Strong ultraviolet luminescence from cerium- and gadolinium-doped cubic boron nitride

Cubic boron nitride has been successfully activated by Gd³⁺ and Ce³⁺ and routinely fabricated under high pressure-high temperature conditions as micropowders, ceramic samples and polycrystalline compacts when doped with appropriate Ce or Gd compounds. Strong UV photoluminescence under 244 and 325 nm laser excitation from the Gd- and Ce-doped cBN is found to be stable over the temperature range of 7-300 K. A remarkable feature in the 244 nm excited spectrum of the Gd-doped ceramic and polycrystalline samples is strong and relatively sharp emission peaking at 315.4 nm assigned to ⁸S_7/2-⁶ P_7/2 electronic transitions of the Gd³⁺ ions. A very strong bright and blue-colored photoluminescence is observed from the Ce-doped cBN resulting from two structured bands peaking at ~390 and ~290 nm that is ascribed to electronic transitions of the Ce³⁺ ion coupled with lattice vibrations of cBN. Efficient emitters have been created with broad bands in the UVB (280-315 nm) and UVA1 (340-400 nm) regions of the electromagnetic spectrum.