| Two types of SBN crystals were grown and analyzed for their spectroscopic and dielectric properties: Sr0.33Ba0.67Nb2O6: Cr and Sr0.58Ba0.42Nb2O6: Cr, Yb. The absorption and EPR spectra show the presence of Cr3+ at interstitial ions beside the ions substituted for Nb5+. Unexpectedly, Yb3+ has not entered to the Sr0.58Ba0.42Nb2O6: Cr crystal at Nb5+ octahedral sites. The crystals differ significantly each other especially for their dielectric properties mainly due to stoichiometry. The former crystal exhibits ferroelectric phase transition at about 378K, while the latter at 340K. We have found spontaneous polarization being equal to 2,44 µC/cm2 (SBN:33:Cr) and to 1 µC/cm2 (SBN:58:Cr:Yb). |
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