Single Crystal PMN-PT Electric Fatigue and Fracture Behavior

2008 ◽  
Author(s):  
E. P. Gorzkowski ◽  
M.-J. Pan ◽  
V. G. DeGiorgi ◽  
S. A. Wimmer ◽  
M. A. Siddiq Qidwai
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Fracture Behavior ◽  
Fatigue Behavior ◽  
Vickers Indentation ◽  
Fatigue And Fracture ◽  
Before And After ◽  
Result Show ◽  
Electric Fatigue ◽  
Over Time

Piezoelectric single crystals are being incorporated into many new devices because of the superior properties they exhibit. Not much attention has been paid to the mechanical robustness of these materials. In this work the fracture and fatigue behavior of Pb(Mg1/3Nb2/3)O3−29 mol% PbTiO3 (PMN-29PT) is studied. Vickers indentation result show that the KIC of this material is 0.3 MPa m1/2. Intentional defects from the indentation show that the <100> direction is the weakest direction and that electrical fatigue is fastest in the <100> direction. By looking at the hysteresis behavior of this material before and after the fatigue runs, the material ages over time.

Orientation Dependence on Fatigue Fracture Behavior of Pure Mg Single Crystals

2018 ◽  
Vol 941 ◽  
pp. 1507-1510
Author(s):  
Yuta Kido ◽  
Akinobu Nakamura ◽  
Masayuki Tsushida ◽  
Hiromoto Kitahara ◽  
Shinji Ando
Keyword(s):  
Single Crystals ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Stress Ratio ◽  
Stress Amplitude ◽  
Fatigue Behavior ◽  
Orientation Dependence ◽  
Fatigue Tests ◽  
Crystal Orientations ◽  
Fatigue Fracture Behavior

It is well known that magnesium (Mg) shows anisotropic fatigue behavior. However, the fatigue mechanisms have yet to be elucidated. The relationships between crystal orientations and crack initiation behavior in Mg single crystals were investigated by uniaxial tension-compression fatigue tests. Three types of round-bar specimens were prepared. The lording direction of AD, BC and EF specimen were [110], [100] and [0001], respectively. Fatigue tests were carried out with the stress ratio R=-1 and the frequency of 10Hz at room temperature in laboratory air. At stress amplitude (σa) over 40 MPa, fatigue lives of BC specimen and EF specimen were the longest and shortest. However, at σa =20 MPa, the fatigue life of all specimens were almost the same. It was found that fatigue lives of Mg single crystals strongly depend on crystal orientations and stress.

Phase Transformations in Lutetium Borides at Heating in Vacuum

2011 ◽  
Vol 172-174 ◽  
pp. 464-469 ◽  
Author(s):  
Anatoliy Taran ◽  
Daniel Voronovich ◽  
Natalya Shitsevalova ◽  
Ganna Levchenko ◽  
Volodymyr Filipov ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Phase Transformation ◽  
Surface Layer ◽  
Single Crystal ◽  
Phase Transformations ◽  
Single Crystals ◽  
X Ray ◽  
Before And After ◽  
Spontaneous Phase ◽  
Crystal Bulk

The LuB12 ® LuB4 ® LuB2 phase transformations on annealing in vacuum (T=(1400÷1800) K, p < 10-2 Pa) are investigated with use of the parent single crystals. SEM and X-ray researches of the corresponding lutetium boride single crystals were carried out before and after their annealing. It is shown that the LuB12 → LuB4 phase transformation takes place in surface layer and transition region spreads inwards the single crystal bulk with time. According to the assessed Lu-B phase diagram the LuB4 phase transformation into other individual phases is impossible, and at first it is shown that under corresponding conditions the LuB4 → LuB2 spontaneous phase transformation takes place both on the surface and in the LuB4 single crystal bulk.

FATIGUE BEHAVIOR AND THE RELATIONSHIP BETWEEN CRACK PROPAGATION AND THE SLIT CONFIGURATION OF C/C COMPOSITES

2013 ◽  
Vol 27 (13) ◽  
pp. 1350094 ◽  
Author(s):  
MD. SHAFIUL FERDOUS ◽  
SOFYAN ARIEF SETYABUDI ◽  
CHOBIN MAKABE ◽  
MASAKI FUJIKAWA
Keyword(s):  
Fatigue Strength ◽  
Crack Growth ◽  
Fracture Behavior ◽  
Maximum Stress ◽  
Fatigue Behavior ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Fatigue And Fracture ◽  
Slit Length ◽  
The Relationship

The fatigue and fracture behavior of C/C composites fabricated using fine-woven carbon fiber laminates with α = 0/90° direction were investigated. Also, the phenomenon of crack growth behavior and the shear damage in the fiber bundle was discussed. Slits of several sizes were cut on both sides of a test section and different sizes of slit length were chosen. The effect of the slit configuration on crack initiation and growth behavior was observed. Specimens with blunt-notches and center-holes were also used to compare the fatigue strength and crack growth behavior. Non-propagating cracks were observed and fatigue limit was defined as the maximum stress at which specimen did not break for N = 107 cycles stress application. The longest fatigue life was obtained in the case of specimens with shorter slits. The relationships between fatigue strengths and specimen shapes were analyzed by stress concentration, K t , and stress intensity factor, K I . The effect of slit configuration on fatigue strength was then discussed regarding both the experimental and calculated consequences.

scholarly journals Microstructure and Texture of Hydrostatic Extrusion Deformed Ni Single Crystals and Polycrystal

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
D. Jakubowska ◽  
J. Zdunek ◽  
M. Kulczyk ◽  
J. Mizera ◽  
K. J. Kurzydłowski
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Single Crystal ◽  
Single Crystals ◽  
Relevant Literature ◽  
Hydrostatic Extrusion ◽  
Total Deformation ◽  
Polycrystalline Nickel ◽  
Before And After

The differences in the microstructure and texture of two Ni single crystals, with different initial orientations (100and110), and of polycrystalline nickel, before and after severe plastic deformation (SPD) produced by hydrostatic extrusion (HE), have been investigated. The crystals were deformed by a two-step HE process with a total deformation value ofε=1.2. The global texture, mechanical properties, and microstructure were examined after the deformation. In every investigated sample, the presence of111fibre texture was noted, while the starting orientation of a100Ni single crystal was preserved in 50% of the volume. The results obtained were compared with the relevant literature data.

Electric Fatigue of PZT Piezoelectric Ceramics under Bias and Unipolar Pulse Cycling Field

2007 ◽  
Vol 336-338 ◽  
pp. 356-358
Author(s):  
Wei Qiang Wang ◽  
Zhen Xing Yue ◽  
Jian Qiang Zhao ◽  
Long Tu Li
Keyword(s):  
Piezoelectric Coefficient ◽  
Strong Field ◽  
Fatigue Behavior ◽  
Hysteresis Loops ◽  
Piezoelectric Ceramics ◽  
Unipolar Pulse ◽  
Before And After ◽  
The Difference ◽  
Electric Fatigue ◽  
Different Characteristics

Electric fatigue of piezoelectric ceramics is very important for piezoelectric actuator applications in strong field. In order to classify the fatigue of ferroelectric and piezoelectric properties, the electric fatigue behavior of piezoelectric ceramics of PZT-PMN-PNN was investigated under bias and unipolar pulse cycling field. The bias and unipolar polarization hysteresis loops are measured before and after cycling. The polarization measurements after cycling show a much smaller decrease than bipolar fatigue, but the piezoelectric coefficient d33 still suffers relatively higher deterioration, which indicates different characteristics for piezoelectric and ferroelectric fatigues. A possible mechanism of the partial pining of switching domains responsible for the difference is discussed in this paper.

Serrated Yield Behavior in Nial Single Crystal

1994 ◽  
Vol 364 ◽  
Author(s):  
J. M. Brzeski ◽  
J.E. Hack ◽  
R. Darolia
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Single Crystal ◽  
Single Crystals ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Fracture Behavior ◽  
Recent Model ◽  
Dynamic Strain ◽  
Yield Behavior

AbstractDynamic strain aging has been characterized in standard purity NiAl single crystals during compression testing. The activation energy for the process suggests carbon and oxygen as the most likely agents. Experimental data is compared with a recent model and implications for the fracture behavior of NiAl are considered.

The observation of defects on (100) CdTe surfaces by chemical etching

1992 ◽  
Vol 50 (2) ◽  
pp. 1424-1425
Author(s):  
M.E. Lee
Keyword(s):  
Single Crystal ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Chemical Etching ◽  
Crystalline Perfection ◽  
Crystalline Defects ◽  
High Incidence ◽  
Crystallographic Defects ◽  
Cdznte Substrates ◽  
Device Technology

The crystalline perfection of bulk CdTe substrates plays an important role in their use in infrared device technology. The application of chemical etchants to determine crystal polarity or the density and distribution of crystallographic defects in (100) CdTe is not well understood. The lack of data on (100) CdTe surfaces is a result of the apparent difficulty in growing (100) CdTe single crystal substrates which is caused by a high incidence of twinning. Many etchants have been reported to predict polarity on one or both (111) CdTe planes but are considered to be unsuitable as defect etchants. An etchant reported recently has been considered to be a true defect etchant for CdTe, MCT and CdZnTe substrates. This etchant has been reported to reveal crystalline defects such as dislocations, grain boundaries and inclusions in (110) and (111) CdTe. In this study the effect of this new etchant on (100) CdTe surfaces is investigated.The single crystals used in this study were (100) CdTe as-cut slices (1mm thickness) from Bridgman-grown ingots.

The stability of dislocation networks under various oxygen-doping conditions in superconducting Bi2Sr2CaCu2Oy single crystals and their influence on the flux pinning properties

1994 ◽  
Vol 52 ◽  
pp. 802-803
Author(s):  
Y. Feng ◽  
X. Y. Cai ◽  
R. J. Kelley ◽  
D. C. Larbalestier
Keyword(s):  
Single Crystals ◽  
Oxygen Content ◽  
Basal Plane ◽  
Flux Pinning ◽  
Pinning Centers ◽  
Before And After ◽  
Anomalous Peak ◽  
Basal Plane Dislocation ◽  
The Stability ◽  
Further Development

The issue of strong flux pinning is crucial to the further development of high critical current density Bi-Sr-Ca-Cu-O (BSCCO) superconductors in conductor-like applications, yet the pinning mechanisms are still much debated. Anomalous peaks in the M-H (magnetization vs. magnetic field) loops are commonly observed in Bi2Sr2CaCu2Oy (Bi-2212) single crystals. Oxygen vacancies may be effective flux pinning centers in BSCCO, as has been found in YBCO. However, it has also been proposed that basal-plane dislocation networks also act as effective pinning centers. Yang et al. proposed that the characteristic scale of the basal-plane dislocation networksmay strongly depend on oxygen content and the anomalous peak in the M-H loop at ˜20-30K may be due tothe flux pinning of decoupled two-dimensional pancake vortices by the dislocation networks. In light of this, we have performed an insitu observation on the dislocation networks precisely at the same region before and after annealing in air, vacuumand oxygen, in order to verify whether the dislocation networks change with varying oxygen content Inall cases, we have not found any noticeable changes in dislocation structure, regardless of the drastic changes in Tc and the anomalous magnetization. Therefore, it does not appear that the anomalous peak in the M-H loops is controlled by the basal-plane dislocation networks.

Weekly Exercise Consistently Reinstates Positive Mood

1998 ◽  
Vol 3 (4) ◽  
pp. 271-280 ◽  
Author(s):  
Hannah Steinberg ◽  
Briony R. Nicholls ◽  
Elizabeth A. Sykes ◽  
N. LeBoutillier ◽  
Nerina Ramlakhan ◽  
...  
Keyword(s):  
Physical Exercise ◽  
Negative Mood ◽  
Real Life ◽  
Positive Mood ◽  
Field Investigation ◽  
Single Bout ◽  
Before And After ◽  
Exercise Class ◽  
Negative Feelings ◽  
Over Time

Mood improvement immediately after a single bout of exercise is well documented, but less is known about successive and longer term effects. In a “real-life” field investigation, four kinds of exercise class (Beginners, Advanced, Body Funk and Callanetics) met once a week for up to 7 weeks. Before and after each class the members assessed how they felt by completing a questionnaire listing equal numbers of “positive” and “negative” mood words. Subjects who had attended at least five times were included in the analysis, which led to groups consisting of 18, 20, 16, and 16 subjects, respectively. All four kinds of exercise significantly increased positive and decreased negative feelings, and this result was surprisingly consistent in successive weeks. However, exercise seemed to have a much greater effect on positive than on negative moods. The favorable moods induced by each class seemed to have worn off by the following week, to be reinstated by the class itself. In the Callanetics class, positive mood also improved significantly over time. The Callanetics class involved “slower,” more demanding exercises, not always done to music. The Callanetics and Advanced classes also showed significantly greater preexercise negative moods in the first three sessions. However, these differences disappeared following exercise. Possibly, these two groups had become more “tolerant” to the mood-enhancing effects of physical exercise; this may be in part have been due to “exercise addiction.”

Mounting an individual submicrometer sized single crystal

1996 ◽  
Vol 211 (6) ◽  
Author(s):  
R. B. Neder ◽  
M. Burghammer ◽  
Th. Grasl ◽  
H. Schulz
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Single Crystal ◽  
Single Crystals ◽  
High Vacuum ◽  
Nanometer Resolution ◽  
Micro Manipulator ◽  
Scanning Electron

AbstractWe developed a new micro manipulator for mounting individual sub-micrometer sized single crystals within a scanning electron microscope. The translations are realized via a commercially available piezomicroscope, adapted for high vacuum usage and realize nanometer resolution. With this novel instrument it is routinely possible to mount individual single crystals with sizes down to 0.1

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