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The process of grain structure formation and development in ferroelectric ceramics based on sodium noiobate are considered Micrographs of the grain boundary regions are described in terms of multifractal parameters Correlations between the multifractal and structural parameters of ferroelectric niobate ceramics are found The process of secondary interrupted recrystallization has been studied The results have been used for optimization of the technology of novel ferroelectric materials [ABSTRACT FROM AUTHOR]

Abstract: Single crystals of La1−x Bi x Mn α O3±β and La1−x−y Bi x A y Mn α O3±β (A=Ba, Pb) are grown, their crystal and electron structure is studied. Relative Mn3+/Mn4+ abundance in each single crystal is determined via fitting experimental Mn2p-spectra with weighted superposition of theoretical spectra of tri- and quadrivalent Mn, and, for barium-free samples, from energy splitting of the Mn3s-spectra components. Strong heterogeneousness of the crystals both in elemental composition and crystal structure is discovered. It is shown that the heterogeneousness displays itself in various oxygenic environments around Mn atoms which give rise to the appearance of Mn4+ ions. A simple model is proposed that allows understanding the nature of the appearance of Mn4+ ions in single crystals of lanthanum–bismuth manganites. [Copyright &y& Elsevier]

Abstract: Valence state of Mn in La1−α Bi β Mn1+δ O3±γ (LBMO) ceramic samples and in orthorhombic manganates RMn2O5 (R=Y, Bi, Eu, Gd), is studied using Mn 2p- and Mn 3s-spectra. Both Mn3+ and Mn4+ ions are shown to be present in those compounds. Relative Mn3+/Mn4+ ions contents are determined by fitting experimental Mn 2p-spectra with weighted superpositions of theoretical spectra of Mn3+ and Mn4+ ions calculated in one-configuration Pauli–Fock approximation considering thermal excitations in initial state. Content of the Mn4+ ions correlates with the deviation δ in La1−α Bi β Mn1+δ O3±γ from stoichiometry, La1−x Bi x MnO3. Separation of low-spin and high-spin components of Mn 3s-spectrum can be sensible to the relative content of Mn3+ and Mn4+ ions. Mn3+/Mn4+ ratios derived from Mn 2p- and from Mn 3s-spectra compare well in the case of the RMn2O5 manganates, while in the case of the LBMO ceramics the results obtained from the Mn 3s spectra are physically meaningless. Due to a complex interplay between 3d-electrons delocalization and strong many-electron effects the 3s spectra of 3d-elements may be misleading. [Copyright &y& Elsevier]