This communication focuses on newly developed glassy electrolytes composed of Na2O-PbCl2-ZnO-V2O5, examining their electrical transport behaviour at ambient temperature. The direct current (DC) conductivity of these materials has been extensively analyzed using variable range hopping models. DC conductivity and hopping frequency have been computed based on the best-fitted plots of the experimental data. The DC conductivity was assessed at various concentrations while maintaining constant temperatures. Additionally, the variation of conductivity data with reciprocal temperature highlights the dynamic behaviour of charge carriers through hopping conduction in sodium oxide-doped glassy systems. Higher electronphonon interaction coupling constant reveals that the present system involves a strong electron-phonon interaction for polaron hopping. The microstructure of the asdeveloped system has been investigated and correlated with transport behaviour. The present study is expected to be a potential one not only for exploring the nature of hopping/migration frequency of Na+ ions for NIBs application but also for academic interest.
Z irconia (Z rO2) stabilized with magnesia (MgO) exhibits excellent mechanical properties, which are influenced by its thermal history. These arise from phase formation in partially stabilized zirconia (PSZ), where ZrO2 exists in cubic, tetragonal and monoclinic phases, stabilized by the addition of M gO. This study examined Mg-PSZ ceramics with 9.25 and 14.5 mol% MgO, sintered at 1500 degrees and 1720 degrees C for 3 h in air, revealing variations in phase composition and microstructure. To assess the effect of M gO morphology, M gO was added either in its raw form or pre-calcined at 1200 degrees C for 2 h. This pre-treatment aimed to modify the powder characteristics and enhance densification. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction were used to analyse phase transformations during pressureless sintering. Pre-calcination significantly impacted the density and microstructure, with the final ceramics reaching 87% to 98% of their theoretical density. Samples with 14.5 mol% MgO showed predominant cubic phases, consistent with the 1720 degrees C sintering temperature. It is evident that polygonal MgO-cubic precipitates form on cubic ZrO2 grains without any post-sintering aging treatment, highlighting the role of pre-calcined MgO in the microstructural evolution. These results support the potential of Mg-PSZ ceramics for high-stress engineering applications.
In the pursuit of sustainable material development, calcium oxide derived from biowaste eggshells was utilized as an eco-friendly precursor in the synthesis of Nd2O3- doped aluminium sodium calcium phosphate glasses. The glasses were synthesized through the melt-quenching technique at around 1060 degrees C. X-ray diffraction patterns verified the non-crystalline structure of the samples. Furthermore, scanning electron microscopy combined with energy-dispersive X-ray spectroscopy was employed to analyze the elemental composition, confirming the inclusion and uniform distribution of calcium within the glass matrix. The optical characteristics of the glasses were examined in detail using a UV-Visible spectrometer to measure the optical band gap and corresponding optical conductivity values. Additionally, the refractive index of each glass sample was measured, revealing a clear compositional dependence influenced by rare-earth doping. Furthermore, Raman spectroscopic studies provided insights into the structural units and phosphate network modifications induced by Nd2O3 incorporation. The incorporation of eggshell-derived CaO demonstrates a viable alternative to conventional calcium sources in compositionally sensitive phosphate glass systems, without adversely affecting the structural and optical properties. This approach highlights a value-added pathway for biowaste utilization while maintaining the functional characteristics required for optical investigations.
A graphene-fortified, low-carbon M gO-C brick recipe assists in-situ formation of ceramic bonding phases in the presence of Al, Si and B4C. Predominant multifaceted beta-silicon carbide (beta-SiC) nanotubes (SiCNTs), along with thin silicon carbide whiskers (SiCWs), magnesium aluminate (M gAl2O4) spinel cuboids and aluminium borate whiskers, form at 1600oC in a reducing environment. A competitive analy sis of conventional graphite-based M gO-C and developed low-carbon M gO-C ensures that graphene facilitates nucleation, accelerates reaction kinetics and provides structured laminae for selective growth of SiC nanostructures. M echanistic pathways governing the evolution of SiCNTs and SiCWs through interfacial reactions among carbon, metallic additives and volatilized Si bearing species are elucidated. The findings demonstrate that graphene not only enhances in situ ceramic bonding but also promotes the formation of reinforcing nanostructures, thereby offering a viable pathway to developing high performance, low carbon refractories suited for demanding steel making applications.
Stir casting is the most appropriate method for producing metal matrix composites (MM Cs) because of its effectiveness, cost and simplicity. MM C provide numerous benefits, including enhanced tensile strength, improved fatigue and creep resistance, superior thermal expansion coefficients and lower weight and density. As a result, these benefits have attracted numerous researchers and industries, including the automotive and aerospace sectors. The present study used a two-step stir-casting method to fabricate M M C containing 12 wt% silicon carbide (SiC) particles in the Al6061 alloy. Adding SiC to the Al6061 alloy increased the hardness and strength of the composites. The fabricated aluminium-reinforced SiC (Al/SiC) composite has a density of 2.6 g/cm3, a porosity of 5.797%, a hardness of 134 HV and a tensile strength of 169 MPa. Al/SiC composite revealed 41% and 36.29% improvement in hardness and tensile strength, respectively, compared to the base alloy. Elemental and phase analyses using EDX and XRD further validated the uniform SiC distribution and the absence of undesirable phases within the composite.
Lithium zinc phosphate glasses with the composition 45P2O5-25ZnO-(30-x)Li2O-xCo3O4 (x = 0-6 mol%) were synthesized via the conventional melt-quenching method. X-ray diffraction confirmed the non-crystalline nature of all prepared glass matrices. Thermal analysis revealed improved thermal stability with cobalt incorporation, suggesting that addition of CoO strengthens the glass matrix. The electrical behaviour was examined over a wide frequency range and different temperature ranges, showing thermally activated conduction. The calculated activation energy lies in the range of 0.12 to 1.24 eV, depending on composition. The observed AC conductivity obeys Jonscher's universal power law, and frequency exponent values below unity suggest a conduction mechanism consistent with correlated barrier hopping. Dielectric analysis (& varepsilon;', & varepsilon;''), electric modulus (M ', M '') and impedance spectra (Z ', Z '') provided further insights into relaxation dynamics and ion transport behaviour.
Zn1-xEuxO (x = 0, 0.01, 0.05 and 0.1) nanomaterials were successfully synthesized via the solution combustion technique and their frequency, temperature-dependent dielectric relaxation and AC conductivity were systematically investigated. X-ray diffraction and Raman scattering confirmed the formation of a single-phase hexagonal wurtzite ZnO structure for all compositions. Thermogravimetry and differential thermal analysis indicated thermal stability of the synthesized samples beyond similar to 500oC. Transmission electron microscopy revealed nearly spherical nanoparticles with an average size of similar to 20 nm for the 5% Eu-doped ZnO sample. Dielectric parameters including dielectric constant (& varepsilon;'), dielectric loss (& varepsilon;''), loss tangent (tan delta), and AC conductivity (sigma ac) were measured over a frequency range of 50 kHz-5 MHz and a temperature range of 100o-400oC. All samples exhibited a decrease in & varepsilon;', & varepsilon;'', tan delta and sigma ac with increasing frequency, attributed to space-charge and dipolar polarization effects. A clear shift of dielectric relaxation (transition temperature) toward higher temperatures with increasing Eu concentration was observed, indicating enhanced defect-mediated polarization and charge carrier dynamics. These results demonstrate that Eu doping effectively modifies the dielectric and electrical behaviour of ZnO nanomaterials, making them promising candidates for advanced dielectric and electronic applications.
Perovskite solar cells (PSCs), which have numerous advantages of low cost, optimum band gap and efficiencies at par with Si solar cells, might become the next generation photovoltaic (PV) technology. Several studies suggest Bi2FeCrO6 (BFCO) could be a prospective lead free and stable absorber material for PSC. In this study, a multilayer PSC using BFCO as the perovskite absorber is designed and modelled. The PV performance of a double perovskite BFCO under different hole transport layers (HTLs) like MoO3, Cu2O, P3HT, NiO, CuSCN, Spiro-Ometad, PEDOT:PSS and NPB is numerically analyzed using SETFOS 5.3 software. To improve the power conversion efficiency (PCE), the impact of several properties, such as thickness, doping and defect concentration of the absorber layer and the charge transport layer, is carefully optimized. Furthermore, the external quantum efficiency of BFCO PSC is investigated, including recombination efficiency, series and shunt resistance, and the examination of many bottom electrodes to assess their influence on device performance. PEDOT:PSS showed the best performance among all HTLs for the BFCO solar cell. The device structure FTO/NSTO/Bi2FeCrO6/PEDOT:PSS/Au displayed the highest PCE of 23.14% with 1.262 V of open circuit voltage, 82.21% of fill factor and 22.30 mA/cm2 of short circuit current.
Glass insulators are critical components in overhead transmission lines, and their reliability is closely tied to residual stress introduced during tempering. Due to their non-uniform geometry, understanding the surface stress distribution is essential for explaining self-explosion failures. This paper presents a coupled CFD-FEA numerical framework to simulate residual stress in large-tonnage tempered glass insulators. CFD is first used to model fluid and temperature fields during tempering. These results are then input into an FEA model to compute stress distribution. Simulations show that the disc region exhibits surface compressive stress of similar to 170 MPa and maximum internal tensile stress of similar to 73 MPa. At the disc-rib junction, tensile stress reaches similar to 90 MPa, while the rib area shows tensile stress of 85-95 MPa and compressive stress of 90-120 MPa. Stress varies across subregions of the head. The simulation results are validated using SCALP-05 photoelastic analysis, confirming their accuracy. This study provides a foundation for understanding failure mechanisms and optimizing the tempering process to improve insulator performance.
This study presents a scalable approach to fabricate the multiwalled carbon nanotube (MWCNT)/TiO2 nanocomposite coated poly imide (PI) Kapton (R) sheets via spray pyrolysis route for flexible electrochemical devices. The fabricated MWCNT/TiO2-polyimide (PI) Kapton (R) film reveals an outstanding electrochemical performance due to effective cocktail effect at MWCNT/TiO2 based electrode-electrolyte heterointerface. The MWCNT-coated polyimide (PI) Kapton (R) sheet-based electrode shows exceptional durability at 10 mV/s and a maximum capacitance of 414 mu F/cm(2). Notably, the specific capacitance rises dramatically up to 25,000 cycles at a scan rate of 30 mV/s and gradually seemed to be stable up to 35,000 cycles. The highest specific capacitance of the composite film is found to be 791 mu F/cm(2). These findings highlight the potential of spray pyrolysis-assisted coating for nanocomposite based flexible electrochemical system towards the application of space electronics and electrochemically stable light weight devices.
Natural magnesite is the primary source for the production of basic refractories and also has certain other industrial uses. India possesses significant magnesite reserves, particularly in the Salem and Almora regions. However, the presence of impurities such as lime, silica and iron oxide in these deposits restricts their use in high-temperature applications. In the present work, the microstructural development and sintering behaviour of dead-burnt fine Almora magnesia is studied between 1550 degrees and 1650 degrees C, and also in the presence of 2 wt% of Al2O3, Cr2O3 and ZrO2. The sintered products were evaluated for densification, strength and thermal shock resistance studies. Also, phase analysis and detailed microstructural evaluation were done. Calcium-containing multicomponent silicates are found to form from the impurities in the matrix part, affecting the properties. Al2O3 addition did not show much benefit, but Cr2O3 and ZrO2 additions showed reduction in the low melting phase in the matrix and significant enhancement in thermal shock resistance for Cr2O3 containing spinel and tetragonal ZrO2 phase formation, respectively.
The Pb4/5Sr1/5 (Z r11/20Ti9/20)O3-Pb(M n1/3Sb2/3)O3-Pb(W1/3Nb2/3)O3 (PSZ T-PM S-PWN) ceramics were prepared via the solid-state reaction method. The effect of sintering temperatures on PSZ T-PM S-PWN phase formation, microstructure and electrical properties were investigated. The X-ray diffraction study confirmed pure perovskite structure formation in the prepared ceramics and the coexistence of rhombohedral and tetragonal phases has been detected in all ceramics at room temperature. Scanning electron micrographs of fractured PSZ T-PM S-PWN ceramics revealed equiaxed grains and the presence of both transgranular and intergranular fracture modes. Optimal electrical properties were obtained at a sintering temperature of 1175oC, characterized by a high dielectric constant (& varepsilon;r=12735), a Curie temperature (TC) of 630 K, a dielectric loss (tan delta) of 0.03, a piezoelectric charge constant (d33) of 341 pC/N, an electromechanical coupling factor (KP) of 0.624, and a mechanical quality factor (Qm) of 1260. These properties indicate strong potential for applications in piezoelectric-related fields, especially under demanding or extreme conditions.
The current study reports the sintering of an aluminium-doped lanthanum germanium-based electrolyte material with the composition La9.5Ge5.5Al0.5O26, performed under both microwave energy and conventional heating. The precursor of the composition La9.5Ge5.5Al0.5O26 was prepared using the mixed oxide method, and the precursor was calcined at 900 degrees, 1000 degrees and 1100 degrees C for 1 h to optimize the minimum calcination temperature for achieving a single phase of La9.5Ge5.5Al0.5O26. The precursor was calcined at 1100 degrees C for 1 h by conventional heating. The calcined powder obtained by microwave and electric heating was sintered at 1350 degrees C for 30 min duration by microwave heating and for 4 h duration at the same temperature by conventional heating. X-ray diffraction (XRD) revealed that the conventionally sintered sample was of a single phase. But when it was further investigated by microwave Raman spectroscopy, it showed the presence of a monoclinic phase (La2GeO5) along with a hexagonal phase. But samples sintered by microwave energy had resulted in the formation of a single hexagonal phase, which was revealed by both XRD and micro Raman spectroscopy. Microwave sintered AlMCMS and AlCCMS samples showed higher conductivity values of 2.21x10-3 and 1.59x10-3 S.cm-1 at 650 degrees C, respectively, whereas conventionally sintered AlMCCS and AlCCCS samples exhibited lower conductivity values of 4.18x10-4 and 5.62x10-4 S.cm-1, respectively, at 650 degrees C.
