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Confirmation of structural phase transition mediated by La-substitution at Nd-sites in Nd2Ce2O7 pyrochlores and optimization of recoverable energy density, energy loss density and fast switching charge capability.

Here we report tuning of structural parameters of La2Sn2O7 by Nd substitution at La-site in a quest to effectively control the dielectric response as a small variation in lattice parameters can result in large dielectric fluctuations. For this purpose, a series of Nd-substituted La2Sn2O7 was synthesized using sol gel auto-combustion route. The formation of stable cubic pyrochlore phase with consistent variation in the lattice parameters was observed in structural analysis. The morphological investigations revealed a spherical shape of La2Sn2O7 particles which transformed to diamond like shape with a systematic variation in grain size by increasing the Nd contents. The variation in grain size dominantly affected the dielectric dispersion in the vast frequency range. Less energy loss and improved dielectric properties make La1.2Nd0.8Sn2O7 a potential candidate for utilization in energy storage devices. The complex modulus analysis provided an insightful view which helped to distinguish the mobility range of charge carriers in different frequency ranges.

Halides based organic-inorganic solar cells have attracted huge attention for efficient energy harvesters owing to their low fabrication cost, large functioning area, long lifetime, and high conversion efficiency. Here we report the fabrication of pristine and aminomethyl piperidinium (4AMP) doped CH3NH3PbBr3 based thin film using spin coating technique to explore its potential for energy harvesting. The structural analysis confirmed the development of the rhombohedral structure of pristine and doped CH3NH3PbBr3. SEM and AFM images revealed that grains for the pure sample are highly compact linked with each other with sharp grain boundaries but their size increased when doped with 4AMP. A direct bandgap of 2.341 eV is noticed for pristine which is slightly decreased to 2.311 eV as a result of doping. The calculation of space charge limited current, PL decay profile analysis, charge transfer resistance, and Mott Schottky analysis provide quite convincing evidence regarding the high conversion efficiency of these films. A sufficiently high value of short circuit current density resulted in high efficiency of pristine MAPbBr3 i.e., 8.46% which increased to 10.21% due to improvement of solar cells parameters such as Voc of 1.46 V when doped with 4AMP. These values of efficiencies make the halide based organic compositions viable for solar cell applications.

The proficient realization of Na-ion batteries (NIBs) having exceptional electrochemical behavior is considered to bridge the hurdles triggered by inadequate resources and costly manufacturing of Li-ion batteries. Herein, we report a facile synthesis of Ni0.06Co2.94O4/CNTs hybrid using the solvothermal route and Ni0.06Co2.94O4 using the hydrothermal approach. The formation of a nest-like conductive framework of Ni0.06Co2.94O4/CNT composites, aligning favorably to form an assembly of a layered structure, supports an efficient Na-ion insertion/extraction process. A high initial charge capacity of 621 and 582 mAh g-1 is delivered by Ni0.06Co2.94O4/CNTs and Ni0.06Co2.94O4 electrodes, respectively which retained up to 328 and 239 mAh g-1 after 100 cycles. The electrodes also delivered excellent rate performance with 119 and 93 mAh g-1 at 5.0C and retained 77 and 64% of initial capacity, respectively when recovered from 0.05C. Additionally, Ni0.06Co2.94O4/CNTs exhibited low impedance over a wide range of frequencies resulting in more Na ions storage and a faster Na insertion/extraction process. The exceptional performance shown by the hybrid electrode is due to the synergistic influence flanked by binary metal oxides and CNTs. Hence, the hybrid of Ni-doped metal oxide and carbonaceous species emerge as an excellent choice for use as an electrode for electrochemical energy storage devices.

Triphase multiferroic composites with higher degree of freedom, provide a new platform for developing novel and smart technological applications. In this context, here we present a new triphase composite, consisting of bismuth ferrite (BFO) and lead zirconate titanate (PZT) synthesized using sol‒gel auto-combustion and solid-state routes, respectively and then subsequently dispersed into a PVDF polymatrix, leading to a triphase composite (BFO-PZT-PVDF). Structural analysis confirmed the composite formation as all the intensity peaks were either matched with BFO or PZT phases. Morphological analysis revealed that pure BFO and PZT formed well defined grains with sharp grain boundaries. However, when they are dispersed in the polymer matrix, their boundaries became diffused. Worth mentioning ferroelectric parameters like saturation polarization, remanent and recoverable energy density are measured from bipolar polarization loops. It is noticed that maximum polarization is decreased while coercivity is increased with the increment of PZT contents in the composite. Vibrating sample magnetometer confirmed the variation in magnetic features, exactly in accordance as required for significant magnetoelectric coupling for practical utilization. The extent of magnetoelectric coupling supports the potential applications of these triphase composites for energy storage and multistate devices.

Intriguing optoelectronic and transport properties with huge compositional range and structural stability make double perovskites interesting for energy harvesting technologies. Here we theoretically investigate the structural, optical, mechanical, and transport properties of K2YAuX6 (X = Cl, Br) double perovskites using the WIEN2K code. Based on the calculated values of the tolerance factor and enthalpy of production, the thermodynamic and structural stability is affirmed. The ductile nature of these compositions is revealed in the computation of Poisson’s ratio (>0.26) and Pugh’s (1.75) ratio. The involvement of s-states of K, p-states of Cl/Br, and d-states of Y and Au in the formation of valence and conduction band edges is exhibited from the density of state plots. Using the Tran-Blaha mBJ potential and spin-orbital coupling, the energy bandgap value for K2YAuCl6 and K2YAuBr6 is reported as 3.20, and 2.70 eV, respectively, which is suitable for the fabrication of light-emitting diodes. Optical behavior is further explored regarding complex dielectric constant, refractive index, optical conductivity, optical loss, and absorption factor. The small value of thermal conductivity with large value of electrical conductivity, Seebeck coefficient, power factor, and figure of merit revealed the potential of these materials for the fabrication of light-emitting diodes and thermoelectric generators.

Loquat (Eriobotrya japonica L.) is an important sub-tropical fruit with very limited postharvest life. Therefore, in the current study, we investigated the effect of calcium chloride (CaCl2) treatments on the shelf life and quality of loquat fruit. After harvest loquat fruit treated with different concentrations of CaCl2 viz. 2%, 4% and 6% for 2 min were kept at room temperature (30±2oC) for 5 and 10 days. Untreated fruit were kept as control. The results showed that fruit treated with 6% CaCl2 exhibited minimum fruit weight loss (9.1%), external browning (8.83%), and internal browning (9.1%) after 10 days shelf period in contrast with control fruit. Lowest total soluble solids contents (9.11%), highest titratable acidity (0.53%) and juice (28%) contents were found in fruit treated with 6% CalCl2 as compared to other treatments. In conclusion, among the tested treatments, application of highest level of CaCl2 (6%) effectively maintained the quality of loquat fruit a room temperature.

Here, we report CNTs-TiO2 nanocomposites synthesized using the hydrothermal technique to investigate their potential utilization in energy storage devices. Different weight percentages (0.3, 0.5, and 0.7 wt.%) of CNTs are added in TiO2 nanoparticles to tune their energy storage capacity. Structural analysis reveals the tetragonal crystal symmetry of TiO2 nanoparticles. Morphological investigations expose that the average particle size of TiO2 is 27 nm whereas the average diameter of CNTs is ~20 nm. Cyclic voltammetry confirms that the specific capacitance of CNTs-TiO2 nanocomposites increases from 149.5 to 367.1 mF/g with increasing concentration of CNTs. However, maximum power density is noticed for nanocomposites with 0.5 wt.% of CNTs. The value of specific capacitance and power density is noticed as 335 mF/g and 400.90 Wkg−1, respectively. In addition, dispersion in dielectric behavior, variation in impedance response, and the presence of relaxation phenomenon are elaborated in a vast frequency range.

Cost-effective synthesis, portability, quick response and fascinating features of semiconducting metal oxide sensors have drawn much accredited to be utilized in wide variety of potential sensing applications. Herein, flexible acetone sensor was fabricated through spray coating method using different conductive inks of carbon nanotubes (CNTs), zinc oxide (ZnO) and silver (Ag) nanoparticles solutions on cellulose paper. Morphological analysis revealed the fiber like morphology of cellulose over which CNTs, ZnO and Ag nanoparticles are uniformly distributed. The energy dispersive X-ray spectroscopic analysis was performed to observe the elemental composition in the as-prepared samples. The recovery time toward acetone was greater for CNTs/Ag acetone sensor at 95% as compared to CNTs/ZnO/Ag sensor. Additionally, sensing time of the samples towards acetone was measured and the observed response time was greater for CNTs/ZnO/Ag (0.52 s) acetone sensor as compared to CNTs/Ag sensor (0.41 s). Hence, CNTs/ZnO/Ag can be easily employed for sensing applications due to quick response.

Intense research work is underway for identifying materials with potential applications in energy storage and energy harvesting systems. The magnesium based scandium chalcogenides have recently emerged as potential candidates for Mg batteries owing to their high Mg ionic conductivity and low electron conduction. At the same time, their band gaps are capable of absorbing electromagnetic radiations in visible to UV range; making them suitable for solar cell applications. In order to analyze the application of MgSc2X4(X = S, Se) compounds in energy devices, in this work we employ density functional theory calculations using the full potential linear augmented plane-wave method for examining their optoelectronic and thermoelectric properties. For the structural properties, the generalized gradient approximation functional designed for solids (PBEsol-GGA) has been used, while modified Becke and Johnson (mBJ) potential functional is used for computing the optoelectronic and transport properties. Our calculated optical properties indicate that these materials can find applications in solar cells. Moreover, the electronic transport properties computed using Boltzmann transport equation suggest carrier concentrations in MgSc2S4 to MgSc2Se4 spinels can be tuned for making them suitable for metal ion batteries.

Using a time efficient and cost effective approach so called sol‒gel dip coating route, we deposited thin films of ZnO and 1% Co & (0%, 0.5%, 1%, and 1.5%) Ga co-doped ZnO on the fluorine doped tin oxide substrates. All the films exhibited hexagonal wurtzite structure. X-rays study revealed that crystallite size increased with increase of doping. Optical parameters like absorbance, transmittance, refractive index, band gap, extinction coefficient and dielectric constants were measured using UV–Vis spectroscopy and it has been noticed that doping resulted in reduction of band gap. It has also been observed that, the films prepared with 1% Co & 1% Ga co-doped ZnO have comparatively smaller band gap and thus have high refractive index and high transmittance in visible region. The calculation of different electrically important factors for instance, high current density, small open circuit voltage, efficiency and fill factor revealed that co-doped ZnO with 1% Co and 1% Ga has relatively high efficiency of 2.43% and thus shows the potential of this composition as an electrode for solar cell devices.

A comprehensive investigation of the physical characteristics of any material provides beneficial information regarding its application viewpoint in different industries. Herein, we report the tunable mechanical and optoelectronic properties of cubic CdZrO3 under variable pressure up to 80 GPa using density functional theory (DFT). The pressure-induced band gap engineering reveals a fantastic fact of transformation of the indirect to direct band gap with increasing pressure. The dielectric response disclosed that optical parameters dragged towards higher energy with an increase of pressure, which unveiled the potential of CdZrO3 for optoelectronic applications. Effective change in optoelectronic is attributed to indirect to direct band gap transition. This study provides a gateway to how the optoelectronic properties of cubic CdZrO3 could be tuned by employing external pressure.

BiFeO3 is the only multiferroic material in which coexistence of ferroelectricity and anti-ferromagnetism can be seen at room temperature. However, small strength of coupling is a main hurdle for its use in multistate memory devices. The single or co-doping of any other material can improve its multiferroicity. In this regard, we synthesized a series with varying concentration of Ni at the place of Cr in BiFe0.9Cr0.1−xNixO3 (x = 0, 0.03, 0.07, 0.1) using sol‒gel auto-combustion route. The rhombohedrally distorted cubic perovskite structure has been observed throughout the series, while the micrographs obtained from scanning electron microscopy exposed that Ni-free composition had diffused grains with no sharp boundaries. Addition of Ni not only reduced the average grain size but also increased the ferroelectric response. Energy density calculations were performed using charge–discharge curves which revealed that increasing Ni/Cr ratio at the Fe site enhanced the energy storage capability. Dielectric study revealed that real part of dielectric constant decreased and concentration-dependent variation remained consistent with morphological change. Impedance spectroscopy exposed that Ni substitution caused an increase in its resistive response, while the relaxation phenomenon and nature of transportation were examined through the shifting of peaks in the complex modulus spectrum.

Pure and palladium (Pd) doped Diamond-like carbon (DLC) thin films have been deposited on glass substrates by using KrF Excimer laser having 248 nm wavelength. The doping concentration of Pd in DLC is 0%, 0.5%, 1.0%, 1.5% and 2.0%. Internal structure, surface morphology, mechanical and electrical characteristics have been carried out by Raman spectroscopy, scanning electron microscopy (SEM), Vickers hardening and four point probes, respectively. Using Raman spectra an improved graphitic behavior of DLC has been observed with increase of Pd contents. Some nano rods were observed at the surface of pure and Pd doped DLC thin films. With increase of Pd concentration in DLC, initially there is an accumulation of particles is observed and when the doping concentration is high i.e. at 2%, cracks formation takes place. The electrical resistivity is decreased by adding Pd into DLC thin films. Further, doping of Pd decreased the hardness of films. These characteristics of Pd doped DLC with increased hardness and electrical conductivity make it potential candidate for electronic devices. Also, doping enhance the graphitic behavior, therefore this material can be used for anti-bacterial and anti- cancerous activities.

Dye Sensitized Solar Cell (DSSC) is a potential too to convert solar energy into electrical energy due to its low cost, ease in synthesis and higher photo electron conversion efficiency (PEC) in contrast with conventional silicon solar cell. The photo-electrode of DSSC is a key component which is responsible for collection and transportation of electrons through the circuit. Sol-gel route was adopted to manufacture photo anodes of 1% Zinc doped titanium dioxide (Zn–TiO2) where FTO glass was used as substrate. These photo anodes were irradiated by 300 keV Cobalt (Co) ions with different fluence rates as 2 × 104 atomscm-2s-1 and 4 × 104 atoms cm-2s-1. We investigated the anatase phase of TiO2 using the Raman spectra which also showed that Zn and Co are completely doped in TiO2. UV–visible spectroscopy showed that band gap of films was decreased by doping and ions implantation. Maximum reduction in band gap is observed at the fluence rate of 4 × 104 atoms cm-2s-1 i.e. 2.77 eV. SEM micrographs showed that the film irradiated with Co ions with fluence rate of 2 × 104 atoms cm-2s-1 have maximum porosity which supports the maximum dye loading on the surface due to which the efficiency of DSSC is enhanced. In all cells, N719 dye is used as sensitizer. The solar simulator results indicated the higher efficiency up to 3.78% is achieved by 300 keV cobalt ions irradiation with fluence rate of 2 × 104 atoms cm-2s-1. The present work shows that the appropriate percentage of Co ions in Zn–TiO2 layer plays a significant role to escalate the effectiveness of DSSC.

Precise control of morphology of functional materials, in particular when grown on nanoscale has revolutionized their physio-chemical characteristics for various applications. These nano-dimensional materials serve as basic building blocks for the development of new technological applications. Here in, we synthesized a series of nanorods and nano flakes of Co/Ni spinel ferrites using a hydrothermal method. NH4F as a surfactant, assisted to precisely control the morphology and dimension of nanostructures. The transformation of inverse spinel structure of cobalt ferrite to mixed spinel upon Ni substitution remarkably influenced their dielectric and ferroelectric response. The increase of dielectric response with Ni substitution was explained on the basis of Maxwell Wagner model. The impedance investigation probed the activation of different electro-active regions in different frequency range. Ferroelectric behavior along with energy density calculation provided a map to estimate the potential of functional nanostructures for energy storage applications. Magnetic properties were also obtained at room temperature showing high coercive hysteresis loops.

With the industrial revolution in electronics, the demand for lithium-ion batteries, particularly those designed for electric vehicles and energy storage systems, has accelerated in recent years. This continuously increasing demand requires high-performance electrode materials, as commonly used graphite anodes show limited lithium intercalation. In this context, Ni-substituted ZnCo2O4 nanostructures, thanks to their high storage capacity, have potential for use as an anode material in lithium-ion batteries. Structural analysis concludes that the prepared materials show improved crystallinity with increasing Ni at the Zn-site in ZnCo2O4. The intermediate composition, Zn0.5Ni0.5Co2O4, of this series exhibits a specific capacity of 65 mA h g−1 at an elevated current rate of 10 A g−1. The lithium insertion/extraction mechanism is investigated via cyclic voltammetry, showing two redox peaks from ZnCo2O4 and a single redox peak from NiCo2O4. Additionally, the lithium diffusion coefficient in the prepared electrodes is computed to be 2.22 × 10−12 cm2 s−1 for the intermediate composition, as obtained using cyclic voltammetry. Electrochemical impedance spectroscopy is used to observe the charge transport mechanism and the charge transfer resistance values of all the samples, which are calculated to be in the range of 235 to 306 Ω.

This paper presents a detailed analytical and non-linear mathematical model describing the I − V characteristics of submicron silicon Carbide (SiC) Metal semiconductor field effect transistor (MESFETs). Silicon Carbide (SiC) MESFET is a wideband device capable to handle high power at microwave frequencies. It is shown that our proposed model can predict the output characteristics of the device both under normal conditions as well as at relatively high drain bias. A comparison of our proposed model is made with Riaz, Khan.M, Shamsir, Kompa, Zhao, Raffo, Josef, Guidry, Mishra and recently reported 4H-silicon carbide (SiC) MESFET large signal I-V models by using the Particle Swarm Optimization (PSO) process. A full SiC MESFET analysis is provided and using experimental data, the validity of the proposed technique is demonstrated. The results show that the new model has the advantages of high accuracy, easily making initial value and robustness over other models. Our proposed technique improves accuracy in predicting the I-V characteristic and output characteristic of SiC MESFETs device. Silicon Carbide (SiC) MESFET is a wide band platform capable of handling microwave frequencies with high efficiency. SiC MESFETs operations are typically conducted under high bias conditions, in which the response is modified from normal. The proposed technique is useful for evaluating the output of high power microwave SiC MESFETs over a wider bias range.