Phonons rocksalt-structure

Both A - and Ei-modes are Raman and IR active. The two nonpolar E2-modes E and E are Raman active only. The Bi-modes are IR and Raman inactive (silent modes). Phonon dispersion curves of wurtzite-structure and rocksalt-structure ZnO throughout the Brillouin Zone were reported in [106-108]. For crystals with wurtzite crystal structure, pure longitudinal or... 

The T-point optical phonons of a crystal with rocksalt structure belong to the irreducible representation... 

The phonon mode frequencies of wurtzite- and rocksalt-structure Mg Zni- O thin films vs. x, as obtained by combination of Raman scattering and IRSE, are plotted for 0 < x < 1 in Fig. 3.13. 

Fig. 3.13. Phonon-mode frequencies of wurtzite-structure PLD-grown Mg Zni- O thin films with Ai-symmetry (panel a, triangles) and Fi-symmetry (panel b, triangles), and of rocksalt-structure PLD-grown Mg Zni- O thin films (circles in both panels) vs. x [43,62,72,74], Open and solid symbols represent TO- and LO-modes, respectively. The dashed lines are linear approximations of the rocksalt-structure phonon modes from [74], the solid lines represent MREI calculations for the wurtzite-structure phonon modes redrawn from [132]. The shaded area, marks the composition range, where the phase transition occurs. Reprinted with permission from [74]...

Fig. 3.15. Phonon mode broadening parameters of PLD-grown rocksalt-structure MgzZni-zO thin films on sapphire. Reprinted with permission from [74]...

Figure 7. Bulk phonon dispersion curves for KBr and RbCl in their <100> and <111> high-symmetry directions. Both crystals have fee lattices and rocksalt structures. Note that the transverse branches, labeled TA (transverse acoustic) and TO (transverse optical), are doubly degenerate in these directions. (Adapted from Fig. 3 of Ref. 32.)...

Since the Raman effect in these rocksalt structures measures the weighted phonon density of states, it is desirable to compute this entity. Cclio et al. (1981) used an 8 parameter shell model with defonnable ions in the spirit of Bilz et al. (1979). They decomposed the density of states into a T breathing part and a quadrupolar deformability of the Se ion. The parameters were adjusted u.sing the lattice constant, the... 

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