کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5447425 1511497 2017 38 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Delocalization in Cr3+ luminescence of clinochlore: A pressure-induced transition from single-ion emission to pair emission
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد مواد الکترونیکی، نوری و مغناطیسی
پیش نمایش صفحه اول مقاله
Delocalization in Cr3+ luminescence of clinochlore: A pressure-induced transition from single-ion emission to pair emission
چکیده انگلیسی
The luminescence spectra of Cr3+ in (Mg,Fe2+)5Al(Si3Al)O10(OH)8-clinochlore, a layered silicate compound, are reported to pressures of ∼25 GPa at 298 K: our results encompass emission from single-ions, paired neighbors and vibronic lines. A transition from sharp single Cr3+ ion (R-line) dominated emission to Cr-Cr pair (N-Line) dominated emission is observed under compression. Since Cr atoms are confined to a discrete layer within the structure, efficient Cr-Cr exchange only occurs within a single layer; the distance between the layers is too large for significant interlayer coupling to occur. This 2-dimensional, single-layer arrangement gives rise to three distinguishable Cr3+ nearest neighbor pairs. Neighbor lines are assigned based on ferromagnetic coupling of these three emitting pairs. We observe a decrease in the separation between the split components of the R-line under compression, confirming that the Cr sites become less distorted up to at least ∼11.0 GPa. An increase in overlap between eg orbitals of neighboring Cr-ions (corresponding to delocalization of the excited state) under compression also likely occurs. The R-to N-line transition is fully reversible and hysteresis is not observed, indicating that this transition is purely electronic in nature. The intensity transfer between the single-ion and paired-ion emission changes with a ∼1/4th power law as a function of the Cr-Cr separation.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Physics and Chemistry of Solids - Volume 109, October 2017, Pages 89-99
نویسندگان
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