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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.

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.

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.

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.

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.