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A series of Sm3+-doped La3Si6N11phosphor materials were synthesized by a high temperature solid-state reaction method. The crystal structure, microstructure, photoluminescence properties, decay curves as well as thermal quenching properties of the as-prepared phosphors were investigated systematically. The excitation spectra contain a wide asymmetric band below 350 nm originating from the host absorption, several sharp excitation peaks in the range of 300–550 nm corresponding to f-f transition of Sm3+. Under the excitation of 369 and 414 nm light, the phosphors exhibit strong narrow-band orange-red emission peaked at 605 nm. The average decay time of La2.99Si6N11:0.01Sm3+sample is fitted to be 0.38 ms and the CIE coordinates were calculated to be (0.6105, 0.3833). For water resistance, La3Si6N11:Sm3+is better than K2SiF6:Mn4+phosphor. After soaking in deionized water for 300 min, the La3Si6N11:Sm3+sample retains approximately 80% of its initial relative emission intensity. When the temperature rises to 423 K (150 °C), the emission intensity of La2.99Si6N11:0.01Sm3+sample remains 85% in comparison to that of room temperature. The activation energy was calculated to be 0.63253 eV, which is higher than those of Sm3+-activated oxide phosphors, indicating that the phosphor has relatively good thermal stability.

As a binary system of BaO-Lu2O3-SiO2ternary system, Lu2O3-SiO2system was optimized and calculated by CALPHAD approach based on available phase diagram and relevant thermodynamic data of RE2O3-SiO2(RE=Lu, Yb, Y) binary systems as well as our experimental data of Lu2O3-SiO2system obtained by quenching experiment. The Gibbs free energy of high temperature solution was described by an ionic two-sublattice model as (Lu3+)P(O2–, SiO20)Q. The calculated phase diagram below 1873 K was in good agreement with experimental data at 1573, 1773 and 1873 K. The calculated Gibbs energies of two intermediate phases Lu2SiO5and Lu2Si2O7, the activity of Lu2O3and SiO2and specific heat capacities of intermediate phases agreed well with experimental results of Y2O3-SiO2system. This tentative study will offer help for the research of single-phase phosphor and related metallurgical slags, refractories, high-temperature superconductivity material systems.

To further understand the energy loss mechanism of the “charge transfer process” that was proposed in our previous work on Eu2+-Mn2+co-doped phosphors, the influence of synthetic temperature and heating time on the photoluminescence (PL) behavior of M5(PO4)3Cl:Eu2+,Mn2+(M=Ca, Sr) phosphors was investigated by analyzing their PL spectra and decay curves. For the Ca phase, an increase in the synthetic temperature resulted in an increase in the loss from the “charge transfer process” since more Eu2+ions were involved in the Eu2+-Mn2+clusters. This was contrary to the thermodynamic expectation. To solve this contradiction, we proposed that the formation of Eu2+-Mn2+clusters was kinetically blocked at lower synthetic temperatures. With an increase in heating time for the phosphors synthesized at lower temperature (such as 1100 °C) the PL intensity decreased, which supported the above assertion.