Rakhimbekov AZ
Zhetysu State University. I.Zhansugurov, Kazakhstan
 Impurity disordered crystals.

Impurity disordering occurs in ionic crystals doped with their ions with a valence different from the main valence ion. In most cases, the formation of solid solutions of the type of substitution occurs when the impurity ion is located at the lattice site of the basic compound. At sufficiently low concentrations of such impurity ions can be seen against the background of the lattice as a primary connection point defects (defects of substitution), attributing to them the defective charge equal to the absolute value of the difference between the basic and the valences of the impurity ions. [1].

Electroneutrality condition requires that the excess charge impurities in solid solution was offset by a charge of any defects of opposite sign.
In solid electrolytes charge is compensated by one of its own kinds of ionic defects (interstitial ions or vacancies), specific to the compound in a pure state, so the type of compensating defects is closely linked to the nature of their own disorder in the lattice of the basic compound: a) solid solutions with high valence impurity cations (the simplest example of this type of solid electrolytes - KCl), and b) solid solutions with low impurity cation valence (halides of alkaline earth elements). [2]

Their electrical conductivity usually increases with increasing concentration of monovalent cations, due to increasing concentration of anion vacancies to compensate the lack of charge impurities.

We consider dioxide Zr (ZrO₂), clean Zr oxide at a temperature below 2000 degrees Celsius are available in two versions - the monoclinic and tetrogonalnoy. The third modification, cubic, stable in pure oxides at very high temperatures to stabilize the entire temperature range with the addition of divalent and trivalent cations. Conditions of its existence depends on many factors, including the technology for the sample. The ionic conductivity of solid oxide electrolytes such as stabilized ZrO₂ is almost entirely due to vacancies O₂.

Changes in the density of solid solutions ZrO₂ - Y₂O₃ confirm vacancy model. Defect structure of solid electrolytes with impurity disorder of not reliably controlled impurity content and will greatly depend on the way in the history of the sample preparation. Effect of heat treatment especially pronounced due to the processes of ordering defects in solid solutions [3].

The transformation of the order-disorder were especially studied for systems ZrO₂ - Y₂O₃.With prolonged firing stabilized ZrO₂ samples at 900⁰-1000 ° C in X-ray superstructure lines appear, which in many cases can not be attributed to either the tetragonal or monoclinic ZrO₂.This changes the mechanical properties of the samples, and the electrical conductivity decreases by 1.5 - 2 times, and at even fligelnyh firing - even an order of magnitude [4].

When heated to a temperature of 1200° C, the sample is returned to its original state.Ordering in such a system exists up to the boiling point [5-6]:
- At high temperatures (1800 ° C or above (to melt)) has not finished ordering in the anion sublattice between the oxygen ions and vacancies. Oxygen ions are displaced from their sites, Zr and Y cations are disordered with each other, each surrounded by a deformed polyhedron O₂;

- At medium temperatures (1100 - 1200 ° C) is the ordering of the oxygen polyhedra. This ordering occurs within small areas that are growing in the processing of roasting;

- At temperatures below 1100 ° C, the slow order in the cation sublattice.
In our paper we attempt to study the electrical properties of solid ionic crystals based on stabilized zirconia in the temperature range 800 - 900 ° C.

Literature

1. Chandra S. Superionic Sol., North-Holland, 1981. 885 p.

2. Phys., Superionic Conductors / ed. M. B. Salamon, Springer - Verlag, Berlin-Heidelberg-New York, 1979. 364 p.

3. Ukshe EA Bukun NG Solid electrolytes. Moscow: Nauka, 1977. 146 s.

4. Chebotina VN, MV Perfiliev Electrochemistry of solid electrolytes. Khimiya, 1978. 345.

5. Godin JG, VG Baranov AU 669863 (USSR), 1979.

6. Andreev, VN, Timoshenko NE, FA Chudnovsky Report thesis VI - Second International Conference on Crystal Growth, Moscow, 1980.