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Single-phase (1 – x)(K0.5Na0.5)NbO3⋅xBaZrO3 (x = 0–0.06) ceramics with new compositions, including those modified with SiO2 and ZnO oxide additions, have been prepared and their crystal structure, microstructure, and dielectric and nonlinear optical properties have been studied. A phase with the perovskite structure and an orthorhombic unit cell has been shown to form in all of the synthesized materials. Partial replacement of cations of the basic composition by cations of the combined additive has been demonstrated to cause an increase in unit-cell volume. The ferroelectric phase transitions in the ceramics have been confirmed by dielectric spectroscopy and laser radiation second harmonic generation measurements. Doping with SiO2 and ZnO oxide additions has been shown to lower the temperatures of the transitions from the orthorhombic ferroelectric phase to a tetragonal ferroelectric one and then to a cubic paraelectric phase. [ABSTRACT FROM AUTHOR]

Single-phase (1 – x)(K0.5Na0.5)NbO3⋅xLiNbO3 (KNN–LN) perovskite-structure ceramic materials with x = 0–0.10 modified with CuO and KCl additions have been prepared by solid-state synthesis, and their phase composition, structure, microstructure, and dielectric and ferroelectric properties have been studied. Increasing the percentage of lithium niobate has been shown to increase their Curie temperature and lower the temperature of their polymorphic phase transition, which is accompanied by a decrease in perovskite cell parameters, in accord with the ionic radii of the A-site cations. The x = 0.2 material has been found to have an increased room-temperature dielectric permittivity, which correlates with the observed increase in spontaneous polarization, as evidenced by laser radiation second harmonic generation intensity measurements. [ABSTRACT FROM AUTHOR]

We have studied the crystal structure and dielectric and local piezoelectric properties of (Na0.5Bi0.5)(Ti1–xMnx)O3 (x = 0–0.1) modified sodium bismuth titanate-based ceramics and observed the formation of a pseudocubic phase with the perovskite structure. Its unit-cell volume first decreases and then, for x ≥ 0.05, increases. The ceramics undergo phase transitions, which show up as anomalies in their dielectric permittivity near ~450 K and peaks at a Curie temperature of ~600 K. As x increases to 0.04, their Curie temperature decreases by 40 K. The phase transitions near 450 K exhibit well-defined relaxor behavior due to the presence of polar regions in the nonpolar matrix. The samples with x < 0.05 have been shown to have an increased room-temperature dielectric permittivity, which correlates with the increased effective piezoelectric coefficient, suggesting that doping with manganese has an advantageous effect on the functional properties of sodium bismuth titanate ceramics. [ABSTRACT FROM AUTHOR]

We have prepared ceramic (LaSr){[Ga(GeMg)]Mg}O (LSGGM) ( x = 0, 0.1, 0.2, 0.4, 0.6, 0.8) samples by solid-state reactions and studied their phase composition, structure, microstructure, and electrical conductivity. Phase-pure solid solutions have been obtained upon substitution of germanium and magnesium cations for up to 20 at % of the gallium cations. The modified samples have been shown to have high density, optimal microstructure, densely packed grains, and high electrical conductivity at high temperatures. [ABSTRACT FROM AUTHOR]

We have prepared CaPbM(PO) (M = Mg, Zn, Cd) and CaPb(PO) solid solutions. A polar whitlockite-like (sp. gr. R3 c) crystal structure exists in the range 0 ≤ x ≤ 1.5 for all of the M cations in CaPbM(PO) and in the range 0 ≤ x ≤ 2.5 for CaPb(PO). X-ray powder diffraction profile analysis results for CaPbCd(PO) powder demonstrate that the small divalent M cations reside predominantly on the octahedral site M5 of the whitlockite structure, the calcium cation occupy the M1-M3 sites, and the lead cations are located primarily on the M4 site. Differential scanning calorimetry, second-harmonic generation, and dielectric permittivity data indicate that all of the synthesized phosphates are high-temperature ferroelectrics. The highest Curie temperatures are offered by the x = 0.5 materials, in which most of the lead resides in the spacious oxygen polyhedra M4 and only a small amount of lead is incorporated into the smaller polyhedra around M1-M3. The nonlinear optical activity has a maximum in the middle of the solid-solution series and is an order of magnitude higher than that of the parent, lead-free phases. [ABSTRACT FROM AUTHOR]

We have prepared solid solutions based on whitlockite-structure ferroelectrics, CaPbR(PO) (R = Sc, Cr, Fe, Ga, In), through Pb substitution for Ca. Single-phase CaPbR(PO) materials with a polar whitlockite-like structure (sp. gr. R3 c) exist in the range 0 ≤ x ≤ 1.5 for all of the R metals studied. X-ray powder diffraction profile analysis results for R = In ( x = 0.5, 0.8, and 1.0) demonstrate that the trivalent cations reside on the octahedral site M5 of the whitlockite structure, the calcium cation occupy the M1-M3 sites, and the lead cations are located predominantly on the M3 site. Differential scanning calorimetry, dielectric permittivity, and second-harmonic generation data attest to a ferroelectric phase transition, whose temperature is 580-610°C in CaR(PO) and decreases monotonically to 480-520°C as x increases to 1.5. [ABSTRACT FROM AUTHOR]

ZrO2-CeO2 (10, 18, and 23 mol % CeO2) solid solutions have been synthesized via coprecipitation. The powders have been sintered at 1875 K, and the electrical conductivity and dielectric properties of the resultant ceramics have been studied. The dielectric relaxation observed in the ceramics can be understood in terms of ionic transport accompanied by the formation of dipoles relaxing in an ac electric field. [ABSTRACT FROM AUTHOR]

The lattice parameters of (La1/2Li1/3+ x )TiO3 ( x = 0, 1/10, 1/6, 1/5, 1/4) ceramics have been determined as functions of temperature, and their microstructure and transport properties have been studied. The results indicate that the oxides retain orthorhombic symmetry upon the structural changes at ≃925 K. According to atomic force microscopy results, the grains in the ceramics consist of nanocrystallites 60 to 120 nm in size. Analysis of the grain bulk and grain boundary contributions to the ionic conductivity of the (La1/2Li1/3+ x )TiO3 solid solutions shows that their bulk conductivity σbulk decreases with increasing x because reducing the concentration of A-site vacancies impedes ionic transport. [ABSTRACT FROM AUTHOR]

The microstructure and dielectric properties of (La0.9Sr0.1)[(Ga1− x Crx)0.8Mg0.2]O3−δ ( x = 0−0.35) oxygen-ion-conducting ceramics have been studied. The dielectric relaxation observed in the ceramics has been interpreted in terms of ionic transport in the grain bulk and across grain boundaries. The grains in the ceramics have been shown to consist of nanoscale domains, which seems to be due to a correlated distribution of the chromium dopant. [ABSTRACT FROM AUTHOR]

(La0.9Sr0.1)[(Ga1 − x Crx)0.8Mg0.2]O3 − δ ( x = 0–0.35) perovskite-like solid solutions have been prepared by ceramic processing route, and their structural parameters, microstructure, and electrical conductivity have been determined. The results indicate that the cation substitutions reduce the unit-cell volume of the solid solutions and raise their total conductivity via an increase in electronic conductivity, while their ionic conductivity seems to decrease with increasing x. [ABSTRACT FROM AUTHOR]

Data are presented on the phase composition, structure, and electrical properties of (La1/2Li1/3 + x ])TiO3 solid solutions with x = 0, 1/10, 1/6, 1/5, and 1/4. The introduction of superstoichiometric lithium oxide into the starting mixture is shown to reduce the ionic conductivity of the solid solutions, which is interpreted in terms of cation ordering and lattice contraction. [ABSTRACT FROM AUTHOR]

Nanocrystalline Lu2O3-TiO2 (33.3-44 mol % Lu2O3) materials with a partially disordered pyrochlore structure, prepared via heat treatment in the range 1400-1750°C, are found to possess high oxygen ionic conductivity. Their 740°C conductivity is 10-3 to 10-2 S/cm, depending on the heat-treatment temperature and composition, which is comparable to that of the well-known fluorite solid electrolyte ZrO2-9 mol % Y2O3. [ABSTRACT FROM AUTHOR]

New oxygen-ion conductors Ln2 + xTi2 - xO7 - x /2 (Ln = Dy-Lu, x = 0.132) with a disordered pyrochlore structure are obtained. Their ionic conductivity attains 10-3 S/cm at 740°C, owing to the presence of defects in both the cation and anion sublattices. The materials contain ~5% LnTi antisite defects. Ln2.132Ti1.868O6.934 ceramics are shown to be stable in the temperature range 1600-1700°C. [ABSTRACT FROM AUTHOR]

Data are presented on the phase composition, crystal structure, microstructure, and dielectric and piezoelectric properties of (1 – y)[(1 – x)Pb(Mg1/3Nb2/3)O3–xPbTiO3]–yPb(Mg1/2W1/2)O3 (x = 0.30–0.36; y = 0, 0.05, 0.10) ceramics. It is shown that the use of fine-particle magnesia as a starting reagent ensures the formation of single-phase materials. The ceramics with a rhombohedral structure are found to exhibit relaxor behavior. Increasing the content of the Pb(Mg1/2W1/2)O3 perovskite leads to ordering of the domain structure of poled ceramics and increases their piezoelectric charge coefficient d31 and the width of their phase transitions. [ABSTRACT FROM AUTHOR]