The photoluminescence properties of Ba0.95−xMxB8O13:Eu3+ (M = Ca, Sr, 0 ≤ x ≤ 0.1) in 100–400 nm regions

The phosphors Ba0.95 − xMxB8O13:Eu3+ (M = Ca, Sr, 0 ≤ x ≤ 0.1) were synthesized by solid-state reaction. Their luminescent properties were studied under ultraviolet (UV) and vacuum ultraviolet (VUV) regions. The excitation spectrum of Ba0.95Eu0.05B8O13 showed that the charge transfer (CT) excitation band of Eu3+ at about 246 nm was dominated in the UV region, while two weak broad bands of the host lattice absorption with maxima at 157 and 183 nm were observed in the VUV region. The band of Ba–O absorption was overlapped with the CT band of Eu3+, which is indicated that the energy of the host lattice absorption can be efficiently transfer to the Eu3+. With the incorporation of Sr2+ into BaB8O13:Eu3+ lattice, the CT band of Eu3+ as well as the band absorption of the host lattice were enhanced. For Ca2+ co-doped BaB8O13:Eu3+, the excitation intensity was decreased, as well as the CT band showed a little blue-shift. The intense red emission located at 612 nm and the improved luminescent intensity of Eu3+ were observed when Ba2+ was replaced by Sr2+ partially in the BaB8O13:Eu3+ lattice, while the incorporation of Ca2+ ions do not show efficient luminescence and the main emission line shift to 588 nm. The shift in CT band of Eu3+ could be explained by the cation structures of borate have an influence on the electron transfer and the energy of the CT band of Eu3+ in the host lattice.