Used in the production of optical glasses with high refractive indices and low dispersion, making them suitable for lenses and prisms in cameras, microscopes, and telescopes. Acts as a dopant in semiconductor materials, particularly in chalcogenide glasses used in infrared detectors and fiber optics. Employed in some types of catalysts for oxidation reactions in chemical synthesis. Investigated for use in thermoelectric materials due to its electronic properties, potentially useful in energy conversion devices. Also found in certain types of acoustic devices because of its piezoelectric characteristics when doped or combined with other materials.