✍ Scribed by Sushil K. Misra; Mojtaba Kahrizi; Stephan Z. Korczak
No coin nor oath required. For personal study only.
EPR spectra of a single crystal of MnZ' -doped calcium cadmium acetate hexahydrate (CaCdAH), as well as those of a single crystal of Cu"-doped deuterated compound calcium cadmium acetate hexadeuterate (CaCdAD), were recorded in the extended range of temperature between room and liquid-helium temperatures for CaCdAH, and between room and liquid-nitrogen temperatures for CaCdAD. The temperature dependences of these spectra revealed the occurrence of only one phase transition in each of Mn'+ -doped CaCdAH and Cu'+-doped CaCdAD crystals, at 146 + 0.5 K and 132 2 0.5 K, respectively. Replacement of protons in a Cu2' -doped CaCdAH crystal by deuterons changed the phase transition temperature (T) of the resulting crystal, Cu*' -doped CaCdAD, only by 2 K, indicating that the protonsideuterons are not instrumental in the occurrence of the phase transition. However, the impurity ions play an important role in the occurrence of phase transitions in that the replacement of the paramagnetic impurity MnZi by CuZ' in CaCdAH modified 7'c significantly, i.e. by 16 K. The spin-Hamiltonian parameters for Mn " in CaCdAH, as well as those for Cuzi in CaCdAD crystals, were evaluated at various temperatures, using a rigorous least-squares procedure, fitting simultaneously all resonant line positions recorded for several orientations of the external magnetic field. The absolute signs of the Mn*' spin-Hamiltonian parameters in CaCdAH were determined from the relative intensities of lines at liquid-helium temperature.
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