Dynamical properties of <sup>119</sup>Sn in crystalline SnI<sub>4</sub> investigated by the Mossbauer effect
I Heilmann; N B Olsen; I Heilmann; Phys. Lab. I, HC Orsted Inst., Univ. of Copenhagen, Copenhagen, Denmark; N B Olsen; Phys. Lab. I, HC Orsted Inst., Univ. of Copenhagen, Copenhagen, Denmark
Журнал:
Journal of Physics C: Solid State Physics
Дата:
1977-05-28
Аннотация:
The intensity I of the <sup>119</sup>Sn Mossbauer line in SnI<sub>4</sub> was measured from 100K to 300K at atmospheric pressure and at 200K at a pressure of 2 kbar. At low temperatures, the slope delta of lnI versus temperature is independent of temperature. Applying a Debye model with rigid motion of the SnI<sub>4</sub> molecules, one obtains an unusually low value of the Debye temperature ( theta =49K) which, however, is confirmed by ultrasonic measurements (57K). Above 170K, an increasing deviation from linearity of lnI versus temperature is observed. Furthermore, at higher pressure, a large increase of the Mossbauer intensity at 200K is observed. These two observations indicate that volume changes strongly influence the lattice dynamics. They are explained by a quasiharmonic model using a Gruneisen parameter equal to gamma =4+or-1.5.
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