Year: 2007
Type: article
Abstract: Using electron spin resonance (ESR), the lattice position and dynamic properties of ${\mathrm{Mn}}^{2+}$ ions were studied in 0.5 and $2\phantom{\rule{0.3em}{0ex}}\mathrm{at.}\phantom{\rule{0.2em}{0ex}}%$ manganese-doped $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$ ceramics prepared by the conventional mixed oxide method. The measurements show that ${\mathrm{Mn}}^{2+}$ ions preferably (up to 97%) substitute for the Sr if the ceramics are prepared with a deficit of Sr ions. Motional narrowing of the ${\mathrm{Mn}}^{2+}$ ESR spectrum was observed when the temperature increased from $120\phantom{\rule{0.3em}{0ex}}\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}240--250\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, which was explained as a manifestation of the off-center position of this ion at the Sr site. From the analysis of the ESR spectra, the activation energy ${E}_{a}=86\phantom{\rule{0.3em}{0ex}}\mathrm{mV}$ and frequency factor $1∕{\ensuremath{\tau}}_{0}\ensuremath{\approx}(1--5){10}^{13}\phantom{\rule{0.3em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$ for the jumping of the impurity between symmetrical off-center positions were determined. Both are in agreement with those previously derived from the dielectric relaxation. This proves that the origin of the dielectric anomaly in $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}:\mathrm{Mn}$ is produced by the reorientation dynamics of ${\mathrm{Mn}}^{2+}$ dipoles.
Source: Physical Review B
Language: Latvian
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2000281464