Exploring structural and optical properties of CLSO:Dy for ultra-sensitive luminescent thermometers and high-bright screen printing

Abstract

Herein, a novel scheme is employed to develop ultra-sensitive luminescent thermometers and high-bright luminescent inks for screen printing. We synthesize CaLa₄Si₃O₁₃ (CLSO):Dy³⁺ by a traditional high-temperature solid-phase method and accurately predict its radiation properties using Judd–Ofelt (J–O) theory. On this basis, Eu³⁺ or Tb³⁺ ions with different radii are introduced into CLSO:Dy³⁺ to modify the crystal structure rigidity. The activation energies of CLSO:Dy³⁺, Dy³⁺/Eu³⁺, and Dy³⁺/Tb³⁺ samples are calculated to be 0.256 eV, 0.315 eV and 0.289 eV, respectively, which demonstrate that Eu³⁺ or Tb³⁺ enhances the structural stiffness, and thus, improves the thermal stability of materials. Simultaneously, the Debye temperature and thermal expansion coefficients as valuable parameters for structural stiffness also confirm the above-mentioned results. Furthermore, we propose a strategy in which the multiplication of LIRs based on multiple emission peaks with opposite thermal quenching properties follow a Boltzmann-type distribution, resulting in a dramatically increased relative sensitivity of CLSO:Dy³⁺, Dy³⁺/Eu³⁺, and Dy³⁺/Tb³⁺ thermometers to 2.92% K⁻¹, 3.32% K⁻¹ and 3.19% K⁻¹, respectively. This work not only provides valuable insights into the development of superior temperature sensitive materials but also develops optical anti-counterfeiting technology based on screen printing.