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Nano-Perovskite materials of Gd-doped BiFeO3 catalyzed the oxidation of glycerol into formic acid in the liquid phase under atmospheric conditions.

Abstract: Recently memristors have emerged as a form of nonvolatile memory that is based on the principle of ion transport in solid electrolytes under the impact of an external electric field. It is perceived as one of the key elements to building next-generation computing systems owing to its peculiar resistive switching characteristics. The switching mechanism in a memristor is mainly governed by filamentary conduction. Further, it can be employed as a memory as well as a logic element, which makes it an ideal candidate for building innovative computer architecture. Moreover, it is capable of mimicking the characteristics of biological synapses, which makes it an ideal candidate for developing a Neuromorphic system. In this review to begin with the switching mechanism of the memristor, primarily focusing on filamentary conduction, is discussed. Few SPICE models of memristor are reviewed, and their critical comparison is performed, which are widely used to build computing systems. An in-depth study on the various crossbar memory architecture augmented with memristors is reviewed. Finally, the application of memristors in neuromorphic computing and hardware implementation of Artificial Neural Networks (ANN) employing memristors is discussed.

In the present study, combustion technique is adopted to study the impact of Mg2+ ion doping on ZnAI2O4 nanoparticles (NPs). L-arginine is used as a fuel component. The Mg2+ ions play a pivotal role in persuading various characteristics of ZnAI2O4 NPs. Various characterization technqiues such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), high resolution scanning electron microscopy (HR-SEM), diffuse reflectance spectroscopy (DRS), Thermo-gravimetric/differential thermal analysis (TG-DTA) and vibrating sample magnetometer (VSM) were carried out in order to synthesize the nanoparticles. Single phase cubic spinel structure of ZnAl2O4 (gahnite) formation was confirmed from the XRD characterization process of the nanoparticles. Estimated average crystallite size range of 11.85 nm to 19.02 nm was observed from Debye-Scherrer. Spherical morphology with uniform distributions was observed from HR-SEM characterization images. From the band gap studies, the attained band gap values were found to lie within 5.41 eV–4.66 eV range. The ZnAl2O4 and Mg:ZnAl2O4 NPs exhibited super-paramagnetic nature confirmed by magnetic measurements. The obtained results make ZnAl2O 4and Mg:ZnAl2O4 NPs appropriate for various optical, catalytic, energy and data storage applications.

Microwave combustion technique (MCT) was used to synthesize of spinel Ni1-xSrxFe2O4 (x = 0.0, 0.1, 0.3 and 0.5) nanoparticles (NPs) by employing the fuel L-arginine. The physical characteristics of the as-prepared NPs were obtained by following methods, viz., powder X-ray diffraction (XRD), high-resolution scanning electron microscope (HR-SEM), energy-dispersive X-ray (EDX), UV-visible diffuse reflectance spectra (UV-Vis DRS), Fourier-transform infrared spectra (FT-IR), and vibrating sample magnetometer (VSM) techniques. The diffraction studies revealed that the average crystallite size exists in the band of 14.25 to 27.52 nm. The HR-SEM pictures revealed the agglomerated and spherical morphology of spinel Ni1-xSrxFe2O4 (x = 0 to 0.5) nanoparticles. Elemental analysis ensured the existence of Ni, Sr, O, and Fe ions. The energy band gap of the NPs was observed to exist in the range of 2.95 to 3.39 eV upon varying the concentration of Sr2+ dopant. The broad peaks at 437 cm−1 and 582 cm−1 correspond to octahedral (B-) metal stretching (Ni-O) and tetrahedral (A-) metal stretching (Fe-O) of nickel ferrite respectively. Magnetic results revealed that the prepared NPs are ferromagnetic in nature. The antibacterial activity (ABA) of gram-positive Staphylococcus aureus and Bacillus subtilis and gram-negative Escherichia coli and Klebsiella pneumonia has been investigated using pure and Sr2+-substituted NiFe2O4 NPs. It was found that the improved activity is intensified with smooth Sr2+ doping as it causes a decrease in the grain size.

Introduction: We report here our success in developing a flexible RRAM stack structure by employing a low-cost method. Bare conductive commercial electric paint is used as anode against Stainless Steel (SS) foil deposited with Mn3O4 thin films forming a BCEP/Mn3O4/SS thin film stack to understand the intrinsic non-volatile resistive switching behavior of Mn3O4. Experimental: Thin film Mn3O4 is deposited on a SS (304) foil by means of potential sweep voltammetry by maintaining typical conditions. Interestingly, the pristine device is subjected to an electroforming process which exhibited a digital type bipolar resistive switching characteristics. The study of the conduction mechanism revealed that the resistive switching arises due to local effect occurring in the bulk of Mn3O4, which corresponds to the growth and annihilation of oxygen vacancy nanofilaments, and this is responsible for the change in resistance state of the RRAM between Low Resistance State (LRS) and High Resistance State (HRS) respectively. Results: In order to affirm the reliability and reproducibility of RRAM structure, the memory retention is monitored over 103 s and subsequently, the endurance test is also carried out ensuring the reproducibility over 100 cycles. Conclusion: Owing to the flexible nature of BCEP/Mn3O4/SS Foil RRAM stack structure, it is perceived to be a prime candidate for future non-volatile memory and flexible electronics applications.

Zinc sulfide (ZnS) nanoparticles have been successfully prepared by sol–gel precipitation method. The successful formation of cubic structure is ensured by XRD analysis and Debye Scherrer’s equation is used to determine the crystallite size which was found to be 36 nm for ZnS sample annealed at 200 °C. Surface morphology was studied using HRSEM as well as HRTEM and lattice parameters of the samples were obtained from SAED pattern which was found to have close resemblance to values attained from XRD pattern. Further elemental mapping of ZnS nanoparticles is confirmed by EDX studies. Further Kubelka Munk function was employed to estimate the band gap value which was seen lying within 3.58 to 3.64 eV. Further the antibacterial activity of ZnS is investigated and it is found to be an antibacterial agent of Escherichia coli and staphylococcus aurous, further it can be employed as an antimicrobial agent for prohibiting implant linked infections.

The microwave combustion process (MCP) is used to synthesize Mg1-xCaxFe2O4 (0 ≤ x ≤ 0.5) spinel nanoparticles using the fuel l-arginine. Synthesized samples were examined by employing techniques such as XRD, HR-SEM, EDX, DRS-UV, TG-DTA and VSM. The XRD corroborated the constitution of the cubic spinel structure and the average crystallite size was valued to lie in the range of 16.09 to 33.10 nm. The morphology of the Mg1-xCaxFe2O4 (0 ≤ x ≤ 0.5) spinel nanoparticles was observed by HR-SEM. EDX studies confirmed the formation of spinel ferrite structure. Further bandgap values were estimated to be in the range of 1.84 eV to 2.00 eV. TG-DTA studies confirmed weight loss and exothermic transitions. The M-H loops exhibited ferromagnetic behaviour.

We report the synthesis of multiferroic BiFeO3 perovskite nanoparticles using the microwave combustion technique. Phase evolution is investigated by X-ray diffraction (XRD), which confirms that the formation of a secondary α-Bi2O3 phase with a monoclinic structure along with the existing rhombohedral (BiFeO3) structure. The average crystalline size has been found at 50 nm. The optical band gap was calculated from the Tauc’s plot it has been found 2.18 eV, as measured by diffuse reflectance spectroscopy (DRS). The appearances of Fourier transform infrared spectroscopy (FT-IR) absorption bands at 550 and 444 cm-1 were correlated to the rhombohedral stretching modes of bismuth ferrite nanostructure. The morphology observations using scanning electron microscopy (SEM) showed the formation of nanosized grains with pores. Energy-dispersive X-ray analysis (EDX) was done to confirm the extent of Bi3+, Fe3+, and O2- in the samples. The magnetization-Field (M-H) hysteresis curves recorded from the vibrating sample magnetometer (VSM) revealed the appearance of ferrimagnetic behavior at room temperature. The specific surface area characterized by N2 adsorption-desorption isotherm is found 44.86 m2 g-1 using Brunauer-Emmett-Teller (BET) technique. The as-fabricated BiFeO3 perovskite nanoparticles were investigated for their superior catalytic activity in two applications, which include (i) the conversion of glycerol to formic acid in a selective liquid phase batch reactor at atmospheric pressure. This bismuth-based nanoparticles exhibit as an efficient multifunctional catalyst with high conversion and selectivity efficiency around 99.2% and 98.5%, respectively, (ii) the photocatalytic degradation of rhodamine B under visible light irradiation is found maximum efficiency (99.9%), when a small amount of H2O2 was added during photocatalysis, indicating the samples possessed photo-Fenton like catalytic activity. Finally, we concluded that the BiFeO3 perovskite nanoparticles' high performance in future multifunctional devices is demonstrated by the simultaneous enhancement of catalytic and photocatalytic activities.

The pure phase of rutile titanium dioxide or titania (R-TiO2) was prepared by means of a strong acidic sol–gel process followed by treatment using a hydrothermal method. The as-prepared titania nanoparticles existed purely in the rutile phase instead of the mixed anatase phase of the respective titania (R-TiO2). The optimized reaction condition and precursor usage were the critical parameters for the formation of the particle size and uniform crystallinity of the rutile phase of TiO2 nanoparticle fabrication. XRD (X-ray diffraction), and Raman spectroscopic techniques were utilized to confirm the formation of the pure rutile phase of titania. SEM (scanning electron microscope) and TEM (Transmission electron microscope) images showed the cauliflower-like morphology of the as-prepared R-TiO2, reduced particle sizes of below 5 nm were observed and confirmed through high resolution images. The catalytic activity of the as-prepared R-TiO2 was tested under visible light irradiation for methylene blue dye degradation reactions. Dye degradation occurred very effectively, even at higher concentrations of methylene blue (MB), at reduced time intervals from 5 to 3 h of reaction time. The as-prepared rutile phase of pure titania nanoparticles was applied in a catalysis application for the purpose of inducing various types of organic dye degradation or catalytic transformation in the presence of visible light.

ZnO–CdS nanocomposites with three different molar ratios of 25:75, 50:50 and 75:25 were synthesized by simple hydrothermal technique. Powder X-ray diffraction patterns confirmed the phase formation of ZnO and CdS in ZnO–CdS nanocomposites. The calculated crystallite size was found in the range of 33–38 nm and 15–21 nm for ZnO and CdS respectively. HRSEM images revealed flake-like morphology for all samples. Energy dispersive X-ray spectra confirmed the presence of all the elements. The estimated optical bandgap was found in the range of 3.71–3.35 eV. IR spectra confirmed the formation of stretching vibration in ZnO and CdS. Dielectric analysis was performed in order to study Ac conductivity, dielectric constant and dielectric loss. Photoconductivity studies revealed that ZnO–CdS nanocomposites material exhibited sound photo-response characteristics.

Ion transport in the solid state has been regarded as imperative with regards to high energy density electrochemical storage devices (for instance, batteries) for efficient electric mobility. Of late, there is another niche application involving ion transport in solid state which manifested itself as nonvolatile memory namely memristor. Such memories are classified under the emerging category of novel solid state Resistive Random Access Memories (RRAM). In 2008, HP labs unveiled the first practical memristor device employing TiO2 and non-stoichiometric titania as bilayer stack structure and on both sides of two titania layers platinum (pt) are used as blocking electrode for ions. It is understood that switching fundamentals are correlated to the filamentary conduction in metal oxide memristors owing to the formation and rupture of the filament-like nano-dendrites, one of the key mechanisms widely accepted in the arena of memristor analysis. This paper critically reviews the fundamental materials being employed in novel memristor memories. It is believed that solid electrolytes (fast ion conductors) are the fundamental building blocks of these memories. We have chosen a few archetypes, solid electrolytes are considered and their impact on the state-of-art research in this domain is discussed in detail. An indepth analysis of the fundamentals of resistive switching mechanism involved in various classes of memristive devices viz., Electrochemical Metallization Memories (ECM) and Valence Change Memories (VCM) is elucidated. A few important applications of memristors such as neuristor and artificial synapse in neuromorphic computing are reviewed as well.

In this work, Magnesium-doped zinc aluminate nanoparticles are synthesized using microwave combustion technique by employing L-alanine as fuel. The incorporation of Mg2+ ions plays a pivotal role in influencing the optical, structural, and magnetic properties of zinc aluminate nanoparticles. The synthesized nanoparticle are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high-resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), and vibrating sample magnetometer (VSM).The XRD patterns confirmed the formation of single-phase cubic spinel structure of ZnAl2O4 (gahnite). The average crystallite sizes estimated from Debye-Scherrer is found to be in the range of 6 to 12 nm. HR-SEM images revealed the spherical morphology with uniform distributions. The optical bandgap of the synthesized nanoparticles is found to be in the range of 5.45 eV–5.76 eV. Magnetic measurement reveals that pure and doped zinc aluminate nanoparticles have superparamagnetic nature. These obtained results of Zn1-xMgxAl2O4 (0 ≤ x ≤ 0.5) are found to be well suited for optoelectronics, magnetic, and catalytic applications.

In the present study, combustion technique is adopted to study the impact of Mg

Use of solid state ionic conductors the so-called Solid Electrolytes has brought new impetus to the field of solid state memories namely resistive random access memory (Re-RAM). In this review article, to begin we present the detailed understanding on the basics of solid electrolytes. Later, the same has been reviewed focusing on its application in novel solid state memory applications. Few examples of solid electrolytes are considered and their impact on the state-of-art research in this domain is discussed in detail. An in-depth analysis on the fundamentals of Resistive switching mechanism involved in various classes of Memristive devices viz., Electrochemical Metallization Memories (ECM) and Valence change Memories (VCM). A few important applications of Memristors such as Neuristor and artificial synapse in neuromorphic computing are reviewed as well. Finally, the most anticipated energy efficient battery-like cells as artificial synapse in brain-inspired computing is also covered.

Modern business is considered to grow in various social, economic and competitive environments which is constantly changing with fast technological advancements, complex and ever increasing cultural and social change. An entrepreneur is expected to interact with these environmental forces which require him to be highly competent in different dimensions like intellectual, attitudinal, behavioral, technical, and managerial aspects. Although entrepreneurship as a discipline has been studied very deeply by researchers, its environmental, social and cultural factors are side lined. Therefore, an attempt is made in this study to delineate these factors to establish a relationship that propagates itself to life of an entrepreneur. For this purpose, a questionnaire is devised covering 1 genetic factor, 8 demographic factors, , 4 trait variables, 8 career choice anchors, 4 circumstantial variables, 1 cognitive variable, 6 pull factors, 5 push factors, 4 economic variables, 9 success variables of an entrepreneurial venture and 6 variables that create barriers to entrepreneurial success. The validity and internal consistency of the questionnaire was tested using Cronbach’s Alpha (α) test. The questionnaire was administered through a google form to 136 entrepreneurs in Delhi/NCR. To measure their performance Chi square (χ2) test, Student’s “t” test, one-way ANOVA (F test ) and Karl Pearson’s Correlation coefficient (r) were used as statistical tools depending on type of data collected for each variable and a test of significance was done by two tailed statistical distribution at p< .05 level of significance and a regression line was drawn to find the fit. The findings of the study came out with a result that all demographic variables except for age and marital status impacted on entrepreneurial performance and a large number of other endogenous & exogenous variables influenced the effectiveness of entrepreneurs.

Employing electrochemical impedance spectroscopy (EIS), we demonstrate a novel approach towards characterizing the switching behavior of nano-ionic memristor, M/TiO2−x/TiO2/M where M = Au, fabricated using combined RF/DC magnetron sputtering techniques. The non-linear resistive switching behavior of the device has been investigated using a constant potential sweep technique to observe I-V switching profile (a pinched hysteresis loop) in which ex-situ impedance response has been measured by interrupting the potential sweep (mV s−1) over different distinct regimes (pristine device, SET and after zero-crossing). Accordingly, the obtained EIS spectra are corroborated with oxide circuit model and the corresponding numerical fittings of the impedance response reveals distinct RC frequency domains as exemplified in the equivalent circuit models obtained using the simulated impedance response and attributed to the interfacial barrier between the stoichiometric and non-stoichiometric TiO2 respectively. It is evident that the device shows various functional features as memory element owing to the transport of mobile charges in TiO2−x when the bias potential (V) is applied across the device. It is revealed that EIS studies render a new insight into much acclaimed formation and annihilation of nanofilament like dendrites (magneli phase of titania, TinO2n−1) which are found to be responsible for the change of switching states between low resistance state (LRS) and high resistance state (HRS) respectively. In order to validate the memory retention and endurance characteristics, the reproducible resistive switching is found to occur consistently over 104 s and the device endurance has been verified by toggling between HRS and LRS over 1000 cycles.

Approximate computing aims at reducing circuit complexity and delay, by allowing leverages in the output for a certain combination of inputs. The reduction in circuit complexity is achieved by minimizing the number of components in the circuit. This paper proposes a plausible approach towards approximate computing with memristors for designing memristor based approximate full adder and subtractor with logic minimization technique. The validation of our proposed approximate adder is verified by designing an 8-bit Ripple Carry Adder (RCA) to perform bitwise pixel addition of two gray scale images of the same size and compare the design with images obtained by exact addition method. Similarly, we have affirmed that the designed 8-bit Ripple Borrow Subtractor (RBS) is verified on foreground detection. Furthermore, to corroborate the above observation, performance metrics like Mean Square Error (MSE), Peak Signal to Noise Ratio (PSNR), Structural Content (SC), Mean Absolute Error (MAE), Average Distance (AD), Mean Average Distance (MAD) and Normalized Absolute Error (NAE) are deduced in MATLAB®. Owing to the logic minimization technique, for a certain combination of inputs, the MSE has been found to be predominant and its impact on PSNR is studied.

Zn1-xCoxAl₂O₄ (0 ≤ x ≤ 0.5) nanoparticles were synthesized employing L-alanine as fuel using MACT (microwave assisted combustion technique). The synthesized samples were characterized following methods such as X-ray Diffraction, high resolution scanning electron microscopy, Energydispersive X-ray spectroscopy; UV-visible diffused reflectance spectroscopy, FT-IR and VSM. The XRD confirmed the cubic spinel structure and the average crystallite size observed lying in the range of 12-19 nm deduced using the Debye Scherrer's equation. The morphology of the Zn1-xCoxAl₂O₄ (0 ≤ x ≤ 0.5) nanoparticles is observed using HR-SEM. EDX analysis is opted for the elemental mapping of pure and cobalt doped zinc aluminate nanoparticles. Further band gap value was calculated using Kubelka Munk function, which was seen lying within 3.73 to 5.45 eV. The strong absorption band at 669, 556 and 500 cm-1 was associated with the vibrations of Zn-O, Al-O and Zn-O-Al of zinc aluminate nanoparticles. The hysteresis loops exhibited conversion from diamagnetic into super paramagnetic behaviour with increase in Co doping.

Microwave combustion process is used to synthesize MAl2O4 (M = Zn and Co) spinel nanoparticles utilizing the fuel l -alanine. Synthesized samples were examined by techniques viz. XRD, HR-SEM, EDX, DRS-UV, PL, TG-DTA, FT-IR, XPS and VSM. The XRD confirmed the formation of cubic spinel structure with the average crystallite size of 14 nm and 11 nm for Cobalt and Zinc aluminate nanoparticles respectively. The morphology of CoAl2O4 (CAO) and ZnAl2O4 (ZAO) nanoparticles was observed by HR-SEM. EDX and XPS studies confirmed the formation of pure spinel aluminate structure. Further band gap values were estimated to be 3.35 and 5.45 eV for CAO and ZAO respectively. The PL spectra of CAO and ZAO nanoparticles were studied with an excitation wavelength of 235 and 205 nm. The strong absorption bands between 500-1100 cm-1 were linked to CAO and ZAO nanoparticles. TG-DTA analysis confirmed weight loss and exothermic transitions. The M − H loops revealed CoAl2O4 and ZnAl2O4 nanoparticles exhibited superparamagnetic behavior.

A microwave combustion method was used to synthesize Cu1-xZnxFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) nanoparticles. The synthesized Zn-doped CuFe2O4 nanoparticles were characterized by techniques such as X-ray diffraction, high-resolution scanning electron microscopy, UV–visible diffuse reflectance spectroscopy, photoluminescence spectroscopy, Fourier transform IR spectroscopy, and vibrating sample magnetometry. X-ray diffraction and Fourier transform IR spectroscopy results confirmed the formation of Cu1-xZnxFe2O4(x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) nanoparticles. The crystallite size and lattice parameter were determined as 15–19 nm and 8.319–8.400 A, respectively. High-resolution scanning electron microscopy revealed the presence of agglomerated spherical particles of Cu1-xZnxFe2O4. Elemental mapping of pure and Zn-doped CuFe2O4 was done by energy-dispersive X-ray analysis. The band gap was calculated with the Kubelka-Munk function and was found to lie in the range from 2.30 to 2.51 eV. Finally, M-H curves were plotted and the magnetic properties, such as coercivity, remanent magnetization, and saturation magnetization, were determined.

Image processing is a type of memory-access-intensive application that requires to access memory for a longer duration thereby lowering the overall throughput of the system by limiting the speed of memory access and bandwidth. This profound memory wall problem can be overcome by using memristor-based Computation-In-Memory (Memory-driven) architecture that can be simultaneously utilized as memory and processing element. To further enhance the computational speed and to perform energy/power-efficient operations, approximate computing is employed by allowing leverages in output for certain combination of inputs. In image processing applications, the computing blocks consist of multipliers and delays whose working is determined by suitable combination of adders. In this work, memristor-based approximate full adder is designed by random incorporation of errors in SUM and CARRY, respectively, and the resulting truth table is verified. The capability of proposed approximate adder is validated by designing (in Cadence Virtuoso) a 4-bit ripple carry adder (RCA) to perform bit-wise pixel addition of two grayscale images of same size and compared with an image obtained by exact addition method.