonlinearities. The origin of these nonlinear effects depends on the temperature and frequency. In the high temperature and low frequency region, the nonlinearities are due to interfacial processes. In the low temperatures and higher frequencies, the nonlinearities may be also correlated with ion-transport processes: hopping and blocking in glass matrix and phase boundaries. The ferroelectric properties of the Bi2VO5.5 nanocrystallites are also possible origin of nonlinear effects. However, their contribution into nonlinearities is weaker than from the other observed processes. It is shown that a decrease of the Bi2VO5.5 crystallites size from micro- to nanometers and introduction of additional structural disorder into material significantly decrease the real part of the third order electric susceptibility coefficient but does not influence the ratio of the third harmonic to the base conductivity. It is suggested that the ferroelectric nanoregions are single-domain and the nonlinearities derived from domain walls probably are not observed.

  • 2.
    Wójcik, Natalia A.
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET). Gdansk Univ Technol, Poland.
    Jonson, Bo
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Barczynski, R. J.
    Gdansk Univ Technol, Poland.
    Kupracz, P.
    Gdansk Univ Technol, Poland.
    Woncke, D.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET). Natl Hellen Res Fdn, Greece.
    Ali, Sharafat
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Electrical properties of Na2O-CaO-P2O5 glasses doped with SiO2 and Si3N42018Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 325, s. 157-162Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sodium-calcium-phosphate glasses doped with SiO2 or Si3N4 having similar sodium ion concentrations were prepared by melt quenching. The conductivity was measured by impedance spectroscopy under nitrogen atmosphere in a wide frequency range (10 mHz-1 MHz) and wide temperature range (153-473 K). At 36.6 degrees C, DC conductivities of all glasses vary between 1.1 *10(-12) and 8.9 * 10(-12) S cm(-1) and have similar activation energies (between 0.87 and 0.91 eV), which are characteristic for an ionic conduction mechanism. The analysis of AC conductivities showed that the spectra are governed by one dynamic process - hopping of the mobile charge carriers - which may be described i.e., by the 'concept of mismatch and relaxation' or by the 'random barrier' model. The obtained results confirmed a higher influence of nitrogen incorporation on the various glass conductivity parameters than shown for silicon doping alone. However, the influence of fundamental structural changes on the glass conductivity is less relevant as is the overall sodium ion concentration, which remains the decisive factor for a high ion conduction.

  • 3.
    Wójcik, Natalia A.
    et al.
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET). Gdańsk University of Technology, Poland.
    Kupracz, P
    Gdańsk University of Technology, Poland;Polish Academy of Science, Poland.
    Barczyński, Ryszard. J
    Gdańsk University of Technology, Poland.
    Jonson, Bo
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Ali, Sharafat
    Linnéuniversitetet, Fakulteten för teknik (FTK), Institutionen för byggd miljö och energiteknik (BET).
    Ion conduction in beryllium-alumino-silicate glasses doped with sodium or sodium and lithium ions2019Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 341, s. 1-7, artikel-id 115055Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electrical properties of beryllium-alumino-silicate glasses containing sodium ions or sodium and lithium ions were studied with impedance spectroscopy technique over a frequency range from 10 mHz to 1 MHz and at temperature range from 213 to 473 K. The frequency- and temperature-dependent conductivity spectra of individual single alkali glasses were superimposed by means of the Summerfield scaling. Mixed-alkali glasses do not overlap into a single master curve. Glasses doped with sodium ions exhibit significantly higher values of D.C. conductivity and lower activation energy (~0.63 eV) than glasses doped with both sodium and lithium ions (~0.95 eV). The observed mixed-alkali effect can be described by the dynamic structure model (DSM). The conductivity pre-exponential factors and activation energy follow the Meyer-Neldel rule in both glass series. It was observed that the replacement of SiO2 by BeO in single cation glasses resulted in decrease in activation energy and pre-exponential factor σ0. In mixed cations glasses similar effect found for D.C. conduction process parameters was assigned to influence of both oxides BeO and Al2O3.

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