Specific Features of Thermal Degradation of Polypropylene in the Presence of Magnesium Hydroxide

Specific features of thermal oxidative degradation of polypropylene and its composite with Mg(OH)₂ were studied by pyrolytic gas chromatography-mass spectrometry and thermal gravimetric analysis.     

Structure and dielectric characteristics of (1 – <Emphasis Type="Italic">x</Emphasis>)BiFeO<Subscript>3</Subscript>–<Emphasis Type="Italic">x</Emphasis>PbTiO<Subscript>3</Subscript> solid solutions

Undoped (1 – x)BiFeO₃–xPbTiO₃ binary solid solutions (0 ≤ x ≤ 0.50, Δx = 0.1) are obtained via a solid-state reaction combined with sintering in accordance with conventional ceramic technology. Features of their crystal structure formation and dielectric properties are studied in a wide range of temperatures and frequencies.     

Phase Pattern of Barium Strontium Titanate System and Dielectric Responses of Its Solid Solutions

Russian Physics Journal - Samples of solid solutions of the system Ba1–x Sr x TiO3 (0 ≤ x ≤1.0) are produced by solid-phase synthesis followed by sintering using conventional...     

Effect of nonstoichiometry on the structure and dielectric properties of bismuth ferrite

Nonstoichiometric bismuth ferrite Bi _x FeO₃ 0.88 ≤ x ≤ 1.04) fabricated via solid-state synthesis is investigated by means of X-ray diffraction and electrical methods. The periodicity of the formation of impurity phases and variations in the structural parameters and densities of ceramic samples is established. The correlation between the number of impurity phases and characteristics of the dielectric spectra in the cation/anion-deficient (0.88 ≤ x < 1.00) and cation/anion-excess (1.00 < x ≤ 1.04) nonstoichiometry regions of Bi _x FeO₃ is confirmed. The observed effects are explained for the actual (defect) structure of bismuth ferrite.     

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Ohne Zusammenfassung     

Ferropiezoelectric properties and microstructure of PbFe1/2Nb1/2O3 ceramics

Ceramic samples of lead ferroniobate (PFN) having a rhombohedral symmetry at room temperature are obtained. Their ferroelectric and magnetic properties in the vicinity of the antiferromagnetic and ferroelectric phase transition temperatures are investigated. The electrophysical parameters of the polarized ceramic are presented. By means of electron-probe microanalysis, the number of inclusions of Fe-containing impurity phases (??0.2 vol %) is revealed to be several times higher than that in grains of the PFN ceramics. It is suggested that the above could be caused by the magnetic properties of PFN at room temperature.     

Phase formation in near-morphotropic region of the PbZr1 ? xTixO3 system, structural defects, and electromechanical properties of the solid solutions

Ceramics of PbZr_{1 − x} Ti _x O₃ solid solutions were systematically studied in the range 0.37 ≤ x ≤ 0.57. The x-T phase diagram (T = 25°C) is constructed containing in single-phase regions isosymmetric states characterized by different concentration dependences of the structural and electrophysical parameters. There are also regions where these states coexist, with their unit cell volume remaining unchanged. The existence of these states is interpreted in terms of the real (defect) structure of the ceramics. Several reasons are indicated that are responsible for the appearance of the phase states and related to the crystallochemical peculiarities of the solid solutions: the alternate valence of titanium ions; the infinitely adaptive structure of titanium dioxide; and the formation, ordering, and rotation of the planes of crystallographic shear. It is shown that the transition from the rhombohedral to tetragonal phase occurs indirectly, through two intermediate phases with lower symmetry whose appearance is favored by the defects in the solid solutions. Original Russian Text ? L.A. Reznichenko, L.A. Shilkina, O.N. Razumovskaya, E.A. Yaroslavtseva, S.I. Dudkina, O.A. Demchenko, Yu.I. Yurasov, A.A. Esis, I.N. Andryushina, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51, No. 5, pp. 958–965.     

Preparation,Structure, and Dielectric and Magnetic Properties of SrFe<Subscript>2/3</Subscript>W<Subscript>1/3</Subscript>O<Subscript>3</Subscript> Ceramics

Polycrystalline samples of SrFe_2/3W_1/3O₃ (SFWO) ceramic were obtained by solid-phase reactions with subsequent sintering using conventional ceramic technology. X-ray diffraction analysis showed that at room temperature, the SFWO ceramic is single-phase and has a perovskite-type structure with tetragonal symmetry and parameters a = 3.941(9) Å, c = 3.955(6) Å, and c/a = 1.0035. In studying the magnetic properties and the Mössbauer effect in SFWO ceramics, it is found that the material is a ferrimagnet, and the iron ions are only in the valence state of Fe³⁺. It is suggested that in the temperature range of T = 150–210°C, a smeared phase transition from a cubic (paraelectric) phase to a tetragonal (ferroelectric) phase takes place in SFWO with decreasing temperature.