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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Low temperature dielectric and conductivity relaxation studies on magnetoelectric Pb(Fe{sub 2/3}W{sub 1/3})O{sub 3}

The single phase perovskite Pb(Fe{sub 2/3}W{sub 1/3})O{sub 3} [PFW] was synthesized by modified low – temperature (sintering at 850°C) solid-state reaction. Rietveld refinement ofroom temperature (RT) X-ray diffraction (XRD) and neutron diffraction (ND) patterns of the samples confirm the single phase formation with cubic structure (Pm-3m). Surface morphology of the compounds was studied by Scanning electron microscope (SEM) and average grain size was estimated to be ∼2 µm. The RT dielectric properties of PFW ceramic are studied as a function of frequency from 100 - 1MHz. The temperature dependent (120 – 293K) dielectric properties were studied at few selected frequencies. We found the frequency dependent dielectric constant shows increasing trend with increase in temperature from 120 – 293K, with minimum dielectric loss. The frequency dependence of dielectric loss shows a maximum in between 10 Hz and 1 kHz, confirms the extrinsic phenomena like interfacial polarization due to space charge accumulation at grain boundaries. Impedance spectroscopy is used to study the electrical behaviour of PFW in the frequency range from 100 to 1MHz and in the temperature range from 120 - 293 K. The frequency-dependent electrical data are analysed by impedance formalisms and shows the relaxation (conduction) mechanism in the sample. We suggest this low temperature sintered PFW is a suitable candidate for the multilayer ceramic capacitorsandrelated negative temperature coefficient of resistance type (NTCR) behavior like that of semiconductors.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Si/SiGe QuBus for single electron information-processing devices with memory and micron-scale connectivity function

The connectivity within single carrier information-processing devices requires transport and storage of single charge quanta. Single electrons have been adiabatically transported while confined to a moving quantum dot in short, all-electrical Si/SiGe shuttle device, called quantum bus (QuBus). Here we show a QuBus spanning a length of 10 μm and operated by only six simply-tunable voltage pulses. We introduce a characterization method, called shuttle-tomography, to benchmark the potential imperfections and local shuttle-fidelity of the QuBus. The fidelity of the single-electron shuttle across the full device and back (a total distance of 19 μm) is (99.7 ± 0.3) %. Using the QuBus, we position and detect up to 34 electrons and initialize a register of 34 quantum dots with arbitrarily chosen patterns of zero and single-electrons. The simple operation signals, compatibility with industry fabrication and low spin-environment-interaction in 28 Si/SiGe, promises long-range spin-conserving transport of spin qubits for quantum connectivity in quantum computing architectures.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2022

Comparison of measurement and simulation of ATLAS cavern radiation background

Sixteen Medipix2 pixel detector based (MPX) devices were operated at various positions within the ATLAS detector and cavern continuously from early 2008 up to 2013. In addition to photons, each MPX detector is capable to detect charged particles, and neutrons as it is covered with a mask of converter materials dividing its area into regions sensitive to thermal or fast neutrons. The MPX detector network was effectively used for real-time measurements of the spectral characteristics and composition of complex radiation fields in ATLAS. This article reports comparison of the results of measurements performed with MPX detectors during the LHC operation period in 2010 and 2011 with Monte Carlo simulations results from the FLUGG and GCALOR codes. For the purpose of this comparison, the MPX detectors were operated in tracking mode with low threshold (8–10 keV) allowing one to distinguish among particle categories based on the recognition of track patterns left by the particles in the MPX sensitive layer. The comparison of measurements with simulations shows that the agreement between measured and simulated data is satisfactory in most cases within a factor of two.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

Artificial Intelligence Thermostat to Detect Faults

Residential air conditioners and heat pumps often experience faults due to inadequate maintenance, which can severely reduce efficiency or even cause system failure. Common issues include dirty or clogged air filters and refrigerant leaks. These problems degrade performance and increase energy use and operating costs. This study presents a smart thermostat with embedded artificial intelligence to detect such faults and alert homeowners when maintenance is needed. The thermostat uses low-cost measurements—including return-air temperature, relative humidity, supply-air temperature, outdoor-air temperature, and condenser subcooling—to identify abnormal operations. Because different faults produce distinct response patterns, tailored algorithms are developed to recognize characteristic fault signatures. The investigation is built on a detailed co-simulation platform that couples EnergyPlus with the DOE/ORNL Heat Pump Design Model (HPDM). EnergyPlus represents the building’s dynamic environment, while HPDM is a high-fidelity, hardware-based model that can simulate fault-free performance as well as a wide range of faults, including gradual degradation such as minor refrigerant leakage. This platform provides a virtual training and testing environment that helps distinguish fault-induced behavior from normal operation and supports development of robust diagnostic algorithms. Using this framework, a Dynamic Bayesian Network was developed to identify two common faults—gradual refrigerant charge loss and indoor airflow blockage—and the AI-embedded thermostat was verified through annual building simulations.

Shen, Bo [ORNL] (ORCID:0000000336600393)↗
DOE OSTI2014

Theoretical spectroscopic investigations of HNS{sup q} and HSN{sup q} (q = 0, +1, −1) in the gas phase

We performed accurate ab initio investigations of the geometric parameters and the vibrational structure of neutral HNS/HSN triatomics and their singly charged anions and cations. We used standard and explicitly correlated coupled cluster approaches in connection with large basis sets. At the highest levels of description, we show that results nicely approach those obtained at the complete basis set limit. Moreover, we generated the three-dimensional potential energy surfaces (3D PESs) for these molecular entities at the coupled cluster level with singles and doubles and a perturbative treatment of triple excitations, along with a basis set of augmented quintuple-zeta quality (aug-cc-pV5Z). A full set of spectroscopic constants are deduced from these potentials by applying perturbation theory. In addition, these 3D PESs are incorporated into variational treatment of the nuclear motions. The pattern of the lowest vibrational levels and corresponding wavefunctions, up to around 4000 cm{sup −1} above the corresponding potential energy minimum, is presented for the first time.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Investigation of structural and electrical properties of La{sub 0.7}(Ba{sub 1-x}Ca{sub x}){sub 0.3}MnO{sub 3} compounds by sol-gel method

In this paper, we explored structural and electrical properties of La{sub 0.7}(Ba{sub 1-x}Ca{sub x}){sub 0.3}MnO{sub 3} (x = 0; 0.03; and 0.05) compounds. The general structure of perovskite manganites is AMnO{sub 3} (A= trivalent rare earth with divalent ion-doped). Average A-site cation size, external pressure, and the variance of the cation size σ{sup 2} are one of many factors that affected to magneto-transport properties of manganites as reported by others. In this work we focus only on the electrical properties in La{sub 0.7}Ba{sub 0.3}MnO{sub 3} Ca-doped compound which may influence crystal structure resulting resistivity phenomena under magnetic field influence. All samples were synthesized by sol-gel method from which fine powders were obtained. The X-ray powder diffraction pattern of powder materials shows that all samples are fully crystalline with a rhombohedral structure. Rietveld refinement shows that the presence of calcium has changed some crystal structural parameters such lattice parameter, Mn–O bond length, and Mn–O–Mn angles. The electrical resistivity of all synthesized materials investigated by four point probe method using Cryogenic Magnet in the temperature range of 50-300 K under influence a magnetic field shows resistivity temperature dependent. In fact presence of calcium has reduced the resistivity. It might occure because it has made an enhancement in the mobility of hopping electrons. The magnetic external field causes the resistivity decreased for all samples because host spin align by delocalizing the charge carries so electron itinerant through the lattice suggested by other authors. Both calcium dopant concentration and the applied external magnetic field shows strong correlation in reduction of resistivity.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

A study of astrometric distortions due to “tree rings” in CCD sensors using LSST Photon Simulator

Imperfections in the production process of thick CCDs lead to circularly symmetric dopant concentration variations, which in turn produce electric fields transverse to the surface of the fully depleted CCD that displace the photogenerated charges. We use PhoSim, a Monte Carlo photon simulator, to explore and examine the likely impacts these dopant concentration variations will have on astrometric measurements in LSST. The scale and behavior of both the astrometric shifts imparted to point sources and the intensity variations in flat field images that result from these doping imperfections are similar to those previously observed in Dark Energy Camera CCDs, giving initial confirmation of PhoSim's model for these effects. In addition, the organized shape distortions were observed as a result of the symmetric nature of these dopant variations, causing nominally round sources to be imparted with a measurable ellipticity either aligned with or transverse to the radial direction of this dopant variation pattern.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1987

Effects of space plasma discharge on the performance of large antenna structures in low Earth orbit

The anomalous plasma around spacecrafts in low Earth orbit represents the coma of an artificial comet. The plasma discharge is caused by an energetic disturbance of charged particles which were formerly in a state of equilibrium. The plasma can effect the passive and active radio frequency operation of large space antennas by inducing corona discharge or strong arcing in the antenna feeds. One such large space antenna is the 15-meter hoop column antenna which consists of a mesh membrane material (tricot knitted gold plated wire) reflector and carbon fiber tension cords. The atomic oxygen in the plasma discharge state can force the wire base metal particles through the gold lattice and oxydize the metal particles to build a Schottky-barrier contact at the point where the wires meet. This effect can cause strong deviations in the reflector performance in terms of antenna pattern and losses. Also, the carbon-fiber cords can experience a strength reduction of 30 percent over a 40-hour exposure time.

Blume, Hans-Juergen C.↗
DOE OSTI2016

Polar Metals by Geometric Design

Gauss's law dictates that the net electric field inside a conductor in electrostatic equilibrium is zero by effective charge screening; free carriers within a metal eliminate internal dipoles that may arise owing to asymmetric charge distributions(1). Quantum physics supports this view(2), demonstrating that delocalized electrons make a static macroscopic polarization, an ill-defined quantity in metals(3)-it is exceedingly unusual to find a polar metal that exhibits long-range ordered dipoles owing to cooperative atomic displacements aligned from dipolar interactions as in insulating phases(4). Here we describe the quantum mechanical design and experimental realization of room-temperature polar metals in thin-film ANiO(3) perovskite nickelates using a strategy based on atomic-scale control of inversion-preserving (centric) displacements(5). We predict with ab initio calculations that cooperative polar A cation displacements are geometrically stabilized with a non-equilibrium amplitude and tilt pattern of the corner-connected NiO6 octahedra-the structural signatures of perovskites-owing to geometric constraints imposed by the underlying substrate. Heteroepitaxial thin-films grown on LaAlO3 (111) substrates fulfil the design principles. We achieve both a conducting polar monoclinic oxide that is inaccessible in compositionally identical films grown on (001) substrates, and observe a hidden, previously unreported(6-10), non-equilibrium structure in thin-film geometries. We expect that the geometric stabilization approach will provide novel avenues for realizing new multifunctional materials with unusual coexisting properties.

Kim, T. H.↗
DOE OSTI2019

Identifying Muon Neutrino Charged-Current Interactions in the MicroBooNE Detector

The MicroBooNE experiment is a short-baseline neutrino experiment at the Fermi National Accelerator Laboratory (FNAL) in the US, receiving a highly pure muon neutrino beam from the Booster Neutrino Beam (BNB) and taking data since October 2015. The main physics goal of MicroBooNE is to clarify the nature of the low-energy excess of electron-like events observed by the MiniBooNE Cherenkov detector, which due to its detector technology is unable to resolve whether the observed excess shower-like events are due to electrons or photons. Instead, MicrooBooNE employs cutting-edge liquid argon time projection chamber (LArTPC) technology, which offers excellent spatial and calorimetric resolution, which makes it possible to reconstruct complex neutrino interactions and to efficiently distinguish different final state particle types. This thesis presents a fully-automated event selection of interactions of the types ν μ +Ar → μ - + X and ν μ + Ar → μ - + p + X developed using the Pandora multi-algorithm approach to pattern recognition for LArTPC experiments. The analysis in this work is performed on a subset of the MicroBooNE Run 1 dataset corresponding to 4.52 × 10 19 protons on target acquired by the MicroBooNE detector between February and October 2016. The analysis quantifies the main signal and background interaction channels that produce a reconstructed neutrino interaction with one and two particles in the final state, and quantifies the extent to which different aspects of the Pandora reconstruction affect the selection performance. MicroBooNE is a surface detector, and therefore cosmic-ray tracks are the main observed background. A direction fitting procedure has been implemented in this analysis to formulate directional probabilities, using the Bethe equation and the high-resolution calorimetric information of MicroBooNE, to reduce this cosmic-ray background. This functionality is used to enhance the efficiency of the Pandora cosmic ray tagging logic, and the impact of this procedure on the reconstruction and event selection performance is analysed. The result of this study is two fully-automated selections of ν μ +Ar → μ - + X (57.91% pure) and ν μ + Ar → μ - + p + X (78.30% pure) with efficiencies of 64.35% and 62.65%, respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

In Situ, Protein-Mediated Generation of a Photochemically Active Chlorophyll Analogue in a Mutant Bacterial Photosynthetic Reaction Center

All possible natural amino acids have been substituted for the native LeuL185 positioned near the B-side bacteriopheophytin (H B ) in the bacterial reaction center (RC) from Rhodobacter sphaeroides. Additional mutations are present that enhance electron transfer to the normally inactive B-side cofactors. About half the isolated RCs with Glu at L185 contain a magnesium chlorin (C B ) in place of H B . The chlorin is not the common BChl a oxidation product 3-desvinyl-3-acetyl chlorophyll a with a C-C bond in ring D and a C=C bond in ring B, but has properties consistent with reversal of these bond orders, giving 17,18-didehydro BChl a. In such RCs, charge-separated state P + C B – forms with ~5% yield. The other half of the GluL185-containing RCs have a bacteriochlorophyll a (BChl a) denoted β B in place of H B . Residues His, Asp, Asn and Gln at L185 yield RCs with ≥85% β B in the H B site, while most other amino acids result in RCs that retain H B (≥95%). To our knowledge, neither bacterial RCs that harbor five BChl a and one chlorophyll analog nor ones with six BChl a have been reported previously. The finding that altering the local environment within a cofactor binding site of a transmembrane complex leads to in situ generation of a photoactive chlorin with an unusual ring oxidation pattern suggests new strategies for amino-acid control over pigment type at specific sites in photosynthetic proteins.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Tailoring LaAlO 3 /SrTiO 3 Interface Metallicity by Oxygen Surface Adsorbates

We report an oxygen surface adsorbates induced metal–insulator transition at the LaAlO 3 /SrTiO 3 interfaces. The observed effects were attributed to the terminations of surface Al sites and the resultant electron-accepting surface states. By controlling the local oxygen adsorptions, we successfully demonstrated the nondestructive patterning of the interface two-dimensional electron gas (2DEG). The obtained 2DEG structures are stable in air and also robust against general solvent treatments. This study provides new insights into the metal–insulator transition mechanism at the complex oxide interfaces and also a highly efficient technique for tailoring the interface properties.

2DEG↗
DOE OSTI2026

An On-Demand Electric Transit Case Study of New Rochelle, New York

Here, this article characterizes the performance and ridership patterns of an on-demand transit (ODT) service utilizing lightweight electric vehicles (EVs) in New Rochelle, New York. Ridership sociodemographics, travel patterns (both temporal and spatiotemporal), and energy use from the service were explored using travel and survey data from September 2019 through December 2023. The ODT service was found to be used more by women (nearly 60%) and younger demographics (>65% under the age of 42), with peak use in the middle of the day and a grocery store as a top origin and destination. The service was utilized primarily for short trips (86% under 2 mi), with approximately one-third of riders using the ODT service to connect to a train or bus. The costs associated with fueling/charging were compared for different types of fleet vehicles, and the small, right-sized EVs were found to have annual charging costs that were roughly half of the refueling costs for conventional hybrid vans, and 24 times lower than a fleet of diesel buses. Evaluating the vehicle fleet and mapping current socio-spatial travel demand can inform system performance, guide service area development, and support future planning such as expansion to nearby communities and transit hubs. The findings in this case study suggest that on-demand electric transit may be a significant and growing space for advancing highly valued public mobility services. Public transport interventions that consider right-sized, electric, on-demand vehicles can help improve mobility access and reduce energy use and refueling costs.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2019

Flexible Geothermal Power Generation utilizing Geologic Thermal Energy Storage (Final Seedling Project Report)

This report concludes that there is a cost-effective strategy for seasonal storage of heat that will provide firm, but dispatchable, electrical generating capacity in times when other renewable energy is not available to meet demand. Deployment of the technology appears to require no new technology, but instead combines solar, geothermal, and conventional oil and gas drilling technologies in a novel way. The study basis is the use of sedimentary geologic formations as a medium for thermal energy storage (TES), specifically for heat collected in concentrating solar collectors. The study identifies methodologies that could be used to transport this heat into and out of the subsurface in order to produce dispatchable electrical power, and reports on initial optimization results. The GeoTES system (heat input, storage, heat recovery, and heat to electric conversion) described in this analysis has the potential to provide a unique pathway for increasing the grid penetration of renewable energy in large blocks of power and across many states and regions. Further, the system can be used both to meet the nation’s flexible energy needs while also improving grid stability and reliability. The present study evaluated the use of a large number of dedicated wells to store and recover the heat, essentially creating a synthetic geothermal reservoir. The use of sedimentary geology allows the wells to be drilled at low cost. Dedicated hot and cold wells are used, arranged in a five-spot well pattern with each hot or cold well surrounded at an appropriate distance by the opposite type of well. In large numbers this becomes alternating rows of hot and cold wells. Each hot and cold well is operated using a push-pull strategy. This configuration provides the ability to immediately recover stored hot fluid from a GeoTES reservoir, or to store the heat over many months for recovery at low loss when needed. This is a practical approach for managing the system’s fluid inventory and reducing parasitic load. The production and injection power requirements are reduced because the rows of wells operating in “push” mode provide help to the wells operating in “pull” mode, and vice-versa. Initial charging of a GeoTES system increases the heat recovery temperature. Increasing the duration of the charging period decreases the magnitude of the temperature fluctuations that occur following prolonged system operation. Because of direct contact of the heated water with the reservoir formation, the production of both hot water and steam from the TES, and the temperature ranges of the recovered fluid (190 – 230°C or 375 – 445°F), conventional geothermal power cycles were used to convert the stored heat to electricity. A power cycle configuration for the GeoTES system was selected following a screening study of a number of flash, and flash/binary hybrid options. This analysis concluded that, of the configurations evaluated, a dual-stage flash steam cycle provides the lowest capital costs per unit net power generation with an acceptable hot brine inlet fluid flow rate. The evaluation included the power plant cost estimate, the cost and number of wells and the associated parasitic loads. Annual power generation performance was simulated to evaluate capacity factor and LCOE. The LCOE calculated for the inherently high capacity GeoTES system was $\$$0.13/kWhe. This value was calculated for the case where the solar thermal collector was sized in such a way that the solar collectors permitted an annual power plant capacity factor of up to 97%. The power cycle was able to provide power to the grid every night of the year, and flexible base-load power during the winter, if needed. This LCOE value compares favorably with reported values for solar photovoltaic plus battery energy storage (PV+BES) systems in the open literature, i.e. $\$$0.148/kWhe for a PV+BES system with 4 hours of electrochemical battery energy storage capacity. Addition of battery energy storage with more hours of storage would further increase PV+BES system LCOE and increase the separation between GeoTES and PV+BES. A GeoTES system would therefore provide superior economics for high capacity and long duration solar energy storage.

14 SOLAR ENERGY↗
DOE OSTI2020

Ultra-thin passivation layers in Cu(In,Ga)Se 2 thin-film solar cells: full-area passivated front contacts and their impact on bulk doping

In the search for highly transparent and non-toxic alternative front layers replacing state-of-the-art CdS in Cu(In,Ga)Se 2 thin-film solar cells, alternatives rarely exceed reference devices in terms of efficiency. Full-area ultra-thin aluminium oxide tunnelling layers do not require any contact patterning and thus overcome the main drawback of insulating passivation layers. Even a few monolayers of aluminium oxide can be deposited in a controlled manner by atomic layer deposition, they show excellent interface passivation properties, low absorption, and suitable current transport characteristics on test devices. Depositing a ZnO-based transparent front contact, however, results in extremely poor solar cell performance. The issue is not necessarily a low quality of the alternative front layer, but rather the intricate relation between front layer processing and electronic bulk properties in the absorber layer. We identify three challenges critical for the development of novel front passivation approaches:(i) both Cd and Zn impurities beneficially reduce the high native net dopant concentration in the space charge region, (ii) sputter deposition of ZnO damages the passivation layer resulting in increased interface recombination, (iii) thermal treatments of devices with ZnO layer result in substantial Zn diffusion, which can penetrate the full absorber thickness already at moderate temperatures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Development of Large Area µRWELL Detectors for CLAS12 High Luminosity Upgrade at Jefferson Lab

The high-luminosity upgrade of the CEBAF Large Acceptance Spectrometer (CLAS12) will significantly enhance the physics reach of experiments in Hall B at JLab. However, at the current luminosity of L = 1 × 1035 cm-2 s-1, the reconstruction efficiency of charged particles in the forward region of the CEBAF Large Acceptance Spectrometer (CLAS12) is at the level of 85% and limited in part by the drift chambers inability to handle high occupancy, in the first tracking region (DC-R1) of the Forward Detector. The reconstruction efficiency is expected to drop even lower at higher luminosities with the current tracking technology. Various options under consideration to achieve the desired performance at a higher luminosity of L = 2 × 1035 cm-2 s-1 include the addition of fast tracking layers to complement DC-R1 or the replacement of DC-R1 with a different tracking detector technology altogether. In either case, a novel generation of compact, simple and robust Micro-Pattern Gaseous Detector (MPGD) known as the Resistive Micro-Well detector (µRWELL) is the ideal candidate to satisfy the requirements in terms of timing O (10 ns) and position O (100 µm) resolutions. A large µRWELL prototype, combined with a two-dimensional U-V strip readout layer based on the novel concept of capacitive-sharing approach has been developed as a proof of principle for fast tracking capabilities in the forward region of CLAS12 high-luminosity upgrade. In this talk, we will present the technical aspects of the design choices of the large µRWELL prototype under development and report on the detector assembly process and preliminary performance characteristic tests. We will also discuss the plans for the test and characterization of the prototype in beam during spring 2023 CEBAF run. Finally, we will report on ongoing R&D efforts on small prototypes with the goal to improve rate capability, spatial resolution performance and minimize material thickness.

Gnanvo, Kondo↗
DOE OSTI2018

Multiscale wavelet decomposition of time-resolved X-ray diffraction signals in cyclohexadiene

We demonstrate how the wavelet transform, which is a powerful tool for compression, filtering, and scaling analysis of signals, may be used to separate large- and short-scale electron density features in X-ray diffraction patterns. Wavelets can isolate the electron density associated with delocalized bonds from the much stronger background of highly localized core electrons. The wavelet-processed signals clearly reveal the bond formation and breaking in the early steps of the photoinduced pericyclic ring opening reaction of 1,3-cyclohexadiene, which are not resolved in the bare signal.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Study of electronic transport in gamma ray exposed nanowires

Graphical abstract: A sharp decline in the I–V characteristics of Cu (and Cd) nanowires was experimentally observed after the gamma ray exposure of nanowires. Irradiation induced transformations in the granular properties and the resonance state of electron–phonon coupling beyond a particular value of external field may be accountable for observed shape of I–V characteristics in gamma ray exposed nanowires. - Highlights: • Cu and Cd nanowires were synthesized by technique of electrodeposition in templates. • The nanowires were exposed to different doses of gamma ray photons. • A sharp decline in the current in I–V characteristics (IVC) was observed. • Structural deviation in terms of granular orientations was also analysed. • The electron–phonon coupling may be responsible for observed sharp decline in IVC. - Abstract: One dimensional nanostructures provide the most restricted and narrow channel for the transport of charge carriers and therefore 1D structures preserve their significance from the viewpoint of electronic devices. The net radiation effect on nanomaterials is expected to be more (due to their increased reactivity and lesser bulk volume) than their bulk counterparts. Radiation often modifies the structure and simultaneously the other physical properties of materials. In this manner, the irradiation phenomenon could be counted as a strong criterion to induce changes in the structural and electrical properties of nanowires. We have studied the effect of gamma rays on the electronic flow through Cu and Cd nanowires by plotting their I–V characteristics (IVC). The IVC of gamma ray exposed nanowires was found to be a combination of the linear and nonlinear regions and a decreasing pattern in the electrical conductivity (calculated from the linear portion of IVC) was observed as we increased the dose of gamma rays.

36 MATERIALS SCIENCE↗