Spectroscopic investigation and colour change of natural topaz exposed to PbO and CrO3 vapour

Chemical Analysis of Thermoluminescent Colorless Topaz Crystal Using Laser-Induced Breakdown Spectroscopy

“…Similarly, natural colorless topaz crystals from Brazil have shown better sensitivity to ultra-violet and gamma radiations compared to colored topaz crystals [6,56]. The current study suggests that the TL response of colorless topaz crystals might be due to intrinsic defects rather than the presence of impurities [3,11]. However, we cannot rule out completely the presence of impurities in concentrations less than the detection limits of the LIBS and EDX.…”

“…Natural colorless topaz is largely utilized in jewelry, and the irradiation process is commonly employed to artificially induce colors in it [2]. In the jewelry industry, artificial methods are employed to induce colors in topaz, which include (i) irradiation with neutron, electrons and gamma rays followed by low-temperature annealing, (ii) colored metal oxide coating and (iii) heat treatment in different chemical atmospheres [3,4].…”

“…High-energy TLD based on topaz crystals has been developed previously [7][8][9][10][11]. The response of fabricated TLD strongly depends on the concentration of transition metals (Ti, V, Cr, Mn, Fe, and Cu), present as impurities in the topaz crystals or intrinsic defects, such as lattice vacancies and interstitials [3,6]. The concentration of these elemental impurities defines the performance of TLD; therefore, precise measurement of these impurities is crucial.…”

Optimized conditions for cobalt diffusion in Sri Lankan colorless topaz and coloration mechanism elucidation through spectro-chemical investigation

“…In both Co treated and untreated samples, an absorption peak was observed at ~420 nm and the edge of this asymmetric broad peak extended to 680 nm. This peak has been assigned to Ocenter interaction with Al ions or due to presence of impurities of Cr, Fe and Mn [23]. The peak was remained after heating up to 950℃, thus implies its thermal stability.…”

“…Different coloration methods such as irradiation followed by heating, surface coating, surface modification, and surface diffusion have been introduced to give color to colorless topaz [5][6][7]. Among them, irradiation is the most common method used to obtain blue topaz where color centers are produced by exposing topaz either to gamma rays or neutrons or electrons, followed by low-temperature heating [8][9][10][11].…”