- Email: [email protected]
Correlation effects in diffusion in a two sublattice structure
Vol. 41, No. 5
ABSTRACTS OF ARTICLES TO BE PUBLISHED IN J. PHYS. CHEM. SOL.
We have achieved a technique for determining the diffusion profiles of impurities in the polymers by using a radio-tracer and a microslicing method. We describe the diffusion profiles of iodine in polyacetylene in the temperature range - 60 + 2O’C. The results show that: (1) iodine penetrates through the interfibril spaces; (2) there is a simultaneous chemical reaction of the first order on the fibrils between polyacetylene and iodine. When the dopant is in solution in pentane, the liquid state interfibril diffusion obeys the Arrhenius law: D=
1.73 x 10e3 exp [- 0.122 (eV)/kT] cm* set-’ .
The kinetic constant of the reaction obeys the similar equation:
vii
fraction measurements performed to determine the lattice cell structure at different temperatures one concludes that implicit effects are more likely to explain the ground state splitting temperature dependence. Received 12 February 198 I Revised 27 July 1981 27.
A NEW METHOD FOR THE STUDY OF THERMOMIGRATION USING A NONISOTHERMAL ELECTROLYTIC CELL F. Millot and P. Gerdanian, Laboratoire des Composes non-stoechiometriques, B&iment 415, Universite de Paris-Sud, 91405 Orsay, France.
An experimental device is described which is essentially a symmetrical electrolytic cell in a temReceived 9 April 198 1 perature gradient. It is composed of a thin solid electrolyte (Zr02-Y,Os) and two symmetric electrodes of the studied oxide. CORRELATION EFFECTS IN DIFFUSION IN 25. We show that the determination of Q* is possible A TWO SUBLATTICE STRUCTURE from the measurement of the Seebeck effects of the G.E. Murch, Chemical Division, Argonne electrodes and electrolyte in two different National Laboratory, Argonne, IL 60439, stationary states. One corresponds to an imposed U.S.A. chemical potential gradient of oxygen by an oxydo reducing atmosphere (H,-H20 or CO-CO*). The other With a Monte Carlo method we have investigated is obtained by replacing this gas phase by an inert gas tracer and conductivity (physical) correlation factors in @r). the simple cubic lattice gas with two f.c.c. inequivalent The validity and the limitations of the method are sublattices and self exclusion by the atoms. Except at discussed from an experimental study on CeO,_,. very low temperatures, excellent agreement was found Received lOApril 1981 between our results for the conductivity correlation factor and Richards’ approximate treatment. At an THE QUANTITATIVE MEASUREMENT OF occupation of 0.5 the Haven Ratio exhibits the charac28. ELECTROMIGRATION IN Ce02_x teristic discontinuity found recently in other lattice gases which give ordered arrangements. On the concenF. Millot and P. Gerdanian, Iaboratoire des tration axis at low temperature we found another disComposes non-stochiometriques, Batiment 415, continuity in the Haven Ratio. All of these disconUniversite de Paris&d, 91405 Orsay, France. tinuities are associated with changes in mechanism. We present an experimental device for the measureReceived 7 April 1980 ment of electromigration in a non-stoichiometric oxide which is composed principally of two symmetrical electrolytic cells: CeO,_, - (Zr02, Y2O3) - Ce02_x+e 26. MORE EXPERIMENTAL INSIGHT ON Eu2+ and which permits one to analyse the variation of the GROUND STATE SPLITTING oxygen composition at the extremities of a CeO,_, D. Nicollin, Dept. de Chimie-Physique, Sciences sample subjected to an electric field. II, 30 quai E-Ansermet, 1211 Genbve 4 The quantitative measurement of the effective Switzerland. charge and ionic transport numbers are discussed in terms of the reduction or elimination of such undesirExperimental results obtained on Eu2+ incorporated able but inherent effects as the exchanges of oxygen into MeFX (Me = Ca, Sr, Ba and X = Cl, Br, I) single between the sample and its neighbourhood and of the crystals are discussed. A possible origin of the observed heat associated with the electrical current. ground state splitting is traced back to the physicoReceived 20 May 1981 chemical features of the host crystals. From X-ray dif-
k = 0.754 exp [- 0.0867 (eV)/kT] set-‘.
ABSTRACTS OF ARTICLES TO BE PUBLISHED IN J. PHYS. CHEM. SOL.
We have achieved a technique for determining the diffusion profiles of impurities in the polymers by using a radio-tracer and a microslicing method. We describe the diffusion profiles of iodine in polyacetylene in the temperature range - 60 + 2O’C. The results show that: (1) iodine penetrates through the interfibril spaces; (2) there is a simultaneous chemical reaction of the first order on the fibrils between polyacetylene and iodine. When the dopant is in solution in pentane, the liquid state interfibril diffusion obeys the Arrhenius law: D=
1.73 x 10e3 exp [- 0.122 (eV)/kT] cm* set-’ .
The kinetic constant of the reaction obeys the similar equation:
vii
fraction measurements performed to determine the lattice cell structure at different temperatures one concludes that implicit effects are more likely to explain the ground state splitting temperature dependence. Received 12 February 198 I Revised 27 July 1981 27.
A NEW METHOD FOR THE STUDY OF THERMOMIGRATION USING A NONISOTHERMAL ELECTROLYTIC CELL F. Millot and P. Gerdanian, Laboratoire des Composes non-stoechiometriques, B&iment 415, Universite de Paris-Sud, 91405 Orsay, France.
An experimental device is described which is essentially a symmetrical electrolytic cell in a temReceived 9 April 198 1 perature gradient. It is composed of a thin solid electrolyte (Zr02-Y,Os) and two symmetric electrodes of the studied oxide. CORRELATION EFFECTS IN DIFFUSION IN 25. We show that the determination of Q* is possible A TWO SUBLATTICE STRUCTURE from the measurement of the Seebeck effects of the G.E. Murch, Chemical Division, Argonne electrodes and electrolyte in two different National Laboratory, Argonne, IL 60439, stationary states. One corresponds to an imposed U.S.A. chemical potential gradient of oxygen by an oxydo reducing atmosphere (H,-H20 or CO-CO*). The other With a Monte Carlo method we have investigated is obtained by replacing this gas phase by an inert gas tracer and conductivity (physical) correlation factors in @r). the simple cubic lattice gas with two f.c.c. inequivalent The validity and the limitations of the method are sublattices and self exclusion by the atoms. Except at discussed from an experimental study on CeO,_,. very low temperatures, excellent agreement was found Received lOApril 1981 between our results for the conductivity correlation factor and Richards’ approximate treatment. At an THE QUANTITATIVE MEASUREMENT OF occupation of 0.5 the Haven Ratio exhibits the charac28. ELECTROMIGRATION IN Ce02_x teristic discontinuity found recently in other lattice gases which give ordered arrangements. On the concenF. Millot and P. Gerdanian, Iaboratoire des tration axis at low temperature we found another disComposes non-stochiometriques, Batiment 415, continuity in the Haven Ratio. All of these disconUniversite de Paris&d, 91405 Orsay, France. tinuities are associated with changes in mechanism. We present an experimental device for the measureReceived 7 April 1980 ment of electromigration in a non-stoichiometric oxide which is composed principally of two symmetrical electrolytic cells: CeO,_, - (Zr02, Y2O3) - Ce02_x+e 26. MORE EXPERIMENTAL INSIGHT ON Eu2+ and which permits one to analyse the variation of the GROUND STATE SPLITTING oxygen composition at the extremities of a CeO,_, D. Nicollin, Dept. de Chimie-Physique, Sciences sample subjected to an electric field. II, 30 quai E-Ansermet, 1211 Genbve 4 The quantitative measurement of the effective Switzerland. charge and ionic transport numbers are discussed in terms of the reduction or elimination of such undesirExperimental results obtained on Eu2+ incorporated able but inherent effects as the exchanges of oxygen into MeFX (Me = Ca, Sr, Ba and X = Cl, Br, I) single between the sample and its neighbourhood and of the crystals are discussed. A possible origin of the observed heat associated with the electrical current. ground state splitting is traced back to the physicoReceived 20 May 1981 chemical features of the host crystals. From X-ray dif-
k = 0.754 exp [- 0.0867 (eV)/kT] set-‘.