| 1. |
- Diosa, J.E. 0, et al.
(författare)
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Dielectric relaxation studies in Cs2SO4
- 2006
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Ingår i: FERROELECTRICS. - 0015-0193. ; 333, s. 253-258
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Tidskriftsartikel (refereegranskat)abstract
- Dielectric measurements of Cs2SO4 show a distinct relaxation at low frequencies at several isotherms ( T < 651 degrees C). For example, the relaxation frequency is around 5.1 kHz at 376 degrees C and increases to approximately 1 MHz at 651 degrees C. The relaxation has an activation energy of 0.97 eV, which is in close agreement whit that of Cs+ transport. We suggest that the observed dielectric relaxation could be produced by the Cs+ jump and SO4- reorientation that cause distortion and change the local lattice polarizability inducing dipoles like CsSO4-.
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| 2. |
- Diosa, J.E. 0, et al.
(författare)
-
Impedance spectroscopy studies of K2SO4 in the intermediate temperature regime
- 2005
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Ingår i: Solid State Communications. - : Elsevier BV. - 0038-1098. ; 136:11-12, s. 601-604
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Tidskriftsartikel (refereegranskat)abstract
- Impedance spectroscopy measurements of K2SO4 have been carried out from 5 Hz to 13 MHz over the temperature range 403-782 T. The plots of corrected imaginary part of permittivity, epsilon", and its real part epsilon' vs. frequency clearly show a new dielectric relaxation around epsilon") = 1.4 X 10(4) Hz at 403 degrees C, which shifts to higher frequencies (similar to 1 MHz) as the temperatures increases. The fma (calculated from the peak position of epsilon") vs. reciprocal T shows an activated relaxation process over the temperature range 403-600 T with activation energy E-a = 1.02 eV, which is close to that derived from the dc-conductivity, E-a = 1.15 eV. We suggest that the observed dielectric relaxation could be produced by the K+ jump and SO4- reorientation that cause distortion and change the local lattice polarizability inducing dipoles like KSO4-.
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| 3. |
- Diosa, J.E. 0, et al.
(författare)
-
Impedance spectroscopy studies of KHSO4 above room temperature
- 2005
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 176:39-40, s. 2913-2916
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Tidskriftsartikel (refereegranskat)abstract
- The dielectric permittivity of polycrystalline KESO4 was measured from 5 Hz to 13 MHz over the temperature range 51-187 degrees C. The corrected imaginary part of permittivity, epsilon", and its real part epsilon' vs. frequency clearly show a new dielectric relaxation around f(max) = 1.5* 10(5) Hz at 51 degrees C which shifts to higher frequencies (similar to 1 MHz) as the temperatures increases. If the measurements are done when increasing the temperature, f(max) decreases sharply (more than two orders of magnitude) around 164 degrees C; however, above this transition temperature, it continues shifting to higher frequencies as the temperature increases. However, if the measurements are done when decreasing, the temperature, f(max) increases abruptly around 146 degrees C, thus showing a hysteretic behaviour. We suggest that the observed dielectric relaxation could be produced by proton jumps and SO4- reorientation, causing distortion and changing the local lattice polarizability to induce dipoles like HSO4-. (c) 2005 Elsevier B.V. All rights reserved.
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| 4. |
- Diosa, J.E. 0, et al.
(författare)
-
Dielectric relaxation in NH4HSO4 above room temperature
- 2006
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Ingår i: SOLID STATE IONICS. - : Elsevier BV. - 0167-2738. ; 177:13-14, s. 1107-1110
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Tidskriftsartikel (refereegranskat)abstract
- The dispersion curves of the dielectric response of NH4HSO4 show that the corrected imaginary part of permittivity, epsilon", and its real part epsilon' versus frequency reveal a dielectric relaxation around 9.1 x 10(5) Hz at 31 degrees C, which shifts to higher frequencies (similar to 10(6) Hz) as the temperatures increases. The relaxation frequency shows an activated relaxation process over the temperature range 31-83 degrees C with activation energy E-a = 0.14 eV, which is close to that derived from the dc conductivity. We suggest that the observed dielectric relaxation could be produced by the H+ jump and SO4- reorientation that cause distortion and change the local lattice polarizability inducing dipoles like HSO4-.
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