Solid State Physics Laboratory

The chapter presents a comprehensive overview of MEMS (microelectromechanical system)-based sensors addressing a critical gap in the existing literature. By delving into their key features, working principles, and diverse applications, we provide a valuable resource for researchers, engineers, and industry professionals. Our exploration encompasses many MEMS sensors, including pressure, accelerometers, gyroscopes, bolometers, magnetic, humidity, flow, optical, biosensors, and microphones. We emphasize the distinctive characteristics of MEMS sensors to provide a comprehensive overview of the MEMS landscape. Additionally, we address the previously unexplored role of MEMS in quantum technology. This chapter sheds light on the contributions of MEMS to the development of quantum sensors demonstrating their potential to revolutionize various fields such as quantum computing, communication, and sensing. We begin by tracing the origins of MEMS sensors to biological inspiration highlighting how the remarkable sensing capabilities of organisms, like the “Touch-Me-Not” plant, have influenced the development of these miniature devices. Next, we delve into the fundamentals of MEMS technology, including fabrication techniques, materials, and design principles. MEMS sensors stand out due to their remarkable combination of miniaturization, energy efficiency, and sensitivity. The chapter delves into the wide-ranging applications of MEMS sensors extending beyond traditional sectors. A table of the consolidated list of sensors, including their functions and basic structural requirements, is also provided. Finally, we discuss the future of MEMS technology in the emerging field of quantum, which combines the principles of quantum mechanics with MEMS technology to create novel devices with unprecedented capabilities. In conclusion, this chapter comprehensively explores MEMS sensors encompassing their historical development, present-day applications, and future prospects. We anticipate that MEMS technology will continue to be a driving force in the evolution of sensing capabilities fostering innovation across diverse industries.

Maintaining nanoparticles (NPs) with identical catalytic properties is important for synthesizing single-walled carbon nanotubes with specific chiralities. The key to preparing NPs with consistent atomic stacking structures lies in preserving nucleation intermediates with uniform configurations and sizes. In this work, the physical mechanism underlying the improvement of structural similarity among intermediates is explored by investigating the structural transformation of M (M = Fe, Co, and Ni) NPs during the nucleation stage. The results show that the distance traversed by intermediates on the potential energy surface (i.e., the energetic displacement) not only determines the size distribution of intermediates but also influences their structural similarity. Furthermore, this distance can be tuned by adjusting the atomic feeding rate; hence, the size and atomic stacking structure of intermediates can be controlled. This work provides insight into achieving NPs with identical catalytic properties by modifying experimental parameters to tune atomic diffusion rates.

Abstract Genomic RNA (gRNA) dimerization is essential for retroviral replication. In the gRNA of human immunodeficiency virus (HIV-1), the hairpin-like dimerization initiation sequence (DIS) forms a kissing-complex (KC) with the DIS sequence in another gRNA, which later converts into a stable extended-duplex (ED). Using coarse-grained simulations, we mapped the transition of HIV-1 DIS RNA hairpins (HPs) to ED and identified multiple intermediates beyond the KC. The KC has an anionic pocket stabilized through the condensation of Mg 2+ ions. Hence, when only K + ions are present at physiological levels, the HPs to ED transitions occur through a different dominant pathway devoid of the KC. We also observed purine base flipping near KC hydrogen bonds, revealing the population of a sub-ensemble of intermediates. The proposed dimerization mechanism of HPs to ED, along with the sub-ensemble of KC conformations and its anionic pocket, provides a strategic framework for designing specific retroviral drugs targeting this pathway. For Table of Contents Use Only

This study investigates the electronic structure and local coordination environment of Fe-doped graphitic ZnO (gZnO) through X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analysis at the Fe and Zn K-edges. XANES spectra of the samples were recorded for Fe doping concentrations of 2, 4, and 6%, along with that of the Fe2O3 standard sample. Key spectral features, such as the pre-edge and absorption edge, indicate that Fe ions predominantly adopt a +3 oxidation state within the ZnO matrix. Polarization-dependent XANES measurements reveal distinct in-plane and out-of-plane electronic environments, particularly pronounced in the 2% Fe-doped sample. The XANES simulations, assuming a model of stacked graphitic ZnO monolayers with Fe substitutions, closely match with the experimental data, validating the layered structural model. Fourier transform EXAFS spectra indicate preferential orientation of the gZnO layers in-plane of the substrate. The magnetic measurements indicate room-temperature ferromagnetism, highlighting its potential applications. These findings offer comprehensive insights into the structural and electronic properties, along with the possible applications of Fe-doped ZnO. This has significant implications for the development of ZnO-based two-dimensional (2D) materials in advanced technological applications.

This study explores the potential of phenolated lignin as a precursor for synthesizing graphene-like carbon materials through laser-induced carbonization (LIC). Key parameters─including formulation, laser speed, laser power, and lignin loading─were optimized to enhance the quality of the resulting LIC materials. Under optimized conditions, this method produced a high-quality, few-layer graphene-like carbon material. Comprehensive materials characterization (XPS, XRD, TGA, Raman spectroscopy, sheet resistivity, and elemental analysis) revealed that the material’s conductivity is driven by the formation of an sp2-hybridized conjugated carbon system and the reduction of both sp3-hybridized carbon and oxygen groups. The introduction of phenolic groups into the lignin structure enhanced its thermostability and conversion efficiency to graphene-like carbon, achieving a low sheet resistance of 6.7 Ω·sq–1. This study demonstrates that phenolated lignin is a promising precursor for the synthesis of conductive graphene-like carbon materials with excellent electronic properties, making it suitable for micro-supercapacitor applications. Furthermore, the resulting printed device exhibited a specific capacitance of 454 mF cm–3 (1.4 mF cm–2) at a scan rate of 5 mV s–1 in cyclic voltammetry (CV) mode and 286 mF cm–3 (0.86 mF cm–2) at a current density of 0.05 mA cm–2 in galvanostatic charge–discharge (GCD) mode.

A quaternary solid state solution with MPB composition, [0.47(Bi0.5Na0.5)TiO3-0.04BaTiO3-0.31Pb(Mg1/3Nb2/3)O3-0.18PbTiO3] has been synthesized using solid state reaction method by incorporating BNT-BT relaxor into the PMN-PT ferroelectric material to explore the combined advantages of relaxor and high Curie temperature ferroelectric material. This combination also eliminates the pyrochlore phase and reduces the lead content. The dielectric measurements were performed at temperatures 30° C to 300° C, in 200 Hz – 2 MHz frequency range. The material was found to have two overlapping Debye type relaxations in its dielectric behaviour. The corresponding two Debye peaks noticed in dielectric loss as function of frequency show a clear shift towards higher frequencies with increasing temperature of measurement.

A ZnTe crystal is a highly promising electro‐optical single crystal for terahertz (THz) generation and detection. However, achieving large‐sized, high‐quality ZnTe crystals for such applications still remains a major challenge owing to incorporation of the tellurium (Te) secondary phase and defect generation during crystal growth, affecting the THz characteristics of ZnTe. Hence, precise growth control along with a comprehensive assessment of optical quality is imperative to develop ZnTe crystals for such advanced applications. This article presents a detailed assessment of optical and THz characteristics of ZnTe crystals grown by the temperature gradient solvent method at two different growth rates of 1 mm hr−1 and 0.4 mm hr−1. The assessment of Te precipitates in grown ZnTe crystals shows a drastic reduction in Te precipitates in ZnTe crystals grown at 0.4 mm hr−1. This is ascertained by a detailed optical assessment through spectroscopic studies using Fourier transform infrared spectroscopy, showing a high infrared transmittance of ≈60%, Raman spectra, showing high optical and crystalline quality, and photoluminescence, showing lower defect luminescence. This has culminated in the enhancement of THz generation and detection characteristics of ZnTe crystals, underlining the potential of this study in enrooting the issues in ZnTe crystal growth for high‐end THz applications.