LiF Layer Research Articles

Effect of Anion Species in Early Stage of SEI Formation Process

We investigate the early stage of the solid electrolyte interphase (SEI) layer formation process in four electrolyte solutions, using electrochemical quartz crystal microbalance (EQCM) and X-ray photoelectron spectroscopy (XPS). The EQCM result proves that the LiBH4 in THF solution form a negligible amount of SEI layer. The SEI formation process of the LiPF6 solution occurs at 2.3 V vs. Li, and the SEI layer continuously grows even during the anodic scan. The electrolyte solutions containing LiTFSA form SEI layer around 1.5 V vs. Li. The XPS study shows that the SEI layer formed at high electrode potential, in the electrolyte containing LiPF6 forms a dense LiF layer. The LiTFSA solution forms a thick SEI layer containing organic components such as lithium alkyl carbonate or polyether.

Interface engineering of sulfide electrolytes for all-solid-state lithium batteries

All-solid-state lithium batteries (ASSLIBs) employing sulfide solid electrolyte hold high promise to replace traditional liquid-electrolyte LIBs due to their high safety and energy density. However, Li dendritic growth in sulfide electrolyte limits the realization of the high energy of ASSLIBs. In this work, we use LiF (or LiI) layer at the interface between Li and sulfide electrolyte and penetrated HFE (or I solution) inside of sulfide electrolyte to suppress the Li dendrite growth. Due to the higher interface energy of LiF/Li than that of LiI/Li, LiF interlayer show much higher capability than LiI in suppressing the Li dendrite. Even if the Li dendrite breaks through LiF (or LiI) interlayer, the Li dendrites will be consumed by coated/penetrated HEF (or I) forming LiF (or LiI) thus preventing Li dendrite growth. A LiNbO3 @LiCoO2/Li7P3S11/Li ASSLIB employing HFE coated/infiltrated Li7P3S11 glass-ceramic as electrolyte, and LiF coated Li metal as anode shows a high reversible discharge capacity of 118.9 mAh g−1 at 0.1 mA cm−2 and retains 96.8 mAh g−1 after 100 cycles. The designed solid electrolyte interphase between Li and solid electrolyte that has a high interface energy to Li provides new opportunity to commercialize the Li metal batteries.

On the Growth of Evaporated LiF on P3HT and PCBM

The electronic properties of thin layers of LiF evaporated onto phenyl-C61-butyric acid methyl ester and poly(3-hexylthiophene) thin films have been examined to better understand how alkali halide salt layers at the interface between the metal electrode and the organic conducting material improve device performance. The chemical state of LiF was investigated for various layer thicknesses via X-ray photoelectron spectroscopy (XPS) and angle-resolved XPS. LiF was found to remain nondissociated up to a layer thickness of 30 A layer and also for sequential depositions of the salt. The electronic properties of the valence band were determined for a range of thicknesses with ultraviolet-photoelectron spectroscopy. Concentration depth profiles were obtained via ion scattering spectroscopy. An interfacial dipole forms on the organic surfaces, and a closed layer of salt was not formed with 16 A of salt deposition as shown via metastable induced electron spectroscopy. The combined results indicate that the salt lay...

Lyman-β narrowband coatings with strong Lyman-α rejection.

Novel narrowband multilayer coatings efficient at a wavelength as short as 100 mn are presented, which pushes shortwards the existing limit of reported narrowband multilayers. Such limit had been established at ~120 nm, close to the MgF2 cutoff wavelength. The new multilayers combine layers of Al, LiF, and SiC, in an Al/LiF/SiC/LiF multilayer design (four layers, starting with the innermost layer). Among these materials, Al and LiF are deposited by evaporation and SiC by ion-beam-sputtering. In addition to a high, narrow peak close to H Lyman β (102.6 nm), these multilayers simultaneously provide a very small reflectance at H Lyman α (121.6 nm). This combined performance is demanded in space instrumentation for astrophysics and solar physics observations among others, where imaging the sky at the important diagnostic spectral line of Lyman β line requires rejecting the frequently much more intense background at Lyman α line. Such is the case for solar corona observations at Lyman β, which is masked by the strong Lyman α line. The multilayer peak is placed close to another important diagnostic tool: the OVI doublet at 103.2 and 103.8 nm. The target of small reflectance at 121.6 nm was seen to be the most critical. The best strategy in multilayer preparation was to prepare it with such minimum reflectance at slightly shorter wavelengths so that the coating evolved to shift it longwards over time. Multilayers kept a remarkable 102.6 nm/121.6 nm reflectance ratio over time in spite of some performance degradation. Hence, a multilayer coating aged of 4 years kept a reflectance of 43% at 102.6 nm and 0.2% at 121.6 nm.

Impact of Specifically Shaped Plasmonic Gold Nanoparticles and a Double Cathode Interfacial Layer on the Performance of Conducting Polymer-Based Photovoltaics

Specifically shaped plasmonic gold nanoparticles (AuNPs) and their combined effect with the double cathode interfacial layer for increasing the power conversion efficiency (PCE) of poly(3-hexylthiophene):(6,6)-phenyl-C61/71-butyric acid methyl ester (P3HT:PC61/71BM)-based polymer solar cells (PSCs) are methodically established. Two diverse donor–acceptor blend polymers, P3HT:PC61BM and P3HT:PC71BM, were used here along with BPhen and BCP as the buffer layers of the conventional LiF:Al cathode contact. Initially, four specifically shaped AuNPs, viz., CTAB capped gold nanorods (AuNRs), gold nanospheres (AuNSs), gold nano-ovals (AuNOs), and gold nanobranches (AuNBs) were separately synthesized and blended along with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transporting layer to obtain four novel nanoparticle-doped hole injecting layers, and their effect on P3HT:PCBM-based polymer photovoltaic device performance was methodically analyzed. The synthesized nanoparticles were ch...

Tailoring Mg:Ag functionalities for organic light-emitting diodes

Abstract Magnesium (Mg) and silver (Ag) alloys are staple electrodes for organic light-emitting diodes (OLEDs). In this study, the Mg:Ag binary phase diagram is used to establish an electrode materials selection guide for both bottom- and top-emitting OLEDs. To achieve low turn-on voltage and high efficiency in bottom-emitting OLEDs, it is found that Mg:Ag cathodes must be selected from AgMg3 Mg phase region which provides the best figure of merits in low work function and high optical reflectance. For top-emitting OLEDs, however, Mg:Ag cathodes in the AgMg3 Mg region show large imaginary refractive index, and thus a stacked Mg:Ag/Ag is found essential to achieve optimal device performance. Furthermore, insertion of a thin LiF layer is found to create an effective charge injection cathode. In order to theoretically compute the devices’ optical characteristics, a database of complex optical constants of various materials including the metals is obtained by using a spectroscopic ellipsometer. This new database is found essential for accurate device optical design and engineering.

In-Situ AFM Imaging of Solid Electrolyte Interphase on Silicon Negative Electrodes with an Artificial Surface Layer

Silicon is regarded as the most promising negative electrode material for next-generation lithium-ion batteries because of the high theoretical capacity. We have developed a Si powder with a flake shape (Si LeafPower®, Si-LP, OIKE & Co., Ltd.) that is 100 nm thick with a 3-5 μm lateral dimension.[1-3] The Si-LP electrode demonstrates a superior cycle performances because the unique flake structure resists pulverization during charge and discharge cycling. For further improvement of cycle performances, inhibition of reductive decomposition of electrolytes on the Si negative electrode is necessary. We tried to suppress the electrolyte decomposition by an artificial surface coating on Si thin films and investigated formation of solid electrolyte interphase (SEI) by in-situ atomic force microscopy (AFM) coupled with a potential sweep. An amorphous Si thin film with the thickness of 100 nm was deposited by RF magnetron sputtering on a mirror polished Cu substrate. After that, LiF layer was sequentially deposited on the Si film electrode by the RF sputtering. AFM observations coupled with cyclic voltammetry were performed in a liquid immersion sample stage equipped with electrochemical connectors. The Si thin film as a working electrode and Li wires as a counter and a reference electrodes were immersed in the electrolyte of 1 M LiTFSI/EC+DEC (1:1 by vol.). AFM scan was conducted with a conventional contact mode at a room temperature in an Ar-filled glovebox. The potential was managed with a potentiostat/galvanostat and the sweep rate was 0.5 mV s-1. In the first cycle of the cyclic voltammetry for the Si film electrode without LiF, a small cathodic current began to flow ~2 V, and a current peak arose around 0.9 V. This current peak disappeared in the second cycle, which indicated an irreversible reductive decomposition reaction of the electrolyte and formation of SEI on the Si electrode. In the AFM image coupled with the potential sweep, surface deposits emerged from ~0.9 V corresponding to the potential of the electrolyte decomposition. On the other hand, a reductive current peak and surface deposits caused by the electrolyte decomposition were not observed in the Si film electrode with LiF coating. Furthermore, the Coulombic efficiencies of the Si film electrodes improved by the LiF-coating. These results indicated that the LiF layer on the Si electrode prevented the electrolyte decomposition, and thus LiF is a very important component for SEI layer. Acknowledgments: This work was supported by ALCA-SPRING (JST, Japan) and KAKENHI (JSPS, Japan) Grant Number 16H04649.

Surface-Modified Ni-Rich Layered Cathode Materials Via Li-Reactive Inorganic Coatings

In recent years, the demand for lithium ion batteries (LIBs) significantly increases due to the wide range of application, from consumer electronics to automotive industry. The improvement of the LIB’s energy density is one of the key factors to the mass market penetration of electric mobility. Currently, LIBs are applied in hybrid (HEV), plug-in hybrid (PHEV) and fully electric (EV) vehicles. Particularly, layered lithium Ni-Co-Mn oxides LiNixCoyMnzO2 (NCM, x + y + z = 1) cathode materials are the most promising candidates for LIBs due to their high capacity, lower cost and enhanced stability compared with LiCoO2.[1] Although the state-of-the-art NCM cathode material is NCM-523, the trend is going towards a higher energy density. Recently, the focus of research is on the cathode materials with high nickel content. For example NCM-811 with a Ni content of 80% can deliver a discharge capacity of 200 mAh/g at 4.3 V. At the same time, the high Ni content causes some disadvantages, such as an unstable electrode structure and rapid capacity fading. One of the challenges is the synthesis and stabilization of Ni-rich materials. In order to avoid cation mixing, an excess of lithium must be ensured. Consequently, the unreacted lithium on the surface of the active material can react with water and CO2 from the air. As a result of the contamination, LiOH and L2CO3 are formed on the surface of the active material. These residues can form an insulating layer of LiF in contact with the electrolyte, which leads an increased internal resistance of the electrode. Furthermore, the highly reactive Ni4+ ions in the delithiated state of the electrode of Ni-rich cathode materials can oxidize the electrolyte and result in active material loss.[2] In this contribution, we investigate the effect of surface modification of NCM-811 via an inorganic coating on the electrochemical performance. The inorganic coating acts as protective layer on the surface of the active material, preventing the direct contact of the cathode material with the electrolyte. Moreover, it suppresses the side reactions on the particle surface. The effect of the coating on the structural and electrochemical properties was investigated in NCM-811/graphite full cells. The cells with coated electrodes were significantly improved with respect to their long-term cycling performance compared to the uncoated electrodes (Figure 1). [1] S.-K. Jung, H. Gwon, J. Hong, K.-Y. Park, D.-H. Seo, H. Kim, J. Hyun, W. Yang and K. Kang, Advanced Energy Materials, 2014, 4, 1300787. [2] W. Liu, P. Oh, X. Liu, M.-J. Lee, W. Cho, S. Chae, Y. Kim and J. Cho, Angewandte Chemie International Edition, 2015, 54, 4440-4457. Figure 1: Cycling performance of uncoated and coated NCM-811/graphite LIB full cells at room temperature using a voltage window of 2.5 – 4.3 V. Three formation cycles at 0.1C and following cycling at 0.5C rate. Figure 1

Molecular Dynamics Study of Interphase Solid Electrolyte/ Electrode in Li-Ion Batteries

Interfacial analysis is critical to analyze the performance of Li-ion batteries, the prediction of reactions occurring at the interface electrode/electrolyte, the formation of the solid electrolyte interface (SEI), affecting the cycling life of the battery. These are issues that computational techniques can address prior to experiments and fabrication. We analyze interphases produced by liquid-solid and solid-solid electrolyte-anode interfaces using molecular dynamics simulations (MD);1-4 thus, experience from liquid electrolytes SEIs is extended to the analysis of alternative solid electrolytes and their SEIs with the anode. The solid electrolyte interphase formed due to a liquid-solid electrolyte-anode is modeled entirely as a LiF layer coating a LiSi nanoparticle (NP). We focus on the mechanical properties of the SEI layer during the expansion of the NP due to charging of a Li-ion battery.2 Several charging rates are tested presenting current dependent phenomena such as a surface reconstruction, amorphization and cracking of the SEI. Extrapolating C-rates, we identified an interval between cracking onset and critical cracking (SEI fully fragmented); this interval corresponds to a volume expansion from 180 to 320%, matching the experimental range of charging maximum of 2200 mAh/g and equivalent to ~200% volume expansion.5 The breaking of LiF bonds begins with those nearest to the SiLi-LiF interface, along a radial direction pointing to the outside of the NP, then forming larger and larger LiF rings until the SiLi alloy totally loses its protective shell. Due to cracking, the anode is exposed to the electrolyte allowing the formation of dendrites. Taking a sample of a cracked LiF, a MD simulation is performed to develop and test a protocol to show the formation of dendrites and what influences them, making them faster or slower to grow.1 In order to avoid, or at least reduce the effect, of the dendrites, we test solids materials as electrolyte. For the solid-solid interfaces, we analyze the ClN and Li (001) planes of the solid Li9N2Cl3 electrolyte interfacing the Li-metal (001) using ab initio MD to identify the electrochemical reactions that may occur at the formation of the interface of an initially discharged battery with or without out a charging power source.6 An atomic concentration analysis does not reveal any significant changes up to 20 ps in any of the two analyzed interfaces, meaning that there is no considerable migration of atoms from electrode to electrolyte and vice versa. Diffusion coefficient of all the atomic species involved decreases with a trend to reach a minimum value, indicating that the atoms reach a stable state, trying to avoid movement. Charge transfer on the Li sites at the interphases is observed, changing its charge from 0 to +1. On interface solid-ClN—Li-metal, N and Cl atoms form bonds with 7-8 Li around them, taking Li from the electrode to achieve a BCC structure with N and Cl as central atoms. On the solid-Li—Li-metal, one Li, originally from the electrolyte, diffuses to the electrode, however, this phenomenon has only occurred once during the whole simulation, indicating that it is possible but it is not recurrent; so at least during the equilibration, the loss of Li of the electrolyte to the electrode is not a considerable problem in these interfaces. However, other solid electrolytes react at the interface forming compounds. For example, Li5PS4Cl, Li7P2S8Br, and Li7P2S8I electrolytes, derivatives such as Li2S, Li3P and LiCl form in the Li/LPSC interface at 50 ps on each face of the solid electrolyte and from analyzing the faces of LPSC, the highest Li-metal consumption is on the (010) face. Author Contributions: D.E.G.-A analyzed the mechanical properties of the LiF solid electrolyte interface and studied the Li/Li9Na2Cl3 interface; L.A. S. performed the molecular dynamics simulation of dendrite formation; C.R.-V. did the interfacial study of Li/Li5PS4Cl2; F.F.-G. did the study of the interfacial Li/Li7P2S8I; M.G. did the study of the interfacial Li/Li7P2S8Br; and J.M.S. directed the research. Selis, L. A.; Seminario, J., RSC Advances 2018, 8 (10), 5255-5267.Galvez-Aranda, D. E.; Seminario, J. M., J. Electrochem. Soc. 2018, 165 (3), A717-A730.Galvez-Aranda, D. E.; Ponce, V.; Seminario, J. M., J. Mol. Model. 2017, 23 (4), 120.Ponce, V.; Galvez-Aranda, D. E.; Seminario, J. M., J. Phys. Chem. C 2017, 121 (23), 12959-12971.Yang, Y.; Wang, Z.; Zhou, R.; Guo, H.; Li, X., Materials Letters 2016, 184, 65-68.Roman-Vicharra, C.; Franco-Gallo, F.; Alaminsky, R.; Galvez-Aranda, D.; Balbuena, P.; Seminario, J., Crystals 2018, 8 (1), 33. Figure 1

Surface cleaning effect of NCM powder and improvement of lithium ion battery on the thermal stability and life cycle employing dielectric barrier discharge technique

Mixed NCM (nikel, cobalt, and manganese) powder was treated by a reactive gas from dielectric barrier discharge (DBD) to prepare a cathode material in Lithium ion (Li-ion) battery. The DBD was mainly sustained using N2 gas at atmospheric pressure, and NF3, SF6, and H2 was fed into the discharge to create the reactive gas. Compare to the non-treated sample, impurities on the surface of the NCM powder were significantly removed in a 5 min when the reactive gas was blow into the powder and mixed properly. F atom content on the surface was increased depending on the time duration of mixing, which form a LiF layer on the surface. Desirable LiF layer suppress a heat flow effectively , resulting a decreasing of exothermic temperature inside the Li-ion battery. Additionally, the treatment of NCM powder employing DBD technique was also contributed to electrochemical performance, which was confirmed by c-rate testing.

Experimental analysis of dark frame growth mechanism in organic light-emitting diodes

Organic light-emitting diodes (OLEDs) were fabricated with heterojunction interfaces and layers that were prepared by cold isostatic pressing (CIP), and the growth characteristics of their non-emission areas, or dark frames (D/Fs), were investigated during storage. We fabricated an OLED with an indium–tin-oxide (ITO)/N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (α-NPD)/tris(8-hydroxylquinoline)aluminum (Alq3)/LiF/Al structure without CIP treatment (Device I), as well as OLEDs that were pressed after the deposition of α-NPD (Device II), Alq3 (Device III), and LiF/Al (Device IV) layers. Although Devices I, II, and III showed typical D/F growth characteristics, the D/F growth rate in Device IV was markedly mitigated, indicating that the Alq3/LiF/Al interfaces dominated the D/F growth. Moreover, we found that the electron injection characteristic was poorer in the electron-only device stored after the LiF layer deposition than in that stored before the LiF deposition. Therefore, the decreased electron injection due to storage at the interfaces was attributed to the D/F growth.

Design of beam shaping assembly based on 3.5 MeV radio-frequency quadrupole proton accelerator for boron neutron capture therapy

Boron neutron capture therapy (BNCT) is expected to be an effective method of improving the treatment results on malignant brain glioma and malignant melanoma, for which no successful treatment has been developed so far. The beam shaping assembly (BSA) of accelerator-based boron neutron capture therapy (A-BNCT) consists of a moderator, a reflector, gamma and thermal neutron shielding and a collimator. The BSA moderates the fast neutron produced in target to epithermal energy range. Design of BSA is one of the key jobs in BNCT project. An optimized study was conducted to design a beam shaping assembly for BNCT facility based on 3.5 MeV 10 mA radio-frequency quadrupole proton accelerator at Dongguan Neutron Science Center. In this simulation work, the neutron produced from the 7Li (p, n) 7Be reaction by 3.5 MeV proton is adopted as a neutron source term. In order to search for an optimized beam shaping assembly for accelerator-based BNCT, Monte Carlo simulation is carried out based on the parameters of moderator material and structure, the Gamma shielding, and the thermal neutron filter in the beam shaping assembly. The beam shaping assembly in this work consists of various moderator materials, teflon as reflector, Bi as gamma shielding, 6Li as thermal neutron filter, and lithium polyethylene as collimator. After comparing the simulation results of Fluental and LiF moderator materials, the beam shaping assembly configuration based on sandwich Fluental-LiF configuration is proposed. The sandwich Fluental-LiF configuration is made up of Fluental and LiF layer by layer, like a sandwich structure, and each layer is 2 cm thick. According to the beam quality requirement of the IAEA-tecdoc-1223 report, the optimized epithermal neutron flux in air at the exit of BSA of the sandwich Fluental-LiF configuration is 9.14×108 n/(cm2·s), which is greater than those of the Fluental configuration (7.81×108 n/(cm2·s)) and LiF configuration (8.79×108 n/(cm2·s)), when the ratio of fast neutron component to gamma ray component to thermal neutron is less than the limiting value of IAEA recommendation. Subsequently, the depth distribution of the equivalent doses in the Snyder head phantom is calculated to evaluate the treatment characteristic. The simulation results show that the therapy rate of the beam shaping assembly based on the sandwich Fluental-LiF configuration is basically equal to that of the Fluental configuration and better than that of the LiF configuration, and the therapy time is less than that of the Fluental configuration. This means that the beam shaping assembly based on the sandwich Fluental-LiF configuration is one of the suitable options for our accelerator-based BNCT.

High efficiency MAPbI3-xClx perovskite solar cell via interfacial passivation.

The trap states at the interface between perovskite and charge-transport layer have a great influence on the performance of perovskite solar cells. Here, a high efficiency MAPbI3-xClx perovskite solar cell has been demonstrated, by introducing a thin layer of LiF or PbF2 between the SnO2/perovskite. Improved charge collection and reduced interfacial charge recombination are realized, leading to remarkable rises of both open-circuit voltage (Voc) and short-circuit current (Jsc). This successful interfacial passivation paved a new way to fabricate high performance perovskite solar cells with large Voc.

Effect of Interface Roughness on Electrical Properties of Ag Cathode and the Role of the LiF Layer to Organic Light Emitting Devices

Effect of Interface Roughness on Electrical Properties of Ag Cathode and the Role of the LiF Layer to Organic Light Emitting Devices

A compact imaging system with a CdTe double-sided strip detector for non-destructive analysis using negative muonic X-rays

A CdTe double-sided strip detector (CdTe-DSD) is an ideal device for imaging and spectroscopic measurements in the hard X-ray range above 10 keV. Recent development enables us to realize an imager with a detection area of ∼10 cm2. An energy resolution of 1–2 keV (FWHM) and a position resolution of a few hundred μm are available from the detector. This type of imager has been long awaited for non-destructive elemental analysis, especially by using negative muons, because energies of characteristic X-rays from muonic atoms are about 200 time higher than those from normal atoms. With the method that uses negative muons, hard X-ray information gives the spatial distribution of elements in samples at a certain depth defined by the initial momentum of the muon beam. In order to study three-dimensional imaging capability of the method, we have developed a compact imaging system based on CdTe-DSD and a ϕ 3 mm pinhole collimator as the first prototype. We conducted experiments with samples which consist of layers of Al, BN and LiF irradiated by negative muon beams in MUSE/J-PARC and successfully reconstruct hard X-ray images of muonic X-rays from B, N and F at various depths.

LiF as an Artificial SEI Layer to Enhance the High-Temperature Cycle Performance of Li4Ti5O12.

Li4Ti5O12 (LTO) is a promising anode material for electric vehicles (EVs) and electrochemical energy storage applications because of its safety, good rate capability, and long cycle life. At elevated temperature, such as 60 °C, it always shows poor cycle performance because of the instability between the electrode material and electrolyte, which may also lead to a serious gassing issue. In this article, a facile hydrothermal method is adopted to coat the LTO powder with a thin LiF layer, in which the LiF acts as an artificial solid electrolyte interface (SEI) layer to prevent the direct contact of LTO and electrolyte, thus improving the high-temperature cycle performance. Electrochemical tests prove that the LiF coating layer has no influence on the kinetics at ambient temperature and greatly enhances the high-temperature cycle stability, and the LTO@LiF composite material keeps 87% of its initial discharge capacity in 300 1C cycles at 60 °C. Moreover, the LiF coating layer exhibits a special self-driven reforming process during the initial cycles, which makes it uniform and more effective at enhancing the stability between electrode/electrolyte interfaces.

Enhanced Cycle Stability of Rechargeable Li-O2 Batteries by the Synergy Effect of a LiF Protective Layer on the Li and DMTFA Additive.

Li metal is an ideal anode for rechargeable Li-O2 batteries because of its large theoretical capacity (3860 mAh g-1). However, problems with the growth of dendrites and reaction with electrolytes and moisture during cycling have prevented its practical application. Herein, we report that the use of a 2 wt % N,N-dimethyltrifluoroacetamide (DMTFA) additive in a dimethyl sulfoxide (DMSO) electrolyte with a LiF layer on the Li anode allows for good cycling performance in Li-O2 batteries. Indeed, a Li-O2 cell with a multiwalled carbon nanotube (MWCNT) cathode, 1.0 M LiNO3/DMTFA + DMSO (2:98 v/v) electrolyte, and a LiF layer on the Li anode could be cycled 92 times at a current density of 1000 mA g-1 with a 1000 mAh g-1.

Activation measurements of the integral cross sections of reactions 7Li(p, n 0 + n 1)7Be g.s. , 6Li(d, n 0 + n 1)7Be g.s. , 7Li(d, 2n)7Be g.s. , 65Сu(p, n)65Zn, 65Сu(d, 2n)65Zn, and 63Сu(d, γ)65Zn

Cross sections of reactions 7Li(p, n 0 + n 1)7Beg.s., 6Li(d, n 0 + n 1)7Beg.s., 7Li(d, 2n)7Be g.s., 65Сu(p, n)65Zn, 65Сu(d, 2n)65Zn, and 63Сu(d, γ)65Zn are measured on the EGP-10 electrostatic tandem accelerator at the All-Russia Research Institute of Experimental Physics by means of activation at proton (deuteron) energies of 2–10 MeV. The technique for making targets and calculating LiF layer thickness is described. Target irradiation, measuring the efficiency of γ-quanta registration, and a procedure for measuring the cross sections of reactions are discussed and their measured values are presented.

Computational analysis of thermoluminescence glow curves from thin layer dosemeters

The Monitoring Service at the Materialprüfungsamt Nordrhein-Westfalen in Dortmund develops a new dosemeter system for large-scale individual dose monitoring. The dosemeters make use of thermoluminescence light from a thin layer of LiF:Mg,Ti. In the large-scale routine dosimetry service, a high number of dosemeters have to be evaluated on a monthly basis, which requires a fast readout. Therefore, thermoluminescence is stimulated by exponential heating of the dosemeters.The main quantity of interest to obtain from a dosemeter is the irradiation dose. Since the data comes in the form of thermoluminescence glow curves, their analysis offers the possibility to extract more information from the data than the irradiation dose, e.g. the fading time. In addition, such an analysis can reduce the uncertainties of the reconstructed irradiation dose, especially for low irradiation doses.Because it is not possible to measure the temperature of the dosemeter during the readout process, the recorded time-dependent glow curves have to be converted to temperature-dependent glow curves before the analysis.

Performance of Three-Layered Organic Light-Emitting Diodes Using the Hole-Transport and Injection Layer of TPD and Teflon-AF, and the Electron-Injection Layer of Li2CO3 and LiF

The performance of three-layered organic light-emitting diodes (OLEDs) was investigated using TPD hole-transport and injection layers, Teflon-AF, and the electron-injection layer of Li2CO3 and LiF. The OLEDs were manufactured in a structure of TPD/Alq3/LiF, TPD/Alq3/Li2CO3, and AF/Alq3/LiF using low-molecular organic materials. In three different three-layered OLEDs, it was found that the device with the TPD/Alq3/LiF structure shows higher performance in maximum luminance, and maximum external quantum efficiency compared to those of the device with TPD/Alq3/Li2CO3 and TPD/Alq3/LiF by 35% and 17%, and 193% and 133%, respectively. It is thought that the combined LiF/Al cathode contributes to a reduced work function and improves an electrical conduction mechanism due to the electron injection rather than the hole transport, which then increases a recombination rate of charge carriers.