Influence of processing parameters on the ferroelectric-relaxor crossover in BNT-based piezoelectric ceramics

2021 ◽  
Vol 130 (18) ◽  
pp. 184102
Author(s):  
Sanu K. Gupta ◽  
Brady J. Gibbons ◽  
Peter Mardilovich ◽  
David P. Cann
Keyword(s):  
Piezoelectric Ceramics ◽  
Processing Parameters ◽  
Ferroelectric Relaxor

Large strain response and fatigue-resistant behavior in lead-free Bi0.5(Na0.80K0.20)0.5TiO3–(K0.5Na0.5)MO3 (M = Sb, Ta) ceramics

RSC Advances ◽  
2015 ◽  
Vol 5 (100) ◽  
pp. 82605-82616 ◽  
Author(s):  
Jigong Hao ◽  
Zhijun Xu ◽  
Ruiqing Chu ◽  
Wei Li ◽  
Juan Du ◽  
...  
Keyword(s):  
Phase Boundary ◽  
Large Strain ◽  
Piezoelectric Ceramics ◽  
Lead Free ◽  
Large Strains ◽  
Strain Response ◽  
Ferroelectric Relaxor ◽  
Free Behavior

BNKT20–KNM100x lead-free piezoelectric ceramics were fabricated to achieve large strain response. Compositions near the ferroelectric–relaxor phase boundary (x = 0.0125) exhibited large strains of 0.39–0.41% with fatigue-free behavior (106 cycles).

Dielectric Relaxation Phenomena in some Lead and Non-Lead Based Ferroelectric Relaxor Materials: Recent Advances

2012 ◽  
Vol 189 ◽  
pp. 233-266
Author(s):  
Parmendra Kumar Bajpai
Keyword(s):  
Dielectric Relaxation ◽  
Solid Solutions ◽  
Piezoelectric Ceramics ◽  
Lead Zirconate ◽  
Ferroelectric Materials ◽  
Relaxation Phenomena ◽  
Pure Lead ◽  
Ferroelectric Relaxor ◽  
Device Applications ◽  
High Dielectric

Relaxors with general formula AA'BB'O3with different cationic distributions at A/B-sites have important device applications in capacitors, piezoelectric ultrasonic transducers, electrostrictive actuators, SAW substrates, etc. The doping or compositional changes in these ceramics can control the high electromechanical characteristics. Lead zirconate titanates (PZT) - based solid solutions exhibit excellent electrochemical properties and are widely used as actuators, transducers, ceramic filters, resonators, sensors and other electronic devices, due to their excellent piezoelectric properties. Although, there has been a concerted effort to develop leadfree piezoelectric ceramics, no effective alternative to PZT has yet been found; most other materials that possess high dielectric and piezoelectric coefficients still contain lead ions. Dielectric relaxation in these materials is of fundamental importance. Recently, new relaxor ferroelectric materials (Pb (B1/3Nb2/3)O3types) have been reported by our group in which the dielectric relaxation character is different from that observed in typical lead based relaxors. In the first part of the review, relaxor characteristics, strategies to synthesize phase pure lead based relaxors and dielectric relaxation phenomena are presented. Deviation of the frequency dependent susceptibility from Curie-Weiss law is analysed both in terms of Gaussian and Lorentzian formalisms. Lead based ferroelectric relaxor materials, due to environmental, health and social reasons are not preferred in devices and attempts are being made to eliminate the lead content from these materials. Sodium bismuth titanate (Na0.5Bi0.5TiO3, abbreviated as NBT), is considered to be one of the excellent candidates for lead-free piezoelectric material. However, pure NBT piezoelectric ceramics are difficult to pole due to its relatively large coercive field and high electrical conductivity. Therefore, many solid solutions of NBT with other ceramics are proposed to improve the relevant properties. In the second part of the review, relaxor behaviour of newly developed solid solutions of NBT is discussed. Finally, the future scope of research on these advance materials is presented.

Nanoscale ferroelectric/relaxor composites: Origin of large strain in lead–free Bi–based incipient piezoelectric ceramics

2016 ◽  
Vol 36 (14) ◽  
pp. 3401-3407 ◽  
Author(s):  
Thi Hinh Dinh ◽  
Jin-Kyu Kang ◽  
Jae-Shin Lee ◽  
Neamul Hayet Khansur ◽  
John Daniels ◽  
...  
Keyword(s):  
Large Strain ◽  
Piezoelectric Ceramics ◽  
Lead Free ◽  
Ferroelectric Relaxor

Microstructural Variations in Melt-Spun Rapidly Solidified Ribbons

1985 ◽  
Vol 43 ◽  
pp. 54-55
Author(s):  
L. A. Bendersky ◽  
W. J. Boettinger
Keyword(s):  
Solid State ◽  
Processing Parameters ◽  
Heat Extraction ◽  
Solid State Reactions ◽  
Careful Examination ◽  
Ion Milling ◽  
Melt Spun ◽  
Wheel Side ◽  
Rapidly Solidified ◽  
Heat Extraction Rate

Rapid solidification produces a wide variety of sub-micron scale microstructure. Generally, the microstructure depends on the imposed melt undercooling and heat extraction rate. The microstructure can vary strongly not only due to processing parameters changes but also during the process itself, as a result of recalescence. Hence, careful examination of different locations in rapidly solidified products should be performed. Additionally, post-solidification solid-state reactions can alter the microstructure.The objective of the present work is to demonstrate the strong microstructural changes in different regions of melt-spun ribbon for three different alloys. The locations of the analyzed structures were near the wheel side (W) and near the center (C) of the ribbons. The TEM specimens were prepared by selective electropolishing or ion milling.

NEW PIEZOELECTRIC CERAMICS

1972 ◽  
Vol 33 (C2) ◽  
pp. C2-243-C2-245
Author(s):  
V. V. KLIMOV ◽  
O. S. DIDKOVSKAJA ◽  
G. E. SAVENKOVA ◽  
Ju. N. VENEVTSEV
Keyword(s):  
Piezoelectric Ceramics

Measurement of Micro Vibration of Car by Piezoelectric Ceramics

2010 ◽  
Vol 130 (5) ◽  
pp. 844-851 ◽  
Author(s):  
Yosuke Kurihara ◽  
Kosuke Masuyama ◽  
Testuo Nakamura ◽  
Takeshi Bamba ◽  
Kajiro Watanabe
Keyword(s):  
Piezoelectric Ceramics ◽  
Micro Vibration

Surface Modification and its Influence on the Microstructure and Creep Resistance of Nickel Based Superalloy René 77 / Modyfikacja Powierzchniowa Oraz Jej Wpływ Na Mikrostrukture I Wytrzymałosc Na Pełzanie Odlewów Z Nadstopu Niklu Ren´E 77

2013 ◽  
Vol 58 (1) ◽  
pp. 95-98 ◽  
Author(s):  
M. Zielinska ◽  
J. Sieniawski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Surface Modification ◽  
Turbine Blades ◽  
Processing Parameters ◽  
Grain Structure ◽  
Creep Tests ◽  
Cobalt Aluminate ◽  
Nickel Based Superalloy ◽  
Average Grain Size

Superalloy René 77 is very wide used for turbine blades, turbine disks of aircraft engines which work up to 1050°C. These elements are generally produced by the investment casting method. Turbine blades produced by conventional precision casting methods have coarse and inhomogeneous grain structure. Such a material often does not fulfil basic requirements, which concern mechanical properties for the stuff used in aeronautical engineering. The incorporation of controlled grain size improved mechanical properties. This control of grain size in the casting operation was accomplished by the control of processing parameters such as casting temperature, mould preheating temperature, and the use of grain nucleates in the face of the mould. For nickel and cobalt based superalloys, it was found that cobalt aluminate (CoAl2O4) has the best nucleating effect. The objective of this work was to determine the influence of the inoculant’s content (cobalt aluminate) in the surface layer of the ceramic mould on the microstructure and mechanical properties at high temperature of nickel based superalloy René 77. For this purpose, the ceramic moulds were made with different concentration of cobalt aluminate in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix ( phase), was determined on the stepped samples. The influence of surface modification on the grain size of up to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of ’ phase and carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form creep tests.

A geometallurgical characterization study of the Crystalkop Reef at the Great Noligwa Mine, Klerksdorp Goldfield, South Africa

2017 ◽  
Vol 120 (3) ◽  
pp. 303-322
Author(s):  
D. Pienaar ◽  
B.M. Guy ◽  
C. Pienaar ◽  
K.S. Viljoen
Keyword(s):  
South Africa ◽  
Treatment Plant ◽  
Processing Parameters ◽  
Processing Plant ◽  
Small Contribution ◽  
Gold Cyanide ◽  
Three Samples ◽  
Characterization Study ◽  
Different Sources

Abstract Mineralogical and textural variability of ores from different sources commonly leads to processing inefficiencies, particularly when a processing plant is designed to treat ore from a single source (i.e. ore of a relatively uniform composition). The bulk of the Witwatersrand ore in the Klerksdorp goldfield, processed at the AngloGold Ashanti Great Noligwa treatment plant, is derived from the Vaal Reef (>90%), with a comparatively small contribution obtained from the Crystalkop Reef (or C-Reef). Despite the uneven contribution, it is of critical importance to ensure that the processing parameters are optimized for the treatment of both the Vaal and C-Reefs. This paper serves to document the results of a geometallurgical study of the C-Reef at the Great Noligwa gold mine in the Klerksdorp goldfield of South Africa, with the primary aim of assessing the suitability of the processing parameters that are in use at the Great Noligwa plant. The paper also draws comparisons between the C-Reef and the Vaal Reef A-facies (Vaal Reef) and attempts to explain minor differences in the recovery of gold and uranium from these two sources. Three samples of the C-Reef were collected in-situ from the underground operations at Great Noligwa mine for mineralogical analyses and metallurgical tests. Laboratory-scale leach tests for gold (cyanide) and uranium (sulphuric acid) were carried out using dissolution conditions similar to that in use at the Great Noligwa plant, followed by further diagnostic leaching in the case of gold. The gold in the ore was found to be readily leachable with recoveries ranging from 95% to 97% (as opposed to 89% to 93% for the Vaal Reef). Additional recoveries were achieved in the presence of excess cyanide (96% to 98%). The recovery of uranium varied between 72% and 76% (as opposed to 30% to 64% for the Vaal Reef), which is substantially higher than predicted, given the amount of brannerite in the ore, which is generally regarded as refractory. Thus, the higher uranium recoveries from the C-Reef imply that a proportion of the uranium was recovered by the partial dissolution of brannerite. As the Vaal Reef contain high amounts of chlorite (3% to 8%), which is an important acid consumer, it is considered likely that this could have reduced the effectiveness of the H2SO4 leach in the case of the ore of the Vaal Reef. Since the gold and uranium recoveries from the C-Reef were higher than the recoveries from the Vaal Reef, the results demonstrate that the processing parameters used for treatment of the Vaal Reef are equally suited to the treatment of the C-Reef. Moreover, small processing modifications, such as increased milling and leach retention times, may well increase the recovery of gold (particularly when e.g. coarse gold, or unexposed gold, is present).

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