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Electrical Characteristics of Dielectrics and Semiconductors at High Pressures in Diamond Anvil Cell

Alexey N. Babushkin 1G. Babushkina 2O. A. Ignatchenko 1

1. Ural State University, Department of Physics, Lenin Av., 51, Ekaterinburg 620083, Russian Federation
2. Russian Academy of Sciences, Ural Division, Institute of Metal Physics, 18 S.Kovalevskaya str., GSP-170, Ekaterinburg 620219, Russian Federation


1. Peculiarities of application of the diamond anvil cell (DAC)
"rounded cone - plane" for study of the electrical characteristics
dielectrics and semiconductors at superhigh pressures.
Measurements have carried out with use of the DAC "rounded cone -
plane"(Verechagin - Yakovlev) type have made from synthetic
polycrystalline "carbonado" - type diamonds. Peculiarities of use
of DAC of such type and the estimations of generated pressures are
in detail described in previous works also are considered in the
2. Results of alkali halides research. Transition in a state with
activation type conductivity. Metallization. Alterity of
metallization pressures and structural transformations pressures.
The alkali halides pressures and temperatures dependencies have
shown, that in all investigated materials at pressures more than
20 GPa the transition in state with high activation type
conductivity is observed. The increase of pressure results in
change of character of resistance temperature dependencies. It
becomes typical to state with free carriers of a charge. The
carriers of a charge concentration in these condition is typical
to semimetals or degenerate semiconductors. The metallization
pressures do not coincide with structural transformations
pressures. The connection of transformations pressures with alkali
halides crystallochemical features is shown.
3. Results of semiconductors research. Metallization. Irreversible
changes, pressure induced amorphisation. Effect of chemical
We analyse the results of experimental investigation's cadmium and
zinc chalcogenydes and oxides resistivity and thermoEMF at wide
pressures (15 - 50 GPa) and temperatures (77 - 400 K) ranges. We have
found out, that the transition reversibility (after pressure
treatment) is connect with the initially structure (sphalerite or
wurtzite) and anion--cation distance (at normal pressures). After
pressure treatment the reversible transitions detected if the
cation--anion distance at normal pressures higher then 0.26 nm. In
other cases after high pressure treatment irreversible electrical
characteristics and colour changes take place.
4. New results: relaxation effects in dielectrics at superhigh
We investigated electrophysical properties (electroconductivity,
dielectric permittivity and loss angel) alkali halides and sulfur on
an alternating current at high pressures. Frequency dependencies of
electroconductivity, capacitivity and loss tangent measurements have
been carried out in the frequency interval 100 Hz - 100 kHz at
pressures from 20 up to 50 GPa and room temperature. In frequency
dependencies of a loss tangent have found out maximums in the
frequency interval 10-100 kHz what probably connected with energy
absorption features.


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Related papers

Presentation: oral at High Pressure School 1999 (3rd), by Alexey N. Babushkin
See On-line Journal of High Pressure School 1999 (3rd)

Submitted: 2003-02-16 17:33
Revised:   2009-06-08 12:55