@article{khosla_narayan_narayan_2023, title={Laser-assisted formation of 3c-SiC and continuous diamond growth using Si-Q carbon on (100) silicon}, volume={12}, ISSN={["2044-5326"]}, DOI={10.1557/s43578-023-01264-7}, abstractNote={The formation of 3c-SiC is of interest due to potential applications in the semiconductor industry; however, there are difficulties in obtaining 3c-SiC by conventional methods. Being a metastable phase, non-equilibrium growth conditions are favorable in the growth process. This paper reports the formation of nano-sized 3c-SiC by nanosecond laser annealing of Si–Q-carbon layers on the silicon (100), which is confirmed by its characteristic LO and TO peaks in the Raman spectra. We also show that the traditional HFCVD technique results in the 6H-polytype instead, as confirmed by SEM, Raman spectroscopy, and EBSD. Further, we investigate the role of these phases on the nucleation of heteroepitaxial diamond on a Si (100) substrate. We show that these phases as interlayers enhance the diamond growth significantly. The HRSTEM studies were performed to understand the interfacial structure and phase responsible for high diamond nucleation. These findings are significant for 3c-SiC and diamond electronics applications. Graphical abstract}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Khosla, Nayna and Narayan, Jagdish and Narayan, Roger}, year={2023}, month={Dec} }
 @article{khosla_narayan_narayan_sun_paranthaman_2023, title={Microstructure and defect engineering of graphite anodes by pulsed laser annealing for enhanced performance of lithium-ion batteries}, volume={205}, ISSN={["1873-3891"]}, url={https://doi.org/10.1016/j.carbon.2023.01.009}, DOI={10.1016/j.carbon.2023.01.009}, abstractNote={Nanosecond pulsed laser annealing significantly improves cyclability and current carrying capacity of lithium-ion batteries (LIBs). This improvement is achieved by engineering of microstructure and defect contents present in graphite in a controlled way by using pulsed laser annealing (PLA) to increase the number density of Li+ ion trapping sites. The PLA treatment causes the following changes: (1) creates surface steps and grooves between the grains to improve Li+ ion charging and intercalation rates; (2) removes inactive polyvinylidene difluoride (PVDF) binder from the top of graphite grains and between the grains which otherwise tends to block the Li+ migration; and (3) produces carbon vacancies in (0001) planes which can provide Li+ charging sites. From X-ray diffraction data, we find upshift in diffraction peak or reduction in planar spacing, from which vacancy concentration was estimated to be about 1.0%, which is higher than the thermodynamic equilibrium concentration of vacancies. The laser treatment creates single and multiple C vacancies which provide sites for Li+ ions, and it also produces steps and grooves for Li+ ions to enter the intercalating sites. It is envisaged that the formation of these sites enhances Li+ ion absorption during charge and discharge cycles. The current capacity increases from an average 360 mAh/g to 430 mAh/g, and C–V shows significant reduction in SEI layer formation after the laser treatment. If the vacancy concentration is too high and charge-discharge cycles are long, then trapping of electrons by Li+ may occur, which can lead to Li0 formation and Li plating causing reduction in current capacity.}, journal={CARBON}, author={Khosla, Nayna and Narayan, Jagdish and Narayan, Roger and Sun, Xiao-Guang and Paranthaman, Mariappan Parans}, year={2023}, month={Mar}, pages={214–225} }
 @article{khosla_narayan_narayan_sun_paranthaman_2023, title={Nanosecond Laser Annealing of NMC 811 Cathodes for Enhanced Performance}, volume={170}, ISSN={["1945-7111"]}, url={https://doi.org/10.1149/1945-7111/acc27d}, DOI={10.1149/1945-7111/acc27d}, abstractNote={Improved performance of lithium-ion batteries (LIBs) plays a critical role in the future of next- generation battery applications. Nickel-rich layered oxides such as LiNi0.8Mn0.1Co0.1O2 (NMC 811), are popular cathodes due to their high energy densities. However, they suffer from high surface reactivity, which results in the formation of Li2CO3 passive layer. Herein, we show the role of nanosecond pulsed laser annealing (PLA) in improving the current capacity and cycling stability of LIBs by reducing the carbonate layer, in addition to forming a protective LiF layer and manipulating the NMC 811 microstructures. We use high-power nanosecond laser pulses in a controlled way to create nanostructured surface topography which has a positive impact on the capacity retention and current capacity by providing an increased active surface area, which influences the diffusion kinetics of lithium-ions in the electrode materials during the battery cycling process. Advanced characterizations show that the PLA treatment results in the thinning of the passive Li2CO3 layer, which is formed on as-received NMC811 samples, along with the decomposition of excess polyvinylidene fluoride (PVDF) binder. The high-power laser interacts with the decomposed binder and surface Li+ to form LiF phase, which acts as a protective layer to prevent surface reactive sites from initiating parasitic reactions. As a result, the laser treated cathodes show relative increase of the current capacity of up to 50%, which is consistent with electrochemical measurements of LiB cells.}, number={3}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Khosla, Nayna and Narayan, Jagdish and Narayan, Roger and Sun, Xiao-Guang and Paranthaman, M. Parans}, year={2023}, month={Mar} }
 @article{joshi_shukla_khosla_vanderwal_stafslien_narayan_narayan_2023, title={Q-Carbon as an Emergent Surface Coating Material for Antimicrobial Applications}, url={http://dx.doi.org/10.2139/ssrn.4467042}, DOI={10.2139/ssrn.4467042}, abstractNote={Q-carbon is a newly discovered allotrope of carbon that exhibits unique functional properties and robust mechanical strength. We propose that the surface of the Q-carbon can be functionalized by doping it with silicon to enhance its performance as a potential implant material. As such, a coating of silicon-doped Q-carbon (Si-Q-carbon) is shown to minimize the formation of biofilm, thus reducing the risk of microbial infection. Here in, we report the formation of Si-Q-carbon coatings of varied thicknesses (10 nm and 20 nm) through the plasma-enhanced chemical vapor deposition (PECVD) technique. The surface composition and the bonding characteristics of the thin films were evaluated by Raman and XPS analysis and showed that the thinnest sample (10 nm) has high sp3 content with an ID/IG ratio of 0.11. Furthermore, wettability and surface energy calculations were undertaken to investigate the surface characteristics of the coatings. The 10 nm sample was found to be more hydrophilic with a water contact angle of 75.3 ± 0.64°. The antibacterial activity of Si-Q-carbon coatings was investigated using a Staphylococcus epidermidis agar plating technique and the adhesion of bacteria was explained in terms of the surface properties of the thin films. We demonstrate that the Si-Q-carbon coating with the highest sp3 content is hydrophilic and showed a 57% reduction in adhered biofilm relative to a glass control. We envisage the potential application of Q-carbon in arthroplasty devices with enhanced mechanical strength and resistance to periprosthetic joint infections (PJIs).}, journal={SSRN}, publisher={Elsevier BV}, author={Joshi, Naveen Narasimhachar and Shukla, Shubhangi and Khosla, Nayna and Vanderwal, Lyndsi and Stafslien, Shane and Narayan, J. and Narayan, Roger}, year={2023} }
 @article{khosla_narayan_2022, title={Fabrication of Q-Carbon Nanostructures, Diamond and Their Composites with Wafer-Scale Integration}, volume={12}, ISSN={["2073-4352"]}, url={https://www.mdpi.com/2073-4352/12/5/615}, DOI={10.3390/cryst12050615}, abstractNote={We report the formation of Q-carbon nanolayers, Q-carbon nanoballs, nanodiamonds, microdiamonds, and their composites by controlling laser and substrate variables. The choice of these parameters is guided by the SLIM (simulation of laser interactions with materials) computer modeling. For a constant film thickness and initial sp3 content, we obtain different microstructures with increasing pulse energy density as a result of different quenching rate and undercooling. This is related to decreasing undercooling with increasing pulse energy density. The structure of thin film Q-carbon evolves into Q-carbon nanoballs with the increase in laser annealing energy density. These Q-carbon nanoballs interestingly self-organize in the form of rings with embedded nanodiamonds to form Q-carbon nanoballs/diamond composites. We form high quality, epitaxial nano, and micro diamond films at a higher energy density and discuss a model showing undercooling and quenching rate generating a pressure pulse, which may play a critical role in a direct conversion of amorphous carbon into Q-carbon or diamond or their composites. This ability to selectively tune between diamond or Q-carbon or their composites on a single substrate is highly desirable for a variety of applications ranging from protective coatings to nanosensing and field emission to targeted drug delivery. Furthermore, Q-carbon nanoballs and nanodiamonds are utilized as seeds to grow microdiamond films by HFCVD. It is observed that the Q-carbon nanoballs contain diamond nuclei of critical size, which provide available nucleation sites for diamond growth, leading to stress-free, adherent, and denser films, which are needed for a variety of coating applications.}, number={5}, journal={CRYSTALS}, publisher={MDPI AG}, author={Khosla, Nayna and Narayan, Jagdish}, year={2022}, month={May} }
 @article{riley_joshi_khosla_narayan_narayan_2022, title={Formation of Q-Carbon with Wafer Scale Integration}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85128322488&partnerID=MN8TOARS}, journal={SSRN}, author={Riley, P.R. and Joshi, P. and Khosla, N. and Narayan, J. and Narayan, R.J.}, year={2022} }
 @article{riley_joshi_khosla_narayan_narayan_2022, title={Formation of Q-carbon with wafer scale integration}, volume={196}, ISSN={["1873-3891"]}, url={https://doi.org/10.1016/j.carbon.2022.06.003}, DOI={10.1016/j.carbon.2022.06.003}, abstractNote={We describe the formation of highly uniform Quenched-carbon (Q-carbon) layers by plasma-enhanced chemical vapor deposition (PECVD) followed by low-energy Ar+ ion bombardment to achieve wafer-scale integration of Q-carbon films. After PECVD, 9 nm and 20 nm thick silicon-doped diamond-like carbon (Si-DLC) films showed complete conversion into Q-carbon using 250eV Ar+ ions via negative biasing. However, this conversion was only partial for 30 nm thick films. Detailed EELS, XPS, Raman, and EDS studies were carried out to confirm the formation of Q-carbon by this method. We discuss the mechanism of Q-carbon formation as a result of low-energy ion bombardment during PECVD of thin films. These ions during negative biasing are energetic enough to create Frenkel defects, which support the conversion of the three-fold coordinated sp2 carbon units in as-deposited carbon into sp3 bonded five-atom tetrahedron units in Q-carbon. This process enhances the atomic number density and fraction of sp3 bonded carbon. These diamond tetrahedra are randomly packed and provide easy nucleation sites for diamond. If the underlying substrate can provide an epitaxial template for diamond growth via domain matching epitaxy, then wafer-scale growth of diamond epitaxial films can be achieved for wafer-scale integration and next-generation novel device manufacturing from diamond-related materials.}, journal={CARBON}, author={Riley, Parand R. and Joshi, Pratik and Khosla, Nayna and Narayan, Roger J. and Narayan, Jagdish}, year={2022}, month={Aug}, pages={972–978} }
 @article{cui_khosla_lai_narayan_manthiram_2022, title={Laser-Assisted Surface Lithium Fluoride Decoration of a Cobalt-Free High-Voltage Spinel LiNi0.5Mn1.5O4 Cathode for Long-Life Lithium- Ion Batteries}, volume={12}, ISSN={["1944-8252"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85145292920&partnerID=MN8TOARS}, DOI={10.1021/acsami.2c18918}, abstractNote={High-voltage spinel LiNi0.5Mn1.5O4 (LNMO) is a promising next-generation cathode material due to its structural stability, high operation voltage, and low cost. However, the cycle life of LNMO cells is compromised by detrimental electrode-electrolyte reactions, chemical crossover, and rapid anode degradation. Here, we demonstrate that the cycling stability of LNMO can be effectively enhanced by a high-energy laser treatment. Advanced characterizations unveil that the laser treatment induces partial decomposition of the polyvinylidene fluoride binder and formation of a surface LiF phase, which mitigates electrode-electrolyte side reactions and reduces the generation of dissolved transition-metal ions and acidic crossover species. As a result, the solid electrolyte interphase of the graphite counter electrode is thin and is composed of fewer electrolyte decomposition products. This work demonstrates the potential of laser treatment in tuning the surface chemistry of cathode materials for lithium-ion batteries.}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Cui, Zehao and Khosla, Nayna and Lai, Tianxing and Narayan, Jagdish and Manthiram, Arumugam}, year={2022}, month={Dec} }
 @article{joshi_riley_denning_shukla_khosla_narayan_narayan_2022, title={Laser-patterned carbon coatings on flexible and optically transparent plastic substrates for advanced biomedical sensing and implant applications}, volume={10}, ISSN={["2050-7534"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85125716163&partnerID=MN8TOARS}, DOI={10.1039/d1tc05176h}, abstractNote={Plasma and laser-based processing for tailoring DLC thin film properties for state-of-the-art wearable sensing applications.}, number={8}, journal={JOURNAL OF MATERIALS CHEMISTRY C}, publisher={Royal Society of Chemistry (RSC)}, author={Joshi, Pratik and Riley, Parand R. and Denning, Warren and Shukla, Shubhangi and Khosla, Nayna and Narayan, Jagdish and Narayan, Roger}, year={2022}, month={Jan} }
 @article{khosla_narayan_narayan_sun_paranthama_2022, title={Microstructure and Defect Engineering of Graphite Anodes by Pulsed Laser Annealing for Enhanced Performance of Lithium-Ion Batteries}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85136200712&partnerID=MN8TOARS}, journal={SSRN}, author={Khosla, N. and Narayan, J. and Narayan, R. and Sun, X.-G. and Paranthama, M.P.}, year={2022} }
 @article{narayan_khosla_2022, title={Self-organization of amorphous Q-carbon and Q-BN nanoballs}, volume={192}, ISSN={["1873-3891"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85125815590&partnerID=MN8TOARS}, DOI={10.1016/j.carbon.2022.03.003}, abstractNote={This paper reports for the first time the formation and self-organization of amorphous Q-carbon and Q-BN nanoballs. This is accomplished by nanosecond laser melting of carbon and BN layers, respectively, in a highly undercooled state and subsequent rapid cooling at normal pressures in air. The size of these Q-carbon and Q-BN nanoballs having a uniform size can be varied from 5 to 100 nm, and self-organized along rings and strings by manipulating laser, carbon film, and substrate parameters. It is envisaged that self-organization is promoted by the undercooling and it occurs along strings and rings, which are formed by the tetrahedral alignment in <100> and <110> directions, respectively. These nanoballs were characterized by HRSEM/TEM/STEM/EELS and Raman to confirm the phase purity and bonding characteristics. The Q-carbon balls exhibit robust ferromagnetism and field emission in pure and undoped form and show highest BCS superconducting transition temperature upon doping with boron. The ferromagnetism in Q-carbon balls can be varied with size and achieve higher coercively than thin films, and these balls can be coated with drugs for targeted delivery. In view of these properties, nanoballs are expected to find novel applications ranging from targeted delivery to nanosensing and superconducting qubits.}, journal={CARBON}, author={Narayan, J. and Khosla, N.}, year={2022}, month={Jun}, pages={301–307} }
 @article{gupta_khosla_govindasamy_saini_annapurna_dhakate_2020, title={Trimetallic composite nanofibers for antibacterial and photocatalytic dye degradation of mixed dye water}, volume={10}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85089866193&partnerID=MN8TOARS}, DOI={10.1007/s13204-020-01540-6}, abstractNote={Membrane technology is an advanced approach to making a healthier and cleaner environment. Using such catalytic membrane technology to get clean, usable water by removal of dye impurities as well as pathogenic microbes is the main goal behind the research work. Here, we present the synthesis and efficacy study of polymethyl methacrylate (PMMA)-based Ag/ZnO/TiO2 trimetallic bifunctional nanofibers with antibacterial and photocatalytic activity. The nanofibers have been proven to be effective for the degradation of methylene blue (MB 93.4%), rhodamine B (Rh 34.6%), auramine-O (Au 65.0%) and fuchsin basic (FB 69.8%) dyes individually within 90 min in daylight. The study is further extended in abating a mixture of these dyes from contaminated water using composite nanofibers. Also, in the case of a mixture of these dyes (3 ppm each), nanofibers show dye degradation efficiency (DDE) of 90.9% (MB), 62.4% (Au) and 90.3% (FB and Rh) in 60 min. The role of Ag nanoparticles with a synergic photocatalytic effect on ZnO and TiO2 is also demonstrated. Also, PMMA/ZnO/TiO2 composite fiber membrane in synergy with silver particles shows better antibacterial activity against Gram-negative bacteria E. coli, making PMMA/Ag/ZnO/TiO2 fibers a promising candidate in water purification.}, number={11}, journal={Applied Nanoscience (Switzerland)}, author={Gupta, A. and Khosla, N. and Govindasamy, V. and Saini, A. and Annapurna, K. and Dhakate, S.R.}, year={2020}, pages={4191–4205} }