Many of you will join traditional, large industries in manufacturing, infrastructure, energy, transportation and electronics. Others may find opportunities in hi-tech industries that have emerged in the last 2 decades, both in production as well as in development. For more information on materials related activities see the web sites of the Department of Materials Engineering and the Materials Research Centre.
Frontier research on physical phenomena in chemistry, biology and materials science
Materials science is truly interdisciplinary, and the IISc website will guide you to materials-related research in chemistry, physics, mechanical engineering and electrical communication engineering. To know more details about the curriculum and content of the courses, click here. Resume : A few years ago, it has been demonstrated that three-Fe-sites lattice distortions called trimerons play a major role in the insulating phase of Fe3O4.
More recently time-resolved X-ray diffraction and optical reflectivity on bulk magnetite show how these trimerons are affected in the out-of-equilibrium Verwey transition induced by ultrashort lasers pulses. Here, we show the very first time-resolved magneto-optical study in thin Fe3O4 film as a function of temperature across the Verwey transition.
Both ultrafast charges and spins dynamics allow us to identify the metal-insulator transition through their main temporal features. In particular, we show that precession behavior is associated to a non-trivial modification of time-dependent effective field across the Verwey transition and is correlated to a transient mixed phase induced by ultrashort pulses. Resume : An electric field was applied during the process of pulsed laser ablation of Au and Ag targets immersed in double-distilled water using a Nd:YAG laser operating at different wavelengths and fluences, thus forming various colloids.
The changes in the size and shape of the nanostructures were investigated as a function of the angle between the direction of the electric field applied and that of the laser beam propagation. Further, the effect was explored of the electric field on the formation of the nanowire network. The colloids were visualized by transmission electron microscopy TEM , while the structure and phase composition were examined by high-resolution transmission electron microscopy HRTEM and selected area electron diffraction SAED. Resume : Plasma spray deposition is one of the most important technologies available for producing the high-performance surfaces required by modern industry.
In this process, powder of the coating material is fed into high-temperature plasma, which melts and accelerates the powder; the molten particles subsequently hit and solidify on the surface to be coated. Most of the applications require coatings with a high density, which are well bonded to the substrate. To obtain good quality coating, the powder particle must be at least partially molten and hit the substrate with a high velocity. Since plasma spray equipment is expensive to operate, the cost of developing new coatings can be very high.
A computer model capable of predicting the coating properties as a function of process parameters will greatly reduce the development time and cost. The 2D computational fluid dynamic technique have been applied to analyze the impacting process and the subsequent temperature fields of two molten ceramic particles in order to tackle the most complete heat transfer and solidification problem in order to characterize the overall coating. Keys words: Plasma spray process; molten ceramic; coating properties; fluid dynamic technique.
Resume : Advanced methods of optical spectroscopy have been developed and applied to study optical properties of various lanthanide-doped fluoride materials. The excitation beam is continuous or modulated into square-shaped pulses using an acousto-optical modulator. Emission is coupled to the double-parallel-detection-paths spectroscopic system covering broad spectral range from UV to NIR nm , which enable to observe both up-converted and down-converted emission and detect signal separately for each emission band .
The typical slow order of ms onset and decay kinetics of the main emission bands are described by a set of differential equations. The fitting of experimental datasets with this model gives deep insight into the energy transfer processes. The work is funded by the CSF, project s  J.
Valenta and M. Greben, AIP Adv. Guille et al.
Expanding frontiers in materials chemistry and physics with multiple anions
The high photon flux combined with a new fast-acquisition-time 4 ms 2D-detector for high photon energies permits time-resolved in situ structural analysis of the selective laser melting process. The high-energy synchrotron-radiation based X-rays result in small scattering angles. Resume : Direct laser writing is a very useful technique to process dielectrics for many applications, like micro-fluidics, photo-electronics or glass cutting for consumer electronics.
Material processing requires accurate control on energy deposition profiles inside the transparent material, which strongly depends on irradiation conditions. Gauss-Bessel beams have been successfully used for ultra-high aspect ratio processing because of the enhanced stability of these beams in comparison with the unstable and complex filamentation regime of Gaussian beams. In this work, we temporally split the input fs laser pulse in two equal pulses with a variable delay.
We compare single and double pulse illumination as a function of delay on the drilling of high aspect ratio nanochannels in borosilicate glass. Our main result is that, with equal energy, splitting the pulse allows increasing the channel width and enables channel drilling for conditions when only index modification was created.
The results strongly depend on the sub-nanosecond delay ie at delays below the standard burst mode of lasers. We report measurements of energy absorption and interpret our results in terms of confinement of the energy deposition. Our results raise novel fundamental questions on laser-matter interaction and we anticipate a wide impact on technological applications to laser processing of transparent materials. Resume : Beam profile engineering, where a desired optical intensity distribution can be generated by an array of phase shifting or amplitude changing elements is a promising approach in laser material processing.
For example, a spatial light modulator SLM is a dynamic diffractive optical element allowing for experimental implementations of controllable beam profile. Both families exhibit non-diffracting properties similar to Bessel beams, where a relatively long focal depth retains unchanging intensity distribution, which makes them a promising approach in laser processing.
Here, we introduce vector versions of those beams with controllable polarization and investigate numerically their spatial spectra. We use vector Mathieu and Weber beams as a basis to construct controllable on-axis phase and amplitude distributions with polarization control. Further, we attempt to generate components of vector Mathieu beams experimentally using SLMs and report on our achievements in the control over the beam shape and dimensions along the propagation axis.
Resume : The creation of a photonic jet at the tip of an optical fibre is an upcoming trend with various applications. The propagative, slightly diverging, light beam coming out of the fibre does not behave in accordance to the usual laws of wave optics. For example, the diffraction limit can be overcome, giving a FWHM smaller than a half wavelength.
These unusual properties make the photonic jet an excellent tool for subwavelength micromachining. The shaping of optical fibre tips is commonly done by thermoforming. Nevertheless, this method has some shortcomings for single mode fibers: the curvature of the tip is harder to control and the effect on the size and shape of the core and its concentration in dopant is unknown.
Chemical Physics - Journal - Elsevier
This study investigates an alternative fabrication process to obtain the desired tip shape: chemical etching. The simulation of the shape of the photonic jet out of single mode fibres was made by 2D FEM modelisation. The chemical etching process was studied both statically and dynamically, along with the effect of the vapours.
By carefully controlling the experimental conditions, shapes in close accordance to the theoretical predictions were obtained.
The tip shapes were observed by optical microscope and the size of the photonic nanojets measured through laser ablation on Si. Eight time less energy has been required for etching using a single mode fiber tip shaped combining both chemical etching and thermoforming.
Intro : Fibre tip shaping, HF, chemical etching, photonic nanojet. Resume : Dr. Such structures have the potential to act as the active components for the detection of biological and chemical analytes using various sensing modalities e. The synthesis is reliant on the formation of Au seeds exhibiting planar defects — without such defects the growth mode is deactivated. Through the engineering of defects, which have been extensively studied using Titan TEM imaging and electron diffraction, such structures have now been produced in high yield.
- Course Descriptions!
- Recent Posts.
- Conference Highlights.
Here, we will describe the techniques used to generate periodic array of seeds, demonstrate their utility in forming substrate-based metallic nanoplates and provide an understanding of the opportunities and challenges that lie ahead. Resume : Fluoride doped by rare-earth RE makes them excellent for optoelectronics and photonics applications.
However, due to the low absorption cross-section of the RE ions, the efficiency of the converting layer needs to be increased. The fabrication of metallic NPs in UHV conditions embedded in fluoride matrix prevent the oxidisation, which could degrade of plasmonic properties of NPs.
- Sonny Preyer - A Fairy Tale of a Different Kind Vol. 1.
- Materials Engineering | Iowa State University Catalog;
- High Power Microwaves, Second Edition (Series in Plasma Physics)?
- Materials Science Undergraduate Program | Applied Physics and Applied Math;
- A People on the Move: The Métis of the Western Plains.
The size of the NPs was controlled by the number of the laser pulses focused on the metallic target and varied between 5 and 20 nm.