Green emitting β$\ubeta$-SiAlON:Eu2+ phosphors derived from chemically modified perhydropolysilazanes

We report the first synthesis of beta-SiAlON:Eu2+ phosphors from single-source precursors, perhydropolysilazane (PHPS), chemically modified with Al(OCH(CH3)(2))(3), and EuCl2. The reactions occurring during the precursor synthesis and the subsequent thermal conversion of polymeric precursors into beta-SiAlON:Eu2+ phosphors have been studied by a complementary set of analytical techniques, including infrared spectroscopy, gas chromatography-mass spectrometry, thermogravimetry-mass spectrometry, X-ray diffraction (XRD), photoluminescence spectroscopy, and scanning electron microscopy. It has been clearly established that Al(OCH(CH3)(2))(3) immediately reacted with PHPS to afford N-Al bonds at room temperature, whereas N-Eu bond formation was suggested to proceed above 600 degrees C accompanied by the elimination of HCl up to 1000 degrees C in flowing N-2. The subsequent 1800 degrees C-heat treatment for 1 h under an N-2 gas pressure at 980 kPa allowed converting the single-source precursors into fine-grained beta-SiAlON:Eu2+ phosphors. XRD analysis revealed that the Al/Si of .09 was the critical atomic ratio in the precursor synthesis to afford single-phase beta-SiAlON (z = .55). Moreover, Eu2+-doping was found to efficiently reduce the carbon impurity in the host beta-SiAlON. The polymer-derived beta-SiAlON:Eu2+ phosphors exhibited green emission under excitation at 460 nm and achieved the highest green emission intensity at the critical dopant Eu2+ concentration at 1.48 at%.