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ESR and microwave conductivity studies in DEM(TCNQ) above room temperature Cabañas, Francisco Xavier
Abstract
Two phase transitions have been found in DEM(TCNQ)₂ at 400(3) K and at 442(6) K to 453(6) K using ESR and measurements of the microwave conductivity. These temperatures are less than the values of 415 K and 483 K previously obtained from temperature dependent Guinier measurements. Below 400(3) K two ESR lines, I and II are observed corresponding to the two stacks, B and A, in DEM(TCNQ)₂. Above 400(3) K and below 453(6) K only one line remains with the same g value as line I. The angular dependence of the g value was fitted to g[sub=‖]² = g[sub=⊥] ²cos2θ + g²sinθ and values of g[sub=⊥] = 2.003551(14) and g[sub=‖] = 2.00273015) were obtained. Between 298 K and 442(6) K the conductivity was that of a semiconductor with an exitation energy E[sub=0] = 0.385(52) e.v. The -4k[sub=⌐] phase transition is postulated at 447(9) K. The phase transition at 400(3) K is due to a transfer of spin density from stack A to stack B, and has no effect on the total spin susceptibility or on the conductivity to within the experimental error.
Item Metadata
Title |
ESR and microwave conductivity studies in DEM(TCNQ) above room temperature
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1981
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Description |
Two phase transitions have been found in DEM(TCNQ)₂ at 400(3) K and at 442(6) K to 453(6) K using ESR and measurements of the microwave conductivity. These temperatures are less than the values of 415 K and 483 K previously obtained from temperature dependent Guinier measurements. Below 400(3) K two ESR lines, I and II are observed corresponding to the two stacks, B and A, in DEM(TCNQ)₂. Above 400(3) K and below 453(6) K only one line remains with the same g value as line I. The angular dependence of the g value was fitted to g[sub=‖]² = g[sub=⊥] ²cos2θ + g²sinθ and values of g[sub=⊥] = 2.003551(14) and g[sub=‖] = 2.00273015) were obtained. Between 298 K and 442(6) K the conductivity was that of a semiconductor with an exitation energy E[sub=0] = 0.385(52) e.v. The -4k[sub=⌐] phase transition is postulated at 447(9) K. The phase transition at 400(3) K is due to a transfer of spin density from stack A to stack B, and has no effect on the total spin susceptibility or on the conductivity to within the experimental error.
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Genre | |
Type | |
Language |
eng
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Date Available |
2010-03-29
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0095552
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.