The temperature dependences of the nuclear-electric-quadrupole frequency vQ of 117In doped in LiTaO3 (TC5938 K) and Li12xInx/3TaO3 with x50.2 (TC5818 K) show that the order-disorder of the Li ions is not the driving mechanism for the ferroelectric instability in LiNbO3 and LiTaO3 systems, and imply that the oxygen order-disorder is the driving mechanism. The significantly different temperature dependences of vQ of 111Cd in these materials compared, to those of 117In, demonstrate that this order-disorder is of dynamic character.
Mechanism of the ferroelectric phase transitions in LiNbO3 and LiTaO3
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SC-YOKOYAMA-A-PRB2002e052107.pdf
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