Elaboration and characterization of new phosphate glasses based on natural phosphate and red clay: influence of the chemical composition on the chemical durability

Abstract

<jats:p>New phosphate glass formulations based on Moroccan natural phosphate minerals alone or with Moroccan red clay additive (containing the P2O5-SiO2-CaO-Al2O3-MgO-Fe2O3-K2O-Na2O-TiO2 complex) have been successfully prepared by the quenching method. The chemical composition of each of the elaborated phosphate glasses was determined by X-ray fluorescence analysis (XRF). These investigated phosphate glasses have an excellent homogeneity as was verified by SEM. Their amorphous behavior was confirmed by XRD and DSC. The increase in density and glass transition temperature due to the addition of clay is believed to be related to the crosslinking of the phosphate chains. Structural investigation of these phosphate glasses was carried out using FTIR and Raman spectroscopies. The results obtained show that the composition of these glasses contains a mixture of ultraphosphate and polyphosphate structural units. The concentrations of this mixture depending on the initial composition of the glass components. A correlation between the chemical composition and the chemical durability of the investigated glasses was studied. The results showed that the dissolution rate of the glasses decreases by increasing the clay composition up to a point. This can be explained by assuming the formation of oxygen bridges and strong bonds within the various glasses.</jats:p>

Effect of Eu3+ and Tb3+ ions concentration on the mechanical, structural, and photoluminescence properties of phosphate glass fibers

“…In this case, the two non-bridging oxygen (NBO) atoms easily connect to a phosphorus atom in the chain metaphosphate (Q 2 ). The absorption bands shown at 1103 and 996 cm − 1 correspond to the asymmetric ʋ as (PO 3 ) and symmetric ʋ s (PO 3 ) stretching vibrations due to PO 4 tetrahedra containing 2 and 3 NBO atoms, respectively [1,28,29]. These two bands are characteristic of the chain end groups (Q 1 ).…”

“…The vibrational bands around 1231 and 1184 cm − 1 are attributed to asymmetric ʋ as (PO 2 ) and symmetric ʋ s (PO 2 ) stretching, respectively [1,26,27]. In this case, the two non-bridging oxygen (NBO) atoms easily connect to a phosphorus atom in the chain metaphosphate (Q 2 ).…”

“…Phosphate glasses (PGs) are easy to produce and have great advantages due to their special properties that include high UV transparency, low infrared transparency, low melting temperature point, high thermal expansion, low dispersion, and regarded as better hosts for lanthanide ions (Ln 3+ ) [1][2][3]. It is well known that the luminescence properties of rare-earth ions (RE ions) result from their electronic structure [Xe] 4f n 5d 2 6s 1 . When these ions are inserted into a glassy network, the most stable and predominant oxidation state is trivalent and the 5d and 6s electronic layers are empty [4].…”