High purity gadolinia / Trace impurities / RNAA / INAASummary. Extensive use of gadolinia for different high technology applications such as infrared absorbing automotive glass, petroleum cracking catalyst, gadolinium-yttrium garnets and color TV tube phosphors requires a precise characterization of the material. A radiochemical neutron activation analysis (RNAA) procedure has been employed to investigate 16 trace impurities in high purity gadolinia. RNAA procedure enhanced the sensitivity of the technique. The concentrations of trace impurities ranged from 20 ng/g to 34 µg/g. The impurity contents were found to be low; therefore, their deleterious effects would be negligible.