Browsing by Author "Mishra, Raghvendra Kumar"

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    A study of control mechanisms in micro and nano system-enhanced polymer nanocomposites under mechanical and electrical stimuli: an experimental and computational investigation
    (Cranfield University, 2023-11) Mishra, Raghvendra Kumar; Chianella, Iva; Yazdani Nezhad, Hamed; Goel, Saurav
    Nanocomposite materials, particularly those reinforced with graphene nanoplatelets (GNPs) and Barium Titanate (BaTiO₃), have been the focus of extensive study within diverse industries aiming to enhance mechanical and electrical properties. This thesis investigates the intricate relationship between external mechanical and electrical stimuli and the effectiveness of these reinforcing agents within nanocomposites, presenting significant findings and novel contributions, while addressing an unexplored aspect within the field. The research highlights a two-part exploration. The first part of the thesis details the creation of GNP/BaTiO₃ polymer nanocomposite fibrils via mechanical stimulation, specifically cold drawing, emphasising the compatibility of recycled polypropylene (PP)/polyethylene terephthalate (PET) blends. The resulting fibrils, exhibiting a significant aspect ratio disparity of 400:1, have demonstrated substantially improved electrical, thermomechanical, and electromagnetic properties. This in-situ mechanical stimulation (cold drawing) not only alters the morphology but also enhances electrical conductivity, limits polymer chain mobility, and reinforces the PP matrix, significantly improving its electrical, thermomechanical, and electromagnetic interference shielding. In the subsequent second part of the thesis, the study explored the integration of graphene-based materials and BaTiO₃ within epoxy composites. Computational modelling and statistical analysis have revealed the influence of these fillers on DC conductivity, dielectric properties, and thermal behaviour. In addition, a comprehensive examination of variations in filler thickness and volume percentage that seemed to significantly impact material’s behaviour has been investigated for the first time under electric fields. Specifically, the investigation into BaTiO₃ nanoparticles and Si-BaTiO3 in epoxy under electric fields has revealed the interplay between electrical stimuli, material properties, and mechanical behaviour, highlighting ferroelectric and piezoelectric effects observed in BaTiO₃ ceramics.i This comprehensive study not only contributes novel findings but also significantly fills a research gap within the field of nanocomposites by presenting an in-depth examination of mechanical and electrical responsiveness, a study that has not been previously undertaken in such a detailed and exhaustive manner. The research conducted, sheds light on the potential for advanced materials in diverse industrial applications and underscores the importance of material selection, offering a pioneering step towards potential industrial utilisation. Additionally, this research offers guidance for further computational exploration, particularly in selecting GNP and BaTiO₃ materials to enhance the electrical and thermal properties of the epoxy matrix
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    Black phosphorus: the rise of phosphorene in 2D materials applications
    (Elsevier, 2024-05-03) Mishra, Raghvendra Kumar; Sarkar, Jayati; Chianella, Iva; Goel, Saurav; Nezhad, Hamed Yazdani
    Few layers Black phosphorus (BP) and phosphorene are two-dimensional (2D) materials renowned for their adjustable bandgaps, high carrier mobility, and anisotropic conductivity, which make them highly promising for applications in the visible and infrared spectrum. The incorporation of these materials into polymer matrices has led to significant advancements in material science, resulting in nanocomposites with enhanced mechanical, electrical, and optical properties. This article provides a thorough analysis of BP/phosphorene polymer nanocomposites, including synthesis techniques (such as exfoliation methods) and manufacturing approaches. Advanced characterisation techniques are utilised to assess the structure, morphology, and properties of these composites. The article highlights the potential applications of these materials in energy storage (e.g., high-capacity batteries), flexible electronics (e.g., bendable displays), environmental sensing, and emerging biomedical fields such as targeted drug delivery. Furthermore, the article discusses potential solutions to tackle the challenges associated with the scalable, cost-effective production and ambient stability of BP/phosphorene, leveraging recent advancements in engineering research. The conclusion outlines future research directions, emphasising the importance of addressing persistent challenges through technological breakthroughs and exploring potential avenues for further advancement.
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    Borophene: a 2D wonder shaping the future of nanotechnology and materials science
    (Elsevier, 2024-05-10) Mishra, Raghvendra Kumar; Sarkar, Jayati; Verma, Kartikey; Chianella, Iva; Goel, Saurav; Nezhad, Hamed Yazdani
    Two-dimensional (2D) materials have attracted considerable research interest due to their precisely defined properties and versatile applications. In this realm, borophene - a single atomic sheet of boron atoms arranged in a honeycomb lattice - has emerged as a promising candidate. While borophenes were theoretically predicted to have unique structural, optical, and electronic properties, the experimental synthesis of crystalline borophene sheets was first demonstrated on metal substrates in 2015, marking a crucial milestone. Since then, research efforts have focused on controlling the synthesis of semiconducting borophene polymorphs and exploring their novel physical characteristics. This review aims to explore the potential of 2D materials, specifically borophene, in various technological fields such as batteries, supercapacitors, fuel cells, and more. The analysis emphasises meticulous scrutiny of synthesis techniques due to their fundamental importance in realising borophene's properties. Specifically, the high carrier mobilities, tuneable bandgaps, and exceptional thermal conductivity of borophene are highlighted. By providing a comprehensive outlook on the significance of borophene in advancing materials science and technologies, this review contributes to shaping the landscape of 2D material research.
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    Computational prediction of electrical and thermal properties of graphene and BaTiO3 reinforced epoxy nanocomposites
    (Eurasia Academic Publishing Group (EAPG), 2021-10-20) Mishra, Raghvendra Kumar; Goel, Saurav; Yazdani Nezhad, Hamed
    Graphene based materials e.g., graphene oxide (GO), reduced graphene oxide (RGO) and graphene nano platelets (GNP) as well as Barium titanate (BaTiO3) are emerging reinforcing agents which upon mixing with epoxy provides composite materials with superior mechanical, electrical and thermal properties as well as shielding against electromagnetic (EM) radiations. Inclusion of the thesereinforcing agents shows improvedperformance;however, the extent of improvement has remained uncertain. In this study, a computational modelling approach was adopted using COMSOL Multiphysics software in conjunction with Bayesian statistical analysis to investigate the effects of including various filler materials e.g.,GO, RGO, GNP and BaTiO3 in influencing the direct current (DC) conductivity (σ), dielectric constant (ε) and thermal properties on the resulting epoxy polymer matrix composites. The simulations were performed for different volume percentage of the filler materials by varying the geometry of the filler material. It was observed that the content of GO, RGO, GNPs and the thickness of graphene nanoplatelets can alter the DC conductivity, dielectric constant, and thermal properties of the epoxy matrix. The lower thickness of GNPs was found to offer the larger value of DC conductivity, thermal conductivity and thermal diffusivity than rest of the graphene nanocomposites, while the RGO showed better dielectric constant value than neat epoxy, and graphenenanocomposites. Similarly, the percentage content and size (diameter) of BaTiO3nanoparticles were observed to alter the dielectric constant, DC conductivity and thermal properties of modified epoxy by several order of magnitude than neat epoxy. In this way, the higher diameter particles of BaTiO3showed better DC conductivity properties, dielectric constant value, thermal conductivity and thermal diffusivity.
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    Development of reduced graphene oxide (rGO) reinforced poly(lactic) acid/ cellulose nanocrystal composite through melt mixing: Effect of nanofiller on thermal, structural, biodegradation and antibacterial properties
    (Elsevier, 2023-08-26) Verma, Kartikey; Siddiki, Salim H.; Maity, Chandan Kumar; Mishra, Raghvendra Kumar; Moniruzzaman, Md
    The intent of this research work was to synthesised a synthetic polymer that is biodegradable, bioresorbable, and biocompatible, while also exhibiting favorable thermal characteristics. The present study reports the successful fabrication of bionanocomposites by incorporating Cellulose nanocrystals (CNCs) and Reduced graphene oxide (rGO) into host matrix (PLA) using the melt-mixing technique. Various weight percentages (wt%) of rGO were employed in the process and various characterization techniques, including BET analysis, XRD, FTIR and field emission scanning electron microscopy (FE-SEM) were used to verify the efficient fabrication of a number of nanoformulations and nanofiller’s effect. Introduction of CNC and rGO in PLA matrix increases the surface area as well as porosity of the composites, established by BET analysis. DSC results indicate that the assimilation of rGO into the polymer matrix improved thermal stability of the composite material and leads to boost in the degree of crystallinity which was supported by XRD analysis. TGA results found no noticeable change in glass transition temperature (Tg) due to the addition of Nanofiller (rGO). The wettability analysis was done by contact angle measurement to determine the hydrophilicity of the composite and it is shown that with the increasing amount of rGO, hydrophilicity increases and contact angle reaches to 69° for 0.75 wt% of rGO in composite in comparision to 100° Neat PLA. The rGO/CNC/PLA nanocomposites exhibit a unique antibacterial effectiveness against both the S. aureus (Gram-positive) and E. coli (Gram-negative) bacterial strains. The highest antimicrobial activity was obtained in the nanocomposite tested against S. aureus. Biodegradation through Lysozyme in PBS solution shows promising result after incorporation of nanofillers. Hence, the nanocomposite manufactured through melt mixing process has promising uses in the biomedical and food packaging industries.
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    Exploring transformative and multifunctional potential of MXenes in 2D materials for next-generation technology
    (Elsevier, 2024-04-26) Mishra, Raghvendra Kumar; Sarkar, Jayati; Verma, Kartikey; Chianella, Iva; Goel, Saurav; Nezha, Hamed Yazdani
    MXenes, a rapidly growing family of two-dimensional (2D) transition metal carbides, nitrides, or carbonitrides (Mn+1XnTx, where M is a transition metal, X is carbon, nitrogen, or both, and T represents surface functional groups), have captured the scientific community's interest due to their exceptional physicochemical properties and diverse technological applications. This comprehensive review explores the latest breakthroughs in MXene synthesis and characterisation, emphasising their multifaceted applications in energy storage, catalysis, sensing, and other cutting-edge domains. This review examines the most widely used MXene synthesis strategies, including selective etching and delamination, and highlight recent advancements in controlling surface terminations, composition, and morphology. The influence of these synthetic parameters on MXene properties is discussed in detail. Characterisation techniques, ranging from spectroscopic methods to electron microscopy, are essential for elucidating MXenes' structure-property relationships. Research into energy storage leverages MXenes' high electrical conductivity, large surface area, and chemical tunability. This has led to significant progress in the field. This paper presents research efforts focused on optimising MXenes for both battery and supercapacitor applications. Additionally, the catalytic prowess of MXenes, particularly in electrocatalysis and photocatalysis, is explored, emphasising their role in green energy technologies and environmental remediation. MXenes' remarkable sensitivity and selectivity make them promising candidates for sensing various gases, biomolecules, and ions, offering exciting possibilities in healthcare and environmental monitoring. Importantly, this review underscores the need for continued optimisation of MXene synthesis protocols to achieve large-scale production, enhanced stability, and precise control over properties across various fields.
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    Low electric field induction in BaTiO3-epoxy nanocomposites
    (Springer, 2023-05-29) Mishra, Raghvendra Kumar; Li, Danning; Chianella, Iva; Goel, Saurav; Lotfian, Saeid; Yazdani Nezhad, Hamed
    Epoxy is widely used material, but epoxy has limitations in terms of brittleness in failure, and thus researchers explore toughening and strengthening options such as adding a second phase or using electromagnetic fields to tailor toughness and strength, on demand and nearly instantaneously. Such approach falls into the category of active toughening but has not been extensively investigated. In this research, Si-BaTiO3 nanoparticles were used to modify the electro-mechanical properties of a high-performance aerospace-grade epoxy so as to study its response to electric fields, specifically low field strengths. To promote uniform dispersion and distribution, the Si-BaTiO3 nanoparticles were functionalised with silane coupling agents and mixed in the epoxy Araldite LY1564 at different content loads (1, 5, 10 wt%), which was then associated with its curing agent Aradur 3487. Real-time measurements were conducted using Raman spectroscopy while applying electric fields to the nanocomposite specimens. The Raman data showed a consistent trend of increasing intensity and peak broadening under the increasing electric field strength and Si-BaTiO3 contents. This was attributed to the BaTiO3 particles’ dipolar displacement in the high-content nanocomposites (i.e., 5 wt% and 10 wt%). The study offers valuable insights on how electric field stimulation can actively enhance the mechanical properties in epoxy composites, specifically in relatively low fields and thin, high-aspect-ratio composite layers which would require in-situ mechanical testing equipped with electric field application, an ongoing investigation of the current research.
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    Nanomaterial integration in micro LED technology: enhancing efficiency and applications
    (Elsevier, 2024-03-27) Mishra, Raghvendra Kumar; Verma, Kartikey; Chianella, Iva; Goel, Saurav; Nezhad, Hamed Yazdani
    The micro-light emitting diode (µLED) technology is poised to revolutionise display applications through the introduction of nanomaterials and Group III-nitride nanostructures. This review charts state-of-the-art in this important area of micro-LEDs by highlighting their key roles, progress and concerns. The review encompasses details from various types of nanomaterials to the complexity of gallium nitride (GaN) and III nitride nanostructures. The necessity to integrate nanomaterials with III-nitride structures to create effective displays that could disrupt industries was emphasised in this review. Commercialisation challenges and the economic enhancement of micro-LED integration into display applications using monolithic integrated devices have also been discussed. Furthermore, different approaches in micro-LED development are discussed from top-down and bottom-up approaches. The last part of the review focuses on nanomaterials employed in the production of micro-LED displays. It also highlights the combination of III-V LEDs with silicon LCDs and perovskite-based micro-LED displays. There is evidence that efficiency and performance have improved significantly since the inception of the use of nanomaterials in manufacturing these.
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    Nanostructured ZnO-CQD hybrid heterostructure nanocomposites: synergistic engineering for sustainable design, functional properties, and high-performance applications
    (Wiley, 2024-05-03) Mishra, Raghvendra Kumar; Chianella, Iva; Sarkar, Jayati; Nezhad, Hamed Yazdani; Goel, Saurav
    Hybrid nanocomposites integrating nanostructured zinc oxide (ZnO) and carbon quantum dots (CQDs) with designed heterostructures possess exceptional optical and electronic properties. These properties hold immense potential for advancements across diverse scientific and technological fields. This review article investigates the synthesis, properties, and applications of ZnO-CQD heterostructure nanocomposites. Recent breakthroughs in fabrication methods are examined, including hydrothermal, microwave-assisted, and eco-friendly techniques. Key preparation methods such as sol-gel, co-precipitation, and electrochemical deposition are discussed, emphasizing their role in controlling heterostructure formation. This review analyses the impact of heterostructures on optical and electronic properties, such as fluorescence, photoluminescence, and photocatalytic activity. Synergistic interactions between ZnO and CQDs within heterostructures are highlighted, demonstrating how they lead to substantial performance improvements. Applications of ZnO-CQD heterostructures span solar cells, LEDs, photodetectors, water purification, antimicrobial treatments, gas sensing, catalysis, biomedical imaging, drug delivery, environmental sensing, and energy storage. Insights are provided into refining synthesis methods, enhancing characterisation techniques, and broadening the application landscape. Challenges like stability are addressed, along with strategies for optimised performance and practical implementation.
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    The role and significance of Magnesium in modern day research-A review
    (Elsevier, 2021-06-24) Satya Prasad, S. V.; Prasad, S. B.; Verma, Kartikey; Mishra, Raghvendra Kumar; Kumar, Vikas; Singh, Subhash
    Magnesium is one of the largely available elements in the earth's crust. It has a low structural density with high specific strength. This unique material property has forced an increase in the use of magnesium and its alloys in various applications pertaining to industrial sector, automobiles, aerospace and biomedical. Since magnesium is a highly reactive metal, it is prone to higher rate of corrosion as compared to its counterparts. Thus, it is essential to analyze the corrosion behavior of magnesium and its alloys in its applications. An appropriate process is to be followed in the design and development of magnesium alloys which overcome the limitations of magnesium and enhance the desired material properties in accordance to their applications. This review paper summarizes the importance of magnesium and its material properties. The influence of various alloying elements on the mechanical properties of magnesium is reviewed. The broad classification of Mg alloys and their behavioral trends are detailed. The corrosion behavior of magnesium and the influence of corrosion products on the material characteristics of magnesium, in aqueous medium, are discussed. The manufacturing techniques of magnesium alloys along with the secondary techniques are also covered. The various applications and the limitations of magnesium in these applications are covered. A complete section is dedicated towards detailing the recent trends of magnesium (Mg) alloys, i.e., the biodegradable nature and applications of Mg alloys. The influence of biocorrosion on Mg alloys and techniques to overcome it have been deliberated. This paper provides a thorough review on recent developments of magnesium with respect to engineering applications.