کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
8151695 1524443 2014 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Effects of temperature on the polymorphism of α,ω-dioctylterthiophene in thin films
موضوعات مرتبط
مهندسی و علوم پایه فیزیک و نجوم فیزیک ماده چگال
پیش نمایش صفحه اول مقاله
Effects of temperature on the polymorphism of α,ω-dioctylterthiophene in thin films
چکیده انگلیسی
Polymorphism of α,ω-dioctylterthiophene (DOTT) thin films (less than 100 nm-thick) deposited onto standard silicon substrates is investigated by combining specular and in-plane grazing incidence X-ray diffraction measurements. Two crystal phases are revealed: the bulk phase (b) and the surface-induced phase (s). Previous results showed that s-phase was the most favored close to the substrate surface while b-phase is predominant at the DOTT-air interface. We show here that the relative proportion of these polymorphs is related to sample preparation. Indeed, the preferential crystallization of one phase or the other can be tuned as a function of substrate temperature during film deposition, s-phase being mainly present at high substrate temperature while b-phase is most observed at low substrate temperature. Particularly noteworthy is that thin films exhibiting only b-phase or only s-phase can be obtained according to sample preparation. Furthermore, when samples are annealed above the melting temperature (smectic G phase), the polymorph observed after cooling back to room temperature depends upon the cooling rate, s-phase being predominant at high cooling rate while it is rather b-phase for slow cooling. This behavior is independent of the crystalline phase that was present at room temperature before annealing.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Crystal Growth - Volume 386, 15 January 2014, Pages 128-134
نویسندگان
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