Dysprosium oxide ceramic arc tube for HID lamps

Polycrystalline dysprosium oxide is a candidate arc tube material for advanced metal halide lamps because of high transparency, low thermodynamic driving potentials for corrosion and reaction with the salt fills, satisfactory mechanical strength and resistance to thermal shock. This material is cubic and can be polished to achieve higher in-line transmittance than the conventional polycrystalline alumina arc tubes. Rare-earth halide fills, glass frit seals and niobium leads were used in the construction of the Dy2O3 lamps. The experimental lamps exhibited a colour temperature of ~2500 K and CRI of ~90 with rapid warm-up behaviour. The transparent Dy2O3 ceramic offers opportunities to push the limit of ceramic envelopes for improved discharge lamps.