Investigação das propriedades magnéticas, ópticas, térmicas e estruturais de nanocristais de SnTe e Sb2 S3 dopados com Mn2+ crescidos no sistema vítreo SNAB: SiO2-Na2CO3-Al2O3-B2O3

Abstract

The search for earth-abundant and non-toxic elements is essential for the manufactureofsustainable optical devices. In this context, dilute magnetic semiconductor (DMS)nanocrystals (NCs) xMn-doped SnTe/Sb2S3 embedded in host glass were synthesizedbythefusion method. Differential Thermal Analysis shows evidence of Sb2S3 phase crystallization peak and changes in glass transition and crystallization temperatures of the host glass with the presence of xMndoped Sb2S3 NCs. Transmission electron microscopy images show the formation of xMn-doped Sb2S3 NCs with increasing size (2.1 to 3.8 nm) as a function of concentration (x = 0.00 to 0.40), as well as the formation of SnTe Quantum Dots (QDs) with an average size of 5 nm, respectively. X-ray diffraction measurements reinforced the evidence for the orthorhombic structure of xMn-doped Sb2S3 NCs embedded in glass and pattern observed in electron diffraction from selected area confirms the SnTe semiconductor crystal nature. Energy dispersive X-ray spectroscopy analyzes confirm the S, Sb and Mn precursor elements of DMS NCs as well as the Sn, Te and Mn precursor elements. Atomic and magnetic force microscopy measurements show the magnetic contrast patterns resulting from the incorporation of Mn atoms into the structure of Sb2S3. The electronic paramagnetic resonance spectrum (EPR) confirms the presence of Mn 2+ ions (3d 5) located in the crystalfield of the SnTe and Sb2S3 semiconductors due to six hyperfine transitions. The redshift of the Raman vibrational mode (1Ag) with increasing xMn concentration gives strong evidence for the presence of Mn 2+ ions in sulfur vacancies (VS) in the Sb2S3 unit cell. Optical absorption and photoluminescence (PL) spectroscopy measurements for xMn-dopedSb2S3NCs show the subtle tunable redshift of the band gap and excitonic recombinationinthegreen-red region, with increasing x concentration. PL confirms that dopant Mn 2+ ions fill VS2that are dominant in Sb2S3. Therefore, the position of the energy states after the increasing concentration of Mn 2+ dopant ions gives rise to a luminescence insight for a future scenario of research and applications involving sustainable DMS NCs.