Trepakov, V A and Savinov, M and Zelezny, V and Pokorny, J and Syrnikov, P and Azzoni, C B and Galinetto, P and Mozzati, M C and Badalyan, A and Deyneka, A and Jastrabik, L (2007) Dielectric permittivity in weakly concentrated SrTiO3:Mn crystals and ceramics. Journal of Physics: Conference Series, 93 . 012017 (6pp).
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Official URL: http://stacks.iop.org/1742-6596/93/012017
Dielectric permittivity ε + iε'' (100 Hz – 1 MHz) supplemented by IR (20 – 650 cm−1) reflectivity and Micro-Raman spectra studies were performed on weakly concentrated SrTiO3:Mn (0.1%) crystals and ceramics sintered with deficit of Ti, keeping the ratio (Ti+Mn)/Sr = 1. Surprisingly, magnitude of permittivity in SrTiO3:Mn crystals appeared to be depressed at low temperatures as in ceramics, reaching only ~3000 at T = 10 K. At the same time, low temperature IR reflectivity in STO:Mn crystals evidences that TO phonons contribution into low-frequency permittivity is nearly the same as in undoped serial SrTiO3 quantum paraelectric crystals. Together with Micro-Raman data, such features are understood as evidences of STO:Mn(0.1%) crystals inhomogeneity and presence of Mn oxides enriched nano-regions. Currently discussed in literature Mn doping related low-temperature dielectric relaxation is faintly pronounced in dielectric losses of STO:Mn(0.1%) crystals and ceramics and increased in reduced crystals, where at least two relaxation contributions with activation energy ~40 meV and ~120 meV can be distinguished displaying at ~20 – 40 K and 76-114 K temperature regions respectively. The fist relaxation is attributed to reorientation of polaronic defects localized on Mn2+ related centres. Possible nature of the second one is discussed.
|Deposited By:||Prof. Alexey Ivanov|
|Deposited On:||06 Aug 2009 11:04|
|Last Modified:||06 Aug 2009 11:32|
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