The double perovskite Eu2CoMnO6 (ECMO), known for its complicated metamagnetic behavior, was studied in this report to examine how postannealing synthesis affects its crystal structure and magnetic and electronic behavior. The slow-cooling, Argon treatment, and quenching procedure during the sample synthesis indicated the important significance of antisite disorder (ASD) in influencing the material’s magnetic response. The magnetic study revealed diverse transitions, including two low-temperature antiferromagnetic (AFM)-like transitions at ?51 and ?10 K in the slow-cooled sample and vibronic ferromagnetic (FM) superexchange interactions at ?105 K in the argon (Ar)-treated sample, while the quenched sample displayed an AFM behavior at low temperatures. The XPS analysis indicated the presence of diverse concentrations of Co and Mn in multiple valence states, specifically (2+, 3+) and (3+, 4+) respectively, across the samples subjected to different annealing processes. The Griffiths phase was particularly noticeable in the quenched sample, highlighting the role of disorder with Griffith’s disorder exponent (?) = 0.81. The M(H) data at 2.5 K under zero-field-cooled mode revealed that the Ar-treated sample had a smooth, saturating-like loop, while the quenched sample had the hysteresis loop shifted toward the positive field axis with a reduced magnetic moment of 2.2 ?B/f.u., and the slow-cooled sample exhibited sharp metamagnetic jumps with an unsaturated magnetic moment of 3.3 ?B/f.u. While M(H) data recorded under a field-cooled protocol altered the position of critical fields (HC) for the slow-cooled sample, the evolution of an extra magnetization jump was noticed in the case of the Ar-annealed sample, and the quenched sample showed the loop shifting completely toward the negative field axis. The loop shift and varying HC values were explained in terms of an exchange bias-like spin-pinning mechanism. Additionally, DFT calculations corroborate the experimental results, revealing an increased likelihood of antisite disorders in the presence of oxygen vacancies, as well as altered behavior of Co and Mn spin states in relation to the disorders and oxygen vacancies. The effect of the disorder and oxygen vacancies on the electrical and magnetic ground states was also investigated, and the results were complemented with the experimentally observed magnetic behavior. This study demonstrates how postannealing conditions may be carefully controlled to regulate the disorder and, thus, magnetic behavior, including valence states, Griffiths phase, and metamagnetic behavior of ECMO, opening up new avenues for developing materials with desired functional properties

Piezoelectric ceramics such as PbZr1-xTixO3 (PZT) show enhanced electro-mechanical properties at morphotropic phase boundary (MPB) separating two ferroelectric polar phases in the compositional phase diagram. Designing MPB in Pb-free perovskite oxide is challenging due to the lack of suitable polar tetragonal oxide with high Curie temperature. In this study, we explored the BiFeO3 – Bi0.5K0.5TiO3 – BaTiO3 ternary phase diagram and searched for Bi-rich perovskite oxides as candidates for piezoceramics near MPB. The phase diagram offers a Bi-rich polar tetragonal (T[001]) phase [0.75BaTiO3–0.25(K0.5Bi0.5)TiO3] and a well-known rhombohedral (R[111]) phase BiFeO3. A solid solution is observed in the entire range between the T[001] phase and the R[111] phase. Structural investigation through powder diffraction and Raman spectroscopy studies suggests the existence of a complex region (MPB), well separated by the rhombohedral and tetragonal phases. The composition (Bi0.670K0.050Ba0.280)(Fe0.62Ti0.38)O3 at the MPB shows a large signal piezoelectric coefficient of =41.5pm/V at room temperature.

Diabetes management requires frequent blood glucose monitoring, yet invasive procedures impede testing. A noninvasive approach to detect random blood glucose (RBG) is crucial for early diagnosis and timely treatment. This work leverages Photoacoustic Spectroscopy for the detection of RBG due to its high sensitivity, specificity, and real-time monitoring capabilities. Therefore PAS has been implemented with a shallow dense neural network using a hybrid loss function (logcosh + huber loss) to estimate RBG. The augmentation of blood glucose is obtained by integrating biological parameters of a person like Body Mass Index, Age, and Spo2 with photoacoustic signal values. The intended hardware setup integrates with a Raspberry Pi 4 enabling real-time monitoring through the Thingspeak cloud platform. Testing with 105 in vivo samples demonstrated accuracies of 2.86 mg/dl (RMSE), 8.77 mg/dl (MAD), and 8.49% (MARD). Overall, an IoT-based PAS portable device is designed to provide smart healthcare services and quality care improvement

Photoacoustic Spectroscopy (PAS) is a potential method for the noninvasive detection of blood glucose. However random blood glucose testing can help to diagnose diabetes at an early stage and is crucial for managing and preventing complications with diabetes. In order to improve the diagnosis, control, and treatment of Diabetes Mellitus, an appropriate approach of noninvasive random blood glucose is required for glucose monitoring. A polynomial kernel-based ridge regression is proposed in this paper to detect random blood glucose accurately using PAS. Additionally, we explored the impact of the biological parameter BMI on the regulation of blood glucose, as it serves as the primary source of energy for the body’s cells. The kernel function plays a pivotal role in kernel ridge regression as it enables the algorithm to capture intricate non-linear associations between input and output variables. Using a Pulsed Laser source with a wavelength of 905 nm, a noninvasive portable device has been developed to collect the Photoacoustic (PA) signal from a finger. A collection of 105 individual random blood glucose samples was obtained and their accuracy was assessed using three metrics: Root Mean Square Error (RMSE), Mean Absolute Difference (MAD), and Mean Absolute Relative Difference (MARD). The respective values for these metrics were found to be 10.94 (mg/dl), 10.15 (mg/dl), and 8.86%. The performance of the readings was evaluated through Clarke Error Grid Analysis and Bland Altman Plot, demonstrating that the obtained readings outperformed the previously reported state-of-the-art approaches. To conclude the proposed IoT-based PAS random blood glucose monitoring system using kernel-based ridge regression is reported for the first time with more accuracy.

Layered perovskites structures are an interesting candidate to explore as a potential electrolyte materials for Solid oxide fuel cell (SOFC) applications. However, achieving a high ionic conductivity (?0.01 S cm?1 below 650 °C) remains a significant challenge to lowering the SOFC operating temperatures. SrBi2Ta2O9 (SBT), an Aurivillius-based layered perovskite, is a well-known ferroelectric material with TC of 320 °C. Site exchange and Bi volatility related defects lead to ionic conductivity in SBT above 700 °C. Here, we aim to control the defect chemistry by doping to promote the oxygen vacancies. We show that Mg doping at the Ta-site in the perovskite block results in 4-fold increase in the bulk conductivity of SBT 3.65 × 10?4 S cm?1 and improvement in the ionic transport number from 0.26 to 0.71. The study provides an opportunity to design new oxide ion conductors in layered ferroelectric oxides

This extensive research delves into the intersection of MRI imaging and deep learning, in the task of identifying and categorizing brain tumors. In addition to models like VGG16 and ResNet101 a designed Convolutional Neural Network (CNN) was developed and thoroughly evaluated showcasing a range of techniques utilized. Augmentation methods were purposefully applied to enrich the dataset, enhancing the models' robustness and adaptability. Evaluation metrics, including the F1 score, recall, accuracy, and precision gave a general picture of the model's performance. Furthermore, leveraging Explainable AI (XAI) techniques such as LIME unveiled insights, into the decision-making processes underlying the models enhancing their interpretability and trustworthiness. The study findings ultimately underscore the potential of learning in revolutionizing automated brain tumor diagnosis and classification poised to enhance patient care pathways and medical diagnostic capabilities significantly. Index Terms-MRI image, deep learning, VGG16, ResNET101, CNN, LIME

Ferroelectric films have been widely studied for their energy harvesting applications and flexible ferroelectric films for their piezoelectric energy harvesting. In this work, we explore tuning the PVDF/BaTiO composite flexible films for pyroelectric energy conversion applications. This work reports the influence of barium titanate particles (BaTiO) in the formation of ?-phase polyvinylidene fluoride (PVDF) on PVDF/BaTiO composite films based on Fourier transform infrared and Raman spectroscopic studies. PVDF/BaTiO composite films with different weight percentages of BaTiO were prepared by spin coating technique. Fourier transform infrared spectroscopy and Raman spectroscopic analysis of PVDF/BaTiO composite films indicated that the polar ?-phase of PVDF nucleated by the incorporation of BaTiO through CF interaction with BaTiO particles as inferred from the filler percentage dependence study of vibration modes. The 15 wt% concentration of PVDF with 5 wt% of BaTiO composite film has higher ?-phase content and better crystallinity. The improved film quality, in turn, enhances the pyroelectric coefficient and pyroelectric energy conversion figure of merit.

Single-phase materials that are simultaneously ferroelectric and ferromagnetic at room temperature are promising for devices such as non-volatile random-access memory. Perovskite BiFeO3 which crystallizes in the polar rhombohedral structure (R3c) is ferroelectric and antiferromagnetic at room temperature. Here, we report a family of perovskite oxides in the BiFeO3 – Bi2/3TiO3 – ATiO3 (where A2+ is divalent alkaline earth metal ions e.g., Ca2+, Sr2+, Ba2+) ternary phase diagram that is polar as well as weak ferromagnetic above room temperature. The composition (Bi0.9167A0.075)(Fe0.9Ti0.1)O3 crystallizes in the polar rhombohedral structure space group R3c as corroborated by powder X-ray and neutron diffraction analysis. The nearly pure A-site perovskite possesses a long-range magnetic ordering above room temperature. These perovskites show a low dielectric loss, and the electrical response is dominated by grain contributions below 723 K. © 2023 Elsevier B.V.

With emerging applications of the internet of things, technologies based on flexible materials draw much attention. In this aspect, flexible multiferroic materials might play a vital role in technologies such as energy harvesting, memory, sensor and much more. This work reports the pyroelectric studies on multiferroic polymer composite films coated on flexible substrates for pyroelectric energy conversion. Polyvinylidene fluoride/cobalt ferrite composite films were prepared by spin coating technique with different weight percentages of cobalt ferrite. The ferroelectric ?-phase of polyvinylidene fluoride in composite films were confirmed by Fourier transform infrared spectroscopy. The polar ?-phase of PVDF nucleated by the incorporation of CoFeO, through CF interaction with CoFeO particles, in PVDF/CoFeO composite films. The composite films reveal an increase in dielectric constant with the addition of cobalt ferrite. A maximum figure of merit value of 20.21% was observed in 15 wt % of CoFeO composite film by using phase sensitive approach. The maximum magnetization was observed in 20 wt % of CoFeO composite film. Improved film quality improves the pyroelectric coefficient and figure of merit for pyroelectric energy conversion.

A hybrid nanogenerator (HNG) offers both high output performance and flexibility by utilizing the synergy between piezoelectric and triboelectric mechanisms. Achieving high output performance, reproducibility, and mechanical stability in a HNG device is still a major challenge. Here, we demonstrate the design and fabrication of a flexible HNG device based on the composite of a lead-free piezoelectric ceramic and the triboelectric polymer poly(dimethylsiloxane) (PDMS). The piezoelectric ceramic oxide (BiKBa)(FeTi)O (BKBFT/MPB-piezo) exhibits improved piezoelectric properties at the morphotropic phase boundary (MPB) in the BiFeO-BiKTiO-BaTiO ternary phase diagram. We find that the composite 90 wt % PDMS-10 wt % MPB-piezo offers optimum device performance and flexibility. Interestingly, the incorporation of multiwalled carbon nanotubes (MWCNTs), a conducting filler, significantly enhances the device’s performance without the aid of electric field poling. MWCNTs form nanoelectrical bridges that aid in charge transfer and improve the composite’s structural homogeneity. The 89 wt % PDMS-10 wt % MPB-piezo-1 wt % MWCNT composite displays a peak-to-peak open-circuit voltage (V), short-circuit current (I), and power density (U) of 22 V, 1.8 ?A, and 72 nW/cm, respectively. Furthermore, we show the capability of the composite to be used as a wearable human pulse sensor.

Research on the development of green and renewable energy sources is becoming more important due to the increasing energy consumption. Various common physical effects can be used to produce generators for gathering energy from the surrounding environment. The uses of these devices for the growing Internet of Things can be significantly improved by adding flexibility. In this study, the improved pyroelectric figures of merit and pyroelectric coefficients of polymer-based flexible multiferroic composite films with two different ferrites are reported. With varying weight percentages of ferrite compositions, PVDF/manganese ferrite and PVDF/nickel ferrite composite films were prepared using the spin coating technique. The enhanced electroactive ?-phase was observed, using hysteresis loops and Fourier transform infrared spectroscopy, in the composite films with 5 and 10 weight percentages of manganese ferrite and nickel ferrite, respectively. The dielectric permittivity and magnetization values of the films increased with the increasing weight percentage of ferrite. The pyroelectric current measurements revealed a maximum pyroelectric energy conversion figure of merit values of 8.67% and 12.19% on the PVDF/manganese ferrite and PVDF/nickel ferrite composite films with 5 wt% of MnFeO content and 10 wt% NiFeO content, respectively.

NaBiTiO (NBT) is a well-known lead-free perovskite that exhibits ferroelectricity below 300 °C. NBT and certain other ferroelectrics, e.g., BiTiO, show oxide ionic conductivity on the order of 10 S cm at elevated temperatures of 650 °C. The origin of ionic conductivity in these ferroelectric oxides has been explained in terms of bismuth deficiency and oxygen vacancy in the perovskite. There is a quest for materials as electrolytes with higher ionic conductivity and at temperatures below 650 °C. NBT-based ferroelectrics have been proposed to be one such candidate for low-temperature ionic conductors as electrolytes in solid oxide fuel cells (SOFCs). In this work, we have explored NaBiTiO-BaTiO-BiFeO and studied the effect of composition on the conductivity behavior using impedance and modulus spectroscopy. We explain the nature of conductivity using the dependence of impedance on the partial pressure of oxygen. At a low BaTiO content, the composition NaBiBaFeMgTiO (NBBTF-C) forms with a rhombohedral structure and shows an ionic conductivity of ?1.02 × 10 S cm at 600 °C, which is similar to that of NBT.

The communication describes prospects of ferrite with composition Co 0.88 Cu 0.12 Fe 2 O 4 suitable for magnetic hyperthermia. Samples were processed by sol-gel method using polyethylene glycol (PEG) as chelating agent keeping ferrite to PEG weight ratios of 1:1, 1:2, and 1:3. Mean particle sizes of annealed powders at 400 ? ranging from 7.1 nm to 5.4 nm were in good agreement with the estimated crystallite sizes from X-ray diffraction patterns using Williamson-Hall analysis. Based on the variation of saturation magnetization with annealing temperature, the optimum weight ratio of ferrite to PEG was found to be 1:2. The heating efficiency of nanoparticles fabricated with ferrite-PEG weight ratio 1:2 was demonstrated using the magnetic induction heating experiment. The values of specific absorption rate 54 W/g and 83.3 W/g for the nanoparticle concentrations, 10 mg/mL and 15 mg/mL reveal the ability of Co-Cu ferrite nanoparticles as a heating agent.

Applied materials research and testing often involve measurements of material properties such as dielectric permittivity, impedance, piezoelectric coefficient, and pyroelectric current under non-ambient conditions and a controlled atmosphere. This requires simultaneous operation of multiple types of equipment and a controlled atmosphere for non-ambient conditions with computer-controlled data collection and operation. Here, we present the design and fabrication of a cost-effective measurement probe and measurement furnace with a capability of 1000°C under a controlled gas atmosphere. The setup, when used in tandem with an LCR meter or a source measure unit, can perform impedance and pyroelectric current measurements up to a temperature of 1000°C under a controlled atmosphere. We demonstrate the measurement capabilities in well-known ferroelectrics and oxide ion conductors including BaTiO, (LaSr)(GMg)O, NaBiTiO, and Pb(Zr Ti)O.

The present work reports on resistive switching (RS) characteristics of Neodymium (Nd)-doped bismuth ferrite (BFO) layers. The Nd (2–10 at%) doped BFO thin film layers were deposited using a spray pyrolysis method. The structural analysis reveals that a higher Nd doping concentration in BFO leads to significant distortion of the prepared Nd:BFO thin films from rhombohedral to tetragonal characteristics. The morphological analysis shows that all the deposited Nd:BFO thin films have regularly arranged grains. The X-ray photoelectron spectroscopy (XPS) analysis reveals that the prepared Nd:BFO thin films have a higher Fe 3+ /Fe 2+ ratio and less oxygen vacancy (V O ) defects which enriches the ferroelectric characteristics in Nd:BFO layers. The polarization-electric field (P-E) and RS characteristics of the fabricated Nd:BFO-based RS device were examined. It was observed that the Nd (7 at%) doped BFO RS device shows large remnant polarization (P r ) of 0.21 ?C/cm 2 and stable RS characteristics.

BiFeO is a ferroelectric and antiferromagnetic material at room temperature. In contrast to the weak ferromagnetism anticipated below T = 640 K, it exhibits no macroscopic moment due to a cycloidal spin ordering. This study attempts to perturb the cycloidal spin ordering and improve the multiferroic properties by substitutions of Al and Sc at Fe site. The compounds BiFeAlO (0 ? x ? 0.3) and BiFeScO (0 ? x ? 0.2), synthesized at high pressures and temperatures, crystallize with perovskite structure in polar space group R3c. With increasing Al/Sc concentration, the compounds undergo marked changes in magnetic properties. While Al-substituted compounds were lossy and exhibited a Maxwell–Wagner effect, the Sc-substituted compounds exhibited ferroelectricity at room temperature.

1T Molybdenum disulfide (1T-MoS 2 ) has been widely studied experimentally as an electrode for supercapacitors due to its excellent electrical and electrochemical properties. Whereas the capacitance value in MoS 2 is limited due to the lower density of electrons near the Fermi level, and unable to fulfill the demand of industry i.e. quantum capacitance preferably higher than 300 ?F/cm 2. Here, we investigated the performance of 2H, 1T, and 1T? phases of MoS 2 in its pristine form and heterostructures with carbon-based structures as an electrode in the supercapacitors using density functional theory. Specifically, we reported that the underneath carbon nanotube (CNT) is responsible for the structural phase transition from 1T to 1T? phase of MoS 2 monolayer in 1T?-MoS 2 /CNT heterostructure. This is the main reason for a large density of states near Fermi level of 1T?-MoS 2 /CNT that exhibits high quantum capacitance (C Q ) of 500 ?F/cm 2 at a potential of 0.6 V. Also, we observed that the nitrogen doping and defects in the underneath carbon surface amplify the C Q of heterostructure for a wider range of electrode potential. Therefore, the 1T?-MoS 2 /N doped CNT can be explored as an electrode for next-generation supercapacitors.

Ambient pressure stable perovskite oxides with all Bi3+ on the A-site are rare, with only four examples known. Due to the lone pair on Bi3+, these materials are seen as the best alternative to Pb-based piezoelectrics, which are used widely in society. The industry standard piezoelectric, Pb (Zr1 - xTix)O3, relies on the [001] polarization of PbTiO3, but there are currently no ambient pressure stable Bi-based perovskites with this polarization vector, preventing the creation of an analogous system. We present the full structural analysis of the orthorhombic phase of (1 - x)Bi (Ti3/8Fe2/8Mg3/8)O3 - xCaTiO3, which crystallizes in Pna21 symmetry with [001] polarization. This symmetry is rare and has only been reported twice for perovskites at ambient conditions. Analysis of maximum entropy method (MEM) models using synchrotron radiation powder X-ray diffraction reveals a disordered A-site configuration, and the MEM/Rietveld technique generates a structural model of this extreme disorder. Combined Rietveld analysis of X-ray and neutron diffraction data yields an accurate description of the local A-site configuration, which we use to understand our dielectric, ferroelectric, and piezoelectric measurements. These results give insight into how to stabilize this unique symmetry and inspire new design principles for Bi-based piezoelectrics.

The compound BiCrMnO, synthesized at high pressure and high temperature, shows a giant dielectric constant over a wide range of temperatures. Two relaxation processes are observed commencing around 200 K and 300 K. The low-temperature relaxation process is attributed to Maxwell–Wagner polarization at the grain boundary, whereas the second relaxation is attributed to the electrode polarization effect. Impedance spectroscopy reveals that the oxide is electrically inhomogeneous and dominant contribution arises from semiconducting grains and insulating grain boundary below room temperature. Above room temperature, the electrode polarization effect also contributes to the observed giant dielectric constant.