A planetary transmission includes four planetary gearsets, two of which are simple planetary gearsets and two of which are compound planetary gearsets. Additionally, methods of forming doped and undoped polycrystalline yttrium aluminum garnet having a mean grain size of between about 1 \u03bcm to about 3 \u03bcm and the yttrium aluminum garnet produced thereby are provided. When the molten steel flow velocity is lower than an inclusion-adherence critical flow velocity of 0.