Structural, thermal and broadband NIR emission properties of Nd³⁺/Pr³⁺/Ag NPs co-doped tellurite glass

Abstract

Nd³⁺/Pr³⁺ co-doped tellurite glasses containing metallic Ag NPs were synthesized by melt-quenching and heat-treating techniques. The amorphous structural nature, fundamental vibrational units and good thermal stability of the prepared tellurite glasses were confirmed by X-ray diffraction (XRD) pattern, Raman spectrum and differential scanning calorimeter (DSC) curve, respectively. The precipitated Ag NPs in a glass matrix with an average diameter ∼5 nm were revealed by transmission electron microscopy (TEM) image, and the radiative property of Nd³⁺ and Pr³⁺ ions was evaluated from the absorption spectrum by Judd-Ofelt theory. Under the excitation of 488 nm Xenon lamp, two broadband near-infrared emissions covering 800-1100 nm and 1250-1650 nm ranges were observed from the fluorescence spectrum. The former originated from the transitions of Pr³⁺:³P_1,0→¹G₄, Pr³⁺:¹D₂→³F_4,3, Nd³⁺:⁴F_3/2→⁴I_11/2 and Nd³⁺:⁴F_3/2→⁴I_9/2, while the latter was contributed by the Pr³⁺:¹G₄→³H₅, Pr³⁺:¹D₂→¹G₄, Pr³⁺:³F₃→³H₄ and Nd³⁺:⁴F_3/2→⁴I_13/2 transitions. With the introduction of Ag NPs, the emission intensity of two broadband near-infrared emissions was further enhanced, in which the peak emission intensity of 1250-1650 nm band was increased by about 56% and the FWHM is up to 250 nm. The obtained results indicate that Nd³⁺/Pr³⁺/Ag NPs co-doped tellurite glass has great potential in realizing ultra-broadband near-infrared emission covering O-, E- and S-bands simultaneously.