Nanoindentation of yttria-doped zirconia: Effect of crystallographic structure on deformation mechanisms

2009 ◽  
Vol 24 (3) ◽  
pp. 719-727 ◽  
Author(s):  
Y. Gaillard ◽  
M. Anglada ◽  
E. Jiménez-Piqué
Keyword(s):  
Phase Transformation ◽  
Tetragonal Zirconia ◽  
Dislocation Nucleation ◽  
Deformation Mechanisms ◽  
Crystallographic Structure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tetragonal Crystals ◽  
Indenter Shape ◽  
Critical Contact

This article presents a nanoindentation study of polycrystalline and single crystals of yttria-doped zirconia with both tetragonal and cubic phases. Analysis of the deformation mechanisms is performed by both atomic force microscopy (AFM) and micro-Raman spectroscopy. Phase transformation from tetragonal to monoclinic phase is clearly distinguished on tetragonal crystals, whereas in cubic crystals the plastic deformation seems to be controlled by dislocation nucleation and interactions. AFM observations in tetragonal zirconia grains have shown that both grain size and autocatalytic transformation strongly influence the size of the transformed zone. Furthermore, the martensitic phase transformation seems to be also strongly dependent of the indenter shape. Experimental results suggest that a critical contact pressure is necessary to induce the phase transformation.

scholarly journals Aging Behavior of Commercial and Synthesized Dental Y-TZP Ceramics

2015 ◽  
Vol 820 ◽  
pp. 297-302 ◽  
Author(s):  
Anelyse Arata ◽  
Tiago Moreira Bastos Campos ◽  
João Paulo Barros Machado ◽  
Walter Kenji Yoshito ◽  
Valter Ussui ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Monoclinic Phase ◽  
Rietveld Method ◽  
Tetragonal Zirconia ◽  
Degradation Process ◽  
Hydrothermal Aging ◽  
Force Microscopy ◽  
Atomic Force ◽  
Oral Environment ◽  
Experimental Group

Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) is used for dental prosthodontics, however, it can present accelerated tetragonal to monoclinic phase transformation in oral environment. The aim of this study was to compare the behavior of a Y-TZP synthesized in laboratory by the coprecipitation method to a commercial Y-TZP, after hydrothermal aging in pressurized reactor (150°C/ 35 hours). The discs were sintered at 1520°C for two hours. The kinetics curve of phase transformation was determined through the data collect by XRD diffractograms treated by the Rietveld method. The experimental and commercial control groups did not present monoclinic phase. After 35 hours of aging, the experimental group presented 69% of monoclinic phase compared to 67% for the commercial group. Scanning electron microscopy and atomic force microscopy images suggested that the commercial group presented heterogeneity of grain size and that the experimental group was more homogeneous. All groups presented superficial degradation process.

Microscopic studies of fast phase transformations in GeSbTe films

2001 ◽  
Vol 674 ◽  
Author(s):  
Ralf Detemple ◽  
Inés Friedrich ◽  
Walter Njoroge ◽  
Ingo Thomas ◽  
Volker Weidenhof ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Data Transfer ◽  
Optical Measurements ◽  
Transfer Rates ◽  
Force Microscopy ◽  
High Data ◽  
Atomic Force ◽  
Transmission Electron ◽  
Future Success ◽  
Microscopic Studies

ABSTRACTVital requirements for the future success of phase change media are high data transfer rates, i.e. fast processes to read, write and erase bits of information. The understanding and optimization of fast transformations is a considerable challenge since the processes only occur on a submicrometer length scale in actual bits. Hence both high temporal and spatial resolution is needed to unravel the essential details of the phase transformation. We employ a combination of fast optical measurements with microscopic analyses using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The AFM measurements exploit the fact that the phase transformation from amorphous to crystalline is accompanied by a 6% volume reduction. This enables a measurement of the vertical and lateral speed of the phase transformation. Several examples will be presented showing the information gained by this combination of techniques.

scholarly journals Epitaxial Order Driven by Surface Corrugation: Quinquephenyl Crystals on a Cu(110)-(2×1)O Surface

Crystals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 373 ◽  
Author(s):  
Roland Resel ◽  
Markus Koini ◽  
Jiri Novak ◽  
Steven Berkebile ◽  
Georg Koller ◽  
...  
Keyword(s):  
Thin Film ◽  
Crystal Surface ◽  
Substrate Surface ◽  
Lattice Misfit ◽  
Crystallographic Structure ◽  
Initial Growth ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Lattice Matching ◽  
Atomic Force

A 30 nm thick quinquephenyl (5P) film was grown by molecular beam deposition on a Cu(110)(2×1)O single crystal surface. The thin film morphology was studied by light microscopy and atomic force microscopy and the crystallographic structure of the thin film was investigated by X-ray diffraction methods. The 5P molecules crystallise epitaxially with (201)5P parallel to the substrate surface (110)Cu and with their long molecular axes parallel to [001]Cu. The observed epitaxial alignment cannot be explained by lattice matching calculations. Although a clear minimum in the lattice misfit exists, it is not adapted by the epitaxial growth of 5P crystals. Instead the formation of epitaxially oriented crystallites is determined by atomic corrugations of the substrate surface, such that the initially adsorbed 5P molecules fill with its rod-like shape the periodic grooves of the substrate. Subsequent crystal growth follows the orientation and alignment of the molecules taken within the initial growth stage.

Self-Assembled Growth of Highly Oriented Para- Sexiphenyl Thin Films Controlled by Elastic Strain

2001 ◽  
Vol 665 ◽  
Author(s):  
Andrei Yu. Andreev ◽  
Helmut Sitter ◽  
Christoph J. Brabec ◽  
Peter Hinterdorfer ◽  
Günter Springholz ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Surface ◽  
Growth Time ◽  
Crystallographic Structure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Degree Of Anisotropy ◽  
Figure Technique ◽  
Crystallographic Planes

ABSTRACTWe have studied the structure and growth regularities of highly ordered para-sexiphenyl (C36H26) thin films deposited by Hot Wall Epitaxy on mica. In particular, atomic force microscopy (AFM) was used to investigate the early growth stage of these films, in order to find the process controlling parameters. It was shown that the substrate temperature and the growth time are important parameters for control of the film morphology, in terms of the degree of anisotropy and long range order. X-ray diffraction pole figure technique and transmission electron microscopy were also used to characterize the crystallographic structure of the thicker films. We have shown that the highly ordered crystallites of para-sexiphenyl (showing needle-like morphology by AFM) are oriented with their (11 1 ) or (11 2 ) crystallographic planes parallel to the substrate surface. For each of these two orientations there are two opposite directions for growth of crystallites reflecting the two-fold symmetry of the mica surface.

Strain Relaxation at Low Misfits: Dislocation Injection vs. Surface Roughening

1995 ◽  
Vol 399 ◽  
Author(s):  
D.D. Perovic ◽  
B. Bahierathan ◽  
D.C. Houghton ◽  
H. Lafontaine ◽  
J.-M. Baribeau
Keyword(s):  
Misfit Dislocation ◽  
Strain Relaxation ◽  
Relaxation Mechanism ◽  
Theoretical Description ◽  
Dislocation Nucleation ◽  
Surface Roughening ◽  
X Ray Diffraction ◽  
Dislocation Generation ◽  
Force Microscopy ◽  
Atomic Force

ABSTRACTTwo competing strain relaxation mechanisms, namely misfit dislocation generation and surface roughening, have been extensively studied using the GexSi1-x/Si (x< 0.5) system as an example. A predictive model has been developed which accurately describes the nature of misfit dislocation nucleation and growth under non-equilibrium conditions. Using optical and electron microscopy, coupled with a refined theoretical description of dislocation nucleation, it is shown that strain relieving dislocations are readily generated at low misfits with a characteristic activation energy barrier regardless of the growth technique employed (i.e. MBE, RTCVD and UHVCVD). Secondly we have studied the alternative elastic strain relaxation mechanism involving surface undulation; x-ray diffraction, electron and atomic force microscopy have been used to characterize GexSi1-x/Si (x<0.5) structures grown by UHVCVD and MBE at relatively higher temperatures. A theoretical model has been used to model the critical thickness for surface wave generation. The conditions governing the interplay between dislocation formation and surface buckling are described in terms of a "morphological instability diagram".

Nanoindentation of Silicon

2008 ◽  
Vol 604-605 ◽  
pp. 29-36 ◽  
Author(s):  
Péter M. Nagy ◽  
P. Horváth ◽  
Gábor Pető ◽  
Erika Kálmán
Keyword(s):  
Atomic Force Microscopy ◽  
Phase Transformation ◽  
Crystalline Silicon ◽  
Defect Density ◽  
Single Crystalline Silicon ◽  
Single Crystalline ◽  
Force Microscopy ◽  
Atomic Force ◽  
Cube Corner ◽  
Loading And Unloading

The nanoindentation behaviours of single crystalline silicon samples has gained wide attention in recent years, because of the anomaly effects in the loading curve, caused by the pressure induced phase transformation of silicon. To further enlighten the phenomenon bulk, ion-implanted, single crystalline Si samples have been studied by nanoindentation and by atomic force microscopy. The implantation of Si wafers was carried out by P+ ions at 40 KeV accelerating voltage and 80 ions/cm2 dose, influencing the defect density and structure of the Si material in shallow depth at the surface. Our experiments provide Young’s modulus and hardness data measured with Berkovich-, spherical- and cube corner indenters, statistics of the pop-in and pop-out effects in the loading- and unloading process, and interesting results about the piling-up behaviour of the Si material.

scholarly journals Nominal PbSe nano-islands on PbTe: grown by MBE, analyzed by AFM and TEM

2004 ◽  
Vol 829 ◽  
Author(s):  
Peter Moeck ◽  
Mukes Kapilashrami ◽  
Arvind Rao ◽  
Kirill Aldushin ◽  
Jeahuck Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Probe Microscopy ◽  
Strain State ◽  
Molecular Beam ◽  
Scanning Probe ◽  
Crystallographic Structure ◽  
Number Density ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

ABSTRACTNominal PbSe nano-islands were grown in the Stranski-Krastanow mode on (111) oriented PbTe/BaF2 pseudo-substrates by molecular beam epitaxy (MBE). The number density and morphology of these islands were assessed by means of atomic force microscopy (AFM). Transmission electron microscopy (TEM) was employed to determine the strain state and crystallographic structure of these islands. On the basis of both AFM and TEM analyses, we distinguish between different groups of tensibly strained islands. The suggestion is made to use such nano-islands as part of nanometrology standards for scanning probe microscopy.

Effect of the spherical indenter tip assumption on nanoindentation

2007 ◽  
Vol 22 (6) ◽  
pp. 1656-1661 ◽  
Author(s):  
L. Ma ◽  
L.E. Levine
Keyword(s):  
Dislocation Nucleation ◽  
Spherical Indenter ◽  
Analysis Model ◽  
Element Analysis ◽  
Finite Element Analysis Model ◽  
Force Microscopy ◽  
Indentation Force ◽  
Irregular Shapes ◽  
Atomic Force ◽  
Oriented Single Crystal

One of the interests and challenges of nanoindentation is determining the shear stress at the onset of plastic yielding, which corresponds to dislocation nucleation. To extract this stress information from experimental load-displacement data, a spherical tip shape is usually assumed. However, it is well known that indenter tips have irregular shapes, especially at the small-length scales that are important for small loads. This will significantly affect the stress distribution under the indentation surfaces. In this work, an indenter tip shape is measured by atomic force microscopy. The measured indenter shape is input into a finite element analysis model for indentation simulations on 〈111〉-oriented single-crystal Al samples in the elastic regime. The resulting stresses, indentation force, and contact area are analyzed and compared to results from a fitted spherical indenter. The deviation of the assumed spherical indenter tip from the real measured indenter tip is studied.

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