Recent Advances in Nanomaterials

Inhaltsverzeichnis

1. Frontmatter

2. Investigation of Microstructural, Optical, and Electronic Properties of Hydrothermally Synthesized MoS2 Decorated SnO2

   Priya Pradeep Kumar, Vinod Singh

   Abstract

   In this work, MoS₂/SnO₂ heterostructures have been synthesized using the hydrothermal method, and structural, optical, and compositional properties were studied by various characterizations revealing the confirmation of the co-existence of MoS₂ and SnO₂ phase in heterostructures with changed properties than the pristine ones, which makes them beneficial for gas sensing applications with a unique combination of structural and optical properties.

3. Synthesis of Titania Nanoparticles and Assessment of Antioxidant Activity

   Yepuri Venkatesh, Patchamatla Satyanarayana Raju, Putchakayala Yanna Reddy

   Abstract

   Nanotechnology has inspired a plethora of research subjects and applications. Nanoparticles, in particular, have been manufactured utilizing a number of physical, chemical, and biological techniques, allowing them to be applied in various engineering and scientific applications. The sol-gel method, a wet chemical approach, was used to synthesize titania nanoparticles in this study; these particles were further characterized using an X-ray diffractogram (XRD), which revealed an anatase phase with a strong peak identified at Bragg angle 25 ^O. Fourier transform infrared spectroscopy (FTIR) analysis revealed TiO₂ vibrational modes as well as their hydroxyl group linkages at 932 and 3247 cm⁻¹, respectively. Analysis of the produced particles using FESEM characterization revealed the aggregation of particles with irregular morphologies. The diffuse reflectance examination of the particles supported light absorption in the ultraviolet range and 90% reflection in the infrared region. Finally, antioxidant studies on titania nanoparticles using the DPPH assay revealed improved scavenging activity.

4. Structural and Magnetic Studies of Nanocrystalline La0.8-xAg0.2BixMnO3(x = 0, 0.05)

   Priyanka Bisht, Rabindra Nath Mahato

   Abstract

   We report the exploration of structural and magnetic properties of nanocrystalline La_0.8Ag_0.2MnO₃ and La_0.75Ag_0.2Bi_0.05MnO₃ compound, synthesized using the citrate sol-gel method. By analyzing X-ray diffraction data, it has been shown that both the nanocrystalline samples crystallized into a rhombohedral structure (\(R\overline{3}c\) space group). The average crystallite size was evaluated to be ~41 and 35 nm by employing Williamson–Hall (W–H) method. SEM images reveal that the particles have an average particle size of 137 and 162 nm which are almost uniform in size. The SEM micrographs reveal the homogeneity of the nanocrystalline compound. At 299 K, paramagnetic to ferromagnetic transition is observed in nanocrystalline La_0.8Ag_0.2MnO₃ based on the temperature dependence of magnetization measurements. La_0.75Ag_0.2Bi_0.05MnO₃ sample shows transition temperature above room temperature which will be beneficial for magnetic refrigeration application.

5. Synthesis of Polymeric Nanoparticles Encapsulating Extract of Datura Stramonium and Study of Its Various in Vitro Activities

   Rani Usha, Rani Asha, Thakur Rajesh

   Abstract

   In the present work, the extract from Datura stramonium is commonly used for its various pharmacological properties and was used for nanoparticles synthesis by ionic gelation method using complex of tragacanth and chitosan as polymers. The synthesized nanoparticles were characterized using techniques like PSA, FTIR, SEM, and TEM. The particle size of nanoparticles thus obtained ranged from 100 to 300 nm. SEM micrograph of nanoparticles showed the roughly spherical structures which appear to be encapsulated in the polymer. TEM images showed somewhat sphere-shaped nanoparticles that might be due to the encapsulation in tragacanth-chitosan complex. Synthesized nanoparticles showed considerable antibacterial action against various bacteria such Pseudomonas aeruginosa and Escherichia coli. Both Datura and chitosan-tragacanth NPs showed clear zone of inhibition showing that both possess antibacterial activity but the zone of inhibition formed by extract-loaded chitosan-tragacanth NPs is better than extract alone which shows they are more promising agents for antimicrobial activity. Before going to further studies the hemocompatibility of the synthesized nanoparticles was also investigated, and after it, the DPPH radical scavenging assay was used to measure the antioxidant activity and HRBC method was used to test the in vitro anti-inflammatory activity. It was found that the synthetic nanoparticles exhibit adequate amount of antioxidant activity, and it was observed by the results that the synthesized nanoparticles provided more protection than the individual plant extract and blank nanoparticles.

6. Synthesis, Characterization and Various in Vitro Activities of Essential Oil-Loaded Polymeric Nanoformulations

   Choudhary Asha, Rani Usha, Salar Raj Kumar, Thakur Rajesh

   Abstract

   The main objectives of the present research were to synthesize cumin essential oil-loaded polymeric nanoformulations using the ionic gelation method and use it in a variety of in vitro activities. Cumminium cyminum is well known in world among the spices and if we discussed its seeds that also contain good amount of oil content having various bioactive compounds like cumin aldehyde, P-cymene, D-limonene, terpinene and eugenol with considerable potential in various in vitro activities. Various techniques were used to characterize the synthesized nanoformulations. Using a particle size analyzer, the nanoformulations obtained had diameters ranging from 20 to 400 nm. The nanoformulations could be aggregated with a nearly spherical shape, as seen by SEM analysis. The nanoformulations, cumin oil and ascorbic acid exhibit strong antioxidant activity, ranging from 27 to 80% as assessed by the DPPH assay.

7. Energy Gap Dependence on the Hydrostatic Pressure and Temperature of GaAs Quantum Wire

   Priyanka, Rinku Sharma

   Abstract

   In this study, we examine the energy gap dependence on the hydrostatic pressure and temperature with the existence of an intense magnetic field and Rashba spin–orbit interaction. First, we employ diagonalizing method to work out the Schrödinger equation. After that, we calculate the energy gap for a GaAs quantum wire. Our numerical outcomes illustrate that the energy gap dependence on the hydrostatic pressure and temperature of a GaAs quantum wire. We also focus on the effect of magnetic field and Rashba spin–orbit interaction on the curve of energy gap vs pressure/temperature.

8. Effect of Annealing Temperature on Microstructural, Optical and Magnetic Properties of spinel-ZnFe2O4 Nano Particles

   Mohd Rehan Ansari, Koteswara Rao Peta

   Abstract

   In this work, zinc ferrite nano-particles (ZF NPs) were synthesized using co-precipitation method and annealed at different temperatures 400, 600 and 800 °C in air ambient. It is observed that temperature significantly effects the structural, optical and magnetic properties of ZF NPs. The high-resolution X-ray diffraction (HR-XRD) spectra of ZF NPs is matched with JCPDS card No. 00–022-1012, which shows a single-phase cubic spinel structure with Fd-3 m space group. The estimated average crystallite size is in the range of 11.8–18.4 nm. The scanning electron microscope images shows that the particle size of ZF NPs is increased due to increase in the nucleation rate of particles during the annealing which is good agreements with the XRD results. EDX elemental analysis showed that the ZF NPs consists of Zn, Fe and O atoms and no other impurities are present. The Fourier transform infrared spectroscopy (FTIR) spectrum having absorption peaks in fingerprint region at 541 cm⁻¹ and 607 cm⁻¹ showing the stretching vibrations of Fe–O and Zn–O bond at tetrahedral and octahedral lattice sites respectively. The optical energy bandgap is decreased from 2.1 eV to 1.9 eV with increase in annealing temperature calculated by diffuse reflectance spectroscopy using Kubelka–Munk function due to increase in the crystallite size. In addition, vibrating sample magnetometer (VSM) showed the superparamagnetic nature of the ZF NPs as M-H curve passing through origin with zero coercivity and remanence.

9. Studies on Zinc Oxide Thin Film and Nanoparticles Synthesized by Chemical Bath Deposition

   S. Pandya, V. K. Pathak, P. D. Lad, M. P. Deshpande

   Abstract

   Zinc Oxide (ZnO) nanoparticles (NPS) and thin film are synthesized by chemical bath deposition technique. Synthesized nanoparticles and thin film are characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM), UV–Visible spectroscopy, Photoluminescence spectroscopy (PL) and Raman Spectroscopy. XRD analysis shows that ZnO NPS and thin film are formed in hexagonal wurtzite structure. A particle size of NPS varies from 40–60 nm, which is confirmed with TEM. UV–Vis absorbance spectrum shows absorption peak at ~ 369.2 nm (3.36 eV) for thin film and at ~ 378.8 nm (3.27 eV) for nanoparticles. Determined band gap from Uv–Vis absorption are 3.11 and 2.81 eV for ZnO thin film and NPS respectively. PL spectra of thin film and NPS show multiple peaks for violet, blue and green emissions which may be attributed to various defect levels present in material. Raman spectrum of ZnO nanoparticles shows presence of different Raman – active modes. Presence of sharp peak for non-polar optical phonons E₂ (high) mode confirms good quality hexagonal wurtzite crystal phase of ZnO nanoparticles.

10. Down-Conversion Fluorescence Study of Non-metal Co-doped Carbon Dots

    Rajnee Yadav, Sanjay, Vikas Lahariya

    Abstract

    In this work, a down-conversion fluorescence study of carbon dots is presented. A facile microwave irradiation route is used to prepare the carbon dots by carbonization of citrus limetta juice in an aqueous medium. Phosphonic acid and ethylenediamine are taken as initial phosphorus (P) and nitrogen (N) sources, respectively. The optical and photoluminescence properties are investigated with different ratios of P to N. UV–Visible absorption spectroscopy and Raman spectroscopy are employed for the optical study. Fluorescence spectra are noted by spectrofluorometer in various excitation wavelengths. The observed absorbance peaks in the ultraviolet region represent n and π molecular transitions. The molar ratio of P to N modifies the electronic transitions. From PL spectra, the excitation-dependent emission spectra are observed. The enhanced down-conversion fluorescence in the green to the red region is blue-shifted with changing initial P/N ratio in carbon dots. The change in emission color with P/N is observed due to changes in emitting states and electronic transitions.

11. Green Synthesis of Carbon Dot (CDs) and Sensing of Metal Ion

    Momina, Ahmad Kafeel

    Abstract

    Carbon dots (CDs) have demonstrated significant promise in the application of ion sensing, water/waste treatment, photo-catalysis, biological imaging, supercapacitor, heavy metal detection, and membrane filtration. In this paper, fluorescent carbon dots (CDs) have been synthesized by solvothermal treatment using fruit waste (apple peel) as a raw material. Ecological solvents such as distilled water and ethanol have been used as solvent to produce CDs. The prepared fluorescent CDs have been characterized by PL spectra, UV–Vis, zeta potential, FTIR, and TEM. Some metal ions like Cr (VI) have human health mutagenic and carcinogenic consequences which can penetrate cells membrane and also lead to DNA mutation. Thus, the green synthesized CDs have been studied for the detection of Cr (VI) ions with detection limit of 3.82 µM.

12. Synthesis of Monosized Silica Microparticles and Fabrication of Size-Controlled Silicon Microwires

    Anjali Saini, Premshila Kumari, Sanjay K. Srivastava, Mrinal Dutta

    Abstract

    The present study has been carried out to fabricate size-controlled monodisperse silica microparticles and SiMW arrays using a silica template via the nanosphere lithography (NSL) technique in accumulation to the metal-catalysed electroless etching (MCEE) technique. Considering the need, importance, and benefits of monosized SiO₂ microparticles as proclaimed in the scientific area with diverse industrial applications, monodispersed silica particles were synthesized by using modified Stober process. Synthesis of monosized microparticles has been achieved by using a silica precursor tetraethyl orthosilicate (TEOS) in an ethanol solution underneath basic conditions and assimilating a surfactant. In this process, a single monolayer closed-pack configuration of SiO₂ microparticles via self-assembled  mechanism formed on the 2-inch silicon wafer by using a simple spin coating technique, and further, non-closed-packed structure was obtained from the closed-packed structure using the reactive ion etching (RIE) process. Using the MCEE technique, the size-controlled SiMW arrays were synthesized. The size and morphology of the microparticles and SiMW arrays were examined by the field-emission scanning electron microscope (FESEM). The SiMW arrays showed less than 15% reflection in the wide range of spectrum (300–1000 nm). The surface composition of the microparticles and SiMWs was studied using FT-IR. Such SiMW arrays may have several potential applications including solar cells.

13. Thermoelectric Properties of LiYSi Half-Heusler Alloy

    Grewal Savita, Kumar Ranjan

    Abstract

    Half-Heusler compounds are a broad class of materials that have attracted attention as possible high-temperature thermoelectric materials due to their favourable electrical transport behaviour and other features useful for device manufacturing. Although half-Heusler compounds exhibit an incredibly wide range of thermal conductivities, these are nonetheless often higher than other cutting-edge thermoelectric materials, which present a unique difficulty. It was observed that the chosen half-Heuslers were direct bandgap semiconductor with high power factors equivalent to the art of thermoelectric materials. Since the computed phonon is positive, the substance is dynamically stable. The high power factor and high Seebeck coefficient of the half-Heusler alloy are also revealed by the density of states. The stability of the material is also revealed by the formation energy. The optimized structure of LiYSi has band gap of 0.70 eV. The calculated power factor of n-type LiYSi is 7.31 × 10¹¹Wm⁻¹ K⁻² s⁻¹ per relaxation time. The calculated power factor per relaxation time of p-type LiYSi is 1.44 × 10¹²Wm⁻¹ K⁻² s⁻¹.The power factor increases with increase in temperature. High n-type thermoelectric performance is produced by the interaction of low lattice thermal conductivity and excellent electrical transport characteristics. This suggests that at high temperatures, LiYSi is a potential n-type half-Heusler thermoelectric material. It is clear that the electronic structure has high valence band degeneracy, which contributes for good transport properties and results good thermoelectric material.

14. Encapsulation of Polyphenols from Murraya Koenigii by Using Two Different Polymer Matrices

    A. Noor, S. P. Khillar, S. Dasgupta, R. Basu

    Abstract

    Plant polyphenols are secondary metabolites that have recently gained attention for their several therapeutic properties. Nevertheless, they are unstable and hence prone to oxidation under light, heat, pH and low bioavailability once ingested which limits their applications. Effective encapsulation techniques have been implemented to overcome these drawbacks and mask the unpleasant flavor and odor also. Delivery systems with natural biopolymers have attracted attention for applications in food and pharmaceuticals. In this study, microspheres of Murraya koenigii polyphenols were synthesized through the extrusion method using two different polymer matrices, alginate and caseinate. The effect of encapsulation on their antioxidant activity and stability was studied for a six-month period. Further, they were evaluated for their size, stability, yield and surface morphology by using SEM and FTIR. In addition, the effects of different temperatures at different time intervals on the release of polyphenols were also studied. The results showed that the caseinate matrix was more effective in the encapsulation process of polyphenols at 80 °C at 7th h than the alginate matrix, and additionally, the polyphenols were maintained from degradation over a six-month period. In addition, the antioxidant property was retained better after encapsulation. Overall, the findings showed that the caseinate matrix was more effective than the alginate in improving the stability of polyphenols encapsulated from Murraya koenigii leaves and could be used as a potential technology for drug delivery techniques in the food industry/ nutraceuticals.

15. Study of Lattice Dynamics of the Graphene Along Highly Symmetry Directions

    Mohammad Imran Aziz, Quddus Khan

    Abstract

    Graphene is a two-dimensional material that has successfully been separated into single- or few-layer sheets from bulk graphite. The graphene structure has interesting features which is the good reason for studying its lattice vibrational properties. Graphene is one of the important areas of research due to its potential for integration into future-generation electronic devices. Graphene exhibits soft nature and hence could be easily integrated with current technology in electronic devices on substrates in comparison to stanene, silicene and germanene. We focus on the lattice dynamical of graphene and try to understand them from their honeycomb and buckled lattice structures. Lattice dynamical properties of single-layer two-dimensional honeycomb lattices exhibit interesting features. We, at present, find the phonon frequencies at Г points along symmetry directions with the help of Python program. The acoustical and optical contributions to the phonon frequencies are also discussed. We hope that phonon frequencies along Г‒M of graphene, 2D materials will have reasonably similar result obtained by other researchers.

16. The Effect of Sintering Temperature on the Photocatalytic Activity of Nickel Ferrite on Methylene Blue

    Anju Ganesh, Richu Rajan, Smitha Thankachan

    Abstract

    Nickel ferrite is synthesized by sol–gel autocombustion method with ethylene glycol as fuel. The thermal stability of the sample is studied using thermogravimetric analysis. The prepared ferrite sample is sintered at 500, 600 and 700 °C. The structure of the ferrite powder hence obtained is characterized by XRD and TEM. The grain size is found to increase with sintering temperature as expected. The photocatalytic degradation of methylene blue is studied using all the samples under sunlight and the degradation was studied using UV–Visible spectrophotometry.

17. Manipulating Superconductivity in Superconductor/Ferromagnet Hybrid Nanostructures

    Asif Majeed, Junaid Ul Ahsan, Harkirat Singh

    Abstract

    In this paper, we have simulated a hybrid structure consisting of a conventional BCS superconductor placed in proximity with a ferromagnet possessing intrinsic spin–orbit coupling (due to crystal mismatch at the interface) to study the effect of spin–orbit interaction on density of states near Fermi energy and the critical temperature. We report that the relationship between the in-plane and out-of-plane magnetic exchange fields (inside the ferromagnet) and the superconducting critical temperature reveals that a single homogenous ferromagnet possessing intrinsic spin–orbit coupling regulates the existence of triplets. We also report that inclusion of spin–orbit coupling in the hybrid structure manifests itself in the form of an energy gap in the density of states in the vicinity of Fermi energy which is attributed to the spin 1 triplets. Our research shows that spin–orbit coupling actively controls the triplets, which is a crucial step in new superconducting spintronic devices being made.

18. Studies on Solution-Processed Cu2ZnSnS4 Nanoparticles

    K. G. Deepa, Praveen C. Ramamurthy

    Abstract

    Cu₂ZnSnS₄ (CZTS) is identified to be a suitable candidate as an absorber layer for solar cells. In this work, CZTS nanoparticles are synthesized by wet-chemical method with non-toxic solvents and characterized for application in solar cells. The precursor concentrations are varied to achieve phase pure CZTS having a Cu-poor and Zn-rich composition, which is ideal for high-efficiency solar cells. Formation of tetragonal kesterite structured CZTS phase is confirmed from the X-ray diffraction analysis. Study also revealed the presence of shoulder peaks corresponding to Cu₂S phase in Cu-rich samples. Sample with Cu/Zn+Sn ratio of 0.85 having a band gap of 1.48 eV and particle size ~ 20 nm is opted for further studies. Minority carrier lifetime of this sample is estimated to be 6 ns from time-resolved photoluminescence measurement. The work function and valence band maximum of CZTS nanoparticle system are also estimated using UPS spectrum. The study demonstrates the suitability of CZTS nanoparticle in solar cells.