Luminescence Properties of (Sr[sub 1−u]Ba[sub u])Si[sub 2]O[sub 2]N[sub 2]:Eu[sup 2+], Yellow or Orange Phosphors for White LEDs, Synthesized with (Sr[sub 1−u]Ba[sub u])[sub 2]SiO[sub 4]:Eu[sup 2+] as a Precursor

Luminescence properties and formation process of , phosphors suitable for white light-emmitting (LEDs), were investigated. These phosphors were synthesized by a method using as a precursor instead of simple oxides. Compared with a conventional solid-state reaction method, this method provides increased luminescence efficiency. X-ray diffraction analysis has indicated that transformation of low-temperature type to high-temperature type, which has a higher luminescence efficiency, occurs with a higher probability when is used as a precursor. Under excitation, shows an emission band peaked at for varied Ba fraction u . This series of materials shows the high integrated photoluminescence intensity at . Particularly, at , it shows the highest quantum output, which is about 1.2 times as high as that of the commercial yellow phosphor, , P46-Y3. The internal quantum efficiency is estimated to be about 80% for samples of and 0.75. The high efficiency and small thermal quenching allow these materials to be applied to white LEDs.