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Lead selenide (PbSe) quantum dots (QDs) doped with Sr 2 + were precipitated in silicate glasses. The absorption and photoluminescence (PL) bands of the glasses blue-shifted as SrO concentration increased. These changes resulted mainly because Sr incorporation increased the band gap of PbSe nanocrystals. After heat treatment at 520 °C for 10 h, mean QD diameters were similar before and after the addition of SrO: ~ 7.2 nm with 0% SrO and ~ 6.9 nm with 10 mol% SrO. However, these two glasses show the absorption bands at 1743 nm and 1246 nm, and PL bands at 1803 and 1370 nm, respectively. These large shifts are due to the increase in the band gap through the formation of Pb 1 − x Sr x Se mixed-type QDs. One typical chemical composition of QDs formed in a glass with 10 mol% SrO after heat treatment at 520 °C for 10 h is Pb 0.89 Sr 0.11 Se with a band gap of ~ 0.58 eV. [ABSTRACT FROM AUTHOR]

The influence of Nd3+ ions was investigated on the precipitation and optical properties of PbS quantum dots ( QDs) inside silicate glasses. The diameters of the PbS QDs decreased as the concentration of Nd3+ in the glass increased as evidenced by blue shifts in the absorption and photoluminescence spectra. Electron energy loss spectroscopy shows that Nd3+ ions exist preferentially inside the PbS nanocrystals rather than in the glass matrix. We postulate that Nd-O clusters are preserved during heat treatment and serve as nucleation sites for PbS crystals. No change in the local bonding scheme of the Nd3+ ions was observed following heat treatment. [ABSTRACT FROM AUTHOR]

Formation of PbS QDs in the glasses containing a small amount of lead oxide was examined. Oversaturation of sulfur only was sufficient to promote the formation of PbS QDs in the glasses. Upon thermal treatment, absorption of PbS QDs was tuned from 824nm to 2213nm. Infrared photoluminescence, especially, mid-infrared photoluminescence from PbS QDs was observed in the range of 1008nm to 2182nm. Ostwald ripening of PbS QDs occurred when the heat-treatment temperature was 530°C or 540°C, and led to the decrease in the absorption coefficients and splitting of the photoluminescence bands. [ABSTRACT FROM AUTHOR]

PbS QDs of ~ 5nm diameter were precipitated in glasses containing Ag nanoparticles after 3 min of 1.5-W continuous-wave laser illumination at λ = 532 nm. Photoluminescence spectra of the PbS QDs recorded in the 1.3~1.6 μm wavelength region revealed conversion of photon energy to thermal energy by surface plasmon resonance. Laser-assisted local heating around Ag NPs can provide a new method to control the spatial distribution of QDs in glasses. [ABSTRACT FROM AUTHOR]

Abstract: Heat-treatment was used to precipitate PbS quantum dots (QDs) in silicate glasses doped with different amounts of Ag2O, and the influence of Ag2O on QDs was investigated. Under given heat-treatment conditions, the absorption coefficients and photoluminescence intensities of PbS QDs increased with the addition of Ag2O. Ag clusters formed by thermal treatment nucleated formation of PbS QDs in glasses. [Copyright &y& Elsevier]

PbSe quantum dots (QDs) were precipitated in borosilicate glasses, and effects of B 2 O 3 content on the optical properties of glasses were investigated. The diameters of the PbSe QDs in glasses increased from 3.70 nm to 7.32 nm as [B 2 O 3 ] increased from 10 mol% to 20 mol% even when all glasses were heat-treated at 460 °C for 10 h. Photoluminescence (PL) peaks extended to wavelengths of 2154 nm when B 2 O 3 content increased to 20 mol%. The viscosities η of glasses at 460 °C decreased significantly with the addition of B 2 O 3 i.e., 2.86 × 10 13 Pa·s at [B 2 O 3 ] = 0.0% to 1.94 × 10 11 Pa·s at [B 2 O 3 ] = 20%. These decreases in η led to a large increase in the diffusion of ions in glass matrix including Pb 2 + and Se 2 − that facilitated the precipitation and growth of PbSe QDs in glasses. These results demonstrate that the wavelength of PL emissions by QDs can be controlled by manipulating the composition of the host glass. [ABSTRACT FROM AUTHOR]

Abstract: The size and spatial distribution of PbS QDs in glasses need to be controlled in order to achieve desired optical characteristics. This paper reports on the use of several rare-earth oxides such as Ho2O3, Er2O3, and La2O3 to control the size of PbS QDs in silicate glasses. Additions of rare-earth oxides result in blue shifts of the absorption bands from 1344nm to 930nm, and the wavelengths of PL bands can be controlled between 1421nm and 1035nm. Additions of up to 0.8mol% of Ho2O3 decreased the diameters of PbS QDs from 4.82nm to 3.02nm. The same tendencies were found for both Er2O3 and La2O3 additions, although the size of PbS QDs increased as the ionic radius of rare-earth ions increased. It is proposed that clusters of RE–O bonds act as nucleating agents for the precipitation of PbS QDs. [Copyright &y& Elsevier]