scholarly journals Comparison between dielectric and pyroelectric properties of PZFNT and BST type ceramics

2019 ◽  
Vol 13 (3) ◽  
pp. 269-276
Author(s):  
Viorica Stancu ◽  
Luminita Amarande ◽  
Mihaela Botea ◽  
Alin Iuga ◽  
Lucia Leonat ◽  
...  
Keyword(s):  
Grain Size ◽  
Laser Pulse ◽  
Pulse Energy ◽  
Room Temperature ◽  
Laser Pulse Energy ◽  
Dielectric Constants ◽  
Ceramic Technology ◽  
Pyroelectric Properties ◽  
Average Grain Size ◽  
Pyroelectric Detectors

Ba0.75Sr0.25TiO3 (BST) and PbZr0.68Fe0.14Nb0.14Ti0.04O3 (PZFNT) ceramic pellets were obtained by ceramic technology and their structural, ferroelectric and pyroelectric properties were investigated. The relative density of BST and PZFNT is about 93% and 90%, respectively, with an average grain size of 102 ?m and 6.45 ?m. Both materials have similar room temperature dielectric constants (~2000), but PZFNT shows higher remnant polarization (~15?C/cm2) and better pyroelectric properties (~1.69?10?4 C/m2K), which recommend it for pyroelectric detectors, infrared radiation- and laser pulse energy-meters.

scholarly journals Enhanced dielectric properties in la modified barium titanate ceramics

2019 ◽  
Vol 32 (2) ◽  
pp. 179-193 ◽  
Author(s):  
Vesna Paunovic ◽  
Zoran Prijic ◽  
Milos Djordjevic ◽  
Vojislav Mitic
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Dielectric Properties ◽  
Curie Temperature ◽  
Room Temperature ◽  
Dissipation Factor ◽  
Dielectric Constants ◽  
Phase Transformation Temperature ◽  
Average Grain Size ◽  
La Doped

Donor/acceptor (La/Mn) doped BaTiO3 ceramics, sintered at different temperatures, were studied regarding their microstructure and dielectric properties as well as the dielectric response in a ferroelectric/paraelectric regime. The concentrations of La3+ as donor, ranging from 0.1 to 5.0 at% were used for doping, while a content of Mn4+ as acceptor was at 0.05 at% in all samples. The sintering temperature of codoped samples were 1290? and 1350?C. A reduction in grain size and fine-grained microstructure with average grain size from 0.5 to 2.0 mm was observed in low doped samples, whereas the abnormal growth of individual grains took place in the 2 at% and 5 at% La doped specimens. The dielectric properties of these samples were investigated as a function of frequency (100Hz - 20 kHz) and temperature (20-180?C). The measured results suggested that both the dielectric constants of the ceramics (er at room temperature and ermax at the Curie temperature) decreased as the concentration of La3+ increased. The dielectric permittivity was in the range of 944 to 3200. For samples doped with 0.1 at% La and sintered at 1350?C, the highest dielectric constant value at room temperature (er= 3200) and Curie temperature (er= 5000) were measured. For all measured samples the dissipation factor was less than 0.09. With an increase in La contents, dielectric measurements exhibited shift in the Curie temperature (Tc) towards the low temperature. Using the Curie-Weiss and the modified Curie-Weiss law, Curie's constant C was calculated as well as the parameterg, which describes the deviation from the linear dependence er of T above the phase transformation temperature. The calculated values for g ranged from 1.01 to 1.43. These values indicate a sharp phase transformation in lowdoped and diffuse phase transformation in highly La doped samples. The phase transition was reflected in the values of C that started to decrease with increasing dopant content.

scholarly journals Experimental and Numerical Investigation of the ECAP Processed Copper: Microstructural Evolution, Crystallographic Texture and Hardness Homogeneity

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 607
Author(s):  
A. I. Alateyah ◽  
Mohamed M. Z. Ahmed ◽  
Yasser Zedan ◽  
H. Abd El-Hafez ◽  
Majed O. Alawad ◽  
...  
Keyword(s):  
Grain Size ◽  
Equal Channel Angular Pressing ◽  
Cross Section ◽  
Room Temperature ◽  
Pure Copper ◽  
High Density ◽  
Ecap Processing ◽  
Heterogeneous Distribution ◽  
Angular Pressing ◽  
Average Grain Size

The current study presents a detailed investigation for the equal channel angular pressing of pure copper through two regimes. The first was equal channel angular pressing (ECAP) processing at room temperature and the second was ECAP processing at 200 °C for up to 4-passes of route Bc. The grain structure and texture was investigated using electron back scattering diffraction (EBSD) across the whole sample cross-section and also the hardness and the tensile properties. The microstructure obtained after 1-pass at room temperature revealed finer equiaxed grains of about 3.89 µm down to submicrons with a high density of twin compared to the starting material. Additionally, a notable increase in the low angle grain boundaries (LAGBs) density was observed. This microstructure was found to be homogenous through the sample cross section. Further straining up to 2-passes showed a significant reduction of the average grain size to 2.97 µm with observable heterogeneous distribution of grains size. On the other hand, increasing the strain up to 4-passes enhanced the homogeneity of grain size distribution. The texture after 4-passes resembled the simple shear texture with about 7 times random. Conducting the ECAP processing at 200 °C resulted in a severely deformed microstructure with the highest fraction of submicron grains and high density of substructures was also observed. ECAP processing through 4-passes at room temperature experienced a significant increase in both hardness and tensile strength up to 180% and 124%, respectively.

Ultrahigh laser pulse energy and power generation at 10 kHz

2012 ◽  
Vol 37 (15) ◽  
pp. 3231 ◽  
Author(s):  
Frederik Fuest ◽  
Michael J. Papageorge ◽  
Walter R. Lempert ◽  
Jeffrey A. Sutton
Keyword(s):  
Power Generation ◽  
Laser Pulse ◽  
Pulse Energy ◽  
Laser Pulse Energy

Intelligent Attenuator For Laser Pulse Energy And Power Stabilization

1983 ◽  
Author(s):  
Malcolm S. White ◽  
Raymond W. Wyatt ◽  
Anthony G. Brett
Keyword(s):  
Laser Pulse ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Power Stabilization

ATOMIC FORCE MICROSCOPY AND XRD ANALYSIS OF SILVER FILMS DEPOSITED BY THERMAL EVAPORATION

2006 ◽  
Vol 20 (02) ◽  
pp. 217-231 ◽  
Author(s):  
MUHAMMAD MAQBOOL ◽  
TAHIRZEB KHAN
Keyword(s):  
Atomic Force Microscopy ◽  
Grain Size ◽  
Surface Characterization ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Xrd Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Average Grain Size ◽  
20 Nm

Thin films of pure silver were deposited on glass substrate by thermal evaporation process at room temperature. Surface characterization of the films was performed using X-ray diffraction (XRD) and atomic force microscopy (AFM). Thickness of the films varied between 20 nm and 72.8 nm. XRD analysis provided a sharp peak at 38.75° from silver. These results indicated that the films deposited on glass substrates at room temperature are crystalline. Three-dimension and top view pictures of the films were obtained by AFM to study the grain size and its dependency on various factors. Average grain size increased with the thickness of the deposited films. A minimum grain size of 8 nm was obtained for 20 nm thick films, reaching 41.9 nm when the film size reaches 60 nm. Grain size was calculated from the information provided by the XRD spectrum and averaging method. We could not find any sequential variation in the grain size with the growth rate.

scholarly journals Understanding of BeCu Interaction Characteristics with a Variation of ns Laser-Pulse Duration

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1423 ◽  
Author(s):  
Dongkyoung Lee
Keyword(s):  
Laser Pulse ◽  
Pulse Duration ◽  
Pulse Energy ◽  
Laser Pulse Energy ◽  
Laser Spot ◽  
Main Body ◽  
Crater Size ◽  
Stamping Process ◽  
Cut Quality ◽  
Mechanical Cutting

An inspection process using a Spring Contact Probe (SCP) is an essential step in the semiconductor-manufacturing process. Many plungers, which are the main body of the SCP, are manufactured by a stamping process. After the stamping process, mechanical cutting is applied and the plunger body may be damaged. Thus, to improve cut quality and productivity while minimizing body damage, laser spot cutting can be used. To fully utilize this technology, it is necessary to investigate interaction characteristics of beryllium copper (BeCu) during laser spot cutting. Effects of a total irradiated laser-pulse energy (1 mJ ~1000 mJ ) and pulse duration (100 ns ~8 ns ) on the material-removal zone, thermal depth, and crater size are examined. The crater size can be affected by the localization of heating dominantly. An incubation model is applied to investigate the correlation between crater size and laser-pulse energy. Surface morphology characteristics such as edge separation, small particles, spatter motion, and soaring-up motion are observed.

Study on Laser Welding of Phone Nuts

2013 ◽  
Vol 815 ◽  
pp. 778-781
Author(s):  
Xiao Hong Wu
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Laser Pulse ◽  
Laser Welding ◽  
Pulse Energy ◽  
Pulse Width ◽  
Peak Power ◽  
Laser Pulse Energy ◽  
304 Stainless Steel ◽  
Power Pulse

Used YAG pulse laser to weld 304 stainless steel nuts, studied about the parameters such as peak power, pulse width, defocus distance impacting on the performance of the joints welded by laser. The studies showed that the tensile strength and torque of the nuts increased as the peak power and the pulse width increased.Burn through in welding easy occur when laser pulse energy is too big, pulse width is too wide or defocus distance is too low.

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