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One of the major obstacles restricting the wide applications of Mg alloys is their low Young's modulus at ∼45 GPa, which is uncompetitive to Al alloy over 60 GPa. To resolve this issue, we proposed a new strategy of designing ultra-light Mg-Li alloys by employing the microscale compounds in both HCP and BCC grains to achieve high Young's modulus. HCP or BCC alone cannot achieve a high modulus due to the segregation of solutes at the grain boundaries and the formation of brittle intermetallics in the interdendritic region. We designed chemistry that is so perfect to arrest the excess solutes inside the BCC matrix during solidification and engulf pre-solidified rare earth particles by HCP primary grains which have such a lean chemical composition that has almost no segregation. During solution heat treatment, the dissolution of solutes pushes the BCC boundary towards HCP grains by Ostwald ripening (BCC structures are interconnected but the HCP structures are isolated). During low-temperature aging heat treatment, nucleation of HCP structure on the rare earth particles inside the BCC grain is found, degrading the strength. Therefore, a novel Mg-Li-Al-Zn-Y-Mn-Gd (LAZWMV) alloy with a very high modulus was designed which reaches Young's modulus as high as 61.4 GPa. Micro-compounds (AlLi and Al-X) with average equivalent diameters of 3.76 µm and 6.55 µm were quantified in 3D using X-ray computed tomography and nanoindentation tests for establishing the microstructure-modulus correlation. The influence of Li addition on Mg-Mg was calculated by DFT calculations and the mechanism of modulus improvements has been proposed. [Display omitted] • Ultra-light Mg-Li alloy was designed with high strength and high modulus. • Super-high Young's Modulus of 61.4 GPa was first reported for a novel Mg alloy. • Nanoindentation uncovers the principles of modulus increase in Mg-Li alloys. • Quantitative 3D characterization of high modulus phase using XCT prectict alloy properties. • DFT calculation of Mg-Mg bonds explores the effects of heat treatments. [ABSTRACT FROM AUTHOR]

Abstract Ba 0.9 Ca 0.1 Ti 0.95 Zr 0.05 O 3 BCZT (10%, 5%) ceramic was prepared via solid state route. BCZT (10%, 5%) presents a coexistence of orthorhombic and tetragonal structures. By Raman spectroscopy the ferroelectric-paraelectric phase transition (T C) is detected. So as to investigate the electrical transport, a complex impedance spectroscopy is highlighted. With the Debye theory-based analysis and a series of Arrhenius relations, the Nyquist diagrams (Z″ versus Z′) are well suitable to an equivalent circuit model. The relaxation was argued to be related with the hopping motions of charge carriers between Ca2+ and Zr4+ ions. At various temperatures, the dielectric datum was analyzed using complex electrical modulus M*. The plot of modulus versus frequency presents a peak of relaxation. Using the universal Jonscher's power law, the AC conductivity for grain contribution is interpreted. Activation energies, determined from conductivity (E a = 1.23eV) and complex modulus (E a = 1.06 eV) are different, which confirms that the transport is ensured by an ion hopping mechanism. However, a dispersion of the conductivity was observed at medium frequencies and was explained using the correlated barrier hopping (CBH) model. [ABSTRACT FROM AUTHOR]

New relaxor ferroelectric ceramic perovskites C a 0.67 L a 0.22 T i ( 1 − x ) C r x O 3 (x = 0.15 and x = 0.2) ( C L T ( 1 − x ) C r x ) were prepared by solid state reaction route. X-Ray diffraction study suggested that these compounds crystallize with orthorhombic symmetry with Pnma space group. The microstructure study of sintered pellets revealed that the grains size decrease with the increase in doping concentration. The dielectric study showed two temperature anomalies that induced an improvement in piezoelectric applications. This study exhibits a relaxor behavior for all compositions with excellent properties. A high permittivity was around 25000 and Δ T r e l a x = 79 K for x = 0.15. The best way to characterize the degree of the dielectric relaxation for relaxor ferroelectrics was established using the Lorentz fit model. Dielectric modulus measurement showed three thermally-activated dielectric relaxations. The low-temperature relaxations R1 are related to the polaron relaxations which are due to the hopping holes. The high-temperature relaxations R2 and R3 are associated with the conductivity originating from the hopping motions of double ionized oxygen vacancies. [ABSTRACT FROM AUTHOR]

This work presents some electrical properties based on the impedance measurements as well as the dielectric constants and electric modulus. In order to through light in the electrical conductivity and dielectric properties of Rb 2 HAsO 4 Te(OH) 6 (Rb As Te), we have carried out complex impedance spectroscopy technique in the frequency range 200 Hz–5 MHz at various temperatures (304 K–493 K). The complex impedance diagram at different temperatures showed a single semicircle, implying that the response originated from a single capacitive element corresponding to the grains. AC and dc conductivities were studied to explore the mechanisms of conduction. The experimental data shows that the ac conductivity of this compound is proportional to ω s (s < 1), the value of s is temperature-dependent. The conductivity evolution versus temperature reveals the presence of the super-ionic- protonic conduction phase transition. The dielectric properties's dependence on both temperature and frequencies of the compound has been reported. The ionic-protonic conductivity and conductivity relaxation calculated from the impedance and modulus spectra respectively were found to be thermally activated. The conductivity relaxation parameters of some H + and Rb + conducting in the RbAsTe material have been determined from an analysis of AC conductivity data measured in a wide temperature range. The near value of activation energies obtained from the hopping frequency and equivalent circuit confirms that the transport is through ion hopping mechanism dominated by the motion of the H + ion in the structure of the investigated material, thus the displacement of the Rb + cations at the level of the tunnels. [ABSTRACT FROM AUTHOR]

In this work, a thin film SiGe was synthesized by the solid source Molecular Beam Epitaxy and identified by X-ray diffractometry and Raman spectroscopy. The effect of the Ge fraction on the structural, electrical conduction and relaxation was studied in detail using impedance analysis. The results of the modulus study reveal the presence of two distinct relaxation processes suggesting the presence of grains and grain boundaries in the sample. The value of exponent ‘ s ’ calculated from the plot of log (σ) versus log (w) ranges 0.32–0.8 suggested that the conduction phenomena in the studied samples pursue hopping conduction. The impedance data were well fitted by two equivalent electrical circuits and confirms the presence of two distinct relaxation processes. The results indicate that the SiGe thin films fabricated by this method are applicable for SiGe-based electronic and optical devices. Moreover, fabrication of high quality SiGe thin films on Si thin film enables the application in solar cell. [ABSTRACT FROM AUTHOR]

We show a fundamental relationship between network structural attributes and ionic transport of lithium iron phosphate glasses x Li 2 O–2Fe 2 O 3 –3 P 2 O 5 (x LFPO; x = 0.375, 0.75, 1.5, 3.0) used for a cathode in lithium-ion batteries. The glass samples have been synthesized using a solid-state reaction method. We have investigated the electrical characteristics of the glass by combinational measurements of electrical impedance in the frequency 100 Hz – 30 MHz and temperature from ambient to 240 °C, differential thermal analysis, X-ray diffraction pattern, and Raman spectroscopy. The ionic hopping and relaxation processes in x LFPO glasses are analyzed by using Cole-Cole, power law, and modulus representations. We reveal that the exponential increase in dc conductivity with increasing Li 2 O in x LFPO glasses is caused by the combination of an increase in non-bridging oxygen sites and a change in the bonding forces of iron valence surrounding the iron phosphate clusters inside the network. The power law conductivity, which is driven by the fractional Rayleigh equation, exhibits that the rate of increase in dc ionic conductivity is the same as the rate of increasing numbers of the ionic charge carriers. Raman spectra show that the increase of depolymerization of the iron phosphate network with the addition of Li 2 O content is due to the conversion of Q 2 to Q 1 and Q 0 species. • x Li 2 O–2Fe 2 O 3 –3 P 2 O 5 glasses were synthesized for a cathode in lithium ion batteries. • Dc conductivity increases exponentially with increasing Li 2 O in x LFPO glasses. • The NBO sites are created by depolymerization of the iron phosphate network. • The Li-ions mobility is affected by the Fe-O bond valence in the iron-phosphate cluster. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Al content is related with structural relaxation and damping capability. [•] Dynamic modulus is insensitive to the frequency especially for storage modulus. [•] Several internal-friction peaks are observed in the Al-free or Al-lean alloys. [•] The damping behavior is proposed to be strongly relied on the level of ordering. [Copyright &y& Elsevier]

Abstract: Nanocrystalline powders of (Ba1− x Ce x )(Zr0.52Ti0.48)O3 [x =0.1 and 0.2] have been synthesized by conventional solid state reaction method. X-ray diffraction patterns confirm the formation of single phase cubic crystal symmetry. The increase in grain size reveals the influence of Ce ions on microstructure. The electrical behavior of sintered pellets investigated by impedance spectra showed frequency dependent behavior. The complex impedance plots display a single semicircle highlighting the influence of grain resistance on the electrical behavior. The modulus curve illustrates the possibility of non-exponential type conductivity. The values of activation energy calculated from both plots of Z″ and M″ confirms that the oxygen vacancies play an important role in the conduction. The temperature dependant dc-resistivity depicts a negative temperature coefficient of resistance behavior of synthesized ceramics. The ac conductivity of both ceramics increases as a function of frequency due to relaxation phenomenon arisen due to mobile charge carriers. [Copyright &y& Elsevier]

Abstract: The electrical properties of the (Na0.6Ag0.4)2PbP2O7 compound were studied using the complex impedance spectroscopy in the temperature range (502–667K). Grain interior, grain boundary and electrode–material interface contributions to the electrical response are identified by the analysis of complex plan diagrams. The imaginary part of the modulus at several temperatures shows a double relaxation peaks, furthermore suggesting the presence of grains and grain boundaries in the sample. An analysis of the dielectric constants ɛ′, ɛ″ and loss tangent tan(δ) with frequency shows a distribution of relaxation times. The dc conductivity of the material is thermally activated with an activation energy about 0.8eV which is in the vicinity of the that obtained from tan(δ) (E =0.7eV) and modulus (E m =0.68eV) studies. [Copyright &y& Elsevier]

Abstract: 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 ceramic was prepared by citrate gel method. The electrical property of this compound was investigated using impedance spectroscopy. The appearance of grain and grain boundary is evident at higher temperature (≥425°C). The depression of semicircle in the impedance plot and the value of full width half maximum (FWHM) of the peaks in the modulus plot show that the compound exhibits non-Debye relaxation process. The impedance analysis further provided the value of relaxation frequency, which is a characteristic intrinsic property of the material. The temperature variation of the bulk conductivity indicated an Arrhenius type of thermally activated process, showing a linear variation upto 425°C and above which it is dominated by grain boundary conduction, which was evident from the slope change at 425°C. The temperature coefficients of the resistance (α) were derived being equal to −1.4×10−2 C−2 at 400°C. The low value of exponent (s) indicates the presence of asymmetric charge defects. [Copyright &y& Elsevier]

• The K 2 ZnGeO 4 compound was prepared by the conventional high temperature solid-state reaction. • Electrical properties of the compound have been studied using complex impedance spectroscopy. • The frequency dependence of the conductivity is interpreted using Jonscher relation. • The overlapping large polaron tunneling (OLPT) model was a closely model to describe the conduction mechanism. In this work, we are focused to study the structural, vibrational and electrical properties of K 2 ZnGeO 4 ceramic compound. The KZGO was prepared by conventional solid-state method. X-ray diffraction (XRD) analysis reveals that the sample is well crystallized in the orthorhombic structure with Pca2 1 space group. Moreover, IR spectrum for this compound confirm the presence of group functionally [GeO4]4-. The electrical measurements was studied in the 40 Hz–1 MHz frequency interval and 533–653 K temperature range. AC conductivity of K 2 ZnGeO 4 is showed on the basis of the overlapping large polaron tunneling (OLPT) model. The activation energy calculated from both the DC conductivity and modulus spectra are close quite to notify that the electrical conductivity and the relaxation process are attributed to the same effect. Thermodynamic parameters for instance the enthalpy ΔH, and the change in entropy ΔS and the free energy of activation ΔF have been determined. [ABSTRACT FROM AUTHOR]

A single phase 0.5(Bi 0.5 La 0.5 Fe)O 3 -0.5(Ba 0.5 Sr 0.5 Ti)O 3 (50BLFO-50BST) is successfully synthesized by incorporating the high-temperature solid-state casting technique. The compound is calcined and sintered respectively at the temperature 1010 °C and 1210 °C. The calcined powder is checked by X-ray diffraction (XRD) and analysed through reitveld analysis. It is found the sample is single phase cubic structure having crystallite size of 54.74 nm. UV-Visible spectroscopic analysis is utilized to study the optical behavior of the material and with the help of Tuc plot optical band gap has been calculated which has been found to be 1.38 eV. The LCR measurements have been analyzed for the frequency and temperature-dependent dielectric, impedance,and modulus properties of the above-prepared ceramic. The impedance study shows the participation of grain and grain boundary in the electrical characteristics of this material. The room temperature ferromagnetic parameters (M r ~0.06 emu/gm and H c ~ 1 kOe) suggest material is a potential candidate for magnetic storage devices. • The material is showing very good dielectric, optical and magnetic property. • The high values of dielectric permittivity and low value of tangent loss can be used for microwave applications. • Optical study reveals material can useful for photovoltaic/photo catalytic activity. • Magnetic study reveals it can be useful magnetic storage devices. [ABSTRACT FROM AUTHOR]

ErCr 1-x Fe x O 3 (0 ≤ x ≤ 1) (ECFO) perovskite compounds are synthesized by sol-gel auto-combustion processes. The impedance measurements were performed at up to 600 °C temperature, 1 Hz- 1 MHz frequency range. Z ' vs Z ' ' /f plots of x = 0, 1 compounds have shown one relaxation peak corresponds to grain boundary relaxation, whereas x = 0.2, 0.4, 0.6, 0.8 compounds have shown two relaxation peaks up to 300 °C which may be corresponds to the grain and grain boundary relaxations at higher and lower frequencies respectively. The f ε ' value increased with increase in Fe content up to x = 0.6 and thereafter gradually decreased with rise in Fe content, this could be the reason of hopping of charge carriers are very high between Cr3+-Fe3+ in x = 0.6 sample. The grain and grain boundary resistance increases due to increase in B-cite cation radii with increase in Fe3+ substitution in place of Cr3+. The complex modulus plots are also noticed that grain and grain boundary resistance is decreased with increase in temperature, which suggests that the samples are having semiconducting nature. Where x = 1.0 sample have very less conductivity in the order of 10−7(S/m), 8 × 10−5(S/m) at 1 Hz, 1 MHz respectively and whereas x = 0.4 sample have high conductivity in the order of 2 × 10−3(S/m), 10−2(S/m) at 1 Hz, 1 MHz respectively. E a of grain is 0.14eV and 0.08eV for x = 0.2 and x = 0.8 respectively, whereas E a of grain boundary is 0.24eV and 0.07eV for x = 0 and x = 1.0 respectively. Based on these results and as per the earlier reports these materials are more suggestible for giant capacitor, solid oxide fuel cell applications. Figure Z′ vs Z"/f of ErCr 1-x Fe x O 3 (x = 0.2) perovskite at different temperatures. Image 1 • Grain and grain boundary resistance increased with increase in Fe content. • The material showed negative temperature coefficient resistance. • ac conductivity of x = 1 sample showed 10−7(S/m), 8 × 10−5(S/m) at 1 Hz, 1 MHz respectively. • x = 0.4 sample showed high conductivity in the order of 2 × 10−3(S/m), 10−2(S/m) at 1 Hz, 1 MHz respectively. • These compounds are useful in giant capacitor and SOFC applications. [ABSTRACT FROM AUTHOR]

In this study, calcined ZrTe 3 O 8 powder mixed with 7%wt of CuO was sintered at 750 °C. The new doped ceramic ZrTe 3 O 8 :7%CuO was synthesized using solid state reaction method and was studied with X-ray diffraction (XRD). At room temperature, the title compound crystallizes in cubic space group Ia 3 ‾ , with lattice parameter a = 11.328(3) Å, and exhibits a complex network of interconnected closed chains built up of TeO 4 E (E = electronic lone pair of Te (IV) atoms). The Zr/CuO 6 octahedra are inserted into these chains ensuring the stability of the structure by Zr/Cu –O–Te bonding contacts. IR and Raman spectroscopic study are employed as means to obtain preliminary structural information and confirms the presence of the ZrO 6 and TeO 4 E groups. Optical properties of the ceramic were explored by using UV–Vis absorption. The magnetic results reveal the appearance of a weak ferromagnetic behavior at low temperature (T C = 46.172 K). In addition, dielectric data were analyzed using real and imaginary permittivity ε ' and ε " respectively, the tan (δ) and the electrical modulus ( M ' and M″) for the sample ZrTe 3 O 8 :7%CuO at various frequencies. The Z ' and Z " versus frequency plots are well fitted to an equivalent circuit model composed of a series combination of two parallel combinations of resistance Ri and constant phase element CPEi. • The ceramic crystallized ain the cubic fluorite structure (Ia 3 ‾). • The Zr/CuO 6 octahedra are inserted into TeO 4 E chains ensuring the stability of the structure by Zr/Cu –O–Te bonding contacts. • The magnetic results reveal the appearance of a weak ferromagnetic behavior at low temperature (T C = 46.172 K). • The equivalent circuit model is composed of a series combination of two parallel combinations of resistance Ri and constant phase element CPEi. [ABSTRACT FROM AUTHOR]