Photoluminescence Properties of the Magnetoplumbite-Type BaMg<sub>6</sub>Ti<sub>6</sub>O<sub>19</sub>:Mn<sup>4+</sup> and Spinel-Type Mg<sub>2</sub>TiO<sub>4</sub>:Mn<sup>4+</sup>

Mn 4+ -doped magnetoplumbite-type BaMg 6 Ti 6 O 19 and spinel-type Mg 2 TiO 4 red phosphors were synthesized by a solid-state reaction. BaMg 6 Ti 6 O 19 :Mn 4+ and Mg 2 TiO 4 :Mn 4+ were formed as main phase above 1200 oC. Although the emission peak of BaMg 6 Ti 6 O 19 :Mn 4+ and Mg 2 TiO 4 :Mn 4+ were almost the same, the excitation peak of BaMg 6 Ti 6 O 19 :Mn 4+ and Mg 2 TiO 4 :Mn 4+ were different. The 4 A 2 → 4 T 1 transition peak of Mg 2 TiO 4 :Mn 4+ shifted to a shorter wavelength side than that of BaMg 6 Ti 6 O 19 :Mn 4+ and 4 A 2 → 4 T 2 shifted to a longer wavelength side. The crystal field splitting energy of Mg 2 TiO 4 :Mn 4+ was lower than that of BaMg 6 Ti 6 O 19 :Mn 4+ . By the additional of R block, the racah parameter B increased and C decreased. Although the increase of B causes a blue-shift of the emission wavelength and the decrease of C causes a red-shift of the emission wavelength, PL emission wavelength was little different due to the influence of both racah parameter. Thus, it was suggested that the existence of R block results in a difference of photoluminescence properties.