Temperature and frequency dependent electrical properties of 50 MeV Li3+ ion irradiated polymeric blends

The polymeric blends of polyvinyl chloride (PVC) and polyethylene terephthalate (PET) with equal composition by weight have been irradiated with 50 MeV Li³⁺ ions at different fluences. The AC electrical properties of polymeric blends were measured in the frequency range 0.05–100 kHz, and at temperature range 40–150 ^°C using LCR meter. There is an exponential increase in conductivity with log of frequency and effect is significant at higher fluences. The value of tan δ and dielectric constant are observed to change appreciably due to irradiation. The loss factor (tan δ) versus frequency plot suggests that the capacitors of polymeric blend of PVC and PET may be useful below 10 kHz. No change in dielectric constant was observed over a wide temperature range up to 150 ^°C. Thermal stability was studied by thermogravimetric analysis. Thermal analysis revealed that chain scission is the dominant phenomena in the polymeric blends resulting in the reduction of its thermal stability. It appears from differential scanning calorimetry studies that the melting temperature decreases as fluence increases. FTIR spectra measurements also revealed that the material suffered severe degradation through bond breaking beyond the fluence of 2.3×10¹³ ions/cm².     

Induced Electronic and Thermal Effects of 86 MeV Nickel Ions in Bisphenol-A Polycarbonate

Bisphenol-A polycarbonate films were irradiated with 86 MeV swift heavy nickel ions at varying fluences, ranging from 1 × 10¹¹ to 1 × 10¹³ ions cm^?2, under vacuum at room temperature, to analyze the induced electrical and thermal modifications. AC conductivity measurements and UV-visible spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques were applied to analyze the changes. A significant, exponential increase in conductivity at higher frequency was observed with the increase of nickel ion fluence. UV-visible analysis corroborated the results of the AC conductivity measurement, revealing the increase in size of the carbon clusters embedded in the polymer network, with the increase of heavy ion fluence. FTIR analysis revealed the formation of alkene and alkyne end groups at higher doses, which further supported the suggestion that the variation in electrical properties induced by the ion irradiation of the polymer was due to development of a carbonaceous phase inside the polymer due to the irradiation. Thermal analysis, i.e., TGA and DSC patterns, showed that chain-scission was the leading phenomena in the heavy ion-irradiated polycarbonate samples, resulting in degradation of their thermal stability.     

AC electrical properties of proton irradiated EVA films

MeV ions passing through polymeric films modify their electrical, optical and thermal properties and these changes are related to changes in the chemical structure of the polymers. Ethylene vinyl acetate (EVA) films were irradiated with 3 MeV proton beam at different fluences of 10¹³, 10¹⁴ and 10¹⁵ ions/cm². AC electrical properties of pristine and irradiated samples were studied in the frequency range 100 Hz to 100 kHz by means of an LCR meter. There is an exponential increase in conductivity with log frequency and conductivity increases as fluence increases. The dielectric loss/constant is observed to change with the fluence. FTIR spectra reveals significant change in intensities of functional groups at a fluence of 10¹⁵ ions/cm² due to scissioning of polymer chains.     

Optical and electrical properties of swift heavy ion beam-irradiated polycarbonate/polystyrene bilayer films

Polycarbonate/polystyrene bilayer films prepared by solvent-casting method were irradiated with 55 MeV carbon ion beam at different fluences ranging from 1×10¹¹ to 1×10¹³ ions cm^?2. The structural, optical, surface morphology and dielectric properties of these films were investigated by X-ray diffraction (XRD), UV–visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, optical microscopy and dielectric measurements. The XRD pattern shows that the percentage of crystallinity decreases while inter-chain separations increase with ion fluence. UV–visible spectroscopy shows that the energy band gap decreases and the number of carbon atoms in nanoclusters increase with the increase in ion fluences. The refractive index is also found to decrease with the increase in the ion fluence. Optical microscopy shows that after irradiation polymeric bilayer films color changes with ion fluences. The FTIR spectra evidenced a very small change in cross-linking and chain scissoring at high fluence. Dielectric constant decreases while dielectric loss and AC conductivity increase with ion fluences.     

Surface and Bulk Structure Characterization of Proton (3 MeV) Irradiated Polycarbonate

Polycarbonate (Makrofol‐N) thin films were irradiated with protons (3 MeV) under vacuum at room temperature with the fluence ranging from 1×10¹⁴ to 1×10¹⁵ protons cm^?2. The change in surface morphology, optical properties, degradation of the functional groups, and crystallinity of the proton‐irradiated polymers were investigated with atomic force microscopy (AFM), UV‐VIS, and Fourier‐transform infrared (FTIR) spectroscopy, and X‐ray diffraction (XRD) techniques, respectively. AFM shows that the root mean square (RMS) roughness of the irradiated polycarbonate surface increases with the increment of ion fluence. The UV‐VIS analysis revealed that in Makrofol‐N the optical band gap decreased by 30% at highest fluence of 1×10¹⁵ protons cm^?2. The band gap can be correlated to the number of carbon atoms, M, in a cluster with a modified Robertson's equation. The cluster size in the proton‐irradiated Makrofol‐N increased from 112 to 129 atoms with the increase of fluence from 1×10¹⁴ to 1×10¹⁵ protons cm^?2. FTIR spectra of proton (3 MeV) irradiated Makrofol‐N showed a strong decrease of almost all absorption bands at about 1× 10¹⁴ protons cm^?2. However, beyond a higher critical dose an increase in intensity of almost all characteristic bands was noticed. The appearance of a new peak at 3,500 cm^?1 (‐OH groups) was observed at the higher fluences in the FTIR spectra of proton‐irradiated polycarbonate. XRD measurements showed an increase of full width at half maximum (FWHM) and the average intermolecular spacing of the main peak, which may be due to the increase of chain scission and the introduction of ‐OH groups in the proton irradiated polycarbonate.     

N+ Implantation-Induced Surface Hardening of Poly (Allyl Diglycol Carbonate) Polymer

The effect of 100 keV N⁺ ions implantation on the surface structure and hardness of poly (allyl diglycol carbonate) (CR-39) polymer was studied. The surface hardness of virgin and implanted CR-39 specimens was determined using a Knoop microhardness test. The surface hardness was found to be enhanced after implantation, e.g., becoming eight times higher at a load of 9.8 mN, for a dose of 2 × 10¹⁶ ions cm^?2. The change in bonding and surface structure of the CR-39 polymer due to implantation was studied using the specular reflectance Fourier transform infrared (FTIR) technique. The disordering produced in the implanted matrix was estimated using the Urbach edge method from the UV-Visible absorption spectra. The relationship of surface hardening with the chemical and structural changes was explored     

Ion beam modification of surface properties of CR-39

The effects of ion-beam bombardment on the physical and chemical properties of poly(allyl diglycol carbonate) (CR-39) polymer have been investigated. CR-39 samples were bombarded with 320 keV Ar and 130 keV He ions at fluences ranging from 1 × 10¹³ to 2 × 10¹⁶ ions/cm². The nature and extent of radiation damage induced were studied by UV–VIS spectrometry, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, as well as Vickers' hardness measurements. In addition, the effect of ion fluence on the wetting properties of ion-beam bombarded CR-39 polymer was determined by measuring the contact angle for distilled water. UV–VIS spectra of bombarded samples reveal that the optical band gap decreases with increasing ion fluence for both Ar and He ions. In the FTIR spectra, changes in the intensity of the bands on irradiation relative to pristine samples occurred with the appearance of new bands. XRD analyses showed that the degree of ordering of the CR-39 polymer is dependent on the ion fluence. Changes of surface layer composition and an increase in the number of carbonaceous clusters produced important change in the energy gap and the surface wettability. The surface hardness increased from 10.54 MPa for pristine samples to 28.98 and 23.35 MPa for samples bombarded with Ar and He ions at the highest fluence, respectively.     

Photoluminescent and thermal behavior of 120 MeV silicon and 84 MeV oxygen ion irradiated PVDC

Photoluminescent, structural and thermal changes induced in polyvinylidenechloride (PVDC) films by irradiation with energetic silicon and oxygen ions have been determined using different techniques viz PL, FTIR, UV-vis, XRD, TGA and AFM. Noticeable photoluminescence was observed in PVDC after irradiation with 84 MeV oxygen ions at fluence 3.2×10¹¹ ions cm⁻², which is attributed to the small carbon cluster formed in the polymer due to irradiation. Quenching and shifting in the position of the PL band towards the longer wavelength side of the spectrum was observed with the increase in ion fluence. UV-vis and FTIR analysis have strongly corroborated the results of PL spectroscopy. X-ray diffractograms and TGA curves show decrease in crystallinity and weight loss, respectively, of PVDC films after irradiation. The strong correlation between the behaviors of different properties were analyzed and discussed in the present paper.     

Radiation damage in triglycine sulphate due to fast neutron irradiation

Abstract

The change in electrical properties of TGS crystals due to induced defects created by fast neutron irradiation of two different energies (2 and 14 MeV) and different integrated neutron fluxes have been studied in the vicinity of phase transition. It is observed that the electrical conductivity increases with increase of neutron fluence up to 1.7 × 10¹⁰ n · cm^?2 and the values of the relative change of electrical conductivity in case of 2 MeV are higher than that of 14 MeV neutrons at the same neutron fluence (φ)     

Carbon (70 MeV) and copper (120 MeV) ions irradiation effects in Makrofol-N

Makrofol-N polycarbonate was irradiated with carbon (70 MeV) and copper (120 MeV) ions to analyze the induced effects with respect to optical and structural properties. In the present investigation, the fluence for carbon and copper beams was kept in the range of 1×10¹¹– 1×10¹³ ions/cm² to study the swift heavy ion induced modifications. UV–VIS, FTIR and XRD techniques were utilized to study the induced changes. The analysis of UV–VIS absorption studies revealed that the optical energy gap was reduced by 17% on carbon irradiation, whereas the copper beam leads to a decrease of 52% at the highest fluence of 1×10¹³ ions/cm². The band gap can be correlated to the number of carbon atoms, N, in a cluster with a modified Robertson's equation. In copper (120 MeV) ions irradiated polycarbonate, the number of carbon atoms in a cluster was increased from 63 to 269 with the increase of ion fluence from 0 to 1×10¹³ ions/cm², whereas N is raised only up to 91 when the same polymer films were irradiated with carbon (70 MeV) ions under similar conditions. FTIR analysis showed a decrease in almost all characteristic absorption bands under irradiation. The formation of hydroxyl (? OH) and alkene (C?C) groups were observed in Makrofol-N at higher fluence on irradiation with both types of ions, while the formation alkyne end (R? C≡ CH) group was observed only after copper ions irradiation. The radii of the alkyne production of about 3.3 nm were deduced for copper (120 MeV) ions. XRD measurements show a decrease in intensity of the main peak and an increase of the average intermolecular spacing with the increase of ion fluence, which may be attributed to the structural degradation of Makrofol-N on swift ion irradiation.     

Optical phase locking of two extended-cavity diode lasers with ultra-low phase noise for atom interferometry

We present a phase coherent laser system with ultra-low phase noise with a frequency difference of 6.9 GHz. The laser system consists of two extended-cavity diode lasers that are optically phase-locked with electrical feedback to the injection current of a slave laser. The bandwidth of the optical phase-locking loop is extended up to 8 MHz. We achieve the residual phase noise of two phase-locked lasers of below ?120 dBrad²/Hz in the offset frequency range of 100 Hz–350 kHz and a flat phase noise of ?127 dBrad²/Hz from 700 Hz to 20 kHz. These results are, to the best of our knowledge, the lowest phase noise level ever reported with two extended-cavity diode lasers.     

Incorporation of NH<Subscript>4</Subscript>NO<Subscript>3</Subscript> into MC-PVA blend-based polymer to prepare proton-conducting polymer electrolyte films

Proton-conducting solid polymer blend electrolytes based on methylcellulose-polyvinyl alcohol:ammonium nitrate (MC-PVA:NH₄NO₃) were prepared by the solution cast technique. The structural and electrical properties of the samples were examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and electrical impedance (EI) spectroscopy. The shifting and change in the intensity of FTIR bands of the electrolyte samples confirm the complex formation between the MC-PVA polymer blend and the NH₄NO₃ added salt. The observed broadening in the XRD pattern of the doped samples reveals the increase of the amorphous fraction of polymer electrolyte samples. The increase in electrical conductivity of polymer electrolyte samples with increasing salt concentration attributed to the formation of charge-transfer complexes, and to increase in the amorphous domains. A maximum ionic conductivity of about 7.39 × 10^?5 S cm^?1 was achieved at room temperature for the sample incorporating 20 wt% of NH₄NO₃. The DC conductivity of the present polymer system exhibits Arrhenius-type dependence with temperature. The decrease in the values of activation energies with increasing salt concentration indicates the ease mobility of ions. The decrease in dielectric constant with increasing frequency was observed at all temperatures. Optical properties such as absorption edge, optical band gap, and tail of localized state were estimated for polymer blend and their electrolyte films. It was found that the optical band gap values shifted towards lower photon energy from 6.06 to 4.75 eV by altering the NH₄NO₃ salt content.     

Enhancement in electrochemical properties of ionic liquid-based nanocomposite polymer electrolytes by 100 MeV Si9+ swift heavy ion irradiation

Swift heavy ion (SHI) irradiation has been used as a tool to enhance the electrochemical properties of ionic liquid-based nanocomposite polymer electrolytes dispersed with dedoped polyaniline (PAni) nanorods; 100 MeV Si⁹⁺ ions with four different fluences of 5?×?10¹⁰, 1?×?10¹¹, 5?×?10¹¹, and 1?×?10¹² ions cm^?2 have been used as SHI. XRD results depict that with increasing ion fluence, crystallinity decreases due to chain scission up to fluence of 5?×?10¹¹ ions cm^?2, and at higher fluence, crystallinity increases due to cross-linking of polymer chains. Ionic conductivity, electrochemical stability, and dielectric properties are enhanced with increasing ion fluence attaining maximum value at the fluence of 5?×?10¹¹ ions cm^?2 and subsequently decrease. Optimum ionic conductivity of 1.5?×?10^?2 S cm^?1 and electrochemical stability up to 6.3 V have been obtained at the fluence of 5?×?10¹¹ ions cm^?2. Ac conductivity studies show that ion conduction takes place through hopping of ions from one coordination site to the other. On SHI irradiation, amorphicity of the polymer matrix increases resulting in increased segmental motion which facilitates ion hopping leading to an increase in ionic conductivity. Thermogravimetric analysis (TGA) measurements show that SHI-irradiated nanocomposite polymer electrolytes are thermally stable up to 240–260 °C.     

Structural,optical and electrical properties of 60 MeV C5+ ion-irradiated poly(3-methylthiophene) films

The structural, optical and electrical properties of 60 MeV C⁵⁺ ion-irradiated poly(3-methylthiophene) (P3MT) synthesized by the chemical oxidation polymerization method have been studied. The P3MT powder was dissolved in chloroform (CHCl₃), and thin films of thickness 2 μm were prepared on glass and Si substrates. The polymerization was confirmed by the FTIR spectrum. Then films were irradiated by 60 MeV C⁵⁺ ions at different fluences. FTIR spectra show methyl group evolution after irradiation. The optical band gap decreases slightly after irradiation and the DC conductivity increases by about one order of magnitude after irradiation at the highest fluence. The role of S _e has also been discussed when compared with 60 MeV Si⁵⁺ ion irradiation of P3MT. The morphological changes are observed using SEM.     

Raman scattering and electrical studies of the phase stability in the Hg<Subscript>1−x</Subscript>Cd<Subscript>x</Subscript>Te

Raman scattering is performed to access phase stability in the boron-implanted Hg_0.7Cd_0.3Te with fluences ranging from 1 × 10¹² to 1 × 10¹⁵ cm^?2. Threshold fluence for the formation of an amorphous phase is invoked here using Thomas–Fermi statistical model. Asymmetric broadening and red shift of the Raman active HgTe-like LO phonon mode are observed with varying fluencies. Electrical properties such as sheet carrier concentration and mobility are also changed with the fluence and reach their saturated values beyond threshold fluence of 5 × 10¹³ cm^?2. Threshold fluence for the formation of amorphous phase is also validated by the Raman measurements and electrical transport properties in the implanted layers. The excess free energy of 6.8 kJ/mole is found corresponding to the threshold fluence for phase transition.     

Preparation and characterization of hexagonal boron nitride and PAMPS-NMPA-based thin composite films and investigation of their membrane properties

The preparation, thermal, morphological, and ion-conducting properties of new composite membranes based on poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) and nitrilotri(methylphosphonic acid) (NMPA)/hexagonal boron nitride (hBN) were carried out throughout this work. Fourier transform infrared (FTIR) spectroscopy was used to characterize the interactions between host polymer, NMPA, and inorganic additive, hBN. Thermal properties of the materials were examined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) tests. TGA results illustrated that all composite membranes are thermally stable up to 200 °C. The surface topography of the films was investigated by scanning electron microscopy (SEM) and verified that hBN uniformly dispersed into the PAMPS-NMPA matrix. The crystallinity of the membranes was characterized by using X-ray diffraction (XRD). X-ray patterns support semicrystalline nature of the composite materials. At anhydrous conditions, the maximum proton conductivity was found as 3.2?×?10^?5 S cm^?1 at 150 °C for PAMPS-NMPA-3hBN via impedance analyzer.     

Effect of swift heavy ion irradiation on thermal,optical and structural properties of poly vinylidene chloride

Poly vinylidene chloride (PVDC) irradiated with lithium (50 MeV), carbon (85 MeV), nickel (120 MeV) and silver ions (120 MeV) having fluence range of 1 × 10¹¹ ions/cm² to 3 × 10¹² ions/cm² have been studied using different techniques i.e. XRD (X-ray diffraction), FTIR (Fourier transform infrared), UV–Visible and TGA (thermo-gravimetric analysis). In XRD analysis, the intensity of diffraction peaks of PVDC irradiated with lithium ions was enhanced at lower fluence as compared to pristine. The shift in optical absorption edge in irradiated PVDC was correlated with the decrease in optical band gap energy. The distinguishable characteristic peaks were observed due to UV–Vis analysis, in lithium irradiated samples of PVDC at higher fluences. The % age decrease in optical band gap energy for the respective ions were 30.9%, 34.16%, 81.1%, 87.02% respectively. Formation of double carbon bonds and breaking of C–O and C–Cl bonds with the release of Cl in irradiated PVDC was observed in FTIR spectra. In Thermogravimetric analysis (TGA), the % age weight loss observed for irradiated samples with increase in ion fluence was lesser than the % age weight loss observed in pristine sample.     

Effect of Zn substitution on the electrical properties of Bi2Co0.1V0.9O5.35 synthesized by sol-gel method

Samples of Bi₂V_0.9Co_0.1-xZn_xO_5.35, 0.02 ≤ x ≤ 0.08 with layered Aurivillius structure were synthesized successfully by sol-gel citrate method. Structural and electrical characterization of compositions has been investigated by X-ray diffraction, thermogravimetric analysis–differential scanning calorimetric (TGA–DSC) analysis and AC impedance spectroscopy. The tetragonal γ phase has been observed for all investigated samples. The AC impedance response of samples has been measured in the frequency range of 20 Hz to 1 MHz. The impedance for pellets decreases as thermal energy increases. The contribution of grain to the conduction process is more than that of grain boundary. The ionic conductivity and dielectric permittivity are found to be composition-dependent and increase with increasing Zn concentration. The maximum electrical conductivity observed for the composition x = 0.08 is σ = 4.51 × 10^?4 S cm^?1 at 300 °C.     

Swift heavy ion induced photoluminescence studies in Aluminum oxide

Aluminum oxide, a promising material for high temperature applications, is synthesized by combustion route and characterized by X-ray diffraction technique. Photoluminescence of aluminum oxide bombarded with 120 MeV swift Au⁹⁺ ions have been studied at room temperature. The observed PL emission with peak at ～420 nm is attributed to F-center while the two more weak emissions with peaks at ～482 and ～525 nm are attributed to aggregates of F-centers. It is found that PL intensity increases with increase in Au⁹⁺ ion fluence up to ～1×10¹³ ions cm^?2 and thereafter it reaches saturation. The Fourier transform Infrared spectroscopy results show the destruction of Al?O?H bonds whereas the XRD results indicate the surface amorphization of Al₂O₃.     

Irradiation effects of 12 eV oxygen ions on polyimide and fluorinated ethylene propylene

Polyimide (PI) and Fluorinated Ethylene Propylene (FEP) samples (15 mm×15 mm×50 μm ) were exposed to atomic oxygen ions of average energy ～12 eV and flux ～5×10¹³ ions cm ^?2 s ^?1, produced in the Electron Cyclotron Resonance (ECR) plasma. The energy and the flux of the oxygen ions at different positions in the plasma were measured by a retarding field analyzer. The fluence of the oxygen ions was varied from sample to sample in the range of ～5×10¹⁶ to 2×10¹⁷ ions cm ^?2 by changing the irradiation period. The pre- and the post-irradiated samples were characterized by the weight loss, Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transform Infrared (FTIR) techniques. The weight of the PI and FEP samples decreased with increasing the ion fluence. However, the erosion yield for the PI is found to be higher, by almost a factor five, when compared with that of FEP. On the surface region of irradiated samples, the concentrations of the carbon, fluorine, and oxygen and their corresponding chemical bonds have changed appreciably. Moreover, blisters and nanoglobules were also observed even at a fluence of ～10¹⁷ ions cm ^?2. This oxygen ion fluence is almost two orders of magnitude lower than that of the 5 eV atomic oxygen, which a satellite encounters in the space, at the low Earth orbit, during its mission period of about 7 years.