Thermo,Iono and photoluminescence properties of 100 MeV Si7+ ions bombarded CaSiO3:Eu3+ nanophosphor

This paper reports on the thermo (TL), iono (IL) and photoluminescence (PL) properties of nanocrystalline CaSiO₃:Eu³⁺ (1–5 mol %) bombarded with 100 MeV Si⁷⁺ ions for the first time. The effect of different dopant concentrations and influence of ion fluence has been discussed. The characteristic emission peaks ⁵D₀→⁷F_J (J=0, 1, 2, 3, 4) of Eu³⁺ ions was recorded in both PL (1×10¹¹–1×10¹³ ions cm^?2) and IL (4.16×10¹²–6.77×10¹² ions cm^?2) spectra. It is observed that PL intensity increases with ion fluence, whereas in IL the peaks intensity increases up to fluence 5.20×10¹² ions cm^?2, then it decreases. A well resolved TL glow peak at ～304 °C was recorded in all the ion bombarded samples at a warming rate of 5 °C s^?1. The TL intensity is found to be maximum at 5 mol% Eu³⁺ concentration. Further, TL intensity increases sub linearly with shifting of glow peak towards lower temperature with ion fluence.     

Luminescence and defect studies of YAlO3:Dy3+, Sm3+ single crystals exposed to 100 MeV Si7+ ion beam

Ionoluminescence (IL) and photoluminescence (PL) spectra for different rare earth ions (Sm³⁺ and Dy³⁺) activated YAlO₃ single crystals have been induced with 100 MeV Si⁷⁺ ions with fluence of 7.81×10¹² ions cm^?2. Prominent IL and PL emission peaks in the range 550–725 nm in Sm³⁺ and 482–574 nm in Dy³⁺ were recorded. Variation of IL intensity in Dy³⁺ doped YAlO₃ single crystals was studied in the fluence range 7.81×10¹²–11.71×10¹² ions cm^?2. IL intensity is found to be high in lower ion fluences and it decreases with increase in ion fluence due to thermal quenching as a result of an increase in the sample temperature caused by ion beam irradiation. Thermoluminescence (TL) spectra were recorded for fluence of 5.2×10¹² ions cm^?2 on pure and doped crystals at a warming rate of 5 °C s^?1 at room temperature. Pure crystals show two glow peaks at 232 (Tg₁) and 328 °C (Tg₂). However, in Sm³⁺ doped crystals three glow peaks at 278 (Tg₁), 332 (Tg₂) and 384 °C (Tg₃) and two glow peaks at 278 (Tg₁) and 331 °C (Tg₂) in Dy³⁺ was recorded. The kinetic parameters (E, b s) were estimated using glow peak shape method. The decay of IL intensity was explained by excitation spike model.     

Li3+ ion irradiation effects on ionic conduction in P(VDF–HFP)–(PC + DEC)–LiClO4 gel polymer electrolyte system

Swift heavy ion irradiation of P(VDF–HFP)–(PC + DEC)–LiClO₄ gel polymer electrolyte system with 48 MeV Li³⁺ ions having five different fluences was investigated with a view to increase the Li⁺ ion diffusivity in the electrolyte. Irradiation with swift heavy ion (SHI) shows enhancement of conductivity at lower fluences and decrease in conductivity at higher fluences with respect to unirradiated polymer electrolyte films. Maximum room temperature (303 K) ionic conductivity is found to be 2.2 × 10^− 2 S/cm after irradiation with fluence of 10¹¹ ions/cm². This interesting result could be ascribed to the fluence-dependent change in porosity and to the fact that for a particular ion beam with a given energy higher fluence provides critical activation energy for cross-linking and crystallization to occur, which results in the decrease in ionic conductivity. The XRD results show decrease in the degree of crystallinity upon ion irradiation at low fluences (≤ 10¹¹ ions/cm²) and increase in crystallinity at high fluences (> 10¹¹ ions/cm²). The scanning electron micrographs (SEM) exhibit increased porosity of the polymer electrolyte films after low fluence ion irradiation.     

First order Raman scattering analysis of transition metal ions implanted GaN

Transition Metal (TM) ions V, Cr, Mn and Co were implanted into GaN/sapphire films at fluences 5×10¹⁴, 5×10¹⁵ and 5×10¹⁶ cm⁻². First order Raman Scattering (RS) measurements were carried out to study the effects of ion implantation on the microstructure of the materials, which revealed the appearance of disorder and new phonon modes in the lattice. The variations in characteristic modes 1GaN i.e. E₂(high) and A₁(LO), observed for different implanted samples is discussed in detail. The intensity of nitrogen vacancy related vibrational modes appearing at 363 and 665 cm⁻¹ was observed for samples having different fluences. A gallium vacancy related mode observed at 277/281 cm⁻¹ for TM ions implanted at 5×10¹⁴ cm⁻² disappeared for all samples implanted with rest of fluences. The fluence dependent production of implantation induced disorder and substitution of TM ions on cationic sites is discussed, which is expected to provide necessary information for the potential use of these materials as diluted magnetic semiconductors in future spintronic devices.     

High-energy ion induced physical and surface modifications in antimony sulphide thin films

Sb₂S₃ thin films prepared by electrodeposition on indium tin oxide coated glass substrate were irradiated with 150 MeV Ni¹¹⁺ ions for various fluence in the range of 10¹¹–10¹³ ions/cm². The modifications in the structure, surface morphology and optical properties have been studied as a function of ion fluence. X-ray diffraction (XRD) analysis indicates a shift in the (2 4 0) peak position towards lower diffraction angle and a decrease in grain size with increase in ion fluence. Presence of microcracks due to irradiation induced grain splitting effect has been observed from the SEM micrograph at higher ion fluence. The optical absorbance spectrum revealed a shift in the fundamental absorption edge and the band gap energy increased from a value of 1.63 eV for as-deposited films to 1.80 eV for the films irradiated with 10¹³ ions/cm².     

100 MeV Si8+ ion induced luminescence and thermoluminescence of nanocrystalline Mg2SiO4:Eu3+

Nanoparticles of Mg₂SiO₄:Eu³⁺ have been prepared by the solution combustion technique and the grain size estimated by PXRD is found to be in the range 40–50 nm. Ionoluminescence (IL) studies of Mg₂SiO₄:Eu³⁺ pellets bombarded with 100 MeV Si⁸⁺ ions with fluences in the range 1.124–22.48×10¹² ions cm^?2 are carried out at IUAC, New Delhi, India. Five prominent IL bands with peaks at 580 nm, 590 nm, 612 nm, 655 nm and 705 nm are recorded. These characteristic emissions are attributed to the luminescence centers activated by Eu³⁺ cations. It is found that IL intensity decreases rapidly in the beginning. Later on, the intensity decreases slowly with further increase of ion fluence. The reduction in the ionoluminescence intensity with increase of ion fluence might be attributed to degradation of Si–O (ν₃) and Si–O (2ν₃) bonds present on the surface of the sample. The red emission with peak at 612 nm is due to characteristic emission of ⁵D₀→⁷F₂ of the Eu³⁺ cations. Thermoluminescence (TL) studies of Mg₂SiO₄:Eu³⁺ pellets bombarded with 100 MeV Si⁸⁺ cations with fluences in the range 5×10¹¹ ions cm^?2 to 5×10¹³ ions cm^?2 are made at RT. Two prominent and well resolved TL glows with peaks at ～220 °C and ～370 °C are observed. It is observed that TL intensity increases with increase of ion fluence. This might be due to creation of new traps during swift heavy ion irradiation.     

Modifications of structural,optical and electrical properties of nanocrystalline bismuth sulphide by using swift heavy ions

Modified chemical bath deposited (MCBD) bismuth sulphide (Bi₂S₃) thin films’ structural, optical and electrical properties are engineered separately by annealing in air for 1 h at 300 °C and irradiating with 100 MeV Au swift heavy ions (SHI) at 5 × 10¹² ions/cm² fluence. It is observed that the band gap of the films gets red shifted after annealing and irradiation from pristine (as deposited) films. In addition, there is an increase in the grain size of the films due to both annealing and irradiation, leading to the decrease in resistivity and increase in thermoemf of the films. These results were explained in the light of thermal spike model.     

Corrosion behavior of tin ions implanted zirconium in 1N H2SO4

In order to study the effect of tin ion implantation on the aqueous corrosion behavior of zirconium, specimens were implanted with tin ions to a fluence ranging from 1 × 10²⁰ to 5 × 10²¹ ions/m², using a metal vapor vacuum arc source (MEVVA) at an extraction voltage of 40 kV. The valence states and depth distributions of elements in the surface layer were analyzed by X-ray photoelectron spectroscopy (XPS) and auger electron spectroscopy (AES) respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the micro-morphology and microstructure of tin-implanted samples. When the fluence was greater than 1 × 10²⁰ ions/m², many small tin balls were produced in the implanted surface. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zirconium in a 1N H₂SO₄ solution. It was found that a significant improvement was achieved in the aqueous corrosion resistance of zirconium implanted with 1 × 10²⁰ ions/m². When the fluence is higher than 1 × 10²⁰ ions/m², the corrosion resistance of zirconium implanted with tin ions decreased compared with that of the non-implanted zirconium. Finally, the mechanism of the corrosion behavior of the tin-implanted zirconium is discussed.     

Highly sensitive hydrogen detection by medium energy Ne+ impact

Hydrogen atoms on solid surfaces were measured directly by elastic recoil detection analysis (ERDA) using medium energy (100–150 keV) Ne⁺ ions with an excellent sensitivity of (～ 1 × 10¹² H/cm²) without any absorber foils and time-of-flight techniques. An electrostatic toroidal analyzer acquired H⁺ ions with energy around 11 keV recoiled from Si(111)-1 × 1-H surfaces. The H⁺ fraction strongly depends upon emerging angle and takes a value more than 50% at the angle below 70° and a saturated value of 17% at the angle above 80° with respect to surface normal. We detected H atoms on the reduced TiO₂(110) exposed to water molecules at room temperature (2 L) and estimated the absolute amount of H to be ～ 2.0 × 10¹⁴ H/cm² corresponding to ～ 38% (～ 0.38 ML) of the bridging oxygen atoms.     

Preparation and characterization of solid polymer electrolytes based on PHEMO and PVDF-HFP

Polymer electrolyte membranes consisting of a novel hyperbranched polyether PHEMO (poly(3-{2-[2-(2-hydroxyethoxy) ethoxy] ethoxy}methyl-3′-methyloxetane)), PVDF-HFP (poly(vinylidene fluoride-hexafluoropropylene)) and LiTFSI have been prepared by solution casting technique. X-ray diffraction of the PHEMO/PVDF-HFP polymer matrix and pure PVDF-HFP revealed the difference in crystallinity between them. The effect of different amounts of PVDF-HFP and lithium salts on the conductivity of the polymer electrolytes was studied. The ionic conductivity of the prepared polymer electrolytes can reach 1.64 × 10^? 4 S·cm^? 1 at 30 °C and 1.75 × 10^? 3 S·cm^? 1 at 80 °C. Thermogravimetric analysis informed that the PHEMO/PVDF-HFP matrix exhibited good thermal stability with a decomposition temperature higher than 400 °C. The electrochemical experiments showed that the electrochemical window of the polymer electrolyte was around 4.2 V vs. Li⁺/Li. The PHEMO/PVDF-HFP polymer electrolyte, which has good electrochemical stability and thermal stability, could be a promising solid polymer electrolyte for polymer lithium ion batteries.     

Modifications in physical,optical and electrical properties of tin oxide by swift heavy Au8+ ion bombardment

Tin oxide thin films were deposited by a novel technique called as modified-SILAR. The preparative parameters were optimized to obtain good quality thin films. As-deposited films were annealed in O₂ atmosphere for 1 h at 500 °C. The annealed films were irradiated using Au⁸⁺ ions with energy of 100 MeV at different fluencies of 1 × 10¹¹, 1 × 10¹², 5 × 10¹² and 1 × 10¹³ ions/cm² using tandem pelletron accelerator. The irradiation-induced modifications in tin oxide thin films were studied using XRD, AFM, optical band gap, photoluminescence and I–V measurements. XRD studies showed formation of tin oxide with tetragonal structure. AFM revealed uniform deposition of the material with increase in grain size after irradiation. Decrease in band gap from 3.51 eV to 2.82 eV was seen with increases in fluency. A decrease in PL intensity, and an additional peak was observed after irradiation. I–V measurements showed a decrease in resistance with fluency.     

Effect of nitrogen ions on the structural,optical, and thermal properties of polyvinyl alcohol/starch blend

This work examines the properties of polyvinyl alcohol (PVA)/starch film containing glycerol as a plasticizer under exposure to different nitrogen ion fluence. The prepared PVA/starch blend was irradiated with ion fluence from 3 × 10¹⁷ to 12 × 10¹⁷ ions.cm⁻². From FTIR, the ion beam irradiation attack and weakens the C–H bond in PVA/starch blend. From XRD findings, the crystallite size of the blend decreased at 3 × 10¹⁷ ions/cm² while it increased at higher fluence up to 9 × 10¹⁷ ions/cm². This indicates the degradation of the blend at low ion fluence compared to crosslinking at high ion fluence. Also, the optical bandgap of the blend was decreased with an increase in ion fluence. Furthermore, the effect of N⁺ ions on some optical dispersion parameters is studied. The thermal stability of the PVA/starch blend shows a decrease in thermal stability upon irradiation with 3 × 10¹⁷ ions/cm² compared to higher thermal stability at higher doses up to 9 × 10¹⁷ ions/cm².     

Oxygen diffusion and surface exchange studies on (La0.75Sr0.25)0.95Cr0.5Mn0.5O3−δ

Oxygen tracer diffusion coefficient (D^⁎) and surface exchange coefficient (k^⁎) have been measured for (La_0.75Sr_0.25)_0.95Cr_0.5Mn_0.5O_3−δ using isotopic exchange and depth profiling by secondary ion mass spectrometry technique as a function of temperature (700–1000 °C) in dry oxygen and in a water vapour-forming gas mixture. The typical values of D^⁎ under oxidising and reducing conditions at ∼ 1000 °C are 4 × 10^− 10 cm² s^− 1 and 3 × 10^− 8 cm² s^− 1 respectively, whereas the values of k^⁎ under oxidising and reducing conditions at ∼ 1000 °C are 5 × 10^− 8 cm s^− 1 and 4 × 10^− 8 cm s^− 1 respectively. The apparent activation energies for D^⁎ in oxidising and reducing conditions are 0.8 eV and 1.9 eV respectively.     

Lithium ion beam impact on selenium nanowires

This study is structured on Li³⁺ ion irradiation effect on the different properties of selenium (Se) nanowires (NW's) (80 nm). Template technique was employed for the synthesis of Se nanowires. Exploration of the effect of 10 MeV Li³⁺ ions on Se NW's was done for structural and electrical analysis with the help of characterization tools. X-ray diffraction revealed the variation in peak intensity only, with no peak shifting. The grain size and texture coefficients of various planes were also found to vary. Current-Voltage characteristics (IVC) show an increment in the conductivity up to a fluence of 1×10¹² ions/cm² and a decrease at the next two fluences. The effects of irradiation are presented in this paper and possible reasons for the variation in properties are also discussed in this study.     

Structural modification of poly(methyl methacrylate) by proton irradiation

A general survey is presented on the structural modification of poly(methyl methacrylate) (PMMA) by proton implantation. The implanted PMMA films were characterized by FT-IR attenuated total reflection (FT-IR ATR), Raman, Rutherford backscattering spectroscopy (RBS), gel permeation chromatography (GPC) and surface profiling. The ion fluence of 350 keV protons ranged from 2×10¹⁴ to 1×10¹⁵ ions/cm². The IR and Raman spectra showed the reduction of peaks from the pendant group of PMMA. The change of absorption and composition was observed by UV–VIS and RBS, respectively. These results showed that the pendant group is readily decomposed and eliminated by proton irradiation. The change of molecular weight distribution was also measured by GPC and G-value of scission was estimated to be 0.67.     

Two photon absorption characteristics of bulk GaTe crystal

We have investigated the structural and optical properties of bulk GaTe crystal grown by vertical Bridgman method. Two photon absorption (TPA) properties of GaTe crystal have been investigated by the open aperture Z-scan technique under 1064 nm wavelength with 4 ns or 65 ps pulse durations. The TPA coefficients are greater in ns regime than that of ps regime. Upon increasing intensity of incident light from 5.02×10⁷ W/cm² to 1.07×10⁸ W/cm², the TPA coefficients increased from 3.47×10^?6 cm/W to 8.53×10^?6 cm/W for nanosecond excitation. Similarly, when intensity of incident light was increased from 6.81×10⁸ W/cm² to 9.94×10⁸ W/cm² the TPA coefficients increased from 3.53×10^?7 cm/W to 6.83×10^?7 cm/W for picosecond excitation. Measured TPA coefficient of GaTe crystal is larger than that of GaSe and GaS layered crystals.     

Optical and electrical properties of Ge-implanted SiO2 layers on n-Si and p-Si

Ge ions of 100 keV were implanted into a 120 nm-thick SiO₂ layer on n-Si at room temperature while those of 80 keV were into the same SiO₂ layer on p-Si. Samples were, subsequently, annealed at 500°C for 2 h to effectively induce radiative defects in the SiO₂. Maximum intensities of sharp violet photoluminescence (PL) from the SiO₂/n-Si and the SiO₂/p-Si samples were observed when the samples have been implanted with doses of 1×10¹⁶ and 5×10¹⁵ cm⁻², respectively. According to current–voltage (I–V) characteristics, the defect-related samples exhibit large leakage currents with electroluminescence (EL) at only reverse bias region regardless of the type of substrate. Nanocrystal-related samples obtained by an annealing at 1100°C for 4 h show the leakage at both the reverse and the forward region.     

Study on the bias-dependent effects of proton-induced damage in CdZnTe radiation detectors using ion beam induced charge microscopy

The influence of damage induced by 2 MeV protons on CdZnTe radiation detectors is investigated using ion beam induced charge (IBIC) microscopy. Charge collection efficiency (CCE) in irradiated region is found to be degraded above a fluence of 3.3 × 10¹¹ p/cm² and the energy spectrum is severely deteriorated with increasing fluence. Moreover, CCE maps obtained under the applied biases from 50 V to 400 V suggests that local radiation damage results in significant degradation of CCE uniformity, especially under low bias, i. e., 50 V and 100 V. The CCE nonuniformity induced by local radiation damage, however, can be greatly improved by increasing the detector applied bias. This bias-dependent effect of 2 MeV proton-induced radiation damage in CdZnTe detectors is attributed to the interaction of electron cloud and radiation-induced displacement defects.     

Electrical and dielectric properties of β-BaB2O4 (BBO) and CsLiB6O10 (CLBO) crystals

In barium borate (BBO) crystals, sodium and potassium ions, inherited due to the preparation technique, are dominant charge carriers. The conductivity between layers is higher; the conductivity activation energy and the conductivity at 350 °C being equal to 1.01±0.05 eV and (1.3±0.2)×10⁻⁸ S/cm, respectively. The conductivity activation energy and the conductivity at 350 °C along the channels are equal to 1.13±0.05 eV and to (4±0.2)×10⁻⁹ S/cm, respectively. Relative static permittivity is almost isotropic, and equal to 7.65±0.05. Upon storing of cesium–lithium borate (CLBO) crystals, pre-heating to 600 °C eliminates the influence of surface humidity. At 500 K, the ionic conductivity ranges from 4×10⁻¹² to 2×10⁻¹⁰ S/cm; the conductivity activation energy ranges from 1.01 to 1.17 eV. Relative static permittivity is equal to 7.4±0.3.     

Structural and optical properties of Ge nanocrystals obtained by hot ion implantation into SiO2 and further ion irradiation

In this work, SiO₂ layers containing Ge nanocrystals (NCs) obtained by the hot implantation approach were submitted to an ion irradiation process with different 2 MeV Si⁺ ion fluences. We have investigated the photoluminescence (PL) behavior and structural properties of the irradiated samples as well as the features of the PL and structural recovery after an additional thermal treatment. We have shown that even with the highest ion bombardment fluence employed (2×10¹⁵ Si/cm²) there is a residual PL emission (12% from the original) and survival of some Ge NCs is still observed by transmission electron microscopy analysis. Even though the final PL and mean diameter of the nanoparticles under ion irradiation are independent of the implantation temperature or annealing time, the PL and structural recovery of the ion-bombarded samples have a memory effect. We have also observed that the lower the ion bombardment fluence, the less efficient is the PL recovery. We have explained such behavior based on current literature data.