Simultaneous broadening and enhancement of Cr3+ photoluminescence in Ba3ZrTa4O15 by chemical unit co-substitution

Abstract

Long-wavelength broadband near-infrared (NIR) phosphors serve as a cornerstone for versatile NIR spectroscopy applications. However, achieving simultaneous enhancement in both bandwidth and luminescence intensity at long wavelengths remains a significant challenge. Here, we report two novel NIR phosphors, Ba₃ZrTa₄O₁₅:Cr³⁺ and Ba₃Al_0.5Ta_4.5O₁₅:Cr³⁺, both exhibiting dual luminescent centers (Cr1 and Cr2). Ba₃ZrTa₄O₁₅:0.04Cr³⁺ emits at 905 nm with a bandwidth of 239 nm under 470 nm excitation. Upon substituting Zr⁴⁺–Zr⁴⁺ with Al³⁺–Ta⁵⁺, the bandwidth increases to 290 nm (room temperature), and the luminescence intensity rises 4 fold. The enhanced luminescence intensity is attributed to lattice contraction, which not only suppresses the non-radiative transitions of Cr1 but also reduces the energy transfer distance between Cr1 and Cr2. This finding offers a new avenue for improving the performance of ultra-broadband NIR phosphors.