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.

Shape of piezoelectric hysteresis loop for non-ferroelastic switching

2003 ◽  
Vol 784 ◽  
Author(s):  
A. K. Tagantsev ◽  
P. Muralt ◽  
J. Fousek
Keyword(s):  
Thin Films ◽  
Electric Field ◽  
Hysteresis Loop ◽  
Single Crystals ◽  
Applied Electric Field ◽  
Piezoelectric Coefficient ◽  
Hysteresis Loops ◽  
Simple Theory ◽  
The Difference

ABSTRACTA simple theory for the shape of the piezoelectric hysteresis loops (piezoelectric coefficient d vs. applied electric field E) is developed for the case of non-ferroelelastic 180° switching in ferroelectrics. The theory provides explanations for specific features of piezoelectric hysteresis loops, which have been observed in single crystals, thin films and in ceramics in particular. The piezoelectric coefficient may show a “hump”, i.e. when E decreases from the tip of the loop down to zero, d passes through a maximum, and a “nose”, i.e. a self-crossing of the loop close to its tips. The theory also explains the difference in the coercive fields seen in the polarization and piezoelectric loops.

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.

Effects of Electric Fatigue on Piezoelectric Ceramics

2006 ◽  
Vol 306-308 ◽  
pp. 91-96 ◽  
Author(s):  
Kwok Lun Lee ◽  
Ai Kah Soh
Keyword(s):  
Fatigue Life ◽  
Linear Relationship ◽  
Mechanical Load ◽  
Fatigue Behavior ◽  
Piezoelectric Ceramics ◽  
Electric Load ◽  
Three Point Bending ◽  
Electric Loading ◽  
Non Linear ◽  
Electric Fatigue

The fatigue behavior of piezoelectric ceramics PZT-5 subjected to three-point bending was investigated under a cyclic electric load coupled with a constant mechanical load. The direction of poling was perpendicular to that of the mechanical load. The fatigue life curves under high and low electric loading were compared. Non-linear relationship was observed between dS/dN and E/Ec.

Wear-Fatigue Behavior of Ni88P11.78Co0.12Fe0.10 and Ni80.55Cr15.25B4.20 Metallic Glasses During Rubbing Against an Eccentric Rotating Ceramic Roller

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
C. Serrar ◽  
P. Guiraldenq
Keyword(s):  
Chemical Composition ◽  
Metallic Glasses ◽  
Photoelectron Spectroscopy ◽  
Fatigue Behavior ◽  
X Ray Diffraction ◽  
Eccentric Rotation ◽  
X Ray ◽  
Before And After ◽  
Fatigue Rupture ◽  
The Difference

The wear-fatigue rupture of Ni88P11.78Co0.12Fe0.10 (NiP) and Ni80.55Cr15.25B4.20 (NiCrB) glasses prepared by planar–flow casting have been studied using a test under simultaneous constant and cyclic loading generated by an eccentric rotation ceramic antagonist. For better apprehending the phenomena related to the structural state changes of samples before and after tests, structural characterization by x-ray diffraction, mechanical characterization by measuring Vickers microhardness (HV 0.1) and chemical composition by X-ray photoelectron spectroscopy (XPS) analysis have been carried out on as-quenched and worn dull side ribbons. Rupture surfaces, in S–N curves, have been measured by scanning electron microscope. Wear-fatigue contact tests consist to impose, simultaneously, a traction strain and cyclic normal stresses which generate traction, compression, rolling, bending and shearing. All results obtained from the two selected glasses (NiP and NiCrB) are systematically compared with those of a nickel pure crystalline foil (Ni). We evaluate mainly the wear mechanism, the mode and the typical rupture surface observed in NiP, NiCrB and Ni specimens. We specify the conditions of obtaining these rupture surfaces which often present in smooth plane, veining and “chevrons” patterns. All results show a great wear and fatigue resistance for the two metallic glasses compared to Ni. The NiCrB wear resistance is superior to that of NiP, while the difference in their fatigue limit is not clearly distinct. The reasons for the differences in wear and fatigue behavior will be discussed in relation to the metallic glass thermal stability, chemical composition, microhardness and surface rupture topography.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

Changes in Platelet Aggregability after Ovariectomy

1979 ◽  
Vol 42 (04) ◽  
pp. 1332-1339 ◽  
Author(s):  
Hiroh Yamazaki ◽  
Takeshi Motomiya ◽  
Minoru Sonoda ◽  
Noboru Miyagawa
Keyword(s):  
Platelet Count ◽  
Platelet Activation ◽  
Ovarian Hormones ◽  
Control Group ◽  
Platelet Aggregability ◽  
Appearance Rate ◽  
Before And After ◽  
The Difference ◽  
Induced Aggregation ◽  
Observation Period

SummaryChanges in platelets in 48 patients with uterine myoma before and after hysterectomy with and without ovariectomy were examined. Bilateral ovariectomy in 25 cases (ovariec-tomized group) and unilateral or non-ovariectomy in 23 cases (control group) were performed at the hysterectomy. Platelet count and an appearance rate of secondary aggregation decreased at one day after and increased at one week after the operation, similarly in both the ovariectomized and the control group. The appearance rate of secondary aggregation was reflected in an intensity of aggregation at 5 min after the addition of reagent to PRP. At one month after the operation, the appearance rate of secondary aggregation induced by 3 μM ADP showed a statistically significant decrease in comparison with the preoperation value (P <0.05) and the enhancement of 5-min aggregation was still observed in the control group, while ceased in the ovariectomized group. The difference between the two groups was significant (P < 0.05). There was almost no change in the speed and intensity of primary and secondary aggregation during the observation period. No significant differences in collagen-induced aggregation were noted between the two groups. The results suggest that ovarian hormones, mainly estrogen, facilitate platelet activation which is mediated by the so-called secondary aggregation.

PENGARUH TERAPI TERTAWA TERHADAP PENURUNAN TEKANAN DARAH LANSIA DI UPT PANTI WREDHA BUDHI DHARMA YOGYAKARTA

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Niken Setyaningrum ◽  
Andri Setyorini ◽  
Fachruddin Tri Fitrianta
Keyword(s):  
Blood Pressure ◽  
Data Analysis ◽  
The Elderly ◽  
Control Group ◽  
Group Comparison ◽  
Control Blood Pressure ◽  
Men And Women ◽  
Treatment Of Hypertension ◽  
Before And After ◽  
The Difference

ABSTRACTBackground: Hypertension is one of the most common diseases, because this disease is suffered byboth men and women, as well as adults and young people. Treatment of hypertension does not onlyrely on medications from the doctor or regulate diet alone, but it is also important to make our bodyalways relaxed. Laughter can help to control blood pressure by reducing endocrine stress andcreating a relaxed condition to deal with relaxation.Objective: The general objective of the study was to determine the effect of laughter therapy ondecreasing elderly blood pressure in UPT Panti Wredha Budhi Dharma Yogyakarta.Methods: The design used in this study is a pre-experimental design study with one group pre-posttestresearch design where there is no control group (comparison). The population in this study wereelderly aged over> 60 years at 55 UPT Panti Wredha Budhi Dharma Yogyakarta. The method oftaking in this study uses total sampling. The sample in this study were 55 elderly. Data analysis wasused to determine the difference in blood pressure before and after laughing therapy with a ratio datascale that was using Pairs T-TestResult: There is an effect of laughing therapy on blood pressure in the elderly at UPT Panti WredhaBudhi Dharma Yogyakarta marked with a significant value of 0.000 (P <0.05)

Klein with Lacan: A Study on the Reception of Lacanian Ideas in Uruguay and Its Effects on Clinical Practices (1955–82)

2020 ◽  
Vol 22 (3) ◽  
pp. 341-361
Author(s):  
Gonzalo Grau-Pérez ◽  
J. Guillermo Milán
Keyword(s):  
Clinical Practice ◽  
Clinical Material ◽  
Clinical Practices ◽  
Before And After ◽  
The Difference ◽  
The 1960S ◽  
The Relationship ◽  
Discursive Approach ◽  
The Way ◽  
Clinical Cases

In Uruguay, Lacanian ideas arrived in the 1960s, into a context of Kleinian hegemony. Adopting a discursive approach, this study researched the initial reception of these ideas and its effects on clinical practices. We gathered a corpus of discursive data from clinical cases and theoretical-doctrinal articles (from the 1960s, 1970s and 1980s). In order to examine the effects of Lacanian ideas, we analysed the difference in the way of interpreting the clinical material before and after Lacan's reception. The results of this research illuminate some epistemological problems of psychoanalysis, especially the relationship between theory and clinical practice.

FRACTIONAL DETERMINATIONS OF URINARY 17-KETOSTEROIDS IN HYPEREMESIS GRAVIDARUM

1962 ◽  
Vol 41 (1) ◽  
pp. 123-128 ◽  
Author(s):  
Pentti A. Järvinen ◽  
Sykkö Pesonen ◽  
Pirkko Väänänen
Keyword(s):  
Hyperemesis Gravidarum ◽  
First Trimester ◽  
Control Group ◽  
Before And After ◽  
Daily Urine ◽  
First Trimester Of Pregnancy ◽  
The Difference

ABSTRACT The fractional determination of 17-ketosteroids in the daily urine was performed in nine cases of hyperemesis gravidarum and in four control cases, in the first trimester of pregnancy both before and after corticotrophin administration. The excretion of total 17-KS is similar in the two groups. Only in the hyperemesis group does the excretion of total 17-KS increase significantly after corticotrophin administration. The fractional determination reveals no difference between the two groups of patients with regard to the values of the fractions U (unidentified 17-KS), A (androsterone) and Rest (11-oxygenated 17-KS). The excretion of dehydroepiandrosterone is significantly higher in the hyperemesis group than in the control group. The excretion of androstanolone seems to be lower in the hyperemesis group than in the control group, but the difference is not statistically significant. The differences in the correlation between dehydroepiandrosterone and androstanolone in the two groups is significant. The high excretion of dehydroepiandrosterone and low excretion of androstanolone in cases of hyperemesis gravidarum is a sign of adrenal dysfunction.

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