Phase transitions in K2Mn2(SO4)(3) langbeinite

We have grown new K2Mn2(SO4)(3) langbeinite crystals and investigated the p hase transitions by ESR and specific heat measurement in these crystals. Al though the growing condition is the same as previous one, we observed more than one phase transitions in the crystals of one batch of harvest. The cry stals of another batch of harvest show definitely only one phase transition at 195 K. The crystals which show several transitions are quite sensitive to the heat treatment, and, in some cases, indicate too many anomalous peak s. However, even for such crystals, if the crystals are once,heat treated a t 250 degrees C, the crystals seem to transform to one which shows only one transition at 195 K. Therefore the crystal which shows singletransition is considered to be more stable than the other ones.