INVESTIGATION OF THE EFFECT OF HETEROVALENT SUBSTUTION OF ELECTROPHYSICAL PROPERTIES OF FE, LI SUBSTITUTED BY MG SPINEL BY THE METHOD OF IMPENDANCE SPECTROSCOPY
Keywords:
spinel, impedance, conductivity, ferroelectric , activation energy.Abstract
By the method of impedance spectroscopy investigated electrophysical properties of ceramics of unstoichiometrical composition (). A change of dielectric properties and conductivity on an alternating current from composition and temperature determined for a frequency range 10−2 − 105Hz. Determined that for all synthesized samples are characteristic two mechanisms of conductivity: activation (T=523−723К) and intermitting (T=293−473К) for that energies of activating form 0,79еВ and 0,10еВ, accordingly. In case of intermittent mechanism the increase of concentration of ions conduces to gradual decrease of energy activation conductivity, that is related with increase of amount of the cations of vacancies caused by deviation from stoichiometry. Hopping of electrons in this case from cation to cation will be mediated through intermediate positions on vacancies. For unsubstituted and poorly substituted (х=0,1) samples was found aberrant behavior of temperature dependences of actual part of dielectric conductivity that is characteristic for substances in the ferroelectric state.
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