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In this work, perovskite oxide SrCeO3 was synthesized using the solution combustion method (SCM). Synthesized samples have been characterized using X‐ray diffraction (XRD), Raman, ultra violet (UV)–visible spectroscopy, and scanning electron microscopy (SEM) techniques. The XRD and Rietveld refinement has confirmed the orthorhombic structure with space group Pnma. The average grain size of this ceramic sample is 1.2 µm. The dielectric constant, dissipation factor, modulus, impedance, and alternating current (AC) and direct current (DC) conductivities were analyzed in the temperature range RT to 600°C and frequency range 20 Hz–2 MHz. Further, it was observed that the role of grain boundaries in dielectric and electrical properties is significant, at low temperatures. The origin of the dielectric relaxation and conduction process is the same. The activation energy for DC conduction (Edc) was found to be.79 eV. Electrical conduction/relaxation is assigned to the diffusion of doubly ionized oxygen (Vo··). The value of DC conductivity (1.2 × 10−3 Ω−1 cm−1 at 600°C) and activation energy of.79 eV is very close to the values reported for doped CeO2‐based oxide ion conductors for SOFCs. This study has demonstrated that SrCeO3 can be an alternative candidate for the oxide ion conductor electrolyte application and the potential to be used as a thermally stable capacitor application for microwave dielectric applications. [ABSTRACT FROM AUTHOR]

Optimization of energy storage performance in dielectric ceramics has been a focus in recent decades due to the benefits of high energy storage density, efficiency, and exceptional temperature stability. In this work, we report huge dielectric constant in La0.55Li0.35TiO3‐δ and sharp decrease in its value with the substitution of Sr and Cu at Ti position. These samples La0.55Li0.35TiO3‐δ (LLTO), La0.55Li0.35Ti0.9Cu0.1O3‐δ (LLTCO) and La0.55Li0.35Sr0.1Ti0.9O3‐δ (LLSTO) were prepared by solid state reaction method. The interfacial polarization of lithium ion aggregation close to the grain boundaries and the dipoles of Li ions in the sample are suggested to be the source of the enormous dielectric values. Parent composition (LLTO) shows highest dielectric constant value (6.29 × 105 at frequency 10 Hz, 7.30×104 at 1 kHz) recorded at room temperature while the lowest dielectric loss value (0.124) was observed for LLSTO at frequency 1 kHz. Structural characterization has been done using X‐ray diffraction (XRD) technique to investigate the crystal structure of the prepared compositions. The XRD patterns show the similar crystal structure for all the compositions with the parent composition LLTO. The optical band gap is calculated by Kulbeka Munk function and Tauc plot using UV–visible diffuse reflectance spectroscopy technique. The maximum band gap value (3.32 eV) is obtained for parent composition while doping of Cu and Sr at Ti site in La0.55Li0.35TiO3‐δ decreases the band gap value. Optical microscopy shows the micron size grains in these samples. Doping of Sr and Cu in perovskite structure of LLTO brings tunability in dielectric and optical properties. [ABSTRACT FROM AUTHOR]

Optimization of energy storage performance in dielectric ceramics has been a focus in recent decades due to the benefits of high energy storage density, efficiency, and exceptional temperature stability. In this work, we report huge dielectric constant in La0.55Li0.35TiO3‐δ and sharp decrease in its value with the substitution of Sr and Cu at Ti position. These samples La0.55Li0.35TiO3‐δ (LLTO), La0.55Li0.35Ti0.9Cu0.1O3‐δ (LLTCO) and La0.55Li0.35Sr0.1Ti0.9O3‐δ (LLSTO) were prepared by solid state reaction method. The interfacial polarization of lithium ion aggregation close to the grain boundaries and the dipoles of Li ions in the sample are suggested to be the source of the enormous dielectric values. Parent composition (LLTO) shows highest dielectric constant value (6.29 × 105 at frequency 10 Hz, 7.30×104 at 1 kHz) recorded at room temperature while the lowest dielectric loss value (0.124) was observed for LLSTO at frequency 1 kHz. Structural characterization has been done using X‐ray diffraction (XRD) technique to investigate the crystal structure of the prepared compositions. The XRD patterns show the similar crystal structure for all the compositions with the parent composition LLTO. The optical band gap is calculated by Kulbeka Munk function and Tauc plot using UV–visible diffuse reflectance spectroscopy technique. The maximum band gap value (3.32 eV) is obtained for parent composition while doping of Cu and Sr at Ti site in La0.55Li0.35TiO3‐δ decreases the band gap value. Optical microscopy shows the micron size grains in these samples. Doping of Sr and Cu in perovskite structure of LLTO brings tunability in dielectric and optical properties. [ABSTRACT FROM AUTHOR]

In this study, the formation of clay nanolayer clusters inside the high‐density polyethylene (HDPE) matrix was evaluated using a specific strategy based on energy equilibrium in the melt mixing stage. Furthermore, the formed interphase region around nanoparticle domains was precisely evaluated considering the molecular structure of the matrix and linear variation of the physical/mechanical characteristics. The obtained results were used in a developed analytical model to predict the tensile modulus of the nanocomposite system containing randomly oriented nanoparticle domains. The domains consisted of exfoliated, intercalated, or aggregated/agglomerated nanolayers placed in different excluded volumes as the components of an equivalent box model. Different comparative studies were performed using the obtained data from different tests, applied to the prepared HDPE/clay nanocomposite samples, and other data from the literature. It was found that the confrontation between the exerted dispersion energy, by the mixer, and interparticle cohesion energy defined the thickness and physical/mechanical characteristics of the final aggregates/agglomerates in a nanocomposite. Though, the size and content of aggregates/agglomerates increased with the content of initially added nanoparticles. Consequently, the random orientation of each nanoparticle domain and formation of the polymer/particle interphase were proved to have determinative impacts on the mechanical properties of the system. [ABSTRACT FROM AUTHOR]

The present paper describes an experimental study on mechanical properties of additively manufactured anti‐tetrachiral auxetic structures under shear and flexural loading. Specimens of ABS material are fabricated using material extrusion technique of additive manufacturing. Experiments are planned using central composite design method. Three process factors, namely, slice thickness, print speed, and contour width, are considered to study their influence on modulus, strength, and specific energy absorption (SEA) of fabricated structures. To perform shear testing on specimen, a novel fixture is designed and fabricated. Flexural properties are measured using three‐point bending test on universal testing machine. It is found that all three process factors significantly affect modulus, strength, and SEA of the structure under shear and flexural loading. Mechanical properties improve with increase in slice thickness, print speed, and contour width. Regression models are developed to predict the response characteristics. In addition, optimized values of process factors are determined to maximize the mechanical properties of the structure. [ABSTRACT FROM AUTHOR]

In the present work, an experimental investigation is performed to study the influence of process parameters on mechanical properties of tetra‐anti‐chiral auxetic structures manufactured by material extrusion (ME) technique of additive manufacturing (AM). Process parameters namely layer height, print speed, and print temperature are considered, while responses are compressive strength (σ), modulus (E), and specific energy absorption (SEA). Specimens of acrylonitrile‐butadiene‐styrene (ABS) polymer are fabricated and then tested under compressive loading. From the experimental results, it is observed that all process parameters significantly influence the mechanical properties of the structure. Scanning electron microscope (SEM) is used to study microstructural defects of the tested specimen. To maximize the responses, optimization of process parameter is performed using desirability function approach. Regressive models are developed to predict the mechanical properties. [ABSTRACT FROM AUTHOR]

ZnO/TiO2 composite ceramics have been prepared by solid-state reaction technique at 900°C. The X-ray diffraction results revealed the formation of secondary phases referred to as spinel Zn2TiO4 and hexagonal ZnTiO3. The structural analysis showed that all the composites that have been prepared have a polycrystalline nature and a hexagonal wurtzite structure. The complex modulus ( M) and electric impedance of the samples have been investigated by broadband dielectric spectroscopy in a wide range of temperature (40°C-110°C) and frequency (0.1 Hz to 10 MHz). The modulus plots (M′′, M′) illustrate the presence of non-Debye type of relaxations attributed to the effects of interfacial and dipolar polarizations. The real and the imaginary parts of the impedance are well fitted to equivalent circuit models. At high temperatures, Z″max varies from 0.03 × 106 to 4.9 × 106 Ω when the TiO2 doping concentration increases from 1 to 7 wt%. From the obtained results, the secondary phase ZnTiO3 plays an important role in the electrical properties. [ABSTRACT FROM AUTHOR]