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Correlation between high-pressure ZrO2 electrical properties and crystallite size

Anna N. Trefilova 1Ilia V. Korionov 1Alexey N. Babushkin 1Witold Łojkowski 2Agnieszka Opalińska 2

1. Ural State University, Department of Physics, Lenin Av., 51, Ekaterinburg 620083, Russian Federation
2. Polish Academy of Sciences, High Pressure Research Center (UNIPRESS), Sokolowska 29/37, Warszawa 01-142, Poland

Abstract

We studied correlation between the sizes of crystallite and resistance ZrO2 at the pressures 22 - 50 GPa and temperatures 77 - 400 K. Nanocrystalline praseodymium doped zirconia powders were produced using a microwave driven hydrothermal process under pressures up to 8 GPa. Nanopowders of zirconia with Pr in solid solutions having Pr contents of 0.5 mol %. The bulk material sample of zirconia having Y2O3 contents of 5 mol %. Size of crystallites changed from 10 to 500 nm.
The dc resistance measurements were carried out in a diamond anvil cell rounded cone-plane type.
1. At a pressures of about 35 GPa the ZrO2 resistance decreases by 3-4 orders of magnitude. The temperature dependence of the resistance of the nanocrystalline samples at all pressure has activation nature (R=R0 exp(Ea/kT)).
2. The temperature dependence of the bulk material resistance (crystallite size near 500 nm) has metallike type (with positive temperature coefficient) at pressure 47 GPa and temperature 320 K.
3. For all samples at pressures 40-43 GPa take place maximums of activation energy and local maximums of resistance. It is possible to suspect existence of structure-phase transition in ZrO2 at pressure about 42 GPa.
4. The activation energy Ea and parameter R0 (bound with parameters of charge carriers) depends from crystallite size. Activation energy is between 0.1-1 eV (size 10 nm) and 0.001-0.01 eV (size 56 nm). Whereas the value of activation energy for bulk ZrO2 is approximately 0.01 eV. It is possible to suspect, that the surface effects essentially change a ZrO2 conductivity mechanism at high pressures.
This work was supported by CRDF grant REC-005 for Ural Center of Research and Education "Advanced materials" and RFBR grant 01-03-96494.

 

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Related papers

Presentation: poster at E-MRS Fall Meeting 2003, Symposium F, by Anna N. Trefilova
See On-line Journal of E-MRS Fall Meeting 2003

Submitted: 2003-05-08 10:16
Revised:   2009-06-08 12:55