A semiconductor material for radiation absorption and detection comprising a composition of stoichiometry Li(M12+, M22+, M32+, . . . )(G1V, G2V, G3V, . . . ) and exhibiting an antifluorite-type order, where Li=1, (M12++M22++M32++ . . . )=1, and (G1V+G2V+G3V+ . . . )=1. The material provides two useful characteristics: [1] a high Li-site density, which when enriched in 6Li, produces exceptional neutron-absorbing capabilities and [2] a semiconducting band-gap for the efficient conversion of absorbed photon and neutron energies into electrical currents. These characteristics can be exploited in applications for power generation or the spectroscopic detection of gamma and neutron radiation. The material can be tailored so as to detect only gamma photons, detect only neutron particles, or simultaneously detect gamma photons and neutron particles.