Nanocrystalline (HoxY1−x)2Ti2O7 luminophores for short- and mid-infrared lasers.

We present a versatile sol–gel approach for low-phonon nanocrystalline (Ho_xY_1−x)₂Ti₂O₇, x = <0.01, 0.40> exhibiting luminescence within the spectral range 2000–3000 nm. The nanocrystalline structure of (Ho_xY_1−x)₂Ti₂O₇ was studied and the effect of the composition and phonon energy on the luminescence properties was evaluated. Regular distribution of Ho³⁺ ions inside the pyrochlore crystal lattice was proved leading to a regular increase of the unit cell parameter. The luminescence intensity recorded at 2025 nm reached a maximum for the composition (Ho_0.03Y_0.96)₂Ti₂O₇. The radiative lifetime recorded at 2025 nm regularly decreased with increasing content of Ho³⁺ ions inside the pyrochlore lattice from 6.32 to 0.22 ms. The phonon energy of the samples was smaller than 700 cm⁻¹ allowing the luminescence spectral range to be extended up to 2900 nm. Further tailoring of the chemical composition can improve the emission at 2860 nm providing a promising high thermally and chemically stable alternative to conventional fluoride or chalcogenide glasses. Highlights: We present a versatile sol–gel approach to preparing (Ho_xY_1−x)₂Ti₂O₇x = <0.01, 0.40>. The content of Ho³⁺ ions in the lattice has a major impact on the luminescence properties. The optimal content of Ho³⁺ ions to maximize the luminescence intensity is identified. Low phonon energy of (Ho_xY_1−x)₂Ti₂O₇ allows the radiative transition at 2860 nm to be activated. [ABSTRACT FROM AUTHOR]