Bi2TeO5 as a novel material for ionizing radiation detection

Bismuth tellurite, Bi2TeO5 (BTeO), has been mainly used as photorefractive material. Since it has adequate properties such as high density (7.91 g/cm³) and high radiation absorption coefficient (7.96 cm²/g at 50 keV) we studied BTeO as a possible material for ionizing radiation direct detection. Crystals were grown by the double crucible Czochralsky method using seeds oriented in the <001> direction. Detectors were made evaporating Au for rear and front contacts; Pd wires of 0.003″ and 0.001″ in diameter were attached to the metal contacts using Ag or C conductive ink. Guard rings were used in order to study possible leakage currents. Dark current properties and response to radiation from ²⁴¹Am and ^99mTc were measured. A dark current density of 42.5 pA/cm², and a resistivity of 7.5×10¹³Ω.cm were obtained for a representative detector assembled with Au contacts, Ag ink and 0.001″ Pd wire, at 2940 V/cm. The mentioned detector yieldeda sensitivity to gamma rays from ²⁴¹Am of 87 nC/R.cm² at the electric field previously mentioned. From these preliminary results, BTeO arises as a new material for ionizing radiation detection, and opens interesting possibilities in this field.