A novel tunable white light emitting multiphase phosphor obtained from Ba₂TiP₂O₉ by introducing Eu³⁺

Tunable white light was realized in samples Ba_2(1−x)TiP₂O₉:2xEu (x = 0–0.80) by introducing orange-red light emitting Eu³⁺ in self-activated blue-green light emitting matrix Ba₂TiP₂O₉. The sample Ba_2(1−x)TiP₂O₉:2xEu is a multiphase system consisting of Ba₂TiP₂O₉, EuPO₄ and TiO₂ when x is greater than or equal to 0.20. The tunable light from blue-green to bluish-white, to white, and eventually to pinky-white of samples Ba_2(1−x)TiP₂O₉:2xEu under UV light excitation is attributed to the light mixture of tunable blue-green light from Ti⁴⁺–O²⁻ charge transfer transition in Ba₂TiP₂O₉ and orange-red light from Eu³⁺ 4f–4f transition mostly in EuPO₄. The Commission International de l’Eclairage chromaticity coordinates, correlated color temperature and color rendering index were tuned from (0.262, 0.339), 9492 K and 74 for matrix sample Ba₂TiP₂O₉ to (0.324, 0.346), 5876 K and 87 for sample Ba_2(1−x)TiP₂O₉:2xEu (x = 0.40) under UV light excitation. Therefore, a kind of promising UV-excited white light emitting multiphase phosphor was obtained.