We report the first synthesis of β-SiAlON:Eu 2+ phosphors from singlesource precursors, perhydropolysilazane (PHPS), chemically modified with Al(OCH(CH 3 ) 2 ) 3 , and EuCl 2 . The reactions occurring during the precursor synthesis and the subsequent thermal conversion of polymeric precursors into β-SiAlON:Eu 2+ 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(CH 3 ) 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 • C accompanied by the elimination of HCl up to 1000 • C in flowing N 2 . The subsequent 1800 • C-heat treatment for 1 h under an N 2 gas pressure at 980 kPa allowed converting the single-source precursors into fine-grained β-SiAlON:Eu 2+ phosphors. XRD analysis revealed that the Al/Si of .09 was the critical atomic ratio in the precursor synthesis to afford singlephase β-SiAlON (z = .55). Moreover, Eu 2+ -doping was found to efficiently reduce the carbon impurity in the host β-SiAlON. The polymer-derived β-SiAlON:Eu 2+ phosphors exhibited green emission under excitation at 460 nm and achieved the highest green emission intensity at the critical dopant Eu 2+ concentration at 1.48 at%.

We report the synthesis of β-SiAlON:Eu 2+ phosphors from novel single source precursors in which strictly controlled chemical composition is established at molecular scale. The two-step synthesis occurs by the chemical modification of perhydropolysilazane (PHPS) with Al(OCH(CH 3 ) 2 ) 3 and AlCl 3 in xylene at room temperature to 140 °C to introduce Al in the PHPS network while controlling the oxygen content followed by the reaction of EuCl 2 with the Al-modified PHPS upon heat-treatment. Gas chromatography-mass spectrometry and thermogravimetry-mass spectrometry analyses revealed that PHPS reacted with Al(OCH(CH 3 ) 2 ) 3 and AlCl 3 via the formation of Al-N bonds. Moreover, AlCl 3 reacted with nitrogenbonded Al alkoxide residue to release 2-chloropropane in an analogy to the non-hydrolytic sol-gel reaction between metal alkoxide and metal chloride. Subsequently, AlCl 3 acted as a Lewis acid catalyst to promote the Friedel-Craft alkylation between xylene solvent and the 2-chloropropane formed in-situ to afford dimethylcumene. On the other hand, EuCl 2 reacted with silylamino moiety to form Eu-N bonds at around 850 °C. β-SiAlON:Eu 2+ phosphors were successfully synthesized by pyrolysis of the precursors under flowing N 2 or NH 3 at 1000 °C, followed by heat treatment at 1800 °C for 1 h under a N 2 gas pressure at 980 kPa. The polymer-derived β-SiAlON:Eu 2+ (z = 0.55, Eu 2+ 0.37 at%) exhibited green emission under excitation at 410 or 460 nm, and the green emission intensity under the excitation at 410 nm was found to be increased by reducing the carbon and chlorine impurities through the polymer-derived ceramics route investigated in this study.

A proposed reaction scheme for in situ controlled low-temperature formation of metallic-Co at the early stage of pyrolysis of perhydropolysilazane (PHPS) coordinated with CoCI2.

A series of β‐SiAlON:Eu2+ phosphors were synthesized from single‐source precursors, perhydropolysilazane chemically modified with Al(OCH(CH3)2)3, AlCl3, and EuCl2. The single‐source precursors were converted to β‐SiAlON:Eu2+ phosphors by pyrolysis under flowing N2 or NH3 at 1000°C, followed by heat treatment at 1800°C under an N2 gas pressure at 980 kPa. By varying the molar ratio of the chemical modifiers, β‐SiAlON:Eu2+ with the compositions close to the theoretical ones expressed as Si6−zAlzOz−2yN8−z+2y:yEu2+ were synthesized, where the z values and Eu2+ contents were controlled in the ranges of .44–.78 and .35–1.48 mol%, respectively. The polymer‐derived β‐SiAlON:Eu2+ phosphors exhibited green emission under excitation at 460 nm attributed to the 4f7–4f6(7f3)5d1 transition of dopant Eu2+. High‐angle annular dark‐field‐scanning transmission microscopy analysis confirmed that the doped‐Eu2+ existed interstitially within the channels along the c axis of host β‐SiAlON. Compared with the conventional powder metallurgy route, the polymer‐derived ceramic route in this study offers some advantages in the grain growth of host β‐SiAlON and photoluminescence properties in terms of green emission intensity under excitation at 460 nm, and the highest intensity was achieved for the polymer‐derived β‐SiAlON:Eu2+ with z = .64 and .37 mol% Eu2+.