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Grimberg R.,National Institute of RandD for Technical Physics
12th International Conference of the Slovenian Society for Non-Destructive Testing: Application of Contemporary Non-Destructive Testing in Engineering, ICNDT 2013 - Conference Proceedings | Year: 2013

The metamaterials, electromagnetic structures with distinguished properties have started to be studied, and especially used, only in the last 10-15 years. One of the possible applications is represented by electromagnetic nondestructive evaluation in the range of UHF and microwave. This paper makes a review of the metamaterial concept; of main realization in the domain of electromagnetic nondestructive evaluation using a "perfect lens", emphasizing the fact that important for the increasing of spatial resolution of the evaluation methods is the use of evanescent waves, and their manipulation being able to do with "poor man's lens". Source


Tabakovic I.,University of Minnesota | Qiu J.-M.,University of Minnesota | Dragos O.,National Institute of RandD for Technical Physics
Journal of the Electrochemical Society | Year: 2016

The CoPt films with 9.7-91 at% Co and thicknesses of 15-20 nm were obtained from a new designed stable hexachloroplatinate solution at a controlled potential deposition. The effects of the substrate (Ru and Cu) and an organic additive (saccharin) on composition, crystal structure and magnetic properties of the CoPt films were studied. It was demonstrated that a Ru electrode substrate provides well-defined surface for the epitaxial growth of hcp phase, resulting in high perpendicular anisotropy. The addition of saccharin (Sacc) as an organic additive into the plating solution caused a dramatic improvement of the epitaxial growth of CoPt film on the Ru substrate. At the film thickness of interest, for bit-patterned media BPM (15-20 nm), the out-of-plane coercivity showed the highest value of 6700 Oe and the squarness Mr/Ms ∼1. © 2016 The Electrochemical Society. Source


Sturm R.,University of Ljubljana | Grimberg R.,National Institute of RandD for Technical Physics | Savin A.,National Institute of RandD for Technical Physics | Grum J.,University of Ljubljana
Composites Part B: Engineering | Year: 2015

In this study the effect of moisture absorption on the mechanical properties of glass-reinforced polyester composites is evaluated using both destructive and nondestructive tests. The composite resins were produced with two different production processes, while the mechanical properties of the composite materials were measured using DMA destruction tests. According to the DMA tests, the dependency in terms of temperature for the real component of the complex elastic modulus (E′), the imaginary component of the complex elastic modulus (E″), as well as tan(δ) can be traced. For a more efficient use of the composite materials, the compliance tensor was obtained with nondestructive tests based on ultrasound. A method for the generation and reception of Lamb waves in plates of composite materials is described, based on using air-coupling, low-frequency, ultrasound transducers in a pitch-catch configuration. The results of the nondestructive measurements made in this study are in good agreement with those obtained when using the DMA destructive tests. © 2014 Elsevier Ltd. All rights reserved. Source


Neamtu B.V.,Technical University of Cluj Napoca | Neamtu B.V.,CNRS Neel Institute | Chicinas I.,Technical University of Cluj Napoca | Isnard O.,CNRS Neel Institute | And 3 more authors.
Intermetallics | Year: 2013

Nanocrystalline Ni3Fe compacts were successfully prepared by spark plasma sintering starting from wet mechanically alloyed powders. The influences of the sintering conditions: sintering temperature, sintering time and particle size on the compact magnetic properties are investigated. It is found that high sintering temperature, increased sintering duration and larger particle size leads to compacts with improved soft magnetic properties. A contamination with carbon of the compacts during the sintering processes has been found to reduce their magnetic properties. It is found that a heat treatment at the temperature of 450 °C during 4 h, in hydrogen atmosphere, leads to an improvement of the compact coercivity and of the maximum relative permeability of the compact to up to 600% and 50% respectively. Spark plasma sintering can consequently be considered as promising compaction technique for processing Ni3Fe nanocrystalline powder in particular and nanocrystalline soft magnetic alloys in general. © 2012 Elsevier Ltd. All rights reserved. Source


Ovari T.-A.,National Institute of RandD for Technical Physics | Chiriac H.,National Institute of RandD for Technical Physics
Journal of Applied Physics | Year: 2014

Magnetoelastic anisotropy calculations and experimental switching field data are used to investigate the origin of the domain wall pinning in rapidly solidified amorphous glass-coated nanowires and submicron wires. The correlation of experimental and calculated results have shown that the magneto-mechanical coupling between internal stresses induced during preparation and magnetostriction is responsible for the pinning of the domain walls in amorphous wires with diameters below 300 nm, whilst in thicker submicron wires demagnetization is also important. The results are important for fully understanding and controlling magnetic switching in rapidly solidified amorphous nanowires for future applications. © 2014 AIP Publishing LLC. Source

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