The origin of bimodal luminescence of β-SiAlON:Eu2+ phosphors as revealed by fluorescence microscopy and cathodoluminescence analysis

• Bimodal emission is originated from β-SiAlON grains with z ≥ 2.
• Coexistence of two kinds of emission centers in the β-SiAlON phase is definite.
• Fluorescence microscopy shows influence of the z value on emission of β-SiAlON.

Eu2+-doped SiAlON phosphors with the composition of EuxSi6−zAlzOzN8−z (0.5 ≤ z ≤ 3) at a fixed x = 0.01 were synthesized by the gas pressure sintering method. Dependence of luminescence properties on the phase compositions in β-SiAlON:Eu2+ phosphors has been examined via fluorescence microscope and scanning electron microscope equipped with a cathodoluminescence spectrometer and an energy dispersive spectrometer. Bimodal emission (green and violet) from β-SiAlON phase is observed in the samples with z ≥ 2, indicating co-existence of two different kinds of coordination for Eu2+ ions in the host lattice.

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