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Title: | Calorimetric study of smectic polymorphism in octyloxyphenyl-nitrobenzoyloxy benzoate + decyloxyphenyl-nitrobenzoyloxy benzoate mixtures |
Authors: | Ema, K. Nounesis, G. Garland, C.W. Shashidhar, R. |
Issue Date: | 1-Mar-1989 |
Publisher: | The American Physical Society |
Citation: | Physical Review A, 1989, Vol.39, 2599 |
Abstract: | Binary mixtures of octyloxyphenyl-nitrobenzoyloxy benzoate (DB8ONO2) and decycloxyphenyl-nitrobenzoyloxy benzoate (DB10ONO2) exhibit a rich variety of smectic polymorphism. An ac calorimetric study has been carried out on six mixtures with mole percent X of the decyl homolog between 51 and 57, a range that includes the Sm-Ad–Nr–Sm-A1 point at X≃56. The sample with X=57 exhibits a first-order direct Sm-Ad–Sm-A1 transition, while the sample with X=51.3 exhibits two transitions—a second-order Sm-Ad–Nr transition with a very small excess heat-capacity peak and a tricritical Nr–Sm-A1 transition with a large heat-capacity peak. For samples with intermediate compositions, only weakly first-order Nr–Sm-A1 heat-capacity peaks are observed in the vicinity of the Sm-Ad–Nr–Sm-A1 point. All six investigated samples exhibit the Sm-A1–Sm-C̃–Sm-C2 phase sequence at lower temperatures. The Sm-A1–Sm-C̃ transition is a weakly first-order phase transition with pretransitional excess heat capacity below the transition temperature. In contrast, the Sm-C̃–Sm-C2 transition is a weakly first-order inverted Landau transition with no pretransitional behavior in the Sm-C2 phase below the transition but a large mean-field excess heat capacity observed in the Sm-C̃ phase above the transition. |
URI: | http://hdl.handle.net/2289/1301 |
ISSN: | 1050-2947 1094-1622 (online) |
Alternative Location: | http://link.aps.org/abstract/PRA/v39/p2599 |
Copyright: | (1989) by the American Physical Society |
Appears in Collections: | Research Papers (SCM) |
Files in This Item:
File | Description | Size | Format | |
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1989 PR-A V39 p2599.pdf | 10p | 1.48 MB | Adobe PDF | View/Open |
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