Chemical tunability of europium emission in phosphate glasses

Abstract

International audienceIn this study the correlation between bulk chemistry and optical properties for a set of Eu-bearing phosphate glasses, containing different alkali elements, synthetized in air and under NH3 flux, was investigated. The chemistry of the glass strongly influences several properties and the effects of bulk chemistry and synthesis conditions on glass structure and on thermal and optical properties are discussed. In alkali-phosphate glasses studied by absorption and photoluminescence spectroscopy we verified that Eu2+ emission band shifts toward higher wavelengths by substituting the alkali cation (Na<NaK<K). Nitridation enhances the glass stability and the synthesis approach carried out enhances the presence of reduced Eu species, producing modifications both on the position and on the broadening of Eu2+ luminescence band. The glass emission tunability is extremely related to the bulk composition and it is possible to adjust the chemistry in order to get the desired lighting in phosphate glasses. (C) 2016 Elsevier B.V. All rights reserved

Europium-Doped Tellurite Glasses: The Eu2+ Emission in Tellurite, Adjusting Eu2+ and Eu3+ Emissions toward White Light Emission

“…The emission of Eu 2+ is almost constant and centered at ≈413 nm when compared with data reported for alkali phosphate excited using the same excitation wavelength [49], it was found to be lower in our case. A relationship between optical basicity and Eu 2+ emission was proposed for phosphate, silicate, and borate glasses [35,49,50]; however, the current results show that tellurite glasses do not follow this relationship. Indeed, with an optical basicity almost double compared to silicates and phosphate, the Eu 2+ emission in tellurite is at almost the same position.…”

Red‐ and green‐emitting nano‐clay materials doped with Eu3+ and/or Tb3+

“…This can also been observed from the CIE color coordinate diagram (CCD) (Figure ). The 5 D 0 → 7 F 2 transition is very sensitive to the local environment around Eu 3+ and its higher intensity in comparison with the 5 D 0 → 7 F 1 indicates that Eu 3+ does not occupy sites with symmetry inversion. In order to understand better the occupied site, the emission parameters Ω 2 and Ω 4 were calculated as reported in the literature using an average index of refraction equal to 1.5.…”

Review: Elaboration, structure, and mechanical properties of oxynitride glasses

“…3,73 The resulting glasses usually are transparent, and it should be noted that the nitrogen content increases with increasing temperature. 41,42,53,[74][75][76] Nevertheless, glasses turn black if the ammonolysis temperature is too high because of a reduction reaction of the phosphorus oxides. 71,73,77…”

“…In the case of phosphorous oxynitride glasses, which were first reported in the early 1980s by Marchand, 71 phosphate salts such as NaPO 3 and LiPO 3 , 34,42,47,71,92,93,94 ammonium phosphates, 53,95 phosphoric acid 45 as well as phosphate oxide glasses are used as starting materials. Under NH 3 flowing gas, the threefold coordinated N 3− anions may subsequently result in the following oxidation reaction: $$$$\begin{equation} {\mathrm{N}}^{3-}\stackrel{}{\longrightarrow}\frac{1}{2}\;{\mathrm{N}}_{2}\nearrow +3\;{\mathrm{e}}^{-} \end{equation}$$$$which confers a reducing character to the oxynitride liquid that may promote the reduction of cations such as copper or silver to metals.…”

“…M-P-O-N glasses are usually synthesized either via the ammonolysis route for large batches (to be dis-cussed later on) [41][42][43][44][45][46][47] or via sputtering for thin films, 48 with nitrogen content up to 33.5 e/o or even slightly higher, although it is unsure if glasses richer in nitrogen are of the same nature. 46,49 They are promising materials as solid-state electrolytes due to their strong ionic conductivity and chemical durability, especially the Li-P-O-N system.…”