UVB emitting phosphors based on singly and co-doped Ce3+, Gd3+ in Li4ZrF8 phosphors

[Display omitted] •Hydrothermal synthesis of phase pure Li4ZrF8.•Efficient luminescence of Ce3+ and Gd3+.•Gd3+ emission Due to Ce3+ → Gd3+ energy transfer.•Narrow line emission at 311 nm suitable for targeted phototherapy. Preparation of Li4ZrF8:Ce3+ and Li4ZrF8:Ce3+,Gd3+ phosphors is described. Data on luminescence characteristics are presented. Hydrothermal route was employed for the synthesis. Li4ZrF8 crystallizes in orthorhombic system with Pnma space group. Li atoms are distributed over two sites, both having same coordination of six. Zr is also similarly distributed over two 8 coordinated sites. Li4ZrF8:Ce3+ emits a broad band UVB light, while the emission of Li4ZrF8:Ce3+,Gd3+ is in form of a narrow line around 311 nm attributed to 6P7/2 → 8S7/2. Both phosphors exhibited a broad excitation spectrum with a peak at 253 nm. The excitation and emission properties are thus adequate enough to obtain UVB light sources using a conventional high pressure mercury vapour lamp or an ultraviolet LED.