This paper reports a novel application of electron paramagnetic resonance (EPR) to the detection of the thermal decompositions of MnO4-4and the CrO42- doped into (NH4)2SO4 and LiNH4SO4 crystals. By heating the sample crystals to temperatures well below the dissociation temperature or the high-temperature structural phase transition temperatures, isolated Mn2+and Cr3+ are detected by EPR. By a comparative study, one can conclude that the thermal decomposition of MnO4- into Mn2+ or of CrO42-into Cr3+, is accomplished through a solid-state chemical reaction between the thermally-excited ammonium hydrogens and the permanganate or the chromate oxygens. It can be inferred that the ammonium hydrogens participating in the thermal decomposition process are mainly the "free" protons released by the ammonium groups.
ASJC Scopus subject areas
- 化學 (全部)