Provided herein are rapid, high quality film sintering processes that include high-throughput continuous sintering of lithium-lanthanum zirconium oxide (lithium-stuffed garnet). The instant disclosure sets forth equipment and processes for making high quality, rapidly-processed ceramic electrolyte films. These processes include high-throughput continuous sintering of lithium-lanthanum zirconium oxide for use as electrolyte films. In certain processes, the film is not in contact with any surface as it sinters (i.e., during the sintering phase).