| Summary: | The shielding and spectroscopic properties of Pr<sup>+3</sup> and Pr<sup>3+</sup>/Ho<sup>3+</sup>-codoped tellurite glass were investigated. The intensity parameters (Ω2 = 3.24-, Ω4 = 1.64-, Ω6 = 1.10 × 10<sup>−20</sup> cm<sup>2</sup>) as well as the radiative lifetimes of <sup>3</sup>F<sub>4</sub> + <sup>5</sup>S<sub>2</sub> and <sup>5</sup>I<sub>6</sub> excited states of Ho<sup>3+</sup> ions were equal to 301 μs and 3.0 μs, respectively. The former value appears to be much higher than that obtained from the lifetime measurement, indicating the presence of various energy transfer processes. The NIR spectrum of Pr<sup>3+</sup>/Ho<sup>3+</sup>-co-doped tellurite glass is dominated by strong Ho<sup>3+</sup>: <sup>5</sup>I<sub>6</sub> emission at around 1200 nm, being the result of the energy transfer from Pr<sup>3+</sup> to Ho<sup>3+</sup> ions. The shielding effectiveness of the prepared glasses showed good performance against high-energy photons. These findings suggest that the prepared glasses could be used in laser technology such as photodynamic therapy (PDT) treatment procedures and as shielding for radiation protection.
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