Extensive attention has been focused toward studies on inexpensive and rare-earth-free garnet-structure vanadate phosphors, which do not have a low optical absorption due to the luminescence color being easily controlled by its high composition flexibility. However, bluish emission phosphors with a high quantum efficiency have not been found until now. In this study, we successfully discovered bluish-white emitting, garnet structure-based LiCaMVO (M = Zn and Mg) phosphors with a high quantum efficiency, and the detailed crystal structure was refined by the Rietveld analysis technique. These phosphors exhibit a broad-band emission spectra peak at 481 nm under near UV-light excitation at 341 nm, indicating no clear difference in the emission and excitation spectra. A very compact tetrahedral [VO] unit is observed in the LiCaMVO (M = Zn and Mg) phosphors, which is not seen in other conventional garnet compounds, and generates a bluish-white emission. In addition, these phosphors exhibit high quantum efficiencies of 40.1% (M = Zn) and 44.0% (M = Mg), respectively. Therefore, these vanadate garnet phosphors can provide a new blue color source for LED devices.

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The Al doped Sr2Si5N8:Eu2+ single crystal Sr2AlxSi5−xOxN8−x:Eu2+ (x ≈ 0.7) were grown by our original single crystal growth method and the precise crystal structure was investigated by single crystal X-ray diffraction analysis for the first time. O atoms are partially substituted for only N1 and N5 sites which are connected with the Si/Al atoms to compensate the “Pauling’s second rule”, which indicates the introduction of Al atoms for Si sites restricts the N sites that can be substituted by O atoms. The Sr2AlxSi5−xOxN8−x:Eu2+ (x ≈ 0.7) phosphors show the change of site selectivity of Eu for Sr sites, which causes the red-shifted emission spectrum of Sr2AlxSi5−xOxN8−x:Eu2+ (x ≈ 0.7) than that of Sr2Si5N8:Eu2+.

2 ], the La atom is coordinated by eight O atoms of two acetylacetonate (acac) anions acting as bidentate ligands, two water molecule as monodentate ligands, one nitrate anions as a bidentate ligand and one N atom of an imidazolate (ImH) molecule as a monodentate ligand. Thus, the coordination number of the La atom is nine in a monocapped square antiprismatic polyhedron. There are three types of intermolecular hydrogen bonds between ligands, the first involving nitrate-water OÁ Á ÁH-O interactions running along the [001] direction, the second involving acac-water OÁ Á ÁH-O interactions along the [010] direction and the third involving an Im-nitrate N-HÁ Á ÁO interaction along the [100] direction (five interactions of this type). Thus, an overall one-dimensional network structure is generated. The molecular plane of an ImH molecule is almost parallel to that of a nitrate ligand, making an angle of only 6.04 (12) . Interestingly, the ImH plane is nearly perpendicular to the planes of two neighbouring acac ligands.