IC die and/or IC die packages including capacitors with a pyrochlore-based insulator material. The pyrochlore-based insulator material comprises a compound of a species A and a species B, each comprising one or more rare earths or metals. In the pyrochlore-based insulator material, oxygen content is advantageously more than three times and less than four times the amount of either of species A or B with crystalline pyrochlore phases having the composition A2B2O7. Within a capacitor, the pyrochlore-based insulator may be amorphous and/or may have one or more crystalline phases. The pyrochlore-based insulator has an exceedingly high relative permittivity of 50-100, or more. The pyrochlore-based insulator material may be deposited at low temperatures compatible with interconnect metallization processes practiced in IC die manufacture as well as IC die packaging.