This article is cited in 9 papers

Ferroelectricity

Specific features of the EPR spectra of KTaO$_3$ : Mn nanopowders

I. S. Golovina^a, B. D. Shanina^a, I. N. Geifman^b, A. A. Andriiko^c, L. V. Chernenko<sup>c

a</sup> Institute of Semiconductor Physics NAS, Kiev
^b Quality Engineering Education, Inc., Buffalo Grove, USA
^c National Technical University of Ukraine "Kiev Polytechnic Institute"

Abstract: The electron paramagnetic resonance spectra of KTaO$_3$ : Mn nanocrystalline powders in the temperature range from 77 to 620 K have been measured and studied for the first time. The change observed in the spectra has been investigated as a function of the doping level. The doping regions in which Mn$^{2+}$ ions are individual paramagnetic impurities have been established, as well as the regions where the dipole-dipole and exchange interactions of these ions begin to occur. The spin-Hamiltonian constants for the spectrum of non-interacting individual Mn$^{2+}$ ions have been determined as follows: $g$ = 2.0022, $D$ = 0.0170 cm$^{-1}$, and $A$ = 85 $\times$ 10$^{-4}$ cm$^{-1}$. A significant decrease in the axial constant $D$ in the KTaO$_3$ : Mn nanopowder, as compared to the single crystal, has been explained by the remoteness of the charge compensator from the paramagnetic ion and by the influence of the surface of the nanoparticle. It has been assumed that the Mn$^{2+}$ ions are located near the surface and do not penetrate deep into the crystallites.

Received: 26.07.2011

 English version: Physics of the Solid State, 2012, 54:3, 551–558

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