کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1473275 991035 2015 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Size dependence of structural, magnetic, and electrical properties in corundum-type Ti2O3 nanoparticles showing insulator–metal transition
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
Size dependence of structural, magnetic, and electrical properties in corundum-type Ti2O3 nanoparticles showing insulator–metal transition
چکیده انگلیسی

Corundum-type Ti2O3 has been investigated over the last half century because it shows unusual insulator–metal (I-M) transition over a broad temperature range (420–550 K). In this work, we successfully synthesized Ti2O3 nanoparticles (20, 70, 300 nm in size) by the low-temperature reduction between precursors of rutile-type TiO2 and the reductant CaH2, in a non-topotactic manner. The reaction time required for obtaining the reduced phase increases with increasing the particle size. Synchrotron X-ray powder diffraction and electron microscopy studies reveal that the symmetry of all the present samples remains the same as that of bulk samples. However, the particle-size reduction results in three important features compared with bulk samples as follows, (i) color shift from dark brown to bluish black, (ii) anisotropic volume contraction involving the shrinkage of Ti–Ti bonds in the ab plane and along the c axis, (iii) reduction of the I-M transition temperature from 420 K to 350 K. These suggest that the a1g band broadening caused by the surface strain effects, which favors narrowing of the band gap, may play a critical role in the suppression of IM transition.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Asian Ceramic Societies - Volume 3, Issue 3, September 2015, Pages 325–333
نویسندگان
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