Síntese e estudo das propriedades ópticas e magnéticas de pontos quânticos de Pb1-xMnxS crescidos em matrizes vítreas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

In this Thesis PbS and Pb1-xMnxS quantum dots (nanocrystals), hosted in glass matrix, were synthesized and characterized. Optical absorption (OA), Electron Paramagnetic Resonance (EPR) and Magnetization curves (SQUID) were used to characterize the as-prepared nanocrystals. Within the range of 0.41 eV (gap of bulk PbS) to 3.5 eV (gap of bulk MnS) the OA bands of the Pb1-xMnxS nanocrystals shift toward lower wavelengths as the Mn content increases. EPR spectra, corresponding to the 2 1 2 + 1 ↔ − electronic transition, show the standard six hyperfine lines of Mn2+ ion when incorporated into PbS nanocrystals, with SI and SII features labeling Mn2+ ions located at the core and at the surface sites, respectively. Magnetization curves show the paramagnetic behavior of the as-prepared Pb1- xMnxS nanocrystals. Atomic Force Microscopic (AFM) images, recorded from the glassbased samples with composition 40SiO . 30Na2CO3 . 4PbO2 . 1Al2O3 . 25B2O3 (mol%) + 2S (%wt) + xMn (%wt (Pb)), confirm the in-situ growth of nanocrystals. The average sizes of the PbS and Pb1-xMnxS nanocrystals were estimated using the four-band envelope function model. The estimated values for the nanocrystals average sizes are in excellent agreement with the data provided by AFM.

ASSUNTO(S)

pontos quânticos matriz vítrea pb1-xmnxs fisica propriedades ópticas propriedades magnéticas

ACESSO AO ARTIGO

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