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  • The phase composition, grain structure and dielectric spectra of the multiferroic Bi1-xGd xFeO3 (0.025≤x≤0.50)

    The investigations of the crystal structure, grain structure and dielectric properties of high-temperature multiferroic Bi1-xGd xFeO3 were carried out over a wide concentration range x = 0.00-0.50.

    Keywords: multiferroic crystal structure, grain structure, dielectric properties

  • The phase composition and physical properties of high-temperature multiferroic BiFeO3 / Nd

    The investigations of the crystal structure, grain structure and dielectric properties of high-temperature multiferroic Bi1-хNdxFeO3 were carried out over a wide concentration range x = 0.00-0.50.

    Keywords: multiferroic crystal structure, grain structure, dielectric properties

  • Studies of low-temperature multiferroic samarium doped bismuth ferrite

    The investigations of the crystal structure, grain structure and dielectric properties of high-temperature multiferroic Bi1-хSmxFeO3 were carried out over a wide concentration range x = 0.00-0.50.

    Keywords: multiferroic crystal structure, grain structure, dielectric properties

  • The structure, grain structure and dielectric properties of multiferroic Bi 1-x La xFeO3 (x = 0.00-0.50)

    The investigations of the crystal structure, grain structure and dielectric properties of high-temperature multiferroic Bi1-x LaxFeO3 were carried out over a wide concentration range x = 0.00-0.50.

    Keywords: multiferroic crystal structure, grain structure, dielectric properties

  • Preparation, microstructure and dielectric spectra of the multiferroic Bi1-xPrxFeO3, x = 0.00-0.50

    The investigations of the crystal structure, grain structure and dielectric properties of high-temperature multiferroic Bi1-хPrxFeO3were carried out over a wide concentration range x = 0.00-0.50.

    Keywords: multiferroic crystal structure, grain structure, dielectric properties

  • Dielectric spectroscopy of ceramic solid solutions based on modified lead titanate

    The manuscript traced the impact of changes in the content of alkaline-earth elements on the dielectric spectra of solid solutions based on lead titanate. Two concentration areas with sharply differing nature of the manifestations of dispersion phenomena were identified. First (0.02≤α1≤0.24) is characterized by strong dispersion ε/ε0 in all temperature range and not allow to generate maximum of ε/ε0 for Curie temperature at low frequencies, the second (0.24≤α1≤0.36) - a sharp decrease of Δε in the ferroelectric phase and complete disappearance of it in the solid solutions, SS, with α1 = 0.36, indicating stabilization of the structure with the introduction of alkaline SS elements. It was found that as increased the concentration of modifiers in the compositions there is a stabilization of their structure with a gradual decrease in the phase transition temperature. Formation of two concentration areas where changes macro properties SS is undoubtedly a consequence of their correlation with the phase diagram of the studied SS, which is experiencing a transformation in the neighborhood of α1 ~ 0.24, due to the transition from two-phase to single-phase state. The results obtained by the authors can be used in the development of high-temperature (α1 0.24 ) anisotropic ferroelectric materials.

    Keywords: ferroelectric piezoceramics, lead titanate, alkaline earth elements, modifiers, solid phase synthesis dielectric spectra

  • Thermodynamic background and the effects of the degradation of the modified lead titanate

    The paper provides information on the influence of thermodynamic prehistory (conditions for obtaining) and the processes associated with time "aging" of the samples in the dielectric properties of the alkaline-earth elements modified lead titanate ceramics. The data shows a dielectric stability of solid solutions (SS) with a high content of alkaline-earth elements (almost independently of the Curie temperature of sintering temperature). This is supported by the fact of reproduction the character of dielectric spectra in SS (α1≥0.22) unlike changed profile curves ε / ε0 (T) |f SS (α1 = 0.04). The splitting of the maxima ε / ε0 (T) |f, obtained on the same samples after 7 months (April 2015) after the initial measurements (September 2014) is the result of degradation of solid solutions close to PbTiO3, probably due to begin the process of self-destruction ceramics.

    Keywords: ferroelectric ceramics, lead titanate, alkaline-earth elements, thermodynamic prehistory, dielectric properties, the effects of degradation

  • Effect of technological regimes on the properties of solid solutions of (1-x) PbZrO3 – x PbTiO3

    In this work we continue the study of ferroelectric compositions of different composition – basics of functional materials piezo technical destination. Considered are solid solutions (TR) binary system (1-x) PbZrO3 – x PbTiO3 (PZT), up to the present time remaining as base of almost all commercially available functional materials. Studied the impact of technological regimes on the properties of solid solutions with 0.135 ≤ x ≤ 0.145, 0.16 ≤ x ≤ 0.18, 0.37 ≤ x ≤ 0.58, 0.75 ≤ x ≤ 0.77, 0.795 ≤ x ≤ 0.805, the research concentration step Δx = 0.0025. The sintering temperature was varied from 1200 °C to 1240 °C, the duration of the extracts 2 and 3 hours. It is established that the structural parameters remain almost constant under variations of conditions in process their production in all ranges (rhombohedral, tetragonal and morphotropic) of the concentrations, and the change of relative dielectric permittivity of unpolarized samples is not more than (10÷12) %. It was shown that the study of solid solutions of multicomponent systems on the basis of lead zirconate titanate is possible with the minimal concentration of the step ∆x = 0.25 mol.%. Application of the considered techniques in the fabrication of functional materials for various purposes provides high reproducibility of their parameters. Obtained results can be useful for development of new ferro-piezoelectric materials on the basis of other complex oxides.

    Keywords: solid solution, lead zirconate titanate, technology, crystal structure, dielectric permittivity

  • Features of the spinel phases formation in system NiO – CoO – CuO – Cr2O3

    The combination of the unique, abnormal properties shown by oxidic systems with structure of spinel on the basis of transitional elements chromites draws attention of researchers for many years. Some systems on the basis of transitional elements chromites (for example, nickel and copper chromites) have critical elements (multicritical points, lines of phase transitions of the second sort, etc.) on the phase chart. Near these elements of the phase chart materials possess unique chemical and physical properties. Therefore development methods of receiving and research of phase forming and properties in NIO-CoO-CuO-Cr2O3 system represent fundamental and practical interest for chemistry and technology of inorganic substances. In this work processes of spinel structure formation in system 0,6 NiCr2O4 – 0,2 CoCr2O4 – 0,2 CuCr2O4 from crystal chemistry positions are considered. Formation of two solid solutions on the basis of nickel (II) chromite – with structure of cubic spinel and with tetragonal distorted structure is established. The influence of cooperative Yahn-Teller effect on processes of a spinel forming and on stabilizing impact of chloride of potassium on process of education of  two spinel solid solutions is suggested. Influence of a power factor of cation stabilization in knots of a crystal lattice as one of the important factor in reaction of spinel structure formation is considered.

    Keywords: spinels, chromites of transitional elements, Jahn-Teller effect