Electron Paramagnetic Resonance of the Thermally-Produced Mn^2+ in Single Crystals of NH4Cl Doped with MnO4^-

周深淵(Shen-Yuan Chou) ； 余健治(Jiang-Tsu Yu)

《Chinese Journal of Physics》 29卷3期 (1991/06) Pp. 253-262

並列摘要

The thermal dissociation of MnO4^- into Mn^2+ in NH4Cl single crystals has been studied by electron paramagnetic resonance (EPR). This thermal dissociation is accomplished through a chemical reaction in the single-crystal state between the thermally excited permanganate oxygens and the ammonium hydrogens. The EPR spectrum of the thermally-produced Mn^2+ shows axial symmetry, with the symmetry axis pointing parallel to one of the cubic axes of the host crystal lattice. A minority of this Mn^2+ shows an EPR spectrum similar to that shown by the doped Mn^2+; this Mn^2+ is located at an interstitial site at a face center, surrounded by four coplanar chlorine ions and two H2O molecules located at the symmetry axis. The majority of this thermally produced Mn^2+ shows a slightly larger zero-field splitting than the minority Mn^2+. The majority Mn^2+ is also located interstitially at a face center, coplanar with four chlorine ions and collinear with one H2O molecule and one NH4^+ group located at the symmetry axis.