The presence of magnetic impurities in topological insulators can disrupt their time reversal symmetry and lead to the emergence of an energy gap. This study delves into the energy band structure and the Kondo effect through the introduction of Gadolinium (Gd) magnetic perturbations (at levels of x=0.1,0.16) into a pure Bi2Se3 single crystal. In the case of the Bi1.9Gd0.1Se3 (5%) single crystal, the Kondo effect becomes observable at temperatures below 50 K. However, the unaltered parent and Bi1.84Gd0.16Se3 (8%) exhibit typical metallic behavior. The pure sample displays the highest magnetoresistance (MR) of around 225% and demonstrates quantum oscillations driven by a nontrivial berry phase. The sample doped with 5% Gd undergoes a transition from negative MR to positive MR due to a presence of mixed magnetic state resulting from the opening of a gap at the Dirac point. This gap opening is confirmed through angle-resolved photoemission spectroscopy (ARPES) measurements. The comparison of the parameters obtained from the SdH and ARPES measurements, the reduction in the kF values in the magnetotransport measurements is likely due to the band bending induced by the Schottky barrier. Thermoelectric properties are assessed across all prepared samples. The undoped sample displays the highest Seebeck coefficient and power factor values of -398.02 mu V K-1 and 6.83mWmK-2, respectively, at room temperature. These values are notably high for thermoelectric applications at room temperature.

Occupied and unoccupied electronic states of altermagnetic MnTe(0001) single crystals were studied by photoemission and inverse-photoemission spectroscopies after establishing a reproducible surface cleaning procedure involving repeated sputtering and annealing cycles. The angle-resolved photoemission spectroscopy (ARPES) exhibited a hole-like band dispersion centered at the Γ¯ point, which was consistent with the reported ARPES results and our density functional theory (DFT) calculations with the on-site Coulomb interaction U. The observed Mn 3d↑-derived peak at −3.5 eV, however, significantly deviated from the DFT + U calculations. Meanwhile, the Mn 3d↓-derived peak at +3.0 eV observed by inverse-photoemission spectroscopy agreed well with the DFT + U results. Based on simulations of the spectral function employing an w-dependent model self-energy, we found significant relaxation effects in the electron-removal process, while such effects were negligible in the electron-addition process. Our study provides a comprehensive picture of electronic states, forming a solid foundation for understanding the magnetic and transport properties of MnTe.

Complex oxides offer distinct advantages for immobilizing radioactive waste. Here, we delve into the deviations in the structure of Gd2Zr2O7 (GZO) ceramics against the irradiation of iodine ions having 100 MeV energy. X-ray diffraction (XRD) and Raman spectroscopy have been exercised to observe the structural changes. XRD analysis reveals that with increasing ion fluence, the suppression or disappearance of superstructure reflections occurs, indicating a pyrochlore to defect fluorite structure transformation. Raman spectra further confirm the change in vibrational mode in GZO, which strongly rely degree of disorder as fluence is enhanced. XRD and Raman techniques provide consistent insights into the structural changes induced by swift heavy ion irradiation (100 MeV I7+). Notably, no amorphization has been observed, highlighting the robustness of Gd2Zr2O7 ceramics for potential nuclear applications in extreme environments.

The urgent need to replace fossil fuels with renewable energy sources in the twenty-first century has been driven by rising fuel prices and the escalating greenhouse effect caused by carbon dioxide emissions. Recent advancements in photovoltaic (PV) solar cell technology offer hope for meeting this demand using sustainable energy sources. Significant advancements have been achieved in the field, indicating numerous possibilities to address the ongoing global energy crisis. Carbon nanomaterials, including graphene, carbon nanotubes, and fullerene, have emerged as splendid applicants for photovoltaic solar cells. These materials are abundant on Earth, possess remarkable electrical properties, exhibit eminent optical absorption, and demonstrate paramount thermal and photostability. Graphene-based solar cells have already achieved notable breakthroughs in PV technology. However, reducing manufacturing costs through the utilization of cost-effective nanostructured materials and processes remains a crucial concern. This chapter provides a comprehensive review of various types of PV technologies using carbon-based materials.

Humidity sensors are critical in a wide range of applications ranging from automotive, biomedical, chemical, and electronics industries, to scientific research laboratories. Here we discussed widely acclaimed synthesis techniques for the preparation of graphene and its derivatives. Graphene, along with its analogues GO, and rGO shows improved surface properties making it sensitive to fractional change in ambient surroundings. GO/rGO-based sensory materials owing to their distinctive physio-chemical features appeared as a competitive sensor in comparison to the widely used metal oxides. The enhancement in the merits of GO-based humidity sensors is ascribed to the various functionalized groups on the GO surface. Pristine GO is employed as a capacitive sensor, whereas reduced GO (rGO) with improved conductivity is extensively utilized as a chemiresistive humidity sensor. Similarly, Graphene quantum dots (GQDs) and 2D- layered graphene have been explored as humidity sensors due to their massive scope of manipulation in properties. The chemiresistive humidity sensor gains an advantage over any type of available sensor owing to its cost-effective fabrication, easier integration with the CMOS platform, and efficient operation. This review aims to establish the evaluability of GO and rGO humidity sensors and their role in the progress of the next generation of flexible sensors for the Internet of Things (IoT).

The exceptional performance of nanomaterials, as a result of their size and unique morphology, has attracted a lot of researchers. The structure and constituents of materials have been modified using a variety of techniques. The ion beam techniques have so far been widely employed to modify the performance of different nanomaterials. The surface configuration and chemical composition of nanomaterials can be altered by energetic ion beams. The ion beam techniques approach is purely physical in comparison to conventional methods. These techniques exhibit outstanding control and reproducibility without adding any impurities to the target materials. Here, current developments in surface modification of nanomaterials employing ion beam methods are thoroughly reviewed.

The cobalt ferrite nanoparticles were synthesized using cobalt nitrate and ferric nitrate as precursor materials by combustion method using sucrose as a fuel. The cobalt ferrite nanoparticle materials were analyzed through field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) spectroscopy. FESEM and XRD techniques reveal that the cobalt ferrite particles are in the crystallite nano range, with their size ranging from 10 to 14 nm. The cobalt ferrite nanoparticle materials have been thermally analyzed by Mettler Toledo and thermogravimetric analysis/differential scanning calorimetry 3+ model; the nanoparticles were found thermally stable at 450°C temperature. Galvanstate 101 (the Netherlands) with three-electrodes system and AUTOLAB potentiostats were used to test electrochemical properties during the synthesis of cobalt ferrite nanoparticle materials; the oxidation and reduction potentials were found to be 384 mV and 186 mV, respectively. Oxidation and reduction currents were found at 35.9 μA and −25.5 μA, respectively. The electrode was made from cobalt ferrite nanoparticles for application, and their properties were excellent.

Complex oxides with pyrochlore and fluorite phases offer several advantages for the Immobilization of actinides or high-level radioactive wastes. In this report, we present the different behavior of structural ordering/crys-tallinity of Gd2Zr2O7 (GZO) ceramics upon sintering at two different temperatures (1400 degrees C-1500 degrees C). XRD and Raman spectroscopy studies revealed the enhancement of structural ordering/crystallinity with the increase of sintering temperature. Further, the ion irradiation experiments using 100 MeV iodine at the fluence of 1.0 x 1014 ions/cm2 were performed to investigate the radiation effects on both GZO ceramics. The irradiation studies insinuate that the GZO ceramic sintered at 1500 degrees C possesses relatively better radiation resistance than GZO ceramic sintered at 1400 degrees C. The variation in the radiation resistance response of GZO ceramics seems associated with the different degrees of structural ordering. These results suggest the role of structural ordering in the radiation resistance response of GZO ceramics. The relatively better radiation tolerance of GZO15 ceramic with some extant pyrochlore phase ordering may be suitable for applications in harsh environments.

Isometric pyrochlore oxides (A 2 B 2 O 7 ) offer a wide range of applications, including electrolytes, sensors, the immobilization of radioactive nuclides, and so on because of their extraordinary structural and physical properties. In the present study, neutron irradiation experiments were used to investigate the irradiation-induced defects in a complex oxide, La 2 Zr 2 O 7 . The grazing incident X-ray diffraction (GI-XRD) and Raman spectroscopy have been used to examine the defects in La 2 Zr 2 O 7 pyrochlore. To obtain more information about the defects in the La 2 Zr 2 O 7 system, positron annihilation spectroscopy was performed. GI-XRD study exhibits the significant amorphization processes and lattice contraction in La 2 Zr 2 O 7 .

Semiconducting materials with a distinctive blend of high electrical and low thermal conductivity are required for efficient thermoelectric devices. In this aspect, Heusler alloys are potential candidates for thermoelectric materials. It has been observed that Co doping in Mn2FeAl enhances the electrical conductivity as well as reduces the thermal conductivity of the system leading to an improvement in figure of merit. The Seebeck coefficient suggested the p-type behavior over the whole temperature range, followed by a maximum at 150 K. Additionally, the electronic properties of the Mn1.5Co0.5FeAl suggest that the observed Raman mode is due to the electronic excitations in the system. Interestingly, this system shows a decoupling between the Seebeck coefficient and electrical conductivity, suggesting the promising potential of Mn1.5Co0.5FeAl as a thermoelectric material and offering valuable insights into its electronic properties.

Isometric pyrochlore oxides (A2B2O7) have prodigious structural and physical properties and are used in a variety of applications like electrolytes, sensors, immobilization of radioactive nuclides, and so on. Herein, the electronic excitation-induced disorder engineering in the Gd2Zr2O7 system on irradiation of 100 MeV I7+ ions with the function of fluence has been investigated. X-ray diffraction (XRD) and Raman spectroscopy techniques were performed to probe the electronic excitation-induced phase transformation. Rietveld’s refinement of the pristine Gd2Zr2O7 sample confirmed an ordered pyrochlore phase. XRD studies show that the superstructure reflection disappeared with the enhanced fluence, which indicates pyrochlore to defect fluorite structure phase transformation. Raman spectroscopy results demonstrate that the structural modifications of Gd2Zr2O7 samples depend strongly on the ion fluence and degrees of disorder augmented with enhanced ion fluence. Both, the complementary techniques provide the compatible elucidation of structural modifications induced by the swift heavy ions (100 MeV iodine) and demonstrate that no amorphization was observed in the Gd2Zr2O7 samples even after irradiation at the highest fluence, and establish the capability of these samples for nuclear applications under hostile environment.  Raman spectra recorded on Gd2Zr2O7 sample before and after irradiation with 100 MeV I7+ ions at a fluence of 1.0 × 1014 ions/cm2.

The magneto-transport and angle-resolved photoelectron spectroscopy (ARPES) of the S-doped Bi1.5Sb0.5Te1.3Se1.7 system have been investigated. Both the positive magnetoresistance (pMR) and negative magnetoresistance (nMR) under a perpendicular magnetic field as well as a changeover from weak antilocalization (WAL) to weak localization (WL) are observed. The interplay between pMR and nMR is elucidated in terms of the dephasing and spin–orbit scattering time scales. The topological surface state bands have been explored using ARPES.

Experimental approaches would involve a significant investment of time and money, but computer simulation delivers accurate predictions in a relatively short period of time. When materials are scaled down from their bulk form to the nanoscale, scientists have seen a number of unexpected and unusual behaviors shown by them. Many molecular devices have functional qualities that have been hypo research articled using computational modeling technologies, such as molecular rectifying, negative differential resistance (NDR), and switch behaviors in many cases. A growing number of low-dimensional materials (or nanomaterials) such as graphene, carbon chain (or nanowires), and carbon nanotubes have received considerable interest in recent years, primarily in the context of practical applications and theoretical study. At the same time, researchers continue to struggle to come up with a structure and modulation of their properties that is relevant. Recently, the remarkable capabilities of carbon-based materials have drawn a great deal of interest, since their applications and functions indicate that they have the potential to replace silicon-based electronic components in the future. It is possible to construct molecular devices as small as nanometers in size and that are freestanding, readily adjusted, have great stability, and are preferred to conventional molecular devices. With the use of an atomistic-level computational technique, the research effort reported in this research article aims to predict the electrical and transport characteristics of a range of nanometer-scaled devices. Experiments using carbon-based materials, such as carbon nanotubes, to determine their transport characteristics.

Cation and anion disordering affect the structural and electronic properties of the isometric A2B2O7 pyrochlore materials. Here, we report a study on the structural response of La2Zr2O7 at two different temperatures (300 K and ~88 K) as a function of ion fluence (1 × 1013, 5 × 1013, and 1 × 1014 ions/cm2). The effect of ion fluence and irradiation temperature on the structural properties have been investigated using the grazing angle x-ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy. GIXRD results confirmed that the weakening/broadening of the diffraction peaks and lattice volume expansion increases monotonically as a function of ion fluence at both the temperatures and are more pronounced at ~88 K. The cation and anion disordering appear to be ion fluence and irradiation temperature-dependent. Raman spectroscopy shows that the atomic disordering is more pronounced with enhanced ion fluence and revealed the involvement of the X48f parameter in the enhancement of disordering in the system. The HRTEM analysis revealed that the deterioration in the atomic ordering (amorphization) is significantly more pronounced at ~88 K. The qualitative analysis of cation/anion disordering and structural deformation revealed that irradiation parameters play a crucial role in developing and altering the properties of the pyrochlore materials for the technological applications.

State of the art applications (nuclear waste host, scintillators, piezoelectric, SOFCs, etc.) of isometric pyrochlore, A(2)B(2)O(7), are very sensitive to the structural assessment upon ion irradiation. In the present study, La2Zr2O7 is irradiated using 1 MeV Xe4+ ions with fluence of 1 x 10(13), 5 x 10(13), and 1 x 10(14) ions/cm(2) at similar to 88 K and 300 K. The impact of irradiation temperature and ion fluence on the structural properties of the La2Zr2O7 are investigated using the GIXRD, Raman spectroscopy and high resolution transmission electron microscopy (HR-TEM). The GIXRD and Raman results indicate that the degradation of the crystallinity (i.e., damage/amorphization) are significantly higher with enhanced fluence at similar to 88 K than that of 300 K. The induced lattice strain also increases with an increase of ion fluence and it is more pronounced at similar to 88 K. The HR-TEM results of the La2Zr2O7 samples exhibit that degradation of the atomic ordering are more pronounced at similar to 88 K. The prominent induced strain and degradation of crystallinity (i.e., damage/amorphization) at similar to 88 K appear to be ion fluence and irradiation temperature-dependent. This study is enlightening the effect of the ion fluence and irradiation temperature on the degradation of crystallinity (i.e., damage/amorphization). (C) 2020 Elsevier B.V. All rights reserved.

The Co1-xZnXFe2O4 (X= 0.0, 0.05 and 0.1) nanoparticles (NPs) were synthesized by a facile and economical thermal decomposition technique. The structural, morphological, optical, and magnetic properties are characterized by XRD, UV-Vis-NIR spectroscopy, Raman spectroscopy, and vibrating sample magnetometer (VSM). XRD study confirms the formation of the cubicspinel crystal structure of samples. The optical band gap is tuned from 1.40 eV to 1.51 eV. The saturation magnetization and coercivity enhance from 67.14 to 75.20 emu/g and 1170.20 to 2033.63 Oe at room temperature, respectively. The tuning in optical and magnetic properties seems to be associated with the redistribution of Co2+ ions at the octahedral and tetrahedral sites. The Raman study confirms the redistribution of Co2+ ions between the octahedral and tetrahedral sites. A quantitative analysis is presented to explain the variation in the optical and magnetic properties.

Here we report on the control of CoFe2O4 (CFO) morphology (in the form of sphere, cube, and hexagonal nanoparticles (NPs)) by tuning the preparative parameters in facile thermal decomposition technique for fine tuning of the structural, optical and magnetic properties. X-ray diffraction study revealed the cubic spinel crystal structure of cobalt ferrite. Raman and X-ray photoelectron spectroscopy confirmed the non-equilibrium cation distribution between sphere, cube, and hexagonal CFO-NPs. Strong correlation between optical band gap and magnetic properties with the CFO -NPs attributed to the non-equilibrium cation distribution between the octahedral and tetrahedral sites for different morphology with a quantitative analysis.

In the present study, we investigated the impact of annealing temperature and time on grain growth and atomic order/disorder in La2Zr2O7 pyrochlore. Experimental results showed that the sample remains in the pyrochlore phase at higher annealing temperature (1500 °C) for a longer time (96 h). The influence of grain growth and atomic order/disorder on the structural properties could be effective in designing and tailoring the pyrochlore materials for energy applications. La2Zr2O7 with different degrees of atomic order was prepared by isothermal annealing at different temperatures (1200 °C, 1300 °C and 1500 °C) for various annealing time (24, 48, and 96 h). Structural and microstructural properties of La2Zr2O7 were investigated using the X-ray diffraction, and Raman spectroscopy techniques. The degree of cation–anion order increases with increasing annealing temperature and time. The curvature-driven grain coarsening of the small grains favored the formation of larger grains. The grain-growth kinetics is studied using the Arrhenius equation $$G_{t}^{n} - G_{0}^{n} = k_{0} \exp \left( { - \frac{{E_{\text{a}} }}{RT}} \right)t^{q}$$ and activation energy for grain growth is found to be 590 ± 21 kJ/mol. A quantitative analysis has been presented to investigate the cation/anion order and microstructural evolution in pure phase polycrystalline La2Zr2O7.