D. Shilo

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Mark van den Boogaard

Radboud University Nijmegen

Stephan Anagnostaras

University of California, San Diego

Steven J Frenda

California State University, Los Angeles

Corinne Montes-Rodriguez

Universidad Nacional Autónoma de México

Jessica Crawford

University of Central Lancashire

Heather Baid

University of Brighton

Paul Ingmundson

University of Texas Health Science Center at San Antonio (UTHSCSA)

Grant Benham

University of Texas - Rio Grande Valley

Seter Siziya

Copperbelt University

Arnaldo A da Silva

Hospital Israelita Albert Einstein

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Papers by D. Shilo

Characterization of Superelastic NiTi Alloys by Nanoindentation: Experiments and Simulations

Acta Physica Polonica A, 2015

$Research paper thumbnail of Comprehensive strain analysis in thin films based on high-resolution x-ray diffraction: Application to implanted LiNbO 3$

Comprehensive strain analysis in thin films based on high-resolution x-ray diffraction: Application to implanted LiNbO 3

Physical Review B, 2001

Strain analysis of thin film heterostructures is expanded to noncubic crystalline symmetries with... more Strain analysis of thin film heterostructures is expanded to noncubic crystalline symmetries with special attention to the practically important hexagonal and rhombohedral systems. The developed formalism is rather general and can be used to study systems with highly anisotropic lattice mismatches (even unknown) and strain degrees. It is applied here to analyze complex structural modifications in the near-surface waveguide layers

Measured and calculated radiative lifetime and optical absorption of In x Ga 1 − x N / G a N quantum structures

by D. Shilo, E. Berkowicz, and Steven Denbaars

Physical Review B, 2000

We apply photoluminescence, photoluminescence excitation, and time-resolved optical spectroscopy ... more

Nano-scale mapping of mechanical properties in mollusk shells

Epj Web of Conferences, 2010

Visualization of Acoustic Wave Fronts in Crystals by Stroboscopic X‐ray Topography

Synchrotron Radiation News, 2002

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The effect of grain and pore sizes on the mechanical behavior of thin Al films deposited under different conditions

Acta Materialia, 2015

ABSTRACT This paper presents a comprehensive study of the relationships between deposition condit... more ABSTRACT This paper presents a comprehensive study of the relationships between deposition conditions, microstructure and mechanical behavior in thin aluminum films commonly used in micro and nano-devices. A particular focus is placed on the effect of porosity, which is present in all thin films deposited by evaporation or sputtering techniques. The influences of the deposition temperature on the grain size, pore size and crystallographic texture were characterized by X-ray diffraction and scanning electron microscopy. The mechanical behavior of the films was investigated using four different methods. Each method is suitable for characterizing different properties and for testing the material at different length scales. Nanoindentation was used to study hardness at the level of individual grains; resonant ultrasound spectroscopy was used to measure the elastic moduli and porosity; and bulge and tensile tests were used to study released films under biaxial and uniaxial tensions. Our results demonstrate that even low porosities may have tremendous effects on the mechanical properties and that different methods allow the capture of different aspects of these effects. Therefore, a combination of several methods is required to obtain a comprehensive understanding of the mechanical behavior of a film. It is also shown that porosity with different pore size leads to very different effects on the mechanical behavior.

Ferromagnetic shape memory flapper for remotely actuated propulsion systems

A New Methodology for Uniaxial Tensile Testing of Free-Standing Thin Films at High Strain-Rates

Experimental Mechanics, 2014

A large strain rate effect in thin free-standing Al films

Scripta Materialia, 2014

Mapping nanomeehanical properties near internal interfaces in biological materials

Materials Research Society Symposium Proceedings, 2011

ABSTRACT Modulus mapping using nanoDMA (Dynamic Mechanical Analysis) is a recently developed tech... more ABSTRACT Modulus mapping using nanoDMA (Dynamic Mechanical Analysis) is a recently developed technique based on a nanoindentation instrument equipped with an AFM-like piezoscanner and dynamic force modulation system. The surface properties, storage and loss moduli are quantified based on the Hertz model for the contact mechanics of the sample-tip configuration. In this approach, the applied load, topography features, and their size may have a pronounced effect on the obtained results. In order to demonstrate that, internal interfaces of deep sea sponge (Monorhaphis chuni), which comprises alternating layers of relatively thick (4 μm in average) biosilica and thin (60 nm) organic material, were characterized using the nanoDMA modulus mapping technique. Experimental data were analyzed in tight interrelation with finite element simulations. This combination allowed us to evaluate elastic modulus of a 60 nm wide organic layers in M. chuni.

$Research paper thumbnail of In situ elastic modulus measurements of ultrathin protein-rich organic layers in biosilica: Towards deeper understanding of superior resistance to fracture of biocomposites$

In situ elastic modulus measurements of ultrathin protein-rich organic layers in biosilica: Towards deeper understanding of superior resistance to fracture of biocomposites

RSC Advances, 2013

A model for large electrostrictive actuation in ferroelectric single crystals

International Journal of Solids and Structures, 2007

A new mode of large electrostrictive actuation, based on 90° domain switching in ferroelectric cr... more A new mode of large electrostrictive actuation, based on 90° domain switching in ferroelectric crystals subjected to combined electromechanical loading, has recently been experimentally demonstrated. In this paper, we develop a model for this phenomenon by assuming a reasonable arrangement of domain walls and formulating equations of motion for these walls. The model captures most of the features observed in

A New Instrument for Tensile Testings of Thin Free Standing Films at High Strain Rates

Experimental Analysis of Nano and Engineering Materials and Structures, 2007

The design of more reliable and sophisticated Micro Electro Mechanical Systems (MEMS) relies on t... more The design of more reliable and sophisticated Micro Electro Mechanical Systems (MEMS) relies on the knowledge, understanding, and ability to control their mechanical response. In recent years, enormous progress has been made in developing new measurement techniques for studying the mechanical response of μm and sub-μm scale specimens (e.g. Kraft and Volkert [1] and Srikar and Spearing [2]). However, there is still a lack of knowledge and testing techniques regarding the response of MEMS structures to mechanical shocks, which can appear during fabrication, deployment, or operation.

Testing system for ferromagnetic shape memory microactuators

Review of Scientific Instruments, 2007

Ferromagnetic shape memory alloys are a class of smart materials that exhibit a unique combinatio... more Ferromagnetic shape memory alloys are a class of smart materials that exhibit a unique combination of large strains and fast response when exposed to magnetic field. Accordingly, these materials have significant potential in motion generation applications such as microactuators and sensors. This article presents a novel experimental system that measures the dynamic magnetomechanical behavior of microscale ferromagnetic shape memory specimens. The system is comprised of an alternating magnetic field generator (AMFG) and a mechanical loading and sensing system. The AMFG generates a dynamic magnetic field that periodically alternates between two orthogonal directions to facilitate martensitic variant switching and to remotely achieve a full magnetic actuation cycle, without the need of mechanical resetting mechanisms. Moreover, the AMFG is designed to produce a magnetic field that inhibits 180 degrees magnetization domain switching, which causes energy loss without strain generation. The mechanical loading and sensing system maintains a constant mechanical load on the measured specimen by means of a cantilever beam, while the displacement is optically monitored with a resolution of approximately 0.1 microm. Preliminary measurements using Ni(2)MnGa single crystal specimens, with a cross section of 100x100 microm(2), verified their large actuation strains and established their potential to become a material of great importance in microactuation technology.

Large Local Deflections of a Dynamic Crack Front Induced by Intrinsic Dislocations in Brittle Single Crystals

Physical Review Letters, 2002

We show that intrinsic dislocations in brittle single crystals can be a source of strong local pe... more We show that intrinsic dislocations in brittle single crystals can be a source of strong local perturbations along the crack path. A theoretical model was developed which predicts substantial crack front deflections. Investigating the crack surfaces in Si crystals with induced dislocation density of 10(9)-10(10) cm(-2) revealed a significant amount of crack front perturbations in the form of V-shaped grooves, which were completely missing in dislocation-free Si specimens. The measured depths of the perturbations were in the range of 2-20 nm and in excellent agreement with the theoretical model.

Investigation of twin-wall structure at the nanometre scale using atomic force microscopy

Nature Materials, 2004

nature materials | VOL 3 | JULY 2004 | www.nature.com/naturematerials 453 T win walls are planar ... more nature materials | VOL 3 | JULY 2004 | www.nature.com/naturematerials 453 T win walls are planar defects that separate domains with uniform, but different, strain or electric polarization. They are observed in a broad class of materials, including ferroelectric, ferroelastic, co-elastic and superconducting crystals, which serve in a wide variety of mechanical, electrical and optical applications 1,2 . One unique characteristic of such crystals is that their physical properties as well as their macroscopic response to mechanical, electrical and optical loads are strongly related to their microstructural domain patterns 3,4 . These, in turn, are governed by the atomistic and mesoscale structure of twin walls and their interaction with other crystal defects. For example, it has been shown that as the dimensions of a ferroelectric thin film reduces to the submicrometre scale, the twin-wall thickness affects the dielectric, piezoelectric and optical properties of the film 5 . Moreover, as the dimensions further reduce to the nanometre scale, the twin-wall thickness dictates the transitions from a multidomain structure to single domain, and from a ferroelectric to a non-ferroelectric phase 6 .

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X-ray imaging of acoustic wave interaction with dislocations

Materials Science and Engineering: A, 2001

We used stroboscopic X-ray topography to visualize the propagation of high-frequency (580MHz), sh... more We used stroboscopic X-ray topography to visualize the propagation of high-frequency (580MHz), short wavelength (6μm) surface acoustic waves in LiNbO3 crystals. The images showed well-resolved individual acoustic wave fronts as well as their distortions caused by scattering on linear dislocations. The observed wave front shapes indicate that a considerable portion of acoustic energy flows along a dislocation line, providing forced

$Research paper thumbnail of Characterization of CdTe/Hg1−xCdxTe heterostructures by high-resolution x-ray diffraction$

Characterization of CdTe/Hg1−xCdxTe heterostructures by high-resolution x-ray diffraction

by N. Mainzer and D. Shilo

Journal of Electronic Materials, 1997

CdTe/Hg1−xCdxTe heterostructures variously heat-treated and implanted with boron were studied by ... more CdTe/Hg1−xCdxTe heterostructures variously heat-treated and implanted with boron were studied by means of high-resolution x-ray diffraction. A novel procedure for simulating diffraction spectra was developed, which is based on direct summation of scattered waves across a heterostructure. In that routine, short-range variations of structural parameters, including concentration of the components, can be taken into account. The new approach allows precise

$Research paper thumbnail of Study of atomic diffusion in crystalline structures by high-resolution X-ray diffraction$

Study of atomic diffusion in crystalline structures by high-resolution X-ray diffraction

by N. Mainzer and D. Shilo

Journal of Crystal Growth, 1999

The ability of high-resolution X-ray diffraction to provide information on atomic diffusion is an... more The ability of high-resolution X-ray diffraction to provide information on atomic diffusion is analyzed, the focus being on the thin film crystalline structures important to modern microelectronics and optoelectronics. Special attention is paid to the Ti diffusion in waveguide layers of LiNbO crystals and to the Hg diffusion in the CdTe/Hg \V Cd V Te heterostructures. The depth-resolved concentration profiles obtained are compared with those measured by secondary ion mass spectrometry. The limitations of the new method, mainly due to the variable strain influence on the lattice parameters, are discussed. .Jt; 68.55.Nq

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Co silicide formation on epitaxial Si[sub 1−y]C[sub y]/Si (001) layers

Journal of Applied Physics, 2000

We investigated the formation and structure of cobalt silicide (CoSi2) on Si1-yCy (0&amp;amp;... more We investigated the formation and structure of cobalt silicide (CoSi2) on Si1-yCy (0&amp;amp;amp;lt;=y=600 °C (iii) a two sublayer structure of CoSi2 is observed, where the upper sublayer contains a very small amount of C and has a homogeneous microstructure, while the lower sublayer, which has a higher C concentration, contains randomly oriented CoSi2 nanocrystallites; (iv) spatial inhomogeneity results in significant

Characterization of Superelastic NiTi Alloys by Nanoindentation: Experiments and Simulations

Acta Physica Polonica A, 2015

$Research paper thumbnail of Comprehensive strain analysis in thin films based on high-resolution x-ray diffraction: Application to implanted LiNbO 3$

Comprehensive strain analysis in thin films based on high-resolution x-ray diffraction: Application to implanted LiNbO 3

Physical Review B, 2001