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Recently, visible-light-driven persulfate-based advanced oxidation processes (AOPs) employing heterogeneous catalysts to generate sulfate radicals (SO4·−) from peroxymonosulfate (PMS, HSO5−) have been extensively investigated in the field of water remediation, to remove organic contaminants. In this study, CeO2/2.0STO visible light photocatalyst with pore structure was synthesized by sol–gel method and impregnation method for photocatalytic methylene blue (MB) degradation via PMS activation. The MB degradation efficiency exhibited a high level at a broad pH range 2–12, and the presence of various organic matter and natural inorganic ions had no significant impact. When the PMS dosage was at 0–0.1 mM, the MB degradation efficiency still reached 100% within 40 min, indicating that the photocatalyst has high PMS utilization rate. The catalyst has high catalytic degradation efficiency on several typical dyes. Reused for 5 cycles, the catalytic activity, crystal form and three-dimensionally ordered macroporous (3DOM) structure of the photocatalyst without change significantly, and the leaching ratios of Sr, Ti and Ce were just under 0.1%. CeO2/2.0STO hole confinement effects and the synergistic effect between strontium titanate (SrTiO3) and ceria (CeO2) result in the excellent photocatalytic performance. The catalyst surface abundant pores absorb MB molecules into its interior, shortening the diffusion path of ROSs and improving contact efficiency. The formation of SrTiO3 and CeO2 heterojunction, which enhanced the separation of photogenerated electron/hole pairs. Experimental results confirmed that 1O2, SO4−·, ·O2− and ·OH all contributed to the MB degradation. [ABSTRACT FROM AUTHOR]

Lead-free ZnTiO3 hexagonal nanocrystals prepared by a facile hydrothermal-based synthesis process exhibit stable ferroelectricity and a high-temperature dielectric anomaly at ~ 728 K. The Curie temperature (Tc) is associated with a probable ferroelectric (FE) to paraelectric transition from LiNbO3 type to ilmenite phase. Direct ferroelectric measurements confirm stable and highly saturated polarization (Ps) up to 723 K, with a Ps ~ 14.6 µC/cm2 at a low coercive field of 2.3 kV/cm. Subsequently, simple, flexible piezoelectric nano (composite) generator is fabricated from ferroelectric nanocrystals with PDMS, and for 40 wt.% nanocrystals loading in the PDMS–nanomaterial composite, the device delivered an open-circuit peak voltage (Vp) of ~ 6.1 V and a short-circuit peak current (Ip) of ~ 66 nA at room temperature, when subjected to a periodic impact at 4 Hz and 15N. A steady power density of ~ 95 µW/cm3 at 1MΩ load is delivered by a single, robust piezo device, stable up to 120 °C that exhibits excellent fatigue performance, and commendable sensitivity of ~ 0.33 ± 0.02 VN−1(33 mVkPa−1) upon repeated periodic impact. The work provides a pathway towards low-cost hydrothermal-based synthesis of lead-free titanate nanomaterials with emerging ferroelectricity and understanding their structure–property relationships for exploring piezoelectric energy harvesting potential. [ABSTRACT FROM AUTHOR]

Presented here is a proof of concept demonstration of the templated grain growth (TGG) process for the development of [001]c fibre-textured Pb(ZrxTi1-x)O3 (PZT) ceramics. BaTiO3 platelets (5 and 10 vol.%) were selected to seed growth of highly oriented PZT grains resulting in texture fractions as high as 94%. The TGG process in PZT was observed to be critically dependent upon the addition of excess PbO liquid phase and may be driven by BaTiO3 dissolution into the matrix. Solid solution incorporation of BaTiO3 during sintering resulted in a structural shift away from the PZT morphotropic phase boundary (MPB) and a decrease in Curie temperature (TC) by ~ 40 °C which still exceeded > 300 °C. Modification of the Zr:Ti ratio in untextured ceramic analogues was explored as a strategy to tailor dielectric, ferroelectric, and electromechanical properties. An initial PZT matrix composition of Pb(Zr0.56Ti0.44)O3 resulted in a final bulk Pb0.947Ba0.053(Zr0.531Ti0.469)O3 ceramic having MPB-like properties of d33 = 453 pC/N, tan δ = 0.017, TC = 340 °C, and Ec = 9.3 kV/cm, which was observed to be similar to commercial 'soft' PZT-5A1. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) titanate nanotubes materials (protonated titanate nanotube (HTNT) and sodium titanate nanotube (NaTNT)) have been reported as low-cost and efficient catalytic materials in chemical syntheses for the production of biofuel precursors with interesting catalytic performance exhibited, even better than some commonly used zeolites, H-MOR, H-β, SO42−/Al2O3, and H-ZSM-5 solid catalysts with environmental benign in focus when compared with homogeneous catalytic materials. This mini-review expressly revealed the significance and potential of using HTNT and NaTNT as sustainable and environmentally benign solid catalysts/supports in various chemical reactions. The critical assessment of biomass valorization and titanate nanostructured materials as catalysts/supports via Green Chemistry approach, #7 (use of renewable feedstocks), #9 (use of catalyst against stoichiometry) and United Nations (UN) Sustainable Development Goals (SDGs), #7 (affordable and clean energy; ensure access to inexpensive, reliable, sustainable, and new energy), is presented as integrated pathways to meet environmental benign technology toward sustainability. Hence, this work follows in the pattern of recent formulated features reported for solid catalysts—'PYSSVR' concept, which means P–production cost, Y–yield, S–stability, S–selectivity, V–versatility, and R–reusability. [ABSTRACT FROM AUTHOR]

We prepared and investigated the composites of the spinel Li4Ti5O12 (LTO) and Marimocarbon (MC) by the hydrothermal method that could form uniform electric paths without aggregation of the LTO particles for high capacity and high rate lithium-ion batteries. MC consisted of many fine carbon nanofilaments (CNFs) intertwined with each other in a complicated fashion. There are vacant space volumes of hundred nanometers between the CNFs. LTO particles were deposited in the space volumes among the tangled CNFs of the MCs. LTO is one of the most attractive anode materials for lithium-ion batteries because of its structural stability and safety. The morphology, microstructure and elemental composition of the LTO/MC composites were characterized by scanning electron microscopy (SEM), and X-ray diffraction (XRD). A charge–discharge test revealed that the LTO/MC composite (MC 10 wt%, prepared using a fluidized bed flow-reactor) produced the specific capacity of 170 mA g−1 at 1C (1C = 175 mA g−1). The LTO/MC composite maintained the specific capacity of 47 mAh g−1 even in the high rate zone at 30C whereas only the pristine LTO the produced 15 mAh g−1 at this rate. The unique structure of the LTO/MC composites can contribute to improving the electrochemical performance of the LTO anode. The LTO/MC composites can provide an effective approach to improve the lithium-ion battery performances. [ABSTRACT FROM AUTHOR]

The center-radial channels throughout dendritic mesoporous silica nanospheres (DMSNs) give rise to easily approachable internal spaces, high specific surface area, large pore volumes, etc. Some other substances with matchable sizes could be decorated into DMSNs' channels. As a result, DMSNs are very fascinating platforms for catalysis, tumor therapy, drug delivery, and so on. In this study, we demonstrate a facile approach of introducing black TiO2-x nanoparticles into DMSNs' center-radial channels. Dendritic mesoporous silica&titania nanospheres (DMSTNs) were initially manufactured by coating DMSNs with tetrabutyl orthotitanate precursor and calcination in air. Black dendritic mesoporous silica&titania nanospheres (b-DMSTNs) with TiO2-x particles dispersed in DMSTNs channels were then developed by reducing DMSTNs with NaBH4 under Ar atmosphere. There exist abundant Ti3+ and oxygen vacancies in TiO2-x bulks. Even though the as-prepared structured material cannot work as cathode materials for lithium-ion battery, they can satisfactorily serve as photocatalysts for H2 production and CO2 reduction under simulated sunlight. The b-DMSTNs can yield ca. (i) 11,939 μmol·g−1 H2 with a 2387 μmol·g−1·h−1 rate in 5 h with the assistance of chloroplatinic acid, greater than that of white DMSTNs which produce about 9578 μmol·g−1 H2 with a 1915 μmol·g−1·h−1 rate; (ii) 14.78 μmol·g−1 CO (74.43%) and 5.07 μmol·g−1 CH4 (25.57%) with its specific selectivity. [ABSTRACT FROM AUTHOR]

Since the previous research confirms the lanthanum titanate (LTO) flexible self-supporting film can be considered as excellent energy storage material, we intend to maximize the performance of LTO to provide higher energy density for practical application. In order to achieve this goal, the Sr element was a choice to substitute with La for increasing the amount of oxygen vacancies in this study, and mechanical flexibility of the film was also maximally preserved. For determining the most appropriate amount of Sr doping, a serious of Sr-doped LTO films marked as LTO-x (0.1 ≤ x ≤ 0.5) were synthesized by electrospinning combined with calcination method. After analyzed by the XRD, SEM, TEM, XPS and electrochemical work station, the LTO-0.3 sample shows the best properties with a maximum capacitance of 1.8 F·cm−2 at 2 mA·cm−2. As a result of that, we fabricated the flexible all-solid-state supercapacitor device with two LTO-0.3 electrodes and PVA-Na2SO4 gel. This LTO-0.3//LTO-0.3 device exhibits excellent cycling stability, outstanding flexibility and high energy density of 209.4 μWh·cm−2 with the corresponding power density of 2.1 mW·cm−2. [ABSTRACT FROM AUTHOR]

K2MgTi7O16@K0.8Mg0.4Ti1.6O4(PMTC) core–shell composite whiskers and TiO2 (TO) whiskers have been obtained from potassium magnesium titanate whisker (K0.8Mg0.4Ti1.6O4, KMTO) by a first different degree ion-controlled exchange reaction and a subsequent heat treatment. These materials have been successfully used as functional fillers to enhance the performance of fluorine–olefin vinyl ether copolymer (FEVE) fluorocarbon coatings. The tribological and electrochemical impedance spectroscopy results indicated that PMTC and TO whiskers can significantly enhance the friction and corrosion resistance of FEVE composite coatings compared with KMTO/FEVE composite coatings. Particularly, the 5 wt. % PMTC/FEVE composite coating displays an enhanced wear resistance (Friction coefficient is 0.632. Wear volume loss is 0.006 mm3) than that of pure FEVE coating. (Fiction coefficient is 0.865 and wear volume loss is 0.177 mm3.) And the |Z|0.01 Hz value of 10 wt.% TO/FEVE composite coating is 109.8 Ω·cm2, which indicates its highly protective nature when compared to that of pure coating (~ 107 Ω·cm2). Besides, the microstructure of cross sections, worn surfaces and wear debris of the composite coatings was analyzed by scanning electron microscopy (SEM), and the related anti-wear and anti-corrosion mechanisms were revealed. The present process and design can be extended to the synthesis and modification of a variety of other layered materials including titanates, tantalates, chalcopyrites, etc. [ABSTRACT FROM AUTHOR]

A class of high-entropy perovskite oxide (HEPO) [(Bi,Na)1/5(La,Li)1/5(Ce,K)1/5Ca1/5Sr1/5]TiO3 has been synthesized by conventional solid-state method and explored as anode material for lithium-ion batteries. The half-battery provides a high initial discharge capacity of about 125.9 mAh g−1 and exhibits excellent cycle stability. An outstanding reversible capacity of 120.4 mAh g−1 and superior delivering retention of ~ 100% can be obtained at 1000 mA g−1 after 300 cycles. Even at a high current density of 3000 mA g−1, a reversible capacity of 70 mAh g−1 can be retained, indicating excellent rate performance. Such outstanding cycle and rate performance can be ascribed to the entropy-stabilized structure offered by mixed aliovalent cations and the charge compensation mechanism in HEPO, respectively. This work highlights the great potential of perovskite high-entropy oxides as anode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

This paper reports that Cu acceptor substitution at the Ti site has significant effects on structure and electrical properties of Aurivillius-phase Bi4Ti3O12 polycrystalline ceramics. Phase purity, microstructure and defect chemistry of Bi4Ti3−xCuxO12−x (BiT–100xCu, x = 0–0.12) are characterized by XRD, SEM, EDS and EPR measurements. Neutron diffraction refinement indicates that BiT–8Cu has an orthorhombic symmetry [space group: B2cb; lattice parameters: a = 5.4116(1) Å, b = 32.833(1) Å, c = 5.4479(1) Å and V = 967.98(5) Å3]. Impedance spectra of BiT–100xCu were measured under variable oxygen partial pressure (pO2). Bi4Ti3O12 shows mixed electronic (hole) and ionic conduction owing to the existence of oxygen vacancies ( V O · · ) arising from the loss of Bi2O3 during sintering. Interestingly, bulk conductivity in Cu-substituted Bi4Ti3O12 ceramics is predominately ionic due to the fact that there are considerably additional oxygen vacancies introduced into the perovskite lattices. The optimum composition of BiT–8Cu shows high ionic conductivity in the bulk with a value of ~ 0.007 S/cm at 650 °C. [ABSTRACT FROM AUTHOR]

Dielectric nanocomposites have attracted extensive attention since the potential application in the field of energy storage. Nevertheless, it is still a challenge to fabricate dielectric nanocomposites with high discharged energy density. Herein, lead-free bismuth sodium titanate (BNT) particles are used as filler in nanocomposite due to their outstanding dielectric properties. In this paper, BNT nanoparticles decorated by dopamine were employed to fabricate BNT@Dopa/poly(vinylidene fluoride) (PVDF) nanocomposites. Dielectric properties and energy storage performance of nanocomposites with BNT nanoparticles enhanced significantly. The maximum dielectric constant (εr) of nanocomposites with BNT@Dopa nanoparticles was 14.15 at the frequency of 1 kHz. The discharged energy density (Udis) of nanocomposites with 3 vol% BNT@Dopa nanoparticles reached 13.09 J/cm3 at 430 kV/mm. The energy efficiency (η) of nanocomposites at 40 °C remained 53.62% at the electric field of 350 kV/mm. The nanocomposite with BNT@Dopa nanoparticles performed excellent fatigue endurance after 106 cycles. These results offer a practicable way to fabricate nanocomposites with high energy density. [ABSTRACT FROM AUTHOR]

The synergism between different surface facets of semiconductor with optimal ratios can contribute to obtain enhanced photocatalytic degradation performance. Herein, a bismuth-based material Bi4Ti3O12 exposed with {001} top facets and {010}/{100} lateral facets was prepared by the molten-salt method. More importantly, the ratio of different exposed facets could be controlled by adjusting the synthesis temperature of molten-salt synthesis process. The as-prepared Bi4Ti3O12 exposed with the optimal ratio of {001} top facets to {010}/{100} lateral facets exhibited the enhanced degradation activity of tetracycline hydrochloride (TC-HCl) under irradiation. The rate constant of optimal sample reached 0.904% min−1, over 3.3 times as compared with that of the counterpart with higher proportion of {001} facets. Besides, active species trapping experiments, photoelectrochemical measurements and selective photodeposition tests were used to illuminate the photocatalytic degradation mechanism. According to that, the enhanced degradation activity could be ascribed to crystal facet synergism which can promote photoinduced carrier separation. This work can give insights into designing and constructing other two-dimensional (2D) bismuth-based materials with the aim of enhancing photocatalytic degradation performance. [ABSTRACT FROM AUTHOR]

This work presents the synthesis of the noble nanocomposites of silica-coated calcium copper titanate-graphene (CCTO@SiO2-GO) by the established sol-gel method. This paper showed the decoration of CCTO@SiO2 NPs on the surface of graphene oxide and how the decoration/attachment depends on various environmental and instrumental factors like sonication time, stirring rate, centrifugation rpm and the thickness of silica shell coated on CCTO NPs. The prepared CCTO@SiO2-GO composites were characterized by suitable characterization techniques. FESEM and TEM confirmed the morphological study of nanocomposites and how the CCTO@SiO2 NPs are attached to the surface of GO sheet. FTIR has shown the presence of O-H, N-C groups which help in the formation of types of bonds between CCTO@SiO2 NPs and GO. This work further revealed an excellent result of a dielectric study, indicating that the best-decorated CCTO@SiO2 NPs over the surface of the GO sheet cause the increment of dielectric constant ε′ from 102 up to 105. Meanwhile, this study also suggested high loss ε″ up to 106 at a lower frequency, i.e. 20 Hz at RT which can be useful for microelectronic devices. This variance of dielectrics is due to the effect of polarization and decoration of CCTO@SiO2 NPs over the GO sheets. As the frequency increases from 20 Hz to 2 MHz, the dielectric constant ε′, as well as the loss of ε″, reached up to 102 values for the highest decorated material. Our study also clearly explained a uniform variation in dielectric constant ranges from 1 × 102 to 1.5 × 104 at a different temperature range from room temperature to 560 °C with a frequency range of 3 × 104 Hz to 2 × 106 Hz, and the value varies accordingly with the synthesis method. [ABSTRACT FROM AUTHOR]

Disconnections were recently shown to play a role in the mechanism of grain boundary motion in general grain boundaries in SrTiO3. In this work, we demonstrate the existence of disconnections in the viewing direction along the projected thickness of transmission electron microscopy samples and characterize possible aspects of the structure of these disconnections. We show that the presence of steps along the viewing direction may result in the appearance of a disordered region at the boundary, while it is actually composed of ordered crystalline material. We discuss the subsequent complications in analysis of transmission electron microscopy data and strict meaning of the term "edge-on" for grain boundaries. [ABSTRACT FROM AUTHOR]

A series of Nb-doped (BiNaK)TiO lead-free piezoelectric ceramics were fabricated by a conventional solid-state reaction method. The X-ray diffraction patterns reveal a pure perovskite structure for all the samples. A giant strain of 0.34% is achieved at 2 mol% Nb-doping concentration, and the corresponding normalized strain $$d_{33}^*$$ reaches 625 pm V, which is one of the best results of the BNT-based ceramics. Complex ac impedance data indicate that only the bulk effect contributes to the resistivity. The compositionally induced disruption of long-range ferroelectric order and relaxor transition contributed to the pinched polarization loops as well as the large electric field-induced strain. The results indicate that appropriate Nb-dopant content can remarkably enhance the strain level of (BiNaK)TiO ceramics, making it a promising candidate for actuator applications. [ABSTRACT FROM AUTHOR]

Nanosheet-assembled hierarchical flower-like titanium phosphate (TiP) is synthesized via hydrothermal treatment of H-titanate nanotubes (Ti-NT) at the optimized conditions of 0.1 M of HPO and hydrothermal temperature of 130 °C. A possible formation mechanism for the TiP flowers, involving the disintegration of Ti-NT and the growth and assembling of TiP nanosheets, is proposed. The main compositions of the uncalcined TiP flowers are titanium hydrogen phosphate hydrates (Ti(HPO)· xHO), which can be transformed to titanium phosphate (TiPO) after high temperature calcination. The photocatalytic activity of the prepared TiP flowers is increased with the increased calcination temperature, which may be attributed to the better photocatalytic activity of TiPO than Ti(HPO)· xHO and the increased crystallization of TiPO. [ABSTRACT FROM AUTHOR]

A complex composed of enzyme (horseradish peroxidase, HRP), layered titanate (TiOx), and magnetic beads (MB) was prepared, and the enzymatic activity of the complex and the repeatable use for the enzyme in the complex were investigated. The HRP/TiOx/MB complex was formed in acetate buffer (pH 4) by electrostatic interaction among the components where HRP and MB have positive charge, whereas TiOx is negatively charged. The resultant complex was sufficiently stable in an aqueous solution, and HRP immobilized on the layered titanate in the complex kept a certain enzymatic activity in which typical enzymatic relationship was observed between substrate concentration and initial reaction rate. By giving a magnetic field using commercial magnets, the HRP/TiOx/MB complex was easily and rapidly recovered, and the recovered complex was able to be used for the next enzymatic reactions. The enzyme/inorganic nanosheet/MB complex proposed in this study is expected to be applied as a new tool in the bioengineering and nanobiotechnological fields. [ABSTRACT FROM AUTHOR]

Bioceramic hydroxyapatite/sodium titanate coating on sandblasted titanium substrate was fabricated by a three-step process. At first, the sandblasted titanium substrate was coated with a flake-like sodium titanate layer by alkali-heat treatment. In the second step, the alkali-heat treated titanium substrate was hydrothermal treated at 180 °C for 4 h with calcium solutions. In the third step, the hydroxyapatite (HA) coating was deposited onto the hydrothermal treated layer via electrochemical deposition method. The surface topography and roughness of the coatings were determined by field emission scanning electron microscope (FESEM) and a mechanical contact profilometer, respectively. The surface compositions were evaluated by X-ray diffraction (XRD), energy-dispersive X-ray spectrum (EDS), and X-ray photoelectron spectroscopy (XPS). The EDS, XPS, and XRD analysis confirm the presence of element Ca, Ca 2+, and CaTiO 3 on sodium titanate layer after hydrothermal treatment with Ca(NO 3) 2 solution, respectively. FESEM micrograph shows the rod/needle-shaped crystallites are highly densely packed on the calcium-ion-containing layer with an average size of ~50 nm in diameter. The results indicate that the sodium titanate layer containing Ca 2+ ions possesses higher ability to induce HA formation compared with the pure sodium titanate layer. It is revealed that surface composition plays an important role in the electrochemical deposition of HA. The calcium-ion-containing layer probably makes the nucleation of HA easy and effectively promotes orientated growth of HA on flake-like sodium titanate surface. The sodium titanate layer possesses a lower corrosion current density and a higher corrosion potential than sandblasted-Ti substrate. The sodium titanate layer should act as a barrier to the release of metal ions from metallic substrate to physiological solutions and thus reducing the electrochemical reaction rate. [ABSTRACT FROM AUTHOR]

This article reports on a new and swift hydrothermal chemical route to prepare titanate nanostructures (TNS) avoiding the use of crystalline TiO as starting material. The synthesis approach uses a commercial solution of TiCl as titanium source to prepare an amorphous precursor, circumventing the use of hazardous chemical compounds. The influence of the reaction temperature and dwell autoclave time on the structure and morphology of the synthesised materials was studied. Homogeneous titanate nanotubes with a high length/diameter aspect ratio were synthesised at 160 °C and 24 h. A band gap of 3.06 ± 0.03 eV was determined for the TNS samples prepared in these experimental conditions. This value is red shifted by 0.14 eV compared to the band gap value usually reported for the TiO anatase. Moreover, such samples show better adsorption capacity and photocatalytic performance on the dye rhodamine 6G (R6G) photodegradation process than TiO nanoparticles. A 98% reduction of the R6G concentration was achieved after 45 min of irradiation of a 10 ppm dye aqueous solution and 1 g L of TNS catalyst. [ABSTRACT FROM AUTHOR]

Nanostructured titanates with different morphologies such as nanoflakes, nanotubes, and nanofibers have been selectively synthesized by a simple solvothermal treatment of commercial anatase TiO using the mixed water-ethanol cosolvent at low alkaline concentration. The effects of solvothermal temperature, volume ratio of HO to CHOH, amount of NaOH and solvents on the formation of titanate nanostructures have been systematically studied through X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). At low concentration of NaOH solution (the actual concentration of OH in the solution is only 0.58 M), different titanate nanostructures are achieved by simply changing the volume ratio of HO to CHOH at 180 °C and titanate nanotubes can be synthesized between 100 and 180 °C. A probable formation mechanism is proposed based on XRD, SEM and TEM analysis. The influence of cosolvent on the transformation from anatase TiO to titanate is also investigated. [ABSTRACT FROM AUTHOR]

Multilayered oxide heteroepitaxial systems, including that of a 1-nm-thick Y2O3-stabilised ZrO2 (YSZ) sandwiched between layers of SrTiO3 (STO) [1], have been a subject of much interest lately due to their significantly enhanced ionic conductivities as compared to the bulk materials. We aim to provide the foundation for understanding this increase in conductivity by considering the atomic configurations at the interfaces of such systems, specifically a ZrO2/STO multilayer system. Possible stable lattice structures of pure ZrO2 in the system are explored using a genetic algorithm in which the interatomic interactions are modelled by simple pair potentials. The energies of several of the more stable of these structures are then evaluated more accurately within density functional theory (DFT). We find that the fluorite ZrO2 phase is unstable as a coherently strained epitaxial layer in the multilayer system. Instead, anatase-, columbite-, rutile-, and pyrite-like ZrO2 epitaxies are found to be more stable, with the anatase-like epitaxy being the most stable structure over a wide range of chemical potential of the components. We also find a high energy metastable structure resembling the tetragonal fluorite structure which is predicted by DFT to be stabilised by SrO-terminated STO but not by TiO2-terminated STO. [ABSTRACT FROM AUTHOR]

Lanthanide ion doping of lead titanate was investigated using structural and differential scanning calorimetry measurements. Dense ceramics samples were prepared with starting compositions, PbLnTiO, assuming A-site substitution of Ln = La, Nd, Sm, Eu, Gd and Dy, at 2 and 8 at.%. Doping with La reduced the tetragonality and cell volume. A systematic recovery in these values was observed for the smaller Ln ions, suggesting the onset of partial substitution of the Ln ions at the B-site. The ferroelectric-paraelectric transition temperatures also recovered, consistent with an increased probability of B-site occupation with decreasing ion size. Evidence for site occupancy obtained from the presence cation vacancies is also discussed. [ABSTRACT FROM AUTHOR]

We have synthesized SrTiO3 (STO) using a newly developed precursor route by chemical solution approach. The new STO precursor solution was prepared in ambient atmosphere. Various characteristic methods, including thermal analyses, infrared spectroscopy, and transmission electron microscopic analyses techniques, were applied to study the thermal decomposition and crystallization behavior of STO precursor gel. The acquirement of single-phase STO powders at the different annealing atmospheres demonstrates that STO with perovskite structure is prone to tolerate the oxygen vacancies defect. Epitaxially grown STO film on textured Ni-W substrate by a seeded nucleation method shows a high c-axis orientation and a good out-of-plane texture. Scanning electron microscopy and atomic force microscopy investigations of STO film reveal the continuous, crack-free, and smooth surface morphology. The results suggest that STO film fabricated by the newly developed precursor route may be suitable to be used as buffer layer for subsequent growth of YBCO in coated conductors. [ABSTRACT FROM AUTHOR]

This article describes the processing and characterisation of lanthanum-doped lead zirconate titanate (PLZT)-based ferroelectric fibres for composite transducer applications. X-ray diffraction of the extruded and sintered fibres indicated some lead loss during sintering; however, the fibres exhibited low porosity (1.54%), high maximum piezoelectric strain (4041 ppm) and relatively low coercive field (0.77 kV/mm). The low coercive field of the lanthanum-doped fibres may be advantageous in terms of facilitating polarization of the fibres in composite architectures. [ABSTRACT FROM AUTHOR]

Intergranular glassy films (IGFs) often play a key role in the formation of microstructure and the resultant properties in titanate-based materials. In this article, a systematic study of IGF structure and chemistry is reported in FeO-doped SrTiO ceramics sintered under different temperatures and dwelling times. IGFs exhibit a large variation in their thicknesses, although majority of them are still formed by the lower energy {100}, {110}, and {111} planes from one side, which is also true for those grain boundaries (GBs) without IGF and reveals no particular effect of crystallography on IGF width. Furthermore, two trends of IGF chemical composition were found coexisting in each sample, one rich in Ti and the other in Sr, and both containing Fe segregants. The change of sintering temperature did not show significant effect on the distributions for both trends. However, increase of the dwelling time is effective to turn some Sr-rich IGFs to Ti-rich IGF, indicating that the former is in a transient state and the equilibrium IGF has most likely a TiO-based composition. [ABSTRACT FROM AUTHOR]

In this study, four kinds of coupling agents (CA), i.e., γ-aminopropyltriethoxysilane (KH-550), (3-glycidyloxypropyl)trimethoxysilane (KH-560), isopropyl tri(di(2-ethylhexyl)pyrophosphate)titanate (NDZ-201), isopropyl tri(di(2-ethylhexyl)phosphate)titanate (NDZ-102), were used to investigate their influences on the thermal conductivity and morphology of aluminum (Al) particle reinforced epoxy composite. The results indicate that the thermal conductivity of the composites increases with increasing Al particles concentration up to 48 vol.%; the surface modification of Al particles has an appreciable effect on the thermal conductivity. The thermal conductivities of the composite containing 48 vol.% Al particles treated with the KH-550, KH-560, NDZ-201, and NDZ-102 couplers, are 1.29, 1.48, 1.27, and 1.36 W/m K, respectively, corresponding to 1.03 W/m K of that without surface treatment. Furthermore, the concentration of CA has an influence on the thermal conductivity of the composites. [ABSTRACT FROM AUTHOR]

This work evaluates the use of fine-grained yttrium-substituted strontium titanate powders for the preparation of planar anode supported solid oxide fuel cells. Starting from a submicron-sized powder of Y-substituted strontium titanate SrYTiO (SYT), which was synthesised via spray pyrolysis followed by a grinding process, suspensions of high solid concentration were prepared by steric stabilisation. From these suspensions, tape casting slurries of up to 25 vol% were produced and further processed to ceramic green tapes using the doctor blade technique. The rheological behaviour of the slurries was investigated in dependence on the content of solids and organic additives. Furthermore, the binder burnout and sintering behaviour of the green sheets were characterised. After firing, crack-free substrates of high planarity were obtained. The achieved properties of the sintered tapes such as density, porosity, warping, mechanical strength, and electrical conductivity were determined in dependence on sintering temperature. [ABSTRACT FROM AUTHOR]

Based on modified constitutive equations and finite element method, calculations have been performed to study the effect of interface bonding on the phase-transition-aided magnetoelectric (ME) response in a new kind of NiMnGa/lead-zirconate-titanate (PZT) multiferroic laminate composites. The results quantitatively show that the ME effect is remarkably dependent on both the interface layer characteristics and the interface layer thickness. Stiffer and thinner interface layers are apt to produce higher ME effect. Calculations are in good agreement with available experimental results. Furthermore, the theoretical approach was improved to consider the enhancement in the magnetostriction of martensites induced by pre-applied opposing stress. Predictions reveal that the usage of single crystal FePd as ferromagnetic phase to form magnetoelectric composite with PZT can produce a high ME up to ~1 V/cm Oe. [ABSTRACT FROM AUTHOR]

Ba(TiSnGe)O (BTSG- x- y; x = 0, 0.05; y = 0-0.05) powders were synthesized by a sol-gel (SG) method and for comparative purposes also by a mixed-oxide (MO) method. In this system, BaGeO functions as sintering additive. Due to smaller particle sizes of the SG powders a higher sintering activity was found, which resulted in reduced grain growth and in a more homogenous grain size distribution for the corresponding ceramics. The dependence on the paraelectric ⇆ ferroelectric phase transition, i.e. the phase transition temperature, the width of the transition region and completeness were examined by dielectric measurements, DTA as well as by SEM, EDX and XRD investigations with respect to the BaGeO content, synthesis method and sintering temperature. The phase transition temperatures of the SG ceramics are remarkably higher than those of the MO ceramics with the same nominal compositions. The reason is a lower tin concentration within the grains of SG ceramics as confirmed by EDX and XRD investigations. The presence of BaGeO in barium titanate-stannate system on the basis of a SG method caused an improved incorporation of tin in the BaTiO lattice. [ABSTRACT FROM AUTHOR]

The paper reports the synthesis, structural and high frequency dielectric properties of Ba(ZrTi)OBZT, nanopowders where x = 0, 0.1, 0.2, 0.3. These powders were synthesized using both microwave assisted and conventional heating, with the former requiring lower temperature and shorter times compared to the latter, viz., 700 °C for 30 min versus 900 °C for 5 h. The synthesized nanopowders were characterized using X-ray diffraction, micro-Raman spectroscopy, transmission electron microscopy, BET surface area analysis, differential scanning calorimetry and high frequency dielectric measurements. All the microwave synthesized BZT compositions were found to have well crystallized, finer nanoparticles with less agglomeration and higher dielectric permittivity compared to the conventionally prepared powders. The rapidity and less demanding processing conditions associated with the microwave assisted method augers well for the general applicability of the technique for the production of nanocrystalline powders. [ABSTRACT FROM AUTHOR]

The objective of this experiment was to develop biomimetic calcium phosphate coatings on low-modulus Ti-7.5Mo substrates treated with NaOH aqueous solutions and subsequent water aging before soaking them in simulated body fluid (SBF). Specimens of commercially pure titanium (c.p. Ti) and Ti-7.5Mo were initially treated with 5 M NaOH at 60 °C for 24 h, resulting in the formation of a porous network structure composed of sodium titanate (NaTiO). Afterward, the specimens were aged in distilled water at 80 °C for 12, 24, or 48 h, and subsequently immersed in 1.5SBF at 37 °C for either 1 or 13 days. The calcium phosphate-forming abilities of the c.p. Ti and Ti-7.5Mo achieved by a single NaOH treatment were low, but were significantly increased by the water aging. The amount of calcium phosphate deposited on the Ti-7.5Mo after NaOH treatment and subsequent water aging for 12 or 24 h was much greater than other conditions. The calcium phosphate-coated Ti-7.5Mo has strong potential as an artificial bone substitute or in other hard tissue-replacement materials with heavy load-bearing requirements due to a favorable combination of bioactivity, low elastic modulus, and low processing costs. [ABSTRACT FROM AUTHOR]

In this study, the mechanism of precursor dissolution and the influence of kinetics of dissolution on titanate nanotube formation were investigated. This comparative study explored the dissolution kinetics for the case of commercial titania powders, one composed of predominantly anatase (>95%) and the other rutile phase (>93%). These nanoparticle precursors were hydrothermally reacted in 9 mol L NaOH at 160 °C over a range of reaction times of between 2 and 32 h. The high surface area nanotube-form product was confirmed using X-ray diffraction, FT-Raman spectroscopy, and transmission electron microscopy. The concentration of nanotubes produced from the different precursors was established using Rietveld analysis with internal and external corundum standardization to calibrate the absolute concentrations of the samples. Interpretation of the dissolution process of the precursor materials indicated that the dissolution of anatase proceeds via a zero-order kinetic process, whereas rutile dissolution is through a second-order process. The TiO nanostructure formation process and mechanism of TiO precursor dissolution was confirmed by non-invasive dynamic light scattering measurements. Significant observations are that nanotube formation occurred over a broad range of hydrothermal treatment conditions and was strongly influenced by the order of precursor dissolution. [ABSTRACT FROM AUTHOR]

BaTiO films on base metal foils are of interest for capacitor applications, but the processing requires reducing atmospheres that influence the film defect chemistry and density. In this study, powders dried from barium titanate solutions and barium titanate films were studied by X-ray diffraction, differential scanning calorimetry, thermal gravimetric analysis, infrared spectroscopy, and spectroscopic ellipsometry at various points in the processing. It was found that atmospheres designed to minimize Ni oxidation delay decomposition of organics, leading to retained carbonate phases. Thus, crystallization of the barium titanate occurs via decomposition of a barium carbonate phase. Retained organics that are present during high temperature processing can cause porosity in the films. On annealing at 1000 °C, there is slightly increase in the refractive index of the film due to further crystallization and densification. The final refractive index is comparable to that of 95% dense barium titanate ceramics. Re-oxidation did not change the refractive index of the film over the wavelength range from 350 to 650 nm. [ABSTRACT FROM AUTHOR]

We have successfully fabricated barium titanate (BaTiO) films on Si (100) and Pt(111)/Ti/SiO/Si substrates using the polyol thermal decomposition (PTD) process by spin-coating technique. In PTD process, we confirmed that the crystalline oxycarbonate BaTiOCO films were directly formed as a consequence of evaporation of polyol precursor solution prepared simply by mixing metal chlorides and ethylene glycol, and then converting them into crystalline BaTiO films through thermal decomposition at >500 °C. This feature makes it possible to grow densely packed and crack-free BaTiO films as thin as 70 Å per cycle. Although PTD is described here for a complex metal-oxide film of BaTiO, other simple and complex metal-oxide thin films with high-dielectric constant materials are also likely to be suitable for deposition with accurate control of film thickness and composition using the polyol precursor solutions. [ABSTRACT FROM AUTHOR]

Automated high resolution electron backscatter diffraction was used to map the local crystallographic texture of Pt and PbZr1− xTi xO3 (PZT) thin films with a resolution as high as 5 nm. The Pt and PZT films consisted of 99.9% and 94.3% {111} textured grains (i.e., with (111) planes parallel to the substrate surface), respectively. The average Pt and PZT grain sizes were 46 ± 30 nm and 65 ± 30 nm, respectively. Quantification of misorientation distributions and the fraction of non-{111}-textured grains demonstrates the potential of this local texture measurement method for quantifying the ferroelectric variability limits of PZT-based capacitors. [ABSTRACT FROM AUTHOR]

A new synthetic route to obtain high-purity strontium titanate, SrTiO3, using the sol–gel-hydrothermal reaction of TiCl4 and a SrCl2 solution in an oxygen atmosphere has been developed. In the synthesized products the SrTiO3 nanoparticles are nearly spherical and decrease in size with the reaction time (48 h) down to a diameter of about 40 nm. The microstructure and composition of the as-synthesized samples were investigated by X-ray diffraction (XRD), high-resolution TEM (HRTEM), Raman spectroscopy, atomic force microscopy (AFM), and energy-dispersive X-ray spectroscopy (EDX). All the samples were identified as cubic perovskite phase. [ABSTRACT FROM AUTHOR]

Orientation controlled, micron-sized dot-patterned PZT films were grown by metal organic chemical vapor phase deposition (MOCVD), and their crystal structure was evaluated. A micron-size dot-patterned SrRuO3 (SRO) buffer layer was initially prepared by MOCVD through a metal mask on the (111) Pt/Ti/SiO2/Si substrate. Then, a PZT film was deposited over the entire substrate. Micron-beam X-ray diffraction and Raman spectroscopy indicated that (111)-orientated PZT was prepared on the SRO covered area, while the (100)/(001)-orientated one was directly grown on Pt-covered substrates. The PZT film grown on SRO was thinner than that on the Pt-covered substrate. The estimated ferroelectric property on the center of the dot pattern was larger than that at the circumference by Raman spectroscopy because the strain is accelerated at the center of the dot. [ABSTRACT FROM AUTHOR]

Barium titanate (BaTiO3) nanocube particles below 20 nm were prepared by solvothermal method. A selection of organic solvent and inorganic materials of Ba and Ti sources was most important for the preparation of nanocubes. A nucleation and particle growth of BaTiO3 nanoparticles led to a formation of the BaTiO3 nanocubes with a size of 10–15 nm at temperatures above 200 °C. [ABSTRACT FROM AUTHOR]

Lead zirconate titanate (PZT) based piezoelectric materials are well known for their excellent piezoelectric properties. However, considering the toxicity of lead and its compounds, there is a general awareness for the development of environmental friendly lead-free materials as evidenced from the legislation passed by the European Union in this effect. Several classes of materials are now being considered as potentially attractive alternatives to PZTs for specific applications. In this paper, attempts have been made to review the recent developments on lead-free piezo materials emphasizing on their preparation, structure–property correlation, etc. In this context, perovskite systems such as bismuth sodium titanate, alkali niobates (ANbO3), etc. and non-perovskites such as bismuth layer-structured ferroelectrics are reviewed in detail. From the above study, it is concluded that some lead-free compositions show stable piezoelectric responses even though they do not match the overall performance of PZT. This has been the stimulant for growing research on this subject. This topic is of current interest to the researchers worldwide as evidenced from the large number of research publications. This has motivated us to come out with a review article with a view that it would give further impetus to the researchers already working in this area and also draw the attention of the others. [ABSTRACT FROM AUTHOR]

Recently, there has been significant interest toward the development of tunable dielectric materials for voltage-controlled, frequency-agile phase shifters and filters operating in the microwave regime. The fundamental challenge in designing materials systems for such tunable devices is the simultaneous requirement of high dielectric tunability (>40%) over a large temperature interval (−10 °C to +90 °C) coupled with low dielectric losses (between 3.0 dB and 4.0 dB in operational bandwidths ranging from several hundred MHz up to 30 or more GHz). We show that a high- and temperature-insensitive tunability can be realized in compositionally graded ferroelectrics and provide a brief review of the results of experimental and theoretical studies on the dielectric properties of Barium Strontium Titanate (Ba1− xSr xTiO3 or BST) multilayer heterostructures. Theoretically, we discuss the role of thermal stresses on the dielectric properties using a non-linear thermodynamic model coupled with basic electrostatic considerations to describe the interlayer interactions between the ferroelectric layers. We show that the thermal strains arising from the thermal expansion coefficient mismatch between the multilayered film and the substrate may have a significant effect on the dielectric permittivity and tunability of BST multilayers. Experimentally, compositionally graded BST multilayers (5 mol% MgO doped and undoped) were grown via metallo-organic solution deposition (MOSD) on Pt–Si substrates and electrically characterized. Optimum conditions were found to exist in BST multilayers consisting of three distinct layers of ~220 nm nominal thickness with compositions corresponding to Ba0.60Sr0.40TiO3 (BST 60/40), BST 75/25, and BST 90/10. At room temperature, the BST heterostructure has a small-signal dielectric permittivity of 360 with a dissipation factor of 0.012 and a dielectric tunability of 65% at 444 kV/cm. These properties exhibit minimal dispersion as a function of temperature ranging from 90 °C to −10 °C. Our results also show that MgO doping improves dielectric loss (tan δ = 0.008), but results in a moderate dielectric tunability of 29% at 444 kV/cm. Electrical measurements at microwave frequencies display a decrease in the dielectric permittivity and tunability for both undoped and MgO-doped BST multilayers. At 10 GHz, the dielectric response, tunability, and the loss characteristics for graded undoped BST are 261, 25% (at 1,778 kV/cm), and 0.078, respectively, and 189 and 15% (at 1,778 kV/cm), and 0.039, respectively, for the MgO-doped graded BST. [ABSTRACT FROM AUTHOR]

The electrothermal properties of the perovskite oxides barium titanate (BTO), lead titanate (PTO), and strontium titanate (STO) are computed near the temperatures of their ferroelectric and/or ferroelastic phase transitions. The computations are performed using a modified 2-4-6 Ginzburg–Landau–Devonshire polynomial as functions of applied electric field and temperature for mechanically free monodomain crystals and for epitaxial thin films subject to perfect lateral clamping. For BTO and PTO, which display weak first-order ferroelectric phase transitions at their Curie points, the application of a bias field exceeding the electrical critical point reduces the dependence of the electrocaloric (EC) response on temperature and automatically reduces its magnitude. Under conditions of perfect lateral clamping, the weak first-order phase change is transformed into second-order phase change. In this instance the electrical critical point is coincident with the Curie temperature and a lower bias field is required to produce a comparable reduction in temperature sensitivity. Comparison of the electrothermal behaviors of BTO and PTO with that computed for STO near the temperature of the second-order ferroelastic phase transition provides insight concerning the EC properties of ferroelectric solid solution systems wherein the Curie temperature and the first-order character of the paraelectric to ferroelectric transition both may change subject to a change in composition. The results illustrate how electrical and mechanical boundary conditions can be adjusted, in conjunction with composition, in altering the EC properties of ferroelectric materials selected for use in a particular temperature range. [ABSTRACT FROM AUTHOR]

Highly stable, water-based barium titanate (BaTiO3) sols were developed by a low cost and straightforward sol–gel process. Nanocrystalline barium titanate thin films and powders with various Ba:Ti atomic ratios were produced from the aqueous sols. The prepared sols had a narrow particle size distribution in the range 21–23 nm and they were stable over 5 months. X-ray diffraction pattern revealed that powders contained mixture of hexagonal- or perovskite-BaTiO3 as well as a trace of Ba2Ti13O22 and Ba4Ti2O27 phases, depending on annealing temperature and Ba:Ti atomic ratio. Highly pure barium titanate with cubic perovskite structure achieved with Ba:Ti = 50:50 atomic ratio at the high temperature of 800 °C, whereas pure barium titanate with hexagonal structure obtained for the same atomic ratio at the low temperature of 500 °C. Transmission electron microscope revealed that the crystallite size of both hexagonal- and perovskite-BaTiO3 phases reduced with increasing the Ba:Ti atomic ratio, being in the range 2–3 nm. Scanning electron microscope analysis revealed that the average grain size of barium titanate thin films decreased with an increase in the Ba:Ti atomic ratio, being in the range 28–35 nm. Moreover, based on atomic force microscope images, BaTiO3 thin films had a columnar-like morphology with high roughness. One of the highest specific surface area reported in the literature was obtained for annealed powders at 550 °C in the range 257–353 m2g−1. [ABSTRACT FROM AUTHOR]

In this work, the effects of Nb2O5 addition on the dielectric properties and phase formation of BaTiO3 were investigated. A core–shell structure was formed for Nb-doped BaTiO3 resulted from a low diffusivity of Nb5+ ions into BaTiO3 when grain growth was inhibited. In the case of 0.3–4.8 mol% Nb2O5 additions, two dielectric constant peaks were observed. The Curie dielectric peak was determined by the ferroelectric-paraelectric transition of grain core, whereas the secondary broad peak at lower temperature was due to strong chemical inhomogeneity in Nb-doped BaTiO3 ceramics. The dielectric constant peak at Curie temperature was markedly depressed with the addition of Nb2O5. On the other hand, the secondary dielectric constant peak was enhanced when sintered above 1280 °C for higher Nb2O5 concentrations (≥1.2 mol%). The Curie temperature was shifted to higher temperatures, whereas the transition temperature corresponding to the secondary peak moved to lower temperatures as increasing the amount of Nb2O5 more than 1.2 mol%. The decrease of this lower transition temperature was assumed to be closely related with the secondary phase formation when Nb concentration greater than 1.2 mol%. From XRD analyses, a large amount of secondary phases was observed when Nb2O5 amount exceeded 1.2 mol%. The coefficients of thermal expansion of Nb-doped BaTiO3 were increased with increasing Nb2O5 contents, resulting in large internal stress between cores and shells. Therefore, the shift of Curie temperature to higher temperatures was attributed to internal stress resulting from the formation of a core–shell structure and a large amount of secondary phase grains. [ABSTRACT FROM AUTHOR]

Bi3.25La0.75Ti2.94V0.06O12 (BLTV) thin film was fabricated on the Pt/TiO2/SiO2/p-Si(100) substrate using sol–gel method. The microstructures and electrical properties of the film after cosubstitution of La and V were investigated. The BLTV thin film shows less highly c-axis oriented than the BIT thin film mainly with fine rod-like grains. Raman spectroscopy shows that TiO6 (or VO6) symmetry decreases and Ti–O (or V–O) hybridization increases for V substitution. The Pr and Ec values of the BLTV thin film are 26.3 μC/cm2 and 98 kV/cm at a voltage of 12 V, respectively. The thin film also exhibits a very strong fatigue endurance up to 1010 cycles and low leakage current density. The excellent properties of the BLTV thin film are attributed to the effective decrease or suppression of oxygen vacancies after La and V cosubstitution in the thin film. [ABSTRACT FROM AUTHOR]

Single crystal growth of lead-based piezoelectric ceramics Pb(Mg1/3Nb2/3)0.68Ti0.32O3 (PMN-32PT) and Pb(Mg1/3Nb2/3)0.42(Ti0.638Zr0.362)0.58O3 (PMN-37PT-21PZ) ceramics via templated grain growth (TGG) was investigated. (001)- and (111)-oriented BaTiO3 (BT) single crystals and (001)-oriented SrTiO3 (ST) single crystals (of approximately 2.5 × 2.5 × 1 mm) were utilized as seeds for the growth experiments. The piezoelectric single crystals were produced in a process that involves at first hot pressing of single crystal in cold isostatically pressed ceramics followed by subsequent sintering of the samples. Growth of (001)-oriented single crystals with BT seeds was observed in both PMN-32PT and PMN-37PT-21PZ matrices. The measured growth lengths were up to 140 and 65 μm, respectively. The grown (001)-oriented single crystals grown were rectangular. The measured growth lengths of the pyramidal-shaped (111) BT single crystals were up to 1 mm, which is much larger than the growth lengths of the (001) single crystals. Experiments on (001) ST-seeded single crystals were not successful. No single crystal growth was observed due to the dissolution of the ST single crystals in the PMN-PZT matrix. The differences were explained by defect-chemical considerations. [ABSTRACT FROM AUTHOR]

High current density pulsed-electron emission is observed from a lead zirconate stannate titanate lanthanum-doped (PLZST) antiferroelectric ceramic disc on application of positive or negative triggering voltage pulses. Electron-emission pulse with a peak current density 1,400 A/cm2 and a full-width at half-maximum (FWHM) duration of 560 ns was recorded in the presence of a 3.5 kV dc extraction voltage. It is higher than the various earlier results obtained using lead zirconate titanate ferroelectric ceramic. Self emission of electrons with a current density of 1.3 A/cm2 and the FWHM duration of about 100 ns were also observed. Strong electrons emission was the co-effect of surface plasma and noncompensated charges at the surface of the antiferroelectric. Field-induced local phase transition in the vicinity close to triple junction results in primary electron emission from these areas. These primary emission electrons ignited surface plasma and then led to the strong emission. [ABSTRACT FROM AUTHOR]

Rare earth (RE) and manganese-modified lead titanate ceramics were studied concerning the presence of two peaks in the temperature dependence of the dielectric permittivity. An eventual incorporation of the RE into A-site and/or B-site in the perovskite structure and the oxygen migration were considered as causes of the observed phenomenon. The structural analysis showed that at least a small amount of Ti4+ could be substituted by the RE ions. It was considered from the pyroelectric and electrical conductivity results that, even when an eventual incorporation of the RE into the A-site and/or B-site of the structure could be possible, both peaks could not be associated with paraelectric–ferroelectric (PE-FE) phase transitions. The observed peak at lower temperatures has been associated with the PE-FE phase transitions, whereas the hopping of oxygen vacancies has been considered as the cause for the dielectric anomaly observed at higher temperatures. [ABSTRACT FROM AUTHOR]

The zinc titanates doped with zirconium were synthesized by conventional solid-state reaction using metal oxides. X-ray diffractometry and differential scanning calorimetry analysis results indicated that the stable region of the hexagonal Zn(Zr x Ti1− x )O3 phase extended to a high temperature (above 945 °C). The c/a value decreased as the Zr concentrations increased, which may be caused by the Zr4+ addition resulting in a shorter distance between the center ion and its nearest neighbors of the octahedron, and the bonding force between the B-site ion and oxygen ion of ABO3 perovskite-like structure becoming stronger. The dielectric properties exhibited a significant dependence on the sintering temperatures and the amount of ZrO2 addition. The dielectric constant decreased and Curie temperature ( T c) increased slightly with the increasing amounts of Zr ions. This is caused by the second phase of ZnZrO3 which was deposited at the grain boundaries and inhibited the grain growth. Furthermore, diffuse phase transition with a maximum permittivity at a transition temperature that is close to room temperature in Zn(Zr x Ti1− x )O3 was observed. [ABSTRACT FROM AUTHOR]

In an attempt to obtain finest possible microparticles of BaTiO3 (BT) with highest possible tetragonality via a solid state route, starting mixtures comprising BaCO3 and TiO2 were subjected to various pretreatments including addition of glycine and mechanical activation. Reaction processes were monitored by the changes in the weight, crystallinity, and morphology in detail. While mechanical activation with glycine significantly increased the rate of reaction and homogeneity of the particle size of the product, BT, simultaneous particle growth of BT was intolerably acute for micro-electronic devices. The fast particle coarsening was predominated by the coalescence of BT tiny particles formed around titania. A mixture with higher homogeneity was attained by using finer starting materials under wet mixing, avoiding significant mechanical stressing. Particle growth of BT was suppressed to ca. 100 nm to obtain fully crystallized BT particles without significant loss of tetragonality and, hence, close to meet our requirements for MLCCs. [ABSTRACT FROM AUTHOR]

The dependence of the shape and size distribution of aggregates of lead zirconate titanate nanoparticles prepared by spray pyrolysis of a sol–gel precursor solution is reported. Decreasing the average heating rate from 300 to 160 °C s−1 in the sub-200 °C section of the reactor decreased the proportion of non-spherical particle aggregates and decreased the maximum size from ~10 to ~5 μm. Microtome sectioning revealed an internal structure composed of <100 nm primary particles. Both solid and hollow particle aggregates were present. [ABSTRACT FROM AUTHOR]