Er³⁺-Doped Soda-Lime Silicate Glass: Artificial Pink Gemstone

Abstract

Er³⁺-doped soda-lime silicate glasses of the composition (in mol%) (65-x)SiO₂:25Na₂O:10CaO:xEr₂O₃ (where x = 0, 1, 2, 3, 4 and 5) were fabricated by conventional melt quenching technique. The physical and optical properties were measured and investigated. The erbium oxide enters the glass network as a modifier by occupying the interstitial space in the network and generating the NBOs to the structure. The molar volume increases with an increase in Er₂O₃ content, which is attributed to the increase in the number of Non-Bridging Oxygen (NBOs). The increase of NBOs in the structure generally leads to an increase in average atomic separation. The density, molar volume and refractive index of glasses increased linearly with increasing Er₂O₃ concentration. The color of glasses was changed from light pink to intense pink as the Er₂O₃ concentration was increased from 1 to 5 mol%. The Vickers hardness of Er³⁺-doped glasses was found to be in the range of 450-500 HV. In this study, it can be concluded that the soda-lime silicate glasses doped with high Er₂O₃ concentration has intense pink color and high value of hardness which is suitable to be cut as gems.