Microstructure and 90° domain assemblages of Pb(Zr, Ti)O3//RuO2 capacitors as a function of Zr-to-Ti stoichiometry

1996 ◽  
Vol 11 (9) ◽  
pp. 2309-2317 ◽  
Author(s):  
B. A. Tuttle ◽  
T. J. Headley ◽  
H.N. Al-Shareef ◽  
J. A. Voigt ◽  
M. Rodriguez ◽  
...  
Keyword(s):  
Single Phase ◽  
Perovskite Phase ◽  
Grain Morphology ◽  
Fluorite Structure ◽  
Second Phase ◽  
Cross Sectional ◽  
Thin Film Capacitors ◽  
Pzt Films ◽  
Granular Morphology ◽  
Phase Differences

Planar microstructure, 90° domain configurations, and cross-sectional perovskite grain morphology were characterized for a series of Pb(Zr, Ti)O3//RuO2 thin film capacitors. Perovskite grain size increased substantially with increasing Zr concentration of the Pb(Zr, Ti)O3 (PZT) films, being on the order of 0.15 μm for PZT 20/80 films and 2.5 μm for PZT 50/50 films. While PZT 20/80 and PZT 30/70 films were single phase perovskite, the PZT 40/60 and 50/50 films contained a second phase with fluorite structure. The second phase matrix consisted of two nanophases, one having fluorite structure while the other was amorphous. Both the amorphous nanophase and the fluorite nanophase were Pb deficient compared to the perovskite phase. Differences in cross-sectional perovskite grain morphology were substantial for these materials, with the PZT 40/60 film being almost entirely columnar and the PZT 20/80 film exhibiting almost entirely granular morphology. Differences in 90° domain wall density were essentially negligible among the films, suggesting that if 90° domains were responsible for the differences in electrical properties, it is not due to 90° domain population.

Zirconolite transformation under reducing conditions

1998 ◽  
Vol 13 (11) ◽  
pp. 3181-3190 ◽  
Author(s):  
B. D. Begg ◽  
E. R. Vance ◽  
B. A. Hunter ◽  
J. V. Hanna
Keyword(s):  
Perovskite Phase ◽  
Charge Compensation ◽  
Fluorite Structure ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Reducing Conditions ◽  
Quadrupole Resonance

The structural behavior of zirconolite (CaZrTi2O7) under reducing conditions at high temperature has been studied, mainly by scanning electron microscopy (SEM) and x-ray diffraction (XRD), but also with x-ray absorption spectroscopy, thermogravimetry, and electron paramagnetic resonance. The partial reduction of Ti4+ to Ti3+, associated with a reducing atmosphere heat treatment, led to the initial formation of perovskite (CaTiO3) as a second phase. As the concentration of Ti3+ in the zirconolite increased, so did the amount of perovskite until the zirconolite was totally transformed into a fluorite structured phase. Analysis of the reduced zirconolites showed them to be consistently deficient in Ca and enriched in Zr, in proportion to the concentration of Ti3+. To determine how electroneutrality was preserved in these reduced zirconolites, a series of zirconolites were prepared in air using In3+ and Ga3+ as models for Ti3+. These samples were then investigated by neutron and x-ray diffraction, SEM, solid state nuclear magnetic resonance (NMR), and nuclear quadrupole resonance (NQR). 71Ga MAS NMR studies of the Ga substituted zirconolite exhibited a narrow resonance at ˜13 ppm which was attributed to six-coordinate Ga incorporated in a trace perovskite phase. Broadline 71Ga NMR and 69/71Ga NQR were required to characterize the Ga incorporated in the zirconolite. The resultant quadrupolar parameters of CQ = 30.0 ± 0.05 MHz and η = 1.0 ± 0.03 indicate that the Ga site is in a highly distorted environment which would suggest that it is located on the five-coordinate Ti site within the zirconolite lattice. These results were complemented by Rietveld refinement of the neutron diffraction data from the In-doped zirconolite sample, which was optimal when all the In was located on the five-coordinate Ti site with the excess Zr located on the Ca site. It would therefore appear that charge compensation for the presence of Ti3+ in zirconolite is effected via the substitution of an appropriate amount of Zr on the Ca site. The Ti3+-stabilized fluorite structure was readily oxidized back to a single phase zirconolite upon heating in air.

Superoonductivity in the R3CaBa3Cu7Oy System with R = Lanthanide

1992 ◽  
Vol 275 ◽  
Author(s):  
H. -C. I. Kao ◽  
J. L. Wang ◽  
R. J. Huang ◽  
C. M. Wang ◽  
M. K. Wu
Keyword(s):  
Single Phase ◽  
Perovskite Phase ◽  
Hole Concentration ◽  
Residual Resistivity ◽  
Lanthanide Ions ◽  
Similar Process ◽  
Oxygen Stoichiometry ◽  
Nominal Composition ◽  
Second Phase ◽  
Ionic Radii

ABSTRACTA series of samples with a nominal composition of R3CaBa3Cu7Oy (abbreviated as R3137), where R = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Tm, was prepared by a similar process as for an 80-K superconductor, La3CaBa3Cu7Oy. Most of the R3137 (except for R = Ce, Tb) had a tetragonal triple-perovskite phase like La3137 identified from the XRD patterns, and they were superconducting except Pr3137. For R3+ radius larger than Dy3+ (0.908 Å), a single phase R3137 was observed, and their Tc(zero)' probably related to the rCu-o distance in the copper-oxygen layer, was spread from 85 to 76 K with a maximum for the Eu3137. Oxygen stoichiometry of these R3137 was slightly decreased with decreasing lanthanide radii. The hole concentration, (Cu-O), was found between 0.47 and 0.38/unit cell. For Smaller R3+ ions, residual resistivity was found in the superconducting samples due to the existence of second phase. From the structural study of La3137, it was known that part of the lanthanide ions had to be fitted into the bigger Ba-site. Because ionic radii of the heavy lanthanides (R3+ < Ho3+ = 0.894 Å) were too small to be located at the Ba-site, it was rather difficult to prepare these single phase R3137.

Pulsed Excimer Laser Deposition and Rapid Thermal Annealing of Ferroelectric Pb(Zr0.52Ti0.48)O3 Thin Films on Si-on-Insulator

1994 ◽  
Vol 361 ◽  
Author(s):  
Yiqing Chen ◽  
Lirong Zheng ◽  
Chenglu Lin ◽  
Xinglong Xu ◽  
Shichang Zou
Keyword(s):  
Electron Microscopy ◽  
Thermal Annealing ◽  
Excimer Laser ◽  
Rapid Thermal Annealing ◽  
Perovskite Phase ◽  
Pyrochlore Phase ◽  
Cross Sectional ◽  
Pzt Films ◽  
Soi Substrates ◽  
Ferroelectric Perovskite

ABSTRACTStoichiometric films of Pb(Zr0.52Ti0.48)O3 (PZT) were successfully deposited on Si-on-Insulator (SOI) substrates, with and without a platinum electrode, by an ArF (λ=193nm) pulsed excimer laser. Rapid thermal annealing (RTA) was used to transform amorphous or pyrochlore phase into ferroelectric perovskite phase. The film structure, composition, morphology, interface and electrical properties were studied by x-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (XTEM) and Sawyer-Tower circuit, respectively. It was found that there was a narrow operational window of annealing time for PZT films at fixed annealing temperature. Pure ferroelectric perovskite phase with mainly (100) and (110) orientations could be obtained in PZT films on Pt coated SOI substrates. The interfaces between the PZT films and both Si and Pt//Si were very abrupt, indicating there was no interdiffusion between them. Ferroelectric hysteresis loops showed a remanent polarization of 15μC/cm2 and a coercive field of 50KV/cm.

Structural and Magnetic Hysteresis Properties of Co-Zr Substituted Hexagonal Barium Ferrites

2015 ◽  
Vol 7 (1) ◽  
pp. 1346-1351
Author(s):  
Ch.Gopal Reddy ◽  
Ch. Venkateshwarlu ◽  
P. Vijaya Bhasker Reddy
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Hysteresis ◽  
Grain Morphology ◽  
Hexagonal Structure ◽  
Ion Composition ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
Barium Ferrites ◽  
Xrd Patterns

Co-Zr substituted M-type hexagonal barium ferrites, with chemical formula BaCoxZrxFe12-2xO19 (where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), have been synthesized by double sintering ceramic method. The crystallographic properties, grain morphology and magnetic properties of these ferrites have been investigated by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). The XRD patterns confirm the single phase with hexagonal structure of prepared ferrites. The magnetic properties have been investigated as a function of Co and Zr ion composition at an applied field in the range of 20 KOe. These studies indicate that the saturation magnetization (Ms) in the samples increases initially up to the Co-Zr composition of x=0.6 and decreases thereafter. On the other hand, the coercivity (Hc) and Remanent magnetization (Mr) are found to decrease continuously with increasing Co-Zr content. This property is most useful in permanent magnetic recording. The observed results are explained on the basis of site occupation of Co and Zr ions in the samples.

scholarly journals Effect of cerium on structural and optical properties of ZnO aerogel synthesized in supercritical methanol

2016 ◽  
Vol 34 (3) ◽  
pp. 659-664 ◽  
Author(s):  
M. Meddouri ◽  
L. Hammiche ◽  
O. Slimi ◽  
D. Djouadi ◽  
A. Chelouche
Keyword(s):  
Zinc Acetate ◽  
Structural Parameters ◽  
Fluorite Structure ◽  
Cubic Phase ◽  
Second Phase ◽  
Acetate Solution ◽  
Supercritical Methanol ◽  
Doped Zno ◽  
Zno Aerogels ◽  
Zno Aerogel

AbstractPure ZnO and Ce-doped (5 at.%) ZnO aerogels were prepared by dissociation of dihydrate zinc acetate and cerium nitrate in methanol, followed by drying in supercritical conditions of the solvent. The concentration of zinc acetate solution and the atomic ratio Ce/Zn were fixed at 0.2 mol/L and 0.05 mol/L, respectively. XRD results showed a hexagonal wurtzite structure of ZnO aerogel crystallites and a formation of a separate second phase of ceria cubic phase with fluorite structure and 7.4 nm in size. The introduction of cerium in the solution had a negative effect on the aerogel crystalline quality. The crystallites size was found to be 16 nm in pure ZnO and 27 nm in Ce-doped ZnO aerogels. The grains of Ce-doped ZnO aerogel had torus shaped morphology with hollow centers, but those of pure ZnO were flattened semispheres. The calculated values of different structural parameters showed that cerium ions introduced into the ZnO lattice occupied interstitial sites and Zn ions substituted Ce ones in ceria lattice during the formation process. FT-IR and UV-Vis absorption spectra have not revealed any particularities due to the presence of cerium atoms in ZnO, indicating that Ce (5 at.%) doping of ZnO crystallites synthesized in supercritical methanol did not strongly affect the optical gap of the semiconductor. Micro-Raman studies confirmed the formation of cubic fluorite structure ceria in ZnO aerogel and showed that Raman active modes of ZnO are amplified with the presence of ceria.

Investigation of Dead Layer Thickness in SrRuO3/Ba0.5Sr0.5TiO3/Au Thin Film Capacitors

2000 ◽  
Vol 655 ◽  
Author(s):  
L. J. Sinnamon ◽  
R. M. Bowman ◽  
J. M. Gregg
Keyword(s):  
Thin Film ◽  
Dielectric Constant ◽  
Layer Thickness ◽  
Perovskite Phase ◽  
Frequency Dispersion ◽  
Dead Layer ◽  
Parameter Ratio ◽  
Thin Film Capacitors ◽  
Dead Layer Thickness ◽  
The Dead

AbstractThin film capacitors with barium strontium titanate (BST) dielectric layers of 7.5 to 950 nm were fabricated by Pulsed Laser Deposition. XRD and EDX analyses confirmed a strongly oriented BST cubic perovskite phase with the desired cation stoichiometry. Room temperature frequency dispersion (ε100 kHz / ε100 Hz) for all capacitors was greater than 0.75. Absolute values for the dielectric constant were slightly lower than expected. This was attributed to the use of Au top electrodes since the same sample showed up to a threefold increase in dielectric constant when Pt was used in place of Au. Dielectric constant as a function of thicknesses greater than 70 nm, was fitted using the series capacitor model. The large interfacial parameter ratio di / εi of 0.40 ± 0.05 nm implied a significant dead-layer component within the capacitor structure. Modelled consideration of the dielectric behaviour for BST films, whose total thickness was below that of the dead layer, predicted anomalies in the plots of d/ ε against d at the dead layer thickness. For the SRO/BST/Au system studied, no anomaly was observed. Therefore, either (i) 7.5 nm is an upper limit for the total dead layer thickness in this system, or (ii) dielectric collapse is not associated with a distinct interfacial dead layer, and is instead due to a through-film effect.

Abstract 77: Ongoing Leakage Revealed by Second Phase Spot Sign Volume Expansion in Multi-Phase Computed Tomography Angiography Strongly Predicts Intracranial Hemorrhage Growth

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Abdulaziz Al Sultan ◽  
Ericka Teleg ◽  
MacKenzie Horn ◽  
Piyush Ojha ◽  
Linda Kasickova ◽  
...  
Keyword(s):  
Volume Expansion ◽  
Single Phase ◽  
Meta Analysis ◽  
Hematoma Expansion ◽  
Second Phase ◽  
Hematoma Volume ◽  
Spot Sign ◽  
Time Resolved ◽  
Multi Phase

Background: CTA spot sign is a predictor of intracerebral hemorrhage (ICH) expansion. This sign can fluctuate in appearance, volume, and timing. Multiphase CTA (mCTA) can identify spot sign through 3 time-resolved images. We sought to identify a novel predictor of follow up total hematoma expansion using mCTA. Methods: This cohort study included patients with ICH between 2012-2019. Quantomo software was used to measure total hematoma volume (ml) from baseline CT & follow-up CT/MRI blinded to spot sign in 3 mCTA phases. Spot sign expansion was calculated by subtracting 1 st phase spot sign volume from 2 nd phase spot sign volume measured in microliters. Results: 199 patients [63% male, mean age 69 years, median NIHSS 11, IQR 6-20] were included. Median baseline ICH volume was 16.1 ml (IQR 5-29.9 ml). Amongst all three mCTA phases, spot sign was best detected on the 2nd phase (23% vs 17.5% 1 st phase vs 22% 3 rd phase). In multivariable regression, spot sign expansion was significantly associated with follow up total hematoma expansion (OR: 1.03 per microliter of spot sign expansion, p=0.01). Figure 1 shows the predicted total hematoma expansion by spot sign expansion. mCTA spot sign had a higher sensitivity for predicting total hematoma volume expansion than single-phase CTA (reported in meta-analysis of 14 studies), 86% vs 53%, respectively, while both having similar specificity, 87% vs 88%, respectively. Conclusion: Spot sign expansion on mCTA is a novel predictor of total hematoma expansion and could be used to select patients for immediate therapeutic intervention in future clinical trials. Using mCTA improves sensitivity while preserving specificity over single-phase CTA.

Development of empirically based customer-derived positioning taxonomy for consumer electronics sector in the Indian emerging market

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Natasha Saqib ◽  
Mir Shahid Satar
Keyword(s):  
Emerging Market ◽  
Consumer Electronics ◽  
Second Phase ◽  
Measurement Scales ◽  
Cross Sectional ◽  
Market Positioning ◽  
Content Type ◽  
Customer Perceptions ◽  
Visual Aesthetics ◽  
Practical Implications

PurposeAn Indian emerging market positioning taxonomy has been developed in response to the literature review's findings that existing positioning typologies/taxonomies are based on managerial perspectives rather than consumer/customer perceptions and are only developed for advanced countries.Design/methodology/approachThis study employs a three-step process for developing and validating a scale in order to conduct its research. In the first phase, items are generated and selected based on a literature review, focus groups and expert opinion. Exploratory factor analysis is used to fine-tune the scale in the second phase. Phase 3 uses CFA to establish convergent, discriminant and nomological validity through the use of CFA.FindingsA consumer-based taxonomy of positioning strategies were developed as a result of the research. Six distinct positioning strategies emerged that was named (1) Value for Money, (2) Functional (3) Premiumisation, (4) Promotional Campaign, (5) Brand Name (6) Visual Aesthetics.Research limitations/implicationsDeveloping and validating measurement scales will be made easier with the help of this paper. Target populations, industry and geography selection and a cross-sectional time horizon are just a few of the study's drawbacks.Practical implicationsThe study's practical implications include six factors/strategies that managers, advertising executives and marketing experts of consumer electronics companies in the Indian emerging market could use to position their products, resulting in the overall success of their organisations.Originality/valueThis study adds to the marketing literature by providing a solid theoretical foundation and a validated instrument for operationalising positioning strategies.

scholarly journals Prevalence of Pathological Gambling in Quebec in 2002

2005 ◽  
Vol 50 (8) ◽  
pp. 451-456 ◽  
Author(s):  
Robert Ladouceur ◽  
Christian Jacques ◽  
Serge Chevalier ◽  
Serge Sévigny ◽  
Denis Hamel
Keyword(s):  
Pathological Gambling ◽  
Telephone Interview ◽  
Phase 1 ◽  
Adult Population ◽  
Total Sample ◽  
Second Phase ◽  
Screening Instruments ◽  
South Oaks Gambling Screen ◽  
Cross Sectional ◽  
Pathological Gamblers

Objective: To assess gambling behaviours and the problems associated with pathological gambling among the adult population of Quebec in 2002. Method: In Phase 1 of this 2-phase study, a total sample of 8842 adults was assessed. We used the South Oaks Gambling Screen (SOGS), adapted for telephone interview, to assess one-half of the sample; the other one-half was evaluated with the Canadian Problem Gambling Index (CPGI). In the study's second phase, we compared the classifications obtained from these screening instruments with classifications obtained by a psychologist using a semistructured clinical telephone interview. Results: The results indicate that the prevalence of pathological gambling in 2002 (at which time 0.8% of the adult population were classified as probable pathological gamblers) did not differ from the proportion obtained in 1996 (1.0%), despite the significant decrease in gambling participation in 2002 (81% vs 90% in 1996). The most popular gambling activities were buying lottery tickets (68%), participating in fundraising draws (40%), gambling in casinos (18%), playing cards with family or with friends (10%), playing bingo (9%), and playing video lotteries (8%). The findings obtained from the SOGS and the CPGI revealed that the 2 instruments perform similarly when identifying pathological gambling prevalence. However, the results of the semistructured clinical telephone interviews differed from the results obtained with the screening instruments: 82% of the gamblers initially identified as probable pathological gamblers by the SOGS or the CPGI were not confirmed by a clinical interview. Conclusion: The discrepancy between the results of the screening questionnaires and the clinical evaluation is significant, and this difference needs to be addressed before further cross-sectional or longitudinal studies are conducted.

scholarly journals Developing a comprehensive tool to assess professional attitude among physicians and medical students

2022 ◽  
Author(s):  
Neda Yavari ◽  
Fariba Asghari ◽  
Zahra Shahvari ◽  
Saharnaz Nedjat ◽  
Bagher Larijani
Keyword(s):  
Medical Students ◽  
Group Discussion ◽  
Cross Sectional Study ◽  
Second Phase ◽  
Validity And Reliability ◽  
Cross Sectional ◽  
Individual Interviews ◽  
Professional Attitude ◽  
Final Questionnaire ◽  
Students Attitudes

It appears that up until now, no comprehensive tool has been developed to assess medical students’ attitudes toward the different dimensions of professionalism. The present study aimed to develop a comprehensive quantitative tool to evaluate medical students’ attitudes toward professionalism. This study consisted of two phases: The first phase was item generation and questionnaire design based on literature review and a qualitative survey. The qualitative data were extracted from 49 semi-structured individual interviews and one focus group discussion. In the second phase, the questionnaire was developed and its face, content, and structure validity and reliability were evaluated. To measure the construct validity of the questionnaire, a cross-sectional study was conducted on 354 medical students at different academic levels at Isfahan University of Medical Sciences. The final questionnaire was loaded on five factors. The factors accounted for 43.5% of the total variance. Moreover, Cronbach's alpha was 0.84 for the total scale, and the interclass correlation coefficient was 0.77 for the test-retest reliability. The 17-item questionnaire measuring medical students’ professional attitude had acceptable validity and reliability and can be adopted in other studies on physicians’ and medical students’ professional attitudes.   

Sign in / Sign up

Export Citation Format

Share Document