Low Temperature Physics: 30, 908 (2004); https://doi.org/10.1063/1.1820022 (4 pages)
Fizika Nizkikh Temperatur: Volume 30, Number 11 (November 2004), p. 1209-1213 ( to contents , go back )
Nonequilibrium processes and ferroelectric phase transition in PbGeTe(Ga)
B.A. Akimov1, V.V. Pryadun1, L.I. Ryabova2, E.I. Slynko3, D.R. Khokhlov1, and V.I. Shtanov2
1The Moscow State University М.В. Lomonosov Faculty of physics , Moscow, 119992, Russia
2The Moscow State University М.В. Lomonosov Chemical Faculty , Moscow, 119992, Russia
3Chernovtsy branch of institute of problems of semi-conductor materiology NAS Ukraine, street. I.Vilde, 5, Chernovtsy, 274001, Ukraine
Received May 25, 2004
The impedance of PbTe(Ga) and
Pb1–xGexTe(Ga) single crystals (0 ≤ x ≤ 0.095) is studied in a 102–106 Hz frequency at temperatures varied from 4.2 to 300 K. The temperature dependences of capacitance for the Pb1–xGexTe(Ga) samples display two peculiarities.
These are a pronounced maximum at T = Tp responsible for by the dielectric anomaly at the ferroelectric phase transition and an increase in capacitance at T < 100 K which shows a strong frequency dependence. The low-temperature effect amplitude decreases monotoneously with increasing
frequency, f, and at f > 105 Hz the effect
almost disappears. The contribution to the capacitance at such low frequences may be associated
with the recharging in the impurity subsystem. The experimental value of Tp turned out to be much higher than the characteristic temperatures of the onset of long-term relaxation
processes, in particular, the delayed photo-conductivity. Hence, the change of the charge states in the impurity subsystem is not followed by thedielectric anomalies of the whole crystal lattice, and the rearrangement of the lattice is local.