We have synthesized Ca2Si5N8：Eu^2＋ phosphor through a solid-state reaction and investigated its structural and luminescent properties. Our Rietveld refinement of the crystal structure of Ca1.9Eu0.1Si5N8 reveals that Eu atoms substituting for Ca atoms occupy two crystallographic positions. Between 10 K and 300 K, Ca2Si5N8：Eu^2＋ phosphor shows a broad red emission band centred at -1.97 eV-2.01 eV. The gravity centre of the excitation band is located at 3.0 eV 3.31 eV. The centroid shift of the 5d levels of Eu^2＋ is determined to be -1.17 eV, and the red-shift of the lowest absorption band to be - 0.54 eV due to the crystal field splitting. We have analysed the temperature dependence of PL by using a configuration coordinate model. The Huang-Rhys parameter S = 6.0, the phonon energy hv = 52 meV, and the Stokes shift △S = 0.57 eV are obtained. The emission intensity maximum occurring at -200 K can be explained by a trapping effect. Both photoluminescence （PL） emission intensity and decay time decrease with temperature increasing beyond 200 K due to the non-radiative process.
This paper investigates the effect of growth temperature on morphology, structure and photoluminescence （PL） of Tb-doped boron nitride （BN） films grown by magnetron sputtering, and the relationships of growth-temperature- structure-PL by scanning electron microscopy, transmission electron microscopy and PL. The characteristic emission lines of the Tb^3＋ were observed in the PL spectra at room temperature. The 473-K-grown film is mainly consisted of amorphous BN particles. With the growth temperature increasing up to 1273 K, the amount of amorphous BN decreases, while the amount of turbostratic BN increases. Correspondingly, the PL intensities from the Tb^3＋ ions increase with the increase of temperature in the range of 473 1273 K.
