Tunable ferroelectric properties in (K0.5Na0.5)NbO3 ceramics fabricated by a simple modification of the conventional sintering technique

2021 ◽  
pp. 1-7
Author(s):  
Jiacheng Li ◽  
Ying Hou ◽  
Tingting Ye ◽  
Tianle Ding ◽  
Junfeng Ding ◽  
...  
Keyword(s):  
Ferroelectric Properties ◽  
Simple Modification ◽  
Conventional Sintering

Microwave Processing and Sintering of PZT and PLZT Ceramics

1988 ◽  
Vol 124 ◽  
Author(s):  
W. B. Harrison ◽  
M. R. B. Hanson ◽  
B. G. Koepke
Keyword(s):  
Lead Titanate ◽  
Microwave Sintering ◽  
Ferroelectric Properties ◽  
Lead Zirconate ◽  
Microwave Processing ◽  
High Density ◽  
Pzt Ceramics ◽  
Conventional Sintering ◽  
Processing Techniques ◽  
Fast Firing

ABSTRACTMicrowave processing techniques were established for all of the thermal treatment steps necessary to prepare high density PZT and PLZT. The microstructure and ferroelectric properties of the microwave processed materials were compared to conventionally sintered and fast fired PZT. Unique high density, small grain size, PZT and PLZT were obtained by microwave sintering either conventionally or fully microwave processed powders. It was estimated that microwave sintering would use only five percent of the energy used by conventional sintering.The suitability of microwave processing for the production of two modifications (Sr and La) of lead zirconate - lead titanate (PZT) ceramics was investigated in this program. A commercial microwave oven was used to evaluate drying, calcining, binder burnoff, and sintering. These materials were then compared to those produced by fast-firing and conventional sintering methods.

Effect of Mg Content on Phase Structure and Electrical Properties of (Ba0.97Ca0.03)(Ti0.96-xZr0.04Mgx)O3 Ceramics

2014 ◽  
Vol 1061-1062 ◽  
pp. 79-82
Author(s):  
Gao Lei Zhao ◽  
Da Xue Zhao ◽  
Shi Ming Li
Keyword(s):  
Phase Structure ◽  
Remanent Polarization ◽  
Electromechanical Coupling ◽  
Ferroelectric Properties ◽  
Electromechanical Coupling Coefficient ◽  
Transitional Behavior ◽  
Conventional Sintering ◽  
Xrd Patterns ◽  
Mg Content ◽  
Mg Doped

The Mg-doped (Ba0.97Ca0.03)(Ti0.96-xZr0.04Mgx)O3 piezoelectric ceramics were prepared by conventional sintering technique. Influences of MgO doping content on the phase structure and dielectric, piezoelectric, and ferroelectric properties were investigated. The XRD patterns suggested that a morphotropic phase boundary (MPB) crossing pseudocubic and tetragonal symmetries occurs at the compositions containing 0.5~0.7 at.% Mg. Because of such transitional behavior, the piezoelectric coefficient (d33), electromechanical coupling coefficient (kp), and remanent polarization (Pr) were enhanced to peak values, 327 pC/N, 37.2%, and 15.79 μC/cm2, respectively. However, the dielectric constant (εr) showed a decreasing tendency with raising Mg content.

Influence of Sintering Temperature on Structure and Electrical Properties of Modified-BNKT Lead-Free Piezoelectric Ceramics

2018 ◽  
Vol 777 ◽  
pp. 55-59 ◽  
Author(s):  
Pharatree Jaita ◽  
Supalak Manotham ◽  
Narumon Lertcumfu
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Mixed Oxide ◽  
Sintering Temperature ◽  
Ferroelectric Properties ◽  
Maximum Density ◽  
Lead Free ◽  
Secondary Phases ◽  
Xrd Pattern ◽  
Conventional Sintering

In this research, the effects of sintering temperature on phase structure, densification, microstructure, and electrical properties of modified-BNKT ceramics were investigated. Conventional sintering of lead-free 0.97Bi0.5(Na0.80K0.20)0.5TiO3-0.03(Ba0.70Sr0.30)O3or 0.97BNKT-0.03BSrT ceramic was investigated to clarify the optimal sintering temperature for densification and electrical properties. All ceramics were prepared by a conventional mixed oxide and sintered at various temperatures from 1100 to 1150°C. XRD pattern indicated all ceramics exhibited a single perovskite without any secondary phases. The maximum density of 5.80 g/cm3with relative density of 99.32% were observed for the ceramic sintered at 1125°C. Grain size tended to increase with increasing the sintering temperature. The good dielectric (Td= 121 °C, Tm= 320 °C and e¢max= 4982) and ferroelectric properties (Pr= 16.66 µC/cm2, Ec= 17.85 kV/cm and Rsq= 0.74) were obtained for the ceramic sintered at optimum sintering temperature of 1125°C.

Epitaxial ferroelectric thin films

1994 ◽  
Vol 52 ◽  
pp. 572-573
Author(s):  
S. G. Ghonge ◽  
E. Goo ◽  
R. Ramesh ◽  
R. Haakenaasen ◽  
D. K. Fork
Keyword(s):  
Single Crystal ◽  
Work Function ◽  
Nonvolatile Memory ◽  
Ferroelectric Properties ◽  
Electrical Contact ◽  
Memory Devices ◽  
Ferroelectric Films ◽  
Si Substrates ◽  
Electro Optic ◽  
Wide Range

Microstructure of epitaxial ferroelectric/conductive oxide heterostructures on LaAIO3(LAO) and Si substrates have been studied by conventional and high resolution transmission electron microscopy. The epitaxial films have a wide range of potential applications in areas such as non-volatile memory devices, electro-optic devices and pyroelectric detectors. For applications such as electro-optic devices the films must be single crystal and for applications such as nonvolatile memory devices and pyroelectric devices single crystal films will enhance the performance of the devices. The ferroelectric films studied are Pb(Zr0.2Ti0.8)O3(PLZT), PbTiO3(PT), BiTiO3(BT) and Pb0.9La0.1(Zr0.2Ti0.8)0.975O3(PLZT).Electrical contact to ferroelectric films is commonly made with metals such as Pt. Metals generally have a large difference in work function compared to the work function of the ferroelectric oxides. This results in a Schottky barrier at the interface and the interfacial space charge is believed to responsible for domain pinning and degradation in the ferroelectric properties resulting in phenomenon such as fatigue.

Simple Modification Measurement of Photodegradability of Polymers by using Photo-induced Chemiluminescence Technique

2013 ◽  
Vol 10 (2) ◽  
pp. 51
Author(s):  
Siti Farhana Zakaria ◽  
Keith R Millington
Keyword(s):  
Free Radicals ◽  
Organic Materials ◽  
Oxidative Degradation ◽  
Working Life ◽  
Bimolecular Reaction ◽  
Synthetic Polymers ◽  
Accelerated Weathering ◽  
Simple Modification ◽  
Uv Absorbers ◽  
Irradiation Period

Polymers and organic materials that are exposed to sunlight undergo photooxidation, which leads to deterioration of their physical properties. To allow adequate performance under outdoor conditions, synthetic polymers require additives such as antioxidants and UV absorbers. A major problem with optimising polymer formulations to maximise their working life span is that accelerated weathering tests are empirical. The conditions differ significantly from real weathering situations, and samples require lengthy irradiation period. Degradation may not be apparent in the early stages of exposure, although this is when products such as hydroperoxides are formed which later cause acceleration of oxidation. A simple way of quantifying the number of free radicals presents in organic materials following exposure to light or heat is by measuring chemiluminescence (CL) emission. Most polymers emit CL when they undergo oxidative degradation, and it originates from the bimolecular reaction of macroperoxy radicals which creates an excited carbonyl.

Effects of LaFeO3 Additions on the Dielectric and Ferroelectric Properties of (K0.5Na0.5)NbO3 Ceramics

2013 ◽  
Vol 27 (11) ◽  
pp. 1228-1232 ◽  
Author(s):  
Hua-Lei CHENG ◽  
Hong-Liang DU ◽  
Wan-Cheng ZHOU ◽  
Fa LUO ◽  
Dong-Mei ZHU
Keyword(s):  
Ferroelectric Properties

Vacuum Operation for Overloaded Anaerobic Treatment Systems

1989 ◽  
Vol 21 (4-5) ◽  
pp. 87-95
Author(s):  
J. De Santis ◽  
A. A. Friedman
Keyword(s):  
Volatile Fatty Acids ◽  
Loading Rate ◽  
Anaerobic Treatment ◽  
Optimum Operating ◽  
Operating Pressure ◽  
Simple Modification ◽  
Anaerobic Reactors ◽  
Fixed Film ◽  
Solids Retention ◽  
High Concentrations

Overloaded anaerobic treatment systems are characterized by high concentrations of volatile fatty acids and molecular hydrogen and poor conversion of primary substrates to methane. Previous experiments with fixed–film reactors indicated that operation with reduced headspace pressures enhanced anaerobic treatment. For these studies, four suspended culture, anaerobic reactors were operated with headspace pressures maintained between 0.5 and 1.0 atm and a solids retention time of 15 days. For lightly loaded systems (0.4 g SCOD/g VSS-day) vacuum operation provided minor treatment improvements. For shock organic loads, vacuum operation proved to be more stable and to support quicker recovery from upset conditions. Based on these studies and a companion set of bioassay tests, it was concluded that: (a) a loading rate of about 1.0 g SCOD/g VSS-day represents a practical loading limit for successful anaerobic treatment, (b) a headspace pressure of approximately 0.75 atm appears to be an optimum operating pressure for anaerobic systems and (c) simple modification to existing systems may provide relief for organically overloaded systems.

An Investigation of the Conductive and Ferroelectric Properties of BZT Films

2020 ◽  
Vol 65 (12) ◽  
pp. 2066-2071
Author(s):  
E. V. Gushchina ◽  
B. R. Borodin ◽  
V. A. Sharov ◽  
V. V. Osipov ◽  
S. I. Pavlov ◽  
...  
Keyword(s):  
Ferroelectric Properties

scholarly journals Composite Ferroelectric Membranes Based on Vinylidene Fluoride-Tetrafluoroethylene Copolymer and Polyvinylpyrrolidone for Wound Healing

Membranes ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 21
Author(s):  
Tamara S. Tverdokhlebova ◽  
Ludmila S. Antipina ◽  
Valeriya L. Kudryavtseva ◽  
Ksenia S. Stankevich ◽  
Ilya M. Kolesnik ◽  
...  
Keyword(s):  
Wound Healing ◽  
Vinylidene Fluoride ◽  
Ferroelectric Properties ◽  
Composite Membranes ◽  
Modern Medicine ◽  
In Vivo Studies ◽  
Cytotoxic Effects ◽  
Complex Process ◽  
Purulent Wounds

Wound healing is a complex process and an ongoing challenge for modern medicine. Herein, we present the results of study of structure and properties of ferroelectric composite polymer membranes for wound healing. Membranes were fabricated by electrospinning from a solution of vinylidene fluoride/tetrafluoroethylene copolymer (VDF–TeFE) and polyvinylpyrrolidone (PVP) in dimethylformamide (DMF). The effects of the PVP content on the viscosity and conductivity of the spinning solution, DMF concentration, chemical composition, crystal structure, and conformation of VDF–TeFE macromolecules in the fabricated materials were studied. It was found that as PVP amount increased, the viscosity and conductivity of the spinning solutions decreased, resulting in thinner fibers. Using FTIR and XRD methods, it was shown that if the PVP content was lower than 50 wt %, the VDF–TeFE copolymer adopted a flat zigzag conformation (TTT conformation) and crystalline phases with ferroelectric properties were formed. Gas chromatography results indicated that an increase in the PVP concentration led to a higher residual amount of DMF in the material, causing cytotoxic effects on 3T3L1 fibroblasts. In vivo studies demonstrated that compared to classical gauze dressings impregnated with a solution of an antibacterial agent, ferroelectric composite membranes with 15 wt % PVP provided better conditions for the healing of purulent wounds.

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