Fourth Polymorph of MnOOH; δ-MnOOH

Abstract

Existence of the fourth polymorph of MnOOH was affirmed. The compound was synthsized by bubbling air into the suspension of amorphous MnO₂ at room temperature, where pH value was around 6. The compound was an antiferromagnet (T_N=58.5K) and dehydrogenized to β-MnO₂ at 270°C.