A novel green-emitting phosphor Na4Zr2Si3O12:Eu2+ for unimodal sensing and light-emitting diodes

Temperature sensors typically use dual-rare-earth-doped dual-emission phosphors. Here, an innovated single-emission green phosphor Na₄Zr₂Si₃O₁₂: xEu²⁺ is proposed, which has the characteristics of simple structure and high temperature sensitivity. Under 325 nm excitation, the Na₄Zr₂Si₃O₁₂: xEu²⁺ phosphor exhibits a broad green emission peak at 512 nm. Na₄Zr₂Si₃O₁₂: xEu²⁺ phosphors show asymmetrical emission peaks due to the fact that Eu²⁺ occupies two types of Na₁ and Na₂ in different environments. The energy transfer between Eu²⁺ belongs to the dipole-dipole interaction. In particular, the unimodal emission characteristics of Na₄Zr₂Si₃O₁₂: xEu²⁺ phosphor under near-ultraviolet (NUV) excitation give it a unique advantage in unimodal sensing applications, with an absolute sensitivity of 0.00738 K^-1 (300 K–425 K). The color saturation (Rg) of green LED device prepared with 365 nm ultraviolet chips can reach 96.2, and the related color temperature (CCT) is 6074K. Moreover, the phosphor has stable weather resistance after 72 h of storage at 85 °C and 85 % humid heat and water environment, and the luminous intensity is maintained at 83.6 % and 82.1 % at room temperature. These characteristics indicate that Na₄Zr₂Si₃O₁₂: xEu²⁺ phosphors have important application value in the field of fluorescent lighting and temperature sensing technology.