A-Lab reported the synthesis of six perovskite-or ilmenite-derived structures: Ba 2 ZrSnO 6 (F m 3m, perovskite), MgTi 2 NiO 6 (R3, Ilmenite), KBaGdWO 6 and KBaPrWO 6 (F 43m, double perovskite), as well as Ba 6 Na 2 Ta 2 V 2 O 17 and Ba 6 Na 2 V 2 Sb 2 O 17 (P 6 3 /mmc, perovskite derivatives). However, our analysis suggest that the powder patterns of these samples more likely correspond to a doped and known perovskite/ilmenite phase mixed with some impurity phases. We will elaborate on this with two detailed examples. We would also like to point In the case of Ba 2 SnZrO 6 , the output of the refinement process, as published in the A-lab paper, contains many significant unmodelled diffraction peaks. Our fit is shown below. We are able to account for all obvious Bragg peaks, and the residuals that remain are characteristic of incorrect peak profiles rather than completely unmodelled diffraction features.