Introduction
Light-emitting diodes (LEDs) are excellent candidates for general lighting because of their rapidly improving efficiency, durability, and reliability, their usability in products of various sizes, and their environmentally friendly constituents. Effective lighting devices can be realized by combining one or more phosphor materials with chips. Accordingly, it is very important that the architecture of phosphors be developed.

Yellow-orange oxynitride Ca-a-SiAlON: Eu2+ phosphors with the compositions of Ca0.8Si9.2Al2.8O1.2N14.8:Eu2+ were obtained via carbothermal reduction and nitridation method. The resulting phosphors can absorb light in the range of 300–500 nm efficiently and show a single intense broad emission band in the wavelength range of 500–700 nm with maximum intensity at 580–601 nm, show that they can be a candidate for warm white LEDs.
 
Using the solid-state reaction method, Ce3+,Tb3+-coactivated Si5AlON7 phosphors were successfully synthesized. The obtained phosphors exhibit high absorption and strong excitation bands in the wavelength range of 240–440 nm, matching well with the light emitting-diode (LED) chip. The phosphors show tunable emissions from blue to green by tuning the relative ratio of the Ce3+ to Tb3+ ions. Thermal quenching properties had also been investigated and the quenching temperature of Si5AlON7:Ce3+,Tb3+ is ~190°C. These results show that it could be a promising candidate for a single-phased color-tunable phosphor applied in UV-chip pumped LEDs.

Si6 -zAlzOzN8-z:xRe (z = 1, Re =Sm or Dy, 0.01≤x ≤ 0.05), were prepared by asolid-state reaction. In β-SiA lON:Sm 2+, broad 4f55d1→4f6 emission and line 5D0→7FJ emission were observed at room temperature. The characteristic 4F9/2 →6H15/2 (blue) and 4F9/2 → 6H13/2 (yellow) transitions of  Dy 3+ were detected in the emission spectra. The residual emission intensity of  Sm 2+ and Dy 3+ at 250  ℃ remains at 84% and 91% of that measured at room temperature , respectively . The high thermal stability reveals that β-SiAlON is a good candidate for high-power UV-LED chips.
  
A novel red-emitting oxonitridosilicate phosphors, Sr2SiNzO4-1.5z:Eu2+, which exhibited broad-band red emission centred at 620 nm under blue light irradiation with a high QE value of 78.0% and good thermal stability, allow it to be an attractive red luminescent material for white LEDs.
 
Color tunable LaCaAl3O7:0.05Ce3+,yTb3+ (LCA:0.05Ce3+,yTb3+) phosphors were synthesized by solid state reaction. The luminescence spectra and the lifetime were investigated in detail. Results confirm that Tb3+ can substitute all La3+ sites without impure phase, and cause luminescence spectra shifting to longer wavelength. Besides, an efficient energy transfer with efficiency over 80% from Ce3+ to Tb3+ was found in the LCA host. Through this efficient energy transfer process, the hues of obtained phosphors changed from blue-white to green light. The results demonstrate its potential of applying in white light-emitting diodes.
 
Y3Al5O12:0.06Ce3+, xMn2+  (YAG:0.06Ce,xMn) phosphors have been synthesized and the effect of different charge compensators on the color adjustment has been investigated for the first time. The results show that Si4+ as charge compensator  exhibits the best tunable effect on controlling the Mn2+ emissions in YAG:0.06Ce, xMn. In Si4+-Mn2+ co-doped samples, the emission color can be tuned from greenish-yellow to red with increasing the content of Mn2+.
 
Eu3+ doped NaSr2Nb5O15 series were firstly synthesized by solid-state reaction method. It exhibits strong absorption in near ultraviolet-blue region and intense red emission with CIE chromaticity coordinates (0.638, 0.355) after adding the charge compensation agent upon 398 nm excitation. The integral intensity of NSN:0.03Eu3+, 0.03Li+ is 64.5% of the commercial Y2O3:Eu3+ and the qu antum efficiency is calculated to be 41.5%. The results show that it can be a promising red-emitting phosphor for white LEDs.

A new chlorogermanate compound Ca8Mg(GeO4)4Cl2 (CMGC) was synthesized via high-temperature solid-state reaction for the first time. The results show that the absorption spectra of CMGC:Eu2+ phosphors cover from 250 to 500 nm, the emission spectra show blue-green (centered at 425 and 510 nm) and green (centered at 510 nm) emission, respectively. These indicated that CMGC:Eu2+ phosphors had a potential application use for white light-emitting diodes.