Sol–gel synthesis and photoluminescence of AlP nanocrystals embedded in silica glasses

AlP nanocrystals embedded in silica glasses were prepared via an easy sol–gel process. The gels synthesized by the hydrolysis of a complex solution of Si(OC2H5)4, Al(NO3)3 · 9H2O and PO(OC2H5)3 were heated at 600 °C for 10 h in an air atmosphere to form an Al2O3–P2O5–SiO2 gel glass. The gel glasses were then heated in the presence of H2–N2 mixed gas, in which the P(V) are reduced by the H2 gas, and react with Al(III) to form fine cubic AlP crystallites embedded in silica glasses. The X-ray diffraction patterns showed (1 1 1), (2 2 0), and (3 1 1) diffraction lines from cubic AlP crystals. The AlP (2 2 0), (3 1 1), (4 2 2), and (4 4 0) diffraction lines were observed in the electron diffraction pattern. The size of AlP nanocrystals was found to be from 5 to 10 nm in diameter by transmission electron microscopy. A strong room temperature photoluminescence (PL) with peaks at 533, 582, 649, and 688 nm was observed from AlP/SiO2 nanocomposites. The PL is suggested to originate from the hydrogen-related species (PL band at 533 nm), the small “peroxy radical” (PL band at 582 nm), and the nonbridging oxygens (PL bands at 649 and 688 nm), respectively.