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Temperature dependent X-ray diffraction (XRD) and dielectric properties of perovskite Ba(Zr${}_{0.2}$Ti${}_{0.8})$O₃ ceramic prepared using a standard solid-state reaction process is presented. Along with phase transitions at low temperature, a new phase transition at high temperature (873${}^{\circ }$C at 20Hz), diffusive in character has been found where the lattice structure changes from monoclinic (space group: $P2∕m)$ to hexagonal (space group: $P6∕mmm$). This result places present ceramic in the list of potential candidate for intended high temperature applications. The AC conductivity data followed hopping type charge conduction and supports jump relaxation model. The experimental value of $d_{33}=98$pC/N was found. The dependence of polarization and strain on electric field at room temperature suggested that lead-free Ba(Zr${}_{0.2}$Ti${}_{0.8})$O₃ is a promising material for electrostrictive applications.

This paper throws light on the preparation of transition metal-doped Mg${}_{0.5-x}T{M}_x$Zn${}_{0.5}$Al₂O₄ ($x=0$, 0.05 and $TM=\mathrm{\text{Co}}$, Ni, Cu) aluminates via solid-state reaction route. The X-ray diffraction characterization analysis confirmed that all the samples have crystallized into the psuedocubic phase having space group Fd3$m$ and were single phased. The incorporation of transition metals viz. Co${}^{2+}$, Ni${}^{2+}$, Cu${}^{2+}$ in the Mg${}_{0.5}$Zn${}_{0.5}$Al₂O₄ matrix does not result in the appearance of new peaks or any considerable shift in diffraction peaks within the limits of XRD experimentation. This infers homogeneous dispersion of dopants at the Mg-site which is attributed to nearly same ionic radii of the dopants to that of Mg-site in Mg${}_{0.5}$Zn${}_{0.5}$Al₂O₄. Lattice structure, bonding nature and hence the spinel formation were verified through Raman scattering technique. The compositional verification was carried out via energy dispersive analysis of X-rays (EDAX). The surface morphology and hence the microstructural studies were carried out using field emission scanning electron microscopy (FESEM). The synthesized Mg${}_{0.5-x}T{M}_x$Zn${}_{0.5}$Al₂O₄ ($x=0$, 0.05 and $TM=\mathrm{\text{Co}}$, Ni, Cu) aluminate samples were tested for polarization studies keeping their insulating nature into consideration and they displayed a sign of well-behaved P-E loop.

The preparation of ${\text{La}}_{0.9}$${\text{Na}}_{0.1}$CrO₃ (LNCO), ${\text{Ni}}_{0.5}$${\text{Cu}}_{0.5}$Fe₂O₄ (NCFO) and their composites of the type $(1-x)$${\text{La}}_{0.9}$${\text{Na}}_{0.1}$CrO₃ (LNCO) $+$ ($x$) ${\text{Ni}}_{0.5}$${\text{Cu}}_{0.5}$Fe₂O₄ (NCFO) $(x=0.25$, 0.50$)$ through solid state route is reported. From X-ray diffraction data analysis, the parent ${\text{La}}_{0.9}$${\text{Na}}_{0.1}$CrO₃ was found to crystallize in orthorhombic structure (Pnma) while ${\text{Ni}}_{0.5}$${\text{Cu}}_{0.5}$Fe₂O₄ has crystallized into the cubic structure (Fd3$m$) further verified via Retvield refinement. The morphology and compositional studies were carried out using field emission scanning electron microscopy (FESEM) and energy dispersive analysis of X-rays (EDAX), respectively. Lattice structure was confirmed via Raman characterization for the prepared samples. The sample formation was further verified through Fourier transform Infra-Red (FTIR) spectroscopy. The dielectric studies reveal the ${\text{La}}_{0.9}$${\text{Na}}_{0.1}$CrO₃$(13*10^4)$ and ${\text{Ni}}_{0.5}$${\text{Cu}}_{0.5}$Fe₂O₄$(1.83*10^4)$ exhibit high dielectric constant. However, their composites show abrupt drop in dielectric constant. The electric modulus study confirmed that the samples exhibit non-Debye character with spread of relaxation time constants.

The results of a comprehensive study of the crystal structure, grain structure, and strength properties of ceramic bismuth ferrite with rare earth elements (REE) obtained by two-stage solid-phase synthesis followed by sintering using conventional ceramic technology are presented. The reasons for the formation of low mechanical strength and the development of destruction phenomena in solid solutions with small REE ($\bar{R}<0.94$ Å) are considered: Tb, Dy, Ho, Er, Tm, Yb, Lu. The causes of the observed phenomena associated with the composite-like structure of the studied media and, as a consequence, the occurrence of local stresses of structural elements that provoke crack formation are established. A source of the latter are also the structural features of the grain landscape. The conclusion is made about the appropriateness of taking into account the information obtained when developing devices based on BiFeO₃/REE multiferroics.

X-ray diffraction studies of synthesized Ba₂TiSi₂O₈ have shown that this compound has a fresnoite structure and is characterized by a polar phase $P$4bm at room temperature. The synthesis of Pb₂TiSi₂O₈ in the fresnoite phase under the selected synthesis conditions has led to the formation of a perovskite tetragonal phase $P$4mm corresponding to PbTiO₃.

This paper presents the results of studies of the structure, microstructure, dependences of the piezoelectric properties on the electric field (dielectric hysteresis loops, reversible nonlinearity, deformation characteristics) and dielectric properties of the ceramic material PCR-13 (based on the PZT system) in the temperature range 300–900K and frequencies of an alternating electric field ($25÷2\cdot 10^6$) Hz. The character of the obtained dependences made it possible to attribute PCR-13 to ferro-hard materials. Using the HF cathodic sputtering method, PCR-13 thin films were fabricated on Si (001) substrates. It is shown that they are polycrystalline textured, while in comparison with bulk material, the film contains tensile stresses of the unit cell in the plane of the substrate and compresses in the perpendicular direction with the value ${\epsilon }_{33}=-0.018$. The capacitance-voltage characteristics of the Al/PCR-13/Si/Al heterostructure were studied. The reasons for the revealed patterns are discussed.

Vinylidene fluoride-trifluoroethylene copolymer films of molar ratio 70/30 with thickness of about 1 $\mu$m have been deposited from solution in ethyl methyl ketone to a glass substrate with an aluminum electrode by spin coating. The solution has been filtrated through a PTFE membrane filter with pore size 0.2 $\mu$m directly before spin coating or it has been used as is (unfiltrated). After deposition of a top electrode, the samples have been polarized by hysteresis loops with an electric field amplitude of about 100 V/$\mu$m. In samples, annealed at temperature 145${}^{\circ }$C for 3 h, a high remanent polarization of about 7.5 $\mu$C/cm² has been achieved, without significant differences between samples fabricated of filtrated or unfiltrated solution. Spherulitic lamella are growing in films fabricated of filtrated solution when they are heated above the melting temperature to 159${}^{\circ }$C for 3 min before the further annealing process at 145${}^{\circ }$C. These films show substantially lower remanent polarization below 4 $\mu$C/cm². Pyroelectric images recorded with a pyroelectric laser scanning microscope show that the spherulites have very small pyroelectric activity, i.e., the spherulites consist of flat-on lamella. In contrast, no spherulitic lamella are growing in films fabricated of unfiltrated solution heated above the melting temperature, melted and annealed under the same conditions. An explanation for this observation is that filtrating changes the structure of the copolymer in solution from polymer coil to rod. Copolymer rods deposited on a substrate will crystallize in flat-on lamella when heated above the melting temperature, in contrast to copolymer coils which crystallize in edge-on lamella.

X-ray diffraction and dielectric studies were performed on synthesized ceramic samples of the section (1–x) (0.8PbMg${}_{1∕3}$Nb${}_{2∕3}$O${}_3\cdot 0.2$BiScO₃)⋅ x(0.8PbTiO${}_3\cdot 0.2$BiScO₃) with $x=0$–1 of the ternary BiScO₃–PbTiO₃–PbMg${}_{1∕3}$Nb${}_{2∕3}$O₃ (BS–PT–PMN) system, including the temperature dependence of thermally stimulated depolarization currents (TSDC). It was found that the samples are solid solutions with a perovskite structure, which have cubic symmetry in the range of x = 0–0.587 and tetragonal symmetry in the range of x = 0.680–1. In the intermediate composition range of x = 0.587–0.680 (morphotropic region — MR), the samples consist of a mixture of solid solutions of different symmetries. Data on the change in dielectric properties and TSDC(T) dependencies of solid solutions with a change in their composition were obtained. It was found that samples of compositions x =0–0.625 and 0.6875–1 exhibit relaxor-ferroelectric and conventional ferroelectric properties, respectively, while samples of compositions x = 0.625–0.6875 combine ferroelectric and relaxor-ferroelectric properties.

The equilibrium and stability of anisotropic strange stars is analyzed. For this purpose, we consider that the anisotropy factor follows the equation σ = k p_r(1 − e^−λ); being k a constant, p_r the radial pressure and e^−λ a metric function. We found that the anisotropy yields considerable changes in some macroscopic properties of strange stars. Despite this, such as is determined in isotropic strange stars, the onset of the instability is marked by the maximum mass point. This indicates that stable and unstable equilibrium configurations can be recognize through the conditions dM/d_ρc > 0 and dM/d_ρc < 0, respectively.