Thermal effects on the surface plasmon resonance of Cu nanoparticles in phosphate glass: impact on Cu⁺ luminescence

Abstract

A joint in situ absorption and photoluminescence spectroscopy study exposes the effect of temperature on copper nanoparticles in phosphate glass and their influence on Cu+ luminescence.

Monovalent copper-mediated UV to NIR luminescence down-shifting in Yb3+-doped glass

“…This appears to be an overestimation if compared to the Cu NPs that have been observed in the glass system without Yb 3+ by transmission electron microscopy (TEM) with an average diameter of about 2.5 nm. 27 However, it should be pointed out that the X-ray beam illuminates an area of the sample orders of magnitude larger than that imaged by TEM, which may explain the higher average particle size obtained by the XRD analysis. Nonetheless, both the optical absorption (Fig.…”

“…2, which is the surface plasmon resonance (SPR) characteristic of Cu NPs. 21,25,27,30,34 The relatively narrow SPR peak and position observed indicate the presence of small non-interacting spherical Cu NPs. 27,34 Therein, the abrupt increase in absorption toward the short wavelength region is due to the 3d → 4sp interband transitions in copper having a threshold of around 2.1 eV (∼590 nm).…”

“…26 On the other hand, a red-shift in emission towards the orange has been attributed to octahedrally coordinated monovalent copper for a range of excitation wavelengths within 300–400 nm. 26 Furthermore, the reduction and clustering of copper into NPs is induced by subsequent HT 25,27 as considered above. Accordingly, in Fig.…”

“…Given the occurrence of a reducing agent tin( ii ) in the matrix, subsequent heat treatment (HT) leads to the reduction of Cu + ions and the precipitation of Cu NPs as shown in previous studies. 21,25,27 Herein, a Cu nanocomposite was obtained by heat-treating the CuYb glass at 500 °C (somewhat above the glass transition temperature, T g , but well below the glass crystallization temperature, T g , vide infra ) for a duration of 5 h; this is referred to as the CuYb-HT glass (photographs of some samples are shown in Fig. S1 of the ESI†).…”

High-Temperature Diffusion of Cu2+ Ions into Natural Plagioclase Crystals: The Role of Li2O

“…The valence shell structure of Cu is 3d 10 4s 1 ; therefore, the valence of Cu can exhibit 0, +1, and +2; nevertheless, controlling the chemical valence state of Cu is complicated . Different valence states of copper dispersed in crystals can show different properties, such as the fluorescence of Cu + , , the fascinating color of Cu 2+ in natural minerals, − and the localized surface plasmon resonance (SPR) of Cu 0 nanoparticles, − so the research of this aspect is very promising. However, there is currently no method to achieve the diffusion of Cu 2+ into plagioclase crystals.…”