In this study, a series of glasses of the system xCdO-10TeO 2-(90−x)GeO 2 were fabricated, varying the modifier oxide content from 10 to 80 wt%. According to XRD analysis, partial crystallization occurred for the glass 60CdO.10TeO 2 .30GeO 2 presenting the formation of GeO 2 and CdTeO 3 ; the 70CdO.10TeO 2 .20GeO 2 glass shows sharp diffraction peaks corresponding to the Cd 3 Al 2 Ge 3 O 12 garnet crystalline phase. Transmission electron microscopy showed that the garnet crystals have sizes below 20 nm. At the highest concentration of CdO (80 wt%), a transparent orange glass can be obtained, and this sample can be identified as an inverted glass where CdO participates as a network former. The optical band gap of the glasses decreases as CdO content increases from 3.91 to 3.0 eV. In general, all glasses show a typical broad emission when excited with UV light (325 nm); chromatic coordinates were calculated and pointed out the presence of emissions in the white, green, and yellow regions. In summary, the obtained glasses are a promising material for IR technologies, nonlinear optics, and design of solid state lighting devices.
The alkaline earth stannates (ASnO3) have been recently investigated for their potential applications, such as components in lithium ion batteries and high-temperature humidity sensors [1]. Rare earth element doped semiconductors materials and perovskites, such SrSnO3, are of interest for visible and infrared light emitting diodes applications [2]. Among the rare earth elements, samarium (Sm 3+ ) is an element which is often employed as dopant for making orange-emitting phosphors [3]. In this work, we present the synthesis of SrSnO3:Sm 3+ nanoparticles using a co-precipitation method and investigated their structural properties and photoluminescent characteristics.In a typical co-precipitation synthesis [4], 55 mL of a 0.02M solution of SnCl4•5H2O and 55 mL of a 0.055M solution of Sr(NO3)3•5H2O were prepared in deionized water. 60 mL of hydrogen peroxide was added independently in both solutions. While keeping the SrNO3 solution under constant stirring, 11 ml of ammonium hydroxide were added to this solution. After 30 min, the SrNO3 solution was slowly mixed with SnCl4 solution, acquiring a cloudy yellow appearance. For Sm-doped samples, Sm(NO3)3•6H2O was added in the following molar concentrations (1, 2 and 4 %). Finally, the samples were washed and centrifuged several times alternating between water and ethanol. Obtained precipitates were dried in an oven at 80 °C for 2 h. Samples were sintered at two different temperatures (800 and 1300 °C) during 4 h.Figure 1a-c) shows FE-SEM images of SrSnO3 spherical nanoparticles annealed at different temperatures. The average particle size is about 20, 65, and 500 nm for samples without annealing, annealed at 800, and 1300 °C, respectively. The SrSnO3 sample annealed at 1300 °C present elongated shapes compared to the other two samples. Sm-doped samples did not show significant changes in the morphology, shape and size respect to the un-doped sample (Fig. 1d). The corresponding Sr, Sn and O maps present a homogenous distribution of these elements (Fig. 2). Structural properties were studied by Raman spectroscopy. Fig. 3 presents the Raman spectra of Sm (4%)-doped SnSnO3 nanoparticles annealed at different temperatures. For sample without annealing, Raman peaks can be observed at 147 and 179 cm -1 assigned to Ag vibrational mode which is related to the Sn-O-Sn and O-Sn-O bonds, respectively. Other band located at 571 cm -1 is associated to surface defects in SnO2 nanocrystals, while the peaks at 701 and 1071 cm -1 are related to presence of SrCO3 [4]. At increased annealing temperature, intense Raman peaks at ll4 (B2g mode), 223 (Ag mode) and 257 cm -1 (Ag mode) are observed, which have been associated with orthorhombic phase of SrSnO3 [5]. On the other hand, the peaks related to SrCO3 decrease due to the annealing temperature. The PL properties of the samples were measured at room temperature, under excitation of a He-Cd laser (λ = 325 nm). Figure 4 shows PL spectra of Sm-doped SrSnO3 annealed at 1300 °C, the spectra reveal a gradual increase in the intensity of transi...
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