Abstract
Hydrothermal treatment of an equimolar mixture of Ni(OH)2 and γ-MnOOH in a 1 N-NH4OH solution gave a new compound NiMnO2(OH). The reaction temperature and pressure were 200°C-320°C and 100 MPa, respectively. SEM photographs showed that the compound had a characteristic rectangular shape and the size of particles was around 5μ×0.1μ×0.1μ. I.R. spectrum and powder X-ray diffraction pattern of the compound were also shown. By calcinating the compound in air atmosphere, it decomposed to a ferromagnetic NiMnO3 of illmenite structure near 350°C and further to Ni1.5Mn1.5O4 of spinel structure above 800°C. TG and DTA data were also given. This is the first case when a ferromagnetic NiMnO3 was obtained under the normal atmospheric pressure.
