Dipole and interfacial polarization phenomena in natural single-crystal calcite studied by the thermally stimulated depolarization currents method

Bogris, N.; Grammatikakis, J.; Papathanassiou, A. N.

doi:10.1103/physrevb.58.10319

Cited by 20 publications

(15 citation statements)

References 17 publications

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“…In dielectrics the fitting parameter 2 in Eq. (2) characterizes the relaxation time of bulk charge carriers: (a) dipole rotation, and (b) space charges, consisting of impurity atoms and Ca-vacancies (Bogris et al, 1998). The dielectric relaxation time estimated at each temperature also obeys the Arrhenian type of equation Note: T c of R-3c , R-3m transition in CaCO 3 reported by Redfern et al (1989) where P is the pressure, v m is the activation volume, E a is the activation energy of the dielectric relaxation and 0,2 is the pre-exponential factor.…”

Section: Impedance Measurements and Orientational Order-disorder Tranmentioning

confidence: 99%

Phase transformations in calcite from electrical impedance measurements

Bagdassarov

Slutskii

2003

Phase Transitions

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The phase transformation in calcite I-IV-V and calcite , aragonite have been characterized by electrical impedance measurements at temperatures 600-1200 C and pressures 0.5-2.5 GPa in a piston cylinder apparatus. The bulk conductivity has been measured from Argand plots in the frequency range 10 5 -10 À2 Hz in an electric cell representing a coaxial cylindrical capacitor. The synthetic polycrystalline powder of CaCO 3 and natural crystals of calcite were used as starting materials. The transformation temperature T c was identified from resistivity-temperature curves as a kink point of the activation energy. At pressure above 2 GPa in ordered phase calcite I, the activation energy E is c. 1.05 eV, and in disordered phase calcite V E is c. 0.75 eV. The pressure dependence of T c for the rotational order-disorder transformation in calcite is positive for pressures <1 GPa and negative for pressures >1 GPa. The transformation boundary of calcite 1-IV is observed only during first heating in samples after a long annealing at low temperatures. The activation energy of calcite I , IV decreases gradually from 1.8 to 1.05 eV with the pressure increase from 0.5 to 2 GPa. The kinetics of calcite , aragonite transformation has been monitored by measuring a time-variation of the electrical resistance of a calcite sample at 10 3 Hz in the stability P-T field of aragonite. The variation of the impedance correlates with the degree of phase transformation, estimated from X-ray powder diffraction studies on quenched products of experiments. The kinetics of calcite ) aragonite transformation may be fitted to the Avrami kinetics with the exponent m $ 1-1.5.

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Section: Impedance Measurements and Orientational Order-disorder Tranmentioning

confidence: 99%

Phase transformations in calcite from electrical impedance measurements

Bagdassarov

Slutskii

2003

Phase Transitions

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“…Assuming an ideal symmetrical barrier model for the dipole, TSDC can be described with a single relaxation mathematically described by Eq. :

J_{normalD} (T) = \frac{A P_{0}}{τ_{0}} exp (\frac{- E_{normala}}{k T}) exp [\frac{- 1}{β τ_{0}} \int_{τ_{0}}^{T} exp ((), - \frac{E_{a}}{K T^{'}}) normald T^{'}] .

…”

Section: Resultsmentioning

confidence: 99%

Dielectric relaxation investigations in barium strontium titanate glass-ceramics: Thermally stimulated depolarization current technique

Zhao

Zhang

et al. 2014

Phys. Status Solidi A

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Different dielectric relaxation processes in barium strontium titanate glass‐ceramics have been investigated using the thermally stimulated depolarization current (TSDC) technique. The TSDC results obtained from the glass‐ceramics polarized under various polarization conditions show the presence of two peaks designated as A and B in ascending order of temperature, respectively. The peak A is determined to be of dipole origin and assumed to be associated with a defect complex. In addition, the peak B is due to space‐charge polarization arising from the interface between the crystalline phases and the glass matrix. It is supposed to be associated with the relaxation of oxygen vacancies. The TSDC characteristics demonstrate that the degree of crystallinity in glass‐ceramics is a predominant factor in deciding the features of dielectric relaxation mechanisms. TSDC plots for the BST glass‐ceramic samples sintered at various temperatures with the same polarization conditions.

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“…It was suggested recently that a systematic trend of the activation volume with the volume of the unit cell occurs [5]. On the other hand, electrical and dielectric measurements have been reported for the entire set of the calcite type crystals previously [6][7][8][9][10][11][12][13]. The conductivity mechanisms were studied in detail by using the Thermally Stimulated Depolarization Current (TSDC) spectroscopy.…”

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confidence: 99%

“…The transport of charge carriers along the volume of the specimen produces TSDC peaks when non-ohmic electrodes are used. By analyzing those signals, the activation energies for the conductivity mechanisms can be obtained accurately [8,10,11]. However, the activation energy E obtained from electrical and dielectric measurements is identical with the activation enthalpy h act [14].…”

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On the Activation Volume for Charge Transport in Carbonate Salts

Turner

Souza

2002

phys. stat. sol. (b)

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Calcite (CaCO 3 ), magnesite (MgCO 3 ) and dolomite (CaMg(CO 3 ) 2 ) are trigonal carbonate salts and constitute the calcite group. The activation volumes for electric charge transport in these materials were obtained from conductivity experiments at various pressure values [1][2][3][4][5]. It was suggested recently that a systematic trend of the activation volume with the volume of the unit cell occurs [5]. On the other hand, electrical and dielectric measurements have been reported for the entire set of the calcite type crystals previously [6][7][8][9][10][11][12][13]. The conductivity mechanisms were studied in detail by using the Thermally Stimulated Depolarization Current (TSDC) spectroscopy. The analyses of the TSDC signals yielded the activation energy for the conductivity processes. The scope of the present work is to estimate the activation volumes from the activation energy values by means of the cBW model and compare them with the experimental values.Varotsos and Alexopoulos have suggested within the frame of the cBW model [14] that the activation volume can be calculated from the activation enthalpy h act and the elastic properties of the material through the following equation:where B denotes the isothermal bulk modulus and dB/dP is its pressure derivative. This model was successfully applied to many different materials [14]. The transport of charge carriers along the volume of the specimen produces TSDC peaks when non-ohmic electrodes are used. By analyzing those signals, the activation energies for the conductivity mechanisms can be obtained accurately [8,10,11]. However, the activation energy E obtained from electrical and dielectric measurements is identical with the activation enthalpy h act [14]. We can therefore replace the activation energy values and the elastic constants into Eq. (1), so as to calculate the values of the activation volume u act calc . The results are shown in Table 1, together with the experimentally determined activation volumes (which are simply labeled by u act ).We observe that the calculated activation volumes are in good agreement with the experimental ones. The divergence between the calculated and the experimental values is less than 6%. The phys. stat. sol. (b) 230, No. 2, R7-R8 (2002)

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Dipole and interfacial polarization phenomena in natural single-crystal calcite studied by the thermally stimulated depolarization currents method

Cited by 20 publications

References 17 publications

Phase transformations in calcite from electrical impedance measurements

Phase transformations in calcite from electrical impedance measurements

Dielectric relaxation investigations in barium strontium titanate glass-ceramics: Thermally stimulated depolarization current technique

On the Activation Volume for Charge Transport in Carbonate Salts

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