•Coefficients of thermal expansion of LSO in a wide temperature range were revealed.•CTEs of LSO along axes a, b, and c are arranged in decreasing order.•Anisotropy relationship between CTE and crystal structure has been discussed.Coefficients of thermal expansion (CTEs) of oriented LSO:Ce using I2/a setting along axes a, b, and c were measured by push-rod dilatometer in the temperature range of 28–1500 °C. Results show that CTE of LSO:Ce in the temperature range 28–1500 °C (and also to 2100 °C) lies in the range of 5 × 10−6 °C−1–11 × 10−6 °C−1. CTEs of LSO:Ce in axes a, b, and c crystallographic directions are functions of temperature and arranged in decreasing order, showing that the strength of chemical bonds along axes a, b, and c should be arranged in increasing order.

In this paper, monovalent cation Li1+ co-doped Lu0.79−xSc0.2Ce0.01LixBO3 (x = 0, 0.005, 0.01, 0.03, 0.05) polycrystal samples were prepared and a series of methods (such as X-ray excited luminescence, diffuse reflectance, fluorescence decay, X-ray Absorption Near Edge Structure (XANES), thermoluminescence, photoluminescence emission and excitation spectra) was used to comprehensively investigate its co-doping effects. It was found that Li co-doping may play a negative role: introducing more point defects and additional color centers (such as Ce4+ and oxygen vacancy). Furthermore, the increase in the number of traps in the vicinity of luminescence center Ce3+ ions will induce the competition absorption of excitation energy with the luminescence centers, and hence deteriorate the luminescence properties.Highlights► Li1+ co-doping does not change the luminescence mechanism of Lu0.79Sc0.2Ce0.01BO3. ► Part of Ce3+ in Li1+ co-doping Lu0.79Sc0.2Ce0.01BO3 samples has been converted to higher valance ion Ce4+. ► Li1+ co-doping deteriorates the luminescence properties of Lu0.79Sc0.2Ce0.01BO3.