抄録
Optical phonons of the ferroelectric-semiconductor Zn1-xLixO ceramics have been studied for several Li-concentrations as a function of temperature by using a micro-probed Raman scattering. With Li-doping, the Raman peak position of the A1(z) mode at 380 cm-1 shifts to a lower frequency side while the E2 mode at 437 cm-1 does not show the Li-dependence. The generalized force constant of A1(z) mode is obtained as a function of Li-concentration. The Li-dependence of the Raman peak positions are well explained by the change of electronic bonding force between nearest two atoms. Because the drastic phonon anomaly was not observed, it suggests that the ferroelectric-phase transition in Zn1-xLixO is caused by the electronic effect rather than by the ionic instability. In addition, it is found that the Raman peak position is proportional to the lattice constant in the wide temperature region.
