Sintering aid mixture, solid-state ion conductor, and method for producing solid-state ion conductors

A sintering aid mixture comprising a sintering precursor selected from a group consisting of a sol-gel precursor, a sol-gel direct precursor prepared from the sol-gel precursor, and any combinations thereof to provide a sol-gel preliminary product and/or a sol-gel, wherein the sol-gel precursor comprises at least one organometallic compound selected from the group consisting of an alkoxide, an acetate, and any combination thereof, and a compact including at most 15% of the sintering aid mixture that when compacted achieves a densification at a sintering temperature at least 5% lower than the same compaction without the sintering aid mixture and has a conductivity increase of a factor of at least 1.5 as compared to the same compaction without the sintering aid mixture.