Structural, electrical and optical studies on AgI-anatase composites

AgI-anatase composites, (x)AgI-(l - x)anatase, were fabricated over a wide composition range of 0-100% AgI for the first time. The electrical conductivity at 300 K increases with increasing AgI content and reaches a maximum (about 3 x 10(-2) S m(-1)) at about 40% AgI. The conductivity is enhanced by about three orders of magnitude in comparison with that of pristine AgI. These composite specimens have been characterized by both scanning electron microscopy and x-ray diffractometry. The observations with a scanning electron microscope show that anatase fine particles are densely packed in an AgI particle of several micrometres in size and such composite particles are three-dimensionally connected to each other to form a composite specimen. The photoluminescence (PL), PL excitation and time-resolved PL spectra of these composites have also been measured at different temperatures between 8 and 278 K. The exciton spectra obtained related to the anatase particles and the AgI domains in anatase-packed AgI particles are discussed in the light of the morphological, structural and conductivity data.