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Intramolecular and Lattice Dynamics in V_{6-n}^{IV}V_ n^V O_7(OCH_3)_{12} Crystal

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Yablokov Y., Augustyniak-Jabłokow M., Borshch S., Daniel C., Hartl H.

Acta Physica Polonica A

2005

vol. 108

issue 2

271-281

Multi-nuclear mixed-valence clusters V_4^{IV}V_2^VO_7(OCH_3)_{12} were studied by X-band EPR in the temperature range 4.2-300 K. An isotropic exchange interactions between four V^{IV} ions with individual spin S_i=1/2 determine the energy levels structure of the compound with the total spin states S=0, 1, and 2, which are doubled and split due to the extra electron transfer. The spin-Hamiltonian approach was used for the analysis of the temperature dependences of the EPR spectra parameters and the cluster dynamics. Two types of the electron transfer are assumed: the single jump transfer leading to the splitting of the total spin states by intervals comparable in magnitude with the exchange parameter J≈100-150 cm^{-1} and the double jump one resulting in dynamics. The dependence of the transition ratesν_{tr} on the energy of the total spin states was observed. In particular, in the range 300-220 K theν_{tr} ≈0.7×10^{10} cm^{-1} and below 180 K the ν_{tr}≈1×10^{10} cm^{-1} was estimated. The g-factors of the spin states were shown to depend on the values of the intermediate spins. A phase transition in the T-range 210-180 K leading to the change in the initial V^{IV} ions localization was discovered.

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1 Acta Physica Polonica A

1 2005

1 Augustyniak-Jabłokow M.

1 Borshch S.

1 Daniel C.

1 Hartl H.

1 Yablokov Y.

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Intramolecular and Lattice Dynamics in V_{6-n}^{IV}V_ n^V O_7(OCH_3)_{12} Crystal