scholarly journals Effect of Processing on Synthesis and Dielectric Behavior of Bismuth Sodium Titanate Ceramics

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Vijayeta Pal ◽  
R. K. Dwivedi ◽  
O. P. Thakur
Keyword(s):  
Phase Transitions ◽  
Citric Acid ◽  
Ethylene Glycol ◽  
Ferroelectric Properties ◽  
Precursor Solution ◽  
Sodium Titanate ◽  
Dielectric Behavior ◽  
Two Phase ◽  
Xrd Patterns ◽  
A Site

An effort has been made to synthesize polycrystalline (Bi1−xLax)0.5Na0.5TiO3 (abbreviated as BLNT) system with compositions x = 0, 0.02, and 0.04 by novel semiwet technique. Preparation of A-site oxides of BLNT for composition x = 0 was optimized using two precursor solutions such as ethylene glycol and citric acid. The XRD patterns revealed that the sample prepared by ethylene glycol precursor solution has single phase perovskite structure with a rhombohedral symmetry at RT as compared to the sample prepared by citric acid. Ethylene glycol precursor has been found to play a significant role in the crystallization, phase transitions, and electrical properties. The studies on structure, phase transitions, and dielectric properties for all the samples have been carried out over the temperature range from RT to 450°C at 100 kHz frequency. It has been observed that two phase transitions (i) ferroelectric to antiferroelectric and (ii) antiferroelectric to paraelectric occur in all the samples. All samples exhibit a modified Curie-Weiss law above Tc. A linear fitting of the modified Curie-Weiss law to the experimental data shows diffuse-type transition. The dielectric as well as ferroelectric properties of BLNT ceramics have been found to be improved with the substitution of La elements.

scholarly journals Comparison of strain and ferroelectric properties of La,Nb and Li,Nb co-modified BNKT–ST ceramics

2020 ◽  
Author(s):  
Rizwan Ahmed Malik ◽  
Adnan Maqbool ◽  
Salman Ali Khan ◽  
Mohsin Saleem ◽  
Muhammad Shoaib Butt ◽  
...  
Keyword(s):  
High Voltage ◽  
Ferroelectric Properties ◽  
Phase Evolution ◽  
Two Phase ◽  
Donor Doping ◽  
Phase Structures ◽  
Donor Dopant ◽  
Nb Doping ◽  
A Site ◽  
Made In

Abstract A comparison between the influence of concurrent A and B-site acceptor-donor (Li,Nb) and donor-donor (La,Nb) doping in Pb-free Bi 0.5 (Na 0.84 K 0.16 ) 0.5 TiO 3 –SrTiO 3 piezoelectrics on structure, ferroelectric and high voltage induced strain were made. In this work, Lithium was chosen as acceptor and Lanthanum was chosen as donor dopant on A-site and Nb 5+ as a B-site donor. Both modifier impurities promoted a phase evolution from the coexistent of two phase structures (rhombohedral-tetragonal) into a more symmetric single pseudocubic structure. Nonetheless, (La,Nb) donor-donor doping induced the phase transition at 1 mol%, while (Li,Nb) acceptor-donor doping at 2 mol%. Interestingly, acceptor-donor (Li,Nb) co-substitution results in the broadening of ergodic relaxor and ferroelectric (ER-FE) mixed phase boundary which is favourable for multidevice applications. This comparative study show that the A-site vacancies play a substantial role to induce the phase transformation from nonergodic-ergodic relaxor (NR-ER) and the improvement in their high voltage induced strain.

Preparation Process of KNN-0.008BF Lead-Free Piezoelectric Ceramics

2015 ◽  
Vol 740 ◽  
pp. 7-10 ◽  
Author(s):  
Guo Yuan Cheng ◽  
Xing Hua Fu ◽  
Xin Jin ◽  
Wen Hong Tao ◽  
Yu Qin Qiang
Keyword(s):  
Citric Acid ◽  
Ethylene Glycol ◽  
Chelating Agents ◽  
Piezoelectric Properties ◽  
Sol Gel ◽  
Great Influence ◽  
Precursor Solution ◽  
Piezoelectric Ceramics ◽  
Preparation Condition ◽  
Preparation Conditions

In this paper, the sol-gel method was used to systematic study of the preparation conditions and sintering conditions about KNN-0.008BF powders. At the same time, microstructure and electrical properties of ceramics were studied and analyzed. In this experiment, citric acid(CA) as metal chelator, ethylene glycol(EG) as esterification and chelating agents. Through a large number of experiments, n(citric acid):n(ethylene glycol)=2:1, n(citric acid):n(Nb5+)=1.5:1 is the best equipped ratio. This ratio can obtained pale yellow transparent solution. Under the experiments condition, PH of the precursor solution and the sintering temperature of powders have great influence on experimental. Experiments confirmed that PH=5-6 and temperature=1100°C is the best preparation condition, in which condition piezoelectric ceramics can obtained excellent structures and piezoelectric properties.

Two-Phase Flow with Phase Transitions Instability

1997 ◽  
Vol 28 (4-6) ◽  
pp. 273-276
Author(s):  
B. V. Kichatov ◽  
I. V. Boyko
Keyword(s):  
Phase Transitions ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase

Development of an ethanolic two-phase system (ETPS) based on polypropylene glycol 2000 + ethylene glycol + ethanol for separation of hydrophobic compounds

2021 ◽  
Author(s):  
Filipe Smith Buarque ◽  
Cleide Mara Faria Soares ◽  
Ranyere Lucena de Souza ◽  
Matheus Mendonça Pereira ◽  
Álvaro Silva Lima
Keyword(s):  
Ethylene Glycol ◽  
Phase System ◽  
Polypropylene Glycol ◽  
Two Phase ◽  
Hydrophobic Compounds ◽  
Ethanol Content ◽  
Coexisting Phases ◽  
Phase Water ◽  
High Ethanol

Two-phase water-free systems containing high ethanol content in the coexisting phases can selectively partition hydrophobic molecules from natural biomass.

scholarly journals Partitioning of bovine lactoferrin in aqueous two-phase system containing poly(ethylene glycol) and sodium citrate

2015 ◽  
Vol 95 ◽  
pp. 118-124 ◽  
Author(s):  
Angélica Ribeiro da Costa ◽  
Jane Sélia dos Reis Coimbra ◽  
Luísa Alexandre Ferreira ◽  
João Carlos Marcos ◽  
Igor José Boggione Santos ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Sodium Citrate ◽  
Bovine Lactoferrin ◽  
Phase System ◽  
Poly Ethylene Glycol ◽  
Two Phase ◽  
Aqueous Two Phase System ◽  
Poly Ethylene

On the nature of the phase transitions of aluminosilicate perrhenate sodalite

2020 ◽  
Vol 235 (6-7) ◽  
pp. 213-223
Author(s):  
Hilke Petersen ◽  
Lars Robben ◽  
Thorsten M. Gesing
Keyword(s):  
Raman Spectroscopy ◽  
Phase Transitions ◽  
Decomposition Temperature ◽  
Second Phase ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Two Phase ◽  
Structure Property Relationships ◽  
Heat Capacity Measurements

AbstractThe temperature-dependent structure-property relationships of the aluminosilicate perrhenate sodalite |Na8(ReO4)2|[AlSiO4]6 (ReO4-SOD) were analysed via powder X-ray diffraction (PXRD), Raman spectroscopy and heat capacity measurements. ReO4-SOD shows two phase transitions in the investigated temperature range (13 K < T < 1480 K). The first one at 218.6(1) K is correlated to the transition of dynamically ordered $P\overline{4}3n$ (> 218.6(1 K) to a statically disordered (<218.6(1) K) SOD template in $P\overline{4}3n$. The loss of the dynamics of the template anion during cooling causes an increase of disorder, indicated by an unusual intensity decrease of the 011-reflection and an increase of the Re-O2 bond length with decreasing temperature. Additionally, Raman spectroscopy shows a distortion of the ReO4 anion. Upon heating the thermal expansion of the sodalite cage originated in the tilt-mechanism causes the second phase transition at 442(1) K resulting in a symmetry-increase from $P\overline{4}3n$ to $Pm\overline{3}n$, the structure with the sodalites full framework expansion. Noteworthy is the high decomposition temperature of 1320(10) K.

scholarly journals Structure and phase transitions in A -site ordered RBaMn2O6 ( R=Pr,Nd ) perovskites with a polar ground state

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
J. Blasco ◽  
G. Subías ◽  
M. L. Sanjuán ◽  
J. L. García-Muñoz ◽  
F. Fauth ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Ground State ◽  
A Site
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