Cyclic Nanoindentation and Raman Microspectroscopy Study of Phase Transformations in Semiconductors

2000 ◽  
Vol 15 (4) ◽  
pp. 871-879 ◽  
Author(s):  
Yury G. Gogotsi ◽  
Vladislav Domnich ◽  
Sergey N. Dub ◽  
Andreas Kailer ◽  
Klaus G. Nickel
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Contact Pressure ◽  
Silicon Germanium ◽  
Hysteresis Loops ◽  
Metallic Phase ◽  
Raman Microspectroscopy ◽  
Displacement Curve ◽  
Depth Sensing ◽  
Load Displacement

This paper supplies new interpretation of nanoindentation data for silicon, germanium, and gallium arsenide based on Raman microanalysis of indentations. For the first time, Raman microspectroscopy analysis of semiconductors within nanoindentations is reported. The given analysis of the load-displacement curves shows that depth-sensing indentation can be used as a tool for identification of pressure-induced phase transformations. Volume change upon reverse phase transformation of metallic phases results either in a pop-out (or a kink-back) or in a slope change (elbow) of the unloading part of the load-displacement curve. Broad and asymmetric hysteresis loops of changing width, as well as changing slope of the elastic part of the loading curve in cyclic indentation can be used for confirmation of a phase transformation during indentation. Metallization pressure can be determined as average contact pressure (Meyer's hardness) for the yield point on the loading part of the load-displacement curve. The pressure of the reverse transformation of the metallic phase can be measured from pop-out or elbow on the unloading part of the diagram. For materials with phase transformations less pronounced than in Si, replotting of the loaddisplacement curves as average contact pressure versus relative indentation depth is required to determine the transformation pressures and/or improve the accuracy of data interpretation.

Characterization of mechanical properties of tungsten carbide/carbon multilayers: Cross-sectional electron microscopy and nanoindentation observations

2001 ◽  
Vol 16 (8) ◽  
pp. 2213-2222 ◽  
Author(s):  
N. J. M. Carvalho ◽  
J. Th. M. De Hosson
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Tungsten Carbide ◽  
Physical Vapor Deposition ◽  
Hysteresis Loops ◽  
Displacement Curve ◽  
Depth Sensing ◽  
Cross Sectional ◽  
Load Displacement ◽  
A New Technique

Multilayers of tungsten carbide/carbon (WC/C) deposited by physical vapor deposition onto steel substrates were subjected to depth-sensing indentation testing. The investigation aimed at probing the influence of dissimilarities between the microstructure of the multilayers and substrate on the system mechanical properties. The resultant load-displacement data were analyzed both by conventional load-displacement (P-δ) and load-displacement squared (P-δ2) plots. Furthermore, it was demonstrated that the occurrence of annular through-thickness cracks around the indentation sites can be identified from the load-displacement curve. Also, analysis of the lower part of the unloading curve permitted us to identify whether the coating had popped up by localized fracture. The cracking mechanism was characterized using a new technique for cross-sectional electron microscopy of the nanoindentations. The information retrieved with this technique eliminates the problems, inherent in assessing at this small contact scales, whether the fracture is by coating decohesion or by interfacial failure. In our case, it was demonstrated that the failure mechanism was decohesion of the carbon lamellae within the multilayers. The mechanical properties (hardness and effective Young's modulus) were also assessed by nanoindentation. The hysteresis loops were analyzed and discussed in terms of the method developed by Oliver and Pharr [J. Mater. Res. 7, 1564 (1992)].

Identification of Pressure-Induced Phase Transformations Using Nanoindentation

2000 ◽  
Vol 649 ◽  
Author(s):  
Vladislav Domnich ◽  
Yury Gogotsi ◽  
Michael Trenary
Keyword(s):  
Boron Carbide ◽  
Phase Transformations ◽  
Single Crystals ◽  
Contact Pressure ◽  
Silicon Germanium ◽  
Elastoplastic Material ◽  
Stabilized Zirconia ◽  
Depth Sensing ◽  
Partially Stabilized Zirconia ◽  
Depth Curves

ABSTRACTA combination of depth-sensing indentation and Raman microspectroscopy has been used for the identification of pressure-induced phase transformations in silicon, germanium, boron carbide and partially stabilized zirconia single crystals. Phase transformations during nanoindentation may be revealed through deviations in the shape of the load-displacement curves from that of a perfect elastoplastic material. Such deviations are often more readily identified if the nanoindentation data are presented as average contact pressure vs. contact depth curves, allowing assessment of the corresponding transformation pressures.

Features of Semiconductors during Nanoindentation

2003 ◽  
Vol 779 ◽  
Author(s):  
Asta Richter ◽  
Bodo Wolf ◽  
Roger Smith ◽  
Margita Günther
Keyword(s):  
Phase Transformation ◽  
Hysteresis Loops ◽  
Maximum Load ◽  
Depth Sensing ◽  
Ion Energy ◽  
Loop Area ◽  
Area Reduction ◽  
Boron Implantation ◽  
The Impact ◽  
Constant Maximum

AbstractSi and InSb were subject to depth sensing multi-cycling nanoindentation. The load-depthcurves exhibited hysteresis loops which are explained in terms of pressure induced phase transformations. In order to study the impact of crystal distortions on phase transformation, the specimens were subject to boron implantation (ion energy 180 keV) of different implantation doses (1014 to 1017 ions/cm2) and indented without annealing. In InSb, the hysteresis loops disappeared after implantation of 1016 ions/cm2, and for Si with its stronger bonds, a dose of 3*1016/cm2 is required for the same effect. Indentation cycling with constant maximum load results in a sudden disappearance of the hysteresis loop after a small gradual loop area reduction during the first initial cycles.

Effect of indentation unloading conditions on phase transformation induced events in silicon

2003 ◽  
Vol 18 (5) ◽  
pp. 1192-1201 ◽  
Author(s):  
Tom Juliano ◽  
Yury Gogotsi ◽  
Vladislav Domnich
Keyword(s):  
Phase Transformation ◽  
Phase Transitions ◽  
Contact Pressure ◽  
Silicon Wafer ◽  
Applied Load ◽  
Raman Microspectroscopy ◽  
Wafer Surface ◽  
Silicon Wafer Surface ◽  
Permissible Range ◽  
Unloading Rate

More than 2500 indentations were made on a silicon wafer surface using a range of different unloading rates and maximum applied loads. The unloading curves were examined for characteristic events (pop-out, kink pop-out, elbow followed by pop-out, and elbow) that were assigned to different phase transitions within the affected material based on Raman microspectroscopy analysis of residual imprints. The effect of unloading rate and maximum applied load on the average contact pressure at the beginning of the event was found. A permissible range for each event to occur was established.

Field-Driven Phase Transformations in Relaxor Ferroelectric Single Crystals

2013 ◽  
Author(s):  
John A. Gallagher ◽  
Christopher S. Lynch
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
Single Crystals ◽  
Driving Force ◽  
Gaussian Model ◽  
Hysteresis Loops ◽  
Relaxor Ferroelectric ◽  
Material Behavior ◽  
Minor Hysteresis Loops ◽  
Good Agreement

Relaxor ferroelectric single crystals such as PMN-PT and PIN-PMN-PT undergo field driven phase transformations when electrically or mechanically loaded in crystallographic directions that provide a positive driving force for the transformation. The observed behavior in certain compositions is a phase transformation distributed over a range of field levels without a distinct forward or reverse coercive field. This work focuses on the material behavior that is observed when the crystals are loaded sufficiently to drive a partial transformation and then unloaded as might occur when driving a transducer to achieve high power levels. A set of experiments was conducted to characterize the minor hysteresis loops that occur with the partial transformations. Distributed transformations have been modeled using a Gaussian distribution of transformation thresholds. In this work the Gaussian model is extended to include the partial transformations that occur when the field is reversed before the transformation is complete. The resulting minor hysteresis loops produced by the model are in good agreement with the experimental results.

Dynamic Responses of TiNi Phase Transformation Cylindrical Shell under Radial Impact Load

2011 ◽  
Vol 675-677 ◽  
pp. 1155-1158
Author(s):  
Hui Jie Zhang ◽  
Zhi Ping Tang ◽  
He Huang
Keyword(s):  
Phase Transition ◽  
Cylindrical Shell ◽  
Phase Transformation ◽  
Stress Wave ◽  
Surface Strain ◽  
Dynamic Responses ◽  
Stress Wave Propagation ◽  
Displacement Curve ◽  
Load Displacement ◽  
Tini Phase

In this paper, radial impact responses of TiNi phase transformation cylindrical shell were experimentally studied on two-directional constraint. The nominal load-displacement curve was gained by advanced SHPB; meanwhile, the deformation process of the cylindrical shell was recorded by the high speed camera (30000 fps). The effect of stress wave on the whole structure during load process was as follows: the load-displacement curve fluctuated fiercely and rose gradually in the beginning period, whose frequency was basically the same as that of the stress wave propagation in the Striker 2; After that, the load-displacement curve tended to flat, the shell structure became to be ellipse as the compression increases, and the whole unload process slowed down. Finally, the surface strain was obtained by processing the shell deformation image, and the dynamic effect of the material phase transition and phase transition hinge on the cylindrical shell was examined.

Heat capacities and enthalpies of fusion and transformation for solvates of some salts with dimethyl sulfoxide and dimethylformamide

1988 ◽  
Vol 53 (12) ◽  
pp. 3072-3079
Author(s):  
Mojmír Skokánek ◽  
Ivo Sláma
Keyword(s):  
Heat Capacity ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Dimethyl Sulfoxide ◽  
Liquidus Temperature ◽  
Molar Heat Capacity ◽  
Solid Phase ◽  
Zinc Nitrate ◽  
Heat Capacities ◽  
Liquid Phases

Molar heat capacities and molar enthalpies of fusion of the solvates Zn(NO3)2 . 2·24 DMSO, Zn(NO3)2 . 8·11 DMSO, Zn(NO3)2 . 6 DMSO, NaNO3 . 2·85 DMSO, and AgNO3 . DMF, where DMSO is dimethyl sulfoxide and DMF is dimethylformamide, have been determined over the temperature range 240 to 400 K. Endothermic peaks found for the zinc nitrate solvates below the liquidus temperature have been ascribed to solid phase transformations. The molar enthalpies of the solid phase transformations are close to 5 kJ mol-1 for all zinc nitrate solvates investigated. The dependence of the molar heat capacity on the temperature outside the phase transformation region can be described by a linear equation for both the solid and liquid phases.

scholarly journals Study on the Strength Performance of Recycled Aggregate Concrete with Different Ages under Direct Shearing

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2312
Author(s):  
Xin Liang ◽  
Fang Yan ◽  
Yuliang Chen ◽  
Huiqin Wu ◽  
Peihuan Ye ◽  
...  
Keyword(s):  
Shear Strength ◽  
Shear Force ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Displacement Curve ◽  
Direct Shear ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Concrete Failure ◽  
Load Displacement

In order to study the mechanical properties of recycled aggregate concrete (RAC) at different ages, 264 standard cubes were designed to test its direct shear strength and cube compressive strength while considering the parameters of age and recycled aggregate replacement ratio. The failure pattern and load–displacement curve of specimens at direct shearing were obtained; the direct shear strength and residual shear strength were extracted from the load–displacement curves. Experimental results indicate that the influence of the replacement ratio for the front and side cracks of RAC is insignificant, with the former being straight and the latter relatively convoluted. At the age of three days, the damaged interface between aggregate and mortar is almost completely responsible for concrete failure; in addition to the damage of coarse aggregates, aggregate failure is also an important factor in concrete failure at other ages. The load–displacement curve of RAC at direct shearing can be divided into elasticity, elastoplasticity, plasticity, and stabilization stages. The brittleness of concrete decreases with its age, which is reflected in the gradual shortening of the elastoplastic stage. At 28 days of age, the peak direct shear force increases with the replacement ratio, while the trend is opposite at ages of 3 days, 7 days, and 14 days, respectively. The residual strength of RAC decreases inversely to the replacement ratio, with the rate of decline growing over time. A two-parameter RAC direct shear strength calculation formula was established based on the analysis of age and replacement rate to peak shear force of RAC. The relationship between cube compressive strength and direct shear strength of recycled concrete at various ages was investigated.

A novel method to determine critical CTOA directly by load-displacement curve

2020 ◽  
Vol 230 ◽  
pp. 107013
Author(s):  
Ying Zhen ◽  
Xuyang Li ◽  
Yuguang Cao ◽  
Shihua Zhang
Keyword(s):  
Displacement Curve ◽  
Novel Method ◽  
Load Displacement

Calculations of Phase Transformations in Welding Simulations

2014 ◽  
Vol 611 ◽  
pp. 46-53 ◽  
Author(s):  
Ladislav Novotný ◽  
Vladimír Ivančo
Keyword(s):  
Heat Flux ◽  
Phase Transformation ◽  
Boundary Conditions ◽  
Phase Transformations ◽  
Diffusion Processes ◽  
Transient Solution ◽  
Welding Simulation

In the paper the principle of welding simulation is presented and the methods of solution of phase transformation are described. The first part characterizes elementary equations of heat transient solution, boundary conditions during welding simulation (prescribing moving heat flux, convection, radiation). The methods of phase transformations’ solution are described for diffusion processes as well as diffusionless processes.

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