Irradiated Mica Research Articles

High resolution AFM studies of irradiated mica—following the traces of swift heavy ions under grazing incidence

High resolution AFM imaging of swift heavy ion irradiated muscovite mica under grazing incidence provides detailed insight into the created nanostructure features. Swift heavy ions under grazing incidence form a complex track structure along the surface, which consists of a double track of nanohillocks at the impact site accompanied by a single, several 100 nm long protrusion. Detailed track studies by varying the irradiation parameters, i.e. the angle of incidence (0.2°–2°) and the kinetic energy of the impinging ions (23, 55, 75, 95 MeV) are presented. Moreover, the track formation in dependence of the sample temperature (between room temperature and 600 °C) and of the chemical composition (muscovite mica and fluorphlogopite mica) is studied.

Investigations of nano-defect morphology and vibrational spectra of swift heavy ion irradiated muscovite mica

Muscovite mica sheets with a thickness of 12 μm were irradiated by various kinds of swift heavy ions in Heavy Ion Research Facility in Lanzhou (HIRFL). During the irradiation process, the fluence was kept in the range 1 × 1010–1 × 1012 ions/cm2, whereas the electronic stopping power Se was in the range from 5.9 to 31.5 keV/nm. The vibrational modifications in irradiated mica were investigated by Fourier-transform infrared (FTIR) spectroscopy and the morphology of the nano-defects on the surface of mica was analyzed by the atomic force microscopy (AFM) in the tapping mode. The infrared spectrum showed that motions from all atomic types in the muscovite mica structure could be found in modes for all vibrations. The intensity of all observed vibrational modes, including the OH stretching motion at 3621 cm−1, was found to decrease with increasing Se values and ion fluences. It was indicated that formation of the defects and structural modifications take place in muscovite mica as a result of swift heavy ion irradiation, and it was found that more defects were introduced in mica by irradiation with higher ion fluences and higher electronic stopping power Se values. The morphology of nano-defects on the surface of mica that depends on the applied Se was discussed in detail this work. Craters were observed in the samples irradiated by Xe ions with electronic stopping power of 21.8 keV/nm or by Bi ions with electronic stopping power of 31.5 keV/nm. While the hillocks with craters on the top were found on the surface of mica irradiated by Kr ions with Se values of 9.0 keV/nm.

Physicochemical variation of mica surface by low energy ion beam irradiation

We report the transformation of smooth and hydrophilic mica surface to a patterned and hydrophobic surface by 12 keV Ar+ and N+ ion bombardment at oblique ion incidence. Periodic ripple pattern has been found on the mica surface when nitrogen like lighter or argon like heavier ions are bombarded at an angle 60° with respect to the surface normal. During ion bombardment the different components of multi-elemental mica are eroded at different rate; as a result surface chemistry is changed, as well as a surface ripple pattern is developed on the surface due to the generation of surface instabilities. The change of surface chemistry and presence of pattern change the hydrophilic nature of the mica surface. X-ray photoelectron spectroscopy (XPS) study of irradiated mica surface shows that the upper K atoms are sputtered most. The vertical and lateral dimensions of the surface patterns are controlled by varying the ion fluence. Contact angle measurement of un-irradiated and irradiated mica surface shows a certain change from hydrophilicity to hydrophobicity. The physicochemical changes of mica surface due to Ar+ and N+ ion bombardment have been discussed.

Structural modification in swift heavy ion irradiated muscovite mica**Project supported by the National Natural Science Foundation of China (Grant Nos. 11675233 and 11505243).

Two-layer monoclinic (2M) muscovite mica sheets with a thickness of 12 μm are irradiated with Sn ions at room temperature with electronic energy loss (dE/dx)e of 14.7 keV/nm. The ion fluence is varied between 1×1011 and 1×1013 ions/cm2. Structural transition in irradiated mica is investigated by x-ray diffraction (XRD). The main diffraction peaks shift to the high angles, and the inter-planar distance decreases due to swift heavy ion (SHI) irradiation. Dehydration takes place in mica during SHI irradiation and mica with one-layer monoclinic (1M) structure is thought to be generated in 2M mica after SHI irradiation. In addition, micro stress and damage cross section in irradiated mica are analyzed according to XRD data. High resolution transmission electron microscopy (HRTEM) is used on the irradiated mica to obtain the detailed information about the latent tracks and structural modifications directly. The latent track in mica presents an amorphous zone surrounded by strain contrast shell, which is associated with the residual stress in irradiated mica.

Effects of swift heavy ion irradiation parameters on optical properties of muscovite mica

Muscovite mica sheets with a thickness of 25μm were irradiated by various kinds of swift heavy ions (Sn, Xe and Bi) in HIRFL (Heavy Ion Research Facility in Lanzhou). The fluences ranged from 1×1010 to 8×1011ions/cm2 were applied. The electronic energy loss (dE/dx)e in mica was changed from 14.7 to 31.2keV/nm. The band gaps and Urbach energy of pristine and irradiated mica were analyzed by ultraviolet–visible spectroscopy (UV–Vis). A red shift of the absorption edge was found in the absorption spectra of muscovite mica irradiated by ions with increasing (dE/dx)e. The results show that the chemical bonds between Tetrahedral–Octahedral–Tetrahedral (TOT) layers of mica were destroyed by ion irradiation. With increasing (dE/dx)e and fluences, the band gaps became narrow and the Urbach energy increased. It suggests that the amount of defects and the proportion of amorphous structure were increased in mica irradiated with increasing (dE/dx)e and fluences.

Dielectric relaxation of gamma irradiated muscovite mica

In the present research, the dielectric relaxation of gamma irradiated muscovite mica was studied in the frequency range of 0.1Hz–10MHz and temperature range of 653–853K, using the dielectric permittivity, electric modulus and conductivity formalisms. The dielectric constants (ϵ′ and ϵ′′) are found to be high for gamma irradiated muscovite mica as compared to the pristine sample. The frequency dependence of the imaginary part of complex electric modulus (M′′) and dc conductivity data conforms Arrhenius law with single value of activation energy for pristine sample and two values of activation energy for gamma irradiated mica sample. The experimentally assessed electric modulus and conductivity information have been interpreted by the Havriliak–Negami dielectric relaxation explanation. Using the Cole–Cole framework, an analysis of real and imaginary characters of the electric modulus for pristine and gamma irradiated sample was executed which reflects the non-Debye relaxation mechanism.

Gamma-radiation-induced dielectric relaxation characteristics of layered crystals of phlogopite mica

In the present investigation, the influence of gamma irradiation on the dielectric relaxation characteristics of phlogopite mica was studied over the frequency range of 0.1Hz–10MHz and in the temperature range of 593–813K by measuring the dielectric permittivity, electric modulus and conductivity. By comparing the dielectric spectra obtained for pristine and irradiated samples, it was observed that gamma irradiation significantly enhances the dielectric constants (ε′ and ε″) of phlogopite mica because of the production of defects and lattice disorder by the gamma irradiation. The values of the activation energy for pristine and irradiated mica (determined from the electric modulus and the conductivity) were found to be substantially similar, suggesting that the same types of charge carriers are involved in the relaxation mechanism. The experimentally measured electric modulus and conductivity data could be well interpreted by the Havriliak–Negami dielectric relaxation function. The scaling of the electric-modulus spectra of both pristine and irradiated mica results in a master curve, which indicates that the relaxation mechanism is independent of temperature. Cole–Cole plots were also employed to analyze the non-Debye relaxation mechanism. This research will boost the reader’s interest concerning the emerging contributions of irradiation and materials such as mica in electrical engineering.

Morphology of heavy ions irradiated mica

The samples of natural mica (muscovite and biotite) were irradiated with energetic heavy ions [ 136Xe (11.56 MeV/n) and 197Au (11.40 MeV/n)] from universal linear accelerator (UNILAC) GSI, Darmstadt, Germany. The simple track etch technique has been used to develop and analyze the morphology of induced heavy ions and natural alpha recoil tracks with the help of atomic force microscopy. Defective structure and lattice disorder have been observed in the environs of the etch pits in these layered crystalline materials. The distribution of defects produced along the tracks, geometrical analysis of tracks shapes and shallowness and their correlations with the structural arrangement of the materials have been discussed in the present investigation. Importance of different ion track geometries in micaceous minerals for the fabrication of nanoterrace material with different stacks having sharp edges with unique properties has been elaborated in the present paper.

Friction force microscopy of heavy-ion irradiated mica

The effects of energetic heavy ions passing through a solid are reflected in the size, shape, and structure of individual latent tracks. Their detailed study thus provides information on the primary processes of energy deposition, which results in bond breaking, lattice disruption, and increased chemical reactivity. Furthermore, ion track cross sections, being objects very limited in size, are well suited for studies of material properties such as friction on a nanometer scale. The present work displays results of scanning force microscopy of mica, irradiated with 11.4 MeV/u Pb28+ and Xe21+ ions at the UNILAC heavy-ion accelerator of the Gesellschaft für Schwerionenforschung. Their track diameters were determined to be 10.6 and 7.5 nm, respectively. Recording topographical and lateral force data simultaneously allows one to quantify the contribution of friction to topographic images. In this way the kinetic friction coefficient of the sensor (Si3N4) on the sample (mica) was measured. It was found that the value obtained from the latent track area and from the intact mica lattice differ by a factor of 2.

Polymer composites containing plasma‐treated mica. I. Flow and mechanical properties

AbstractSuzorite mica has been surface modified by microwave plasma treatment in ethylene gas. The surface‐treated mica was used as a filler in polyethylene, polystyrene, and a mixture of these two polymers. Significant changes in rheological behavior ensue. These indicate that adhesion between polyethylene and irradiated mica is superior to that of interfaces using unirradiated mica. In contrast, ethylene irradiation reduces the ability of filled polystyrene compounds to store elastic energy in melt flow, an effect consistent with impaired adhesion at interfaces involving these components. An intermediate situation exists in the case of the two‐polymer blend. The tensile properties of these systems also reflect surface treatment, reinforcement occurring in polyethylene‐containing compounds, while the tensile properties of polystyrene composites deteriorate. Plasma‐induced surface modifications of fillers to produce desired property changes in specified polymer matrixes are implied by the present work, but a fuller understanding of the chemistry of surface modification reactions is needed to substantiate these implications.