Effects of A/B-Site Co-Doping on Microstructure and Dielectric Thermal Stability of AgNbO3 Ceramics

2021 ◽  
Vol 13 (5) ◽  
pp. 741-747
Author(s):  
Hongpei Ran ◽  
Huiling Du ◽  
Cuiying Ma ◽  
Yingying Zhao ◽  
Danni Feng ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Dielectric Properties ◽  
Doping Level ◽  
Orthorhombic Phase ◽  
Co Doping ◽  
Lead Free Ceramics ◽  
Average Grain Size ◽  
Phase Transition Temperatures ◽  
Calculated Activation Energy ◽  
Grain Growth Kinetics

AgNbO3-based lead-free ceramics are a promising candidate material for capacitors, where thermal stability is a key property for applications in severe and complex environments. This study investigated the fabrication of Ag1-3xBixNb1-3/5x(Zn1/2Ti1/2)xO3 (ABNZT-x) (x = 0, 0.005, 0.01, 0.02, or 0.04) via a solid-state reaction under oxygen flow. The microstructure, dielectric properties, and impedance spectra of the AgNbO3 samples co-doped with Bi3+, Zn2+, and Ti4+ were systematically characterized. All samples exhibited an orthorhombic phase structure, where the average grain size decreased with increasing co-doping level, the grain growth kinetics was studied by phase-field simulation. The phase transition temperatures became lower and the maximum permittivity values decreased. These findings demonstrated that enhanced dielectric thermal stability had been achieved. The grain conduction effect was observed during the impedance spectroscopy analysis, where the calculated activation energy decreased with increasing co-doping level. This ABNZT-x ceramic system exhibited stable dielectric properties, and shows promise for use as a functional material in electronic devices.

Effect of co doping on the electric and dielectric properties of Bi3.8-xEr0.2YbxTi3O12 lead-free ceramics

2021 ◽  
pp. 162899
Author(s):  
M.A. Wederni ◽  
W. Hzez ◽  
A. Rached ◽  
R. Meftah ◽  
H. Rahmouni ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Lead Free ◽  
Co Doping ◽  
Lead Free Ceramics

scholarly journals Sintering Temperature, Frequency, and Temperature Dependent Dielectric Properties of Na0.5Sm0.5Cu3Ti4O12 Ceramics

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4805
Author(s):  
Hicham Mahfoz Kotb ◽  
Hassan A. Khater ◽  
Osama Saber ◽  
Mohamad M. Ahmad
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Low Dielectric ◽  
Average Grain Size ◽  
Conventional Sintering ◽  
Calculated Activation Energy

NSCTO (Na0.5Sm0.5Cu3Ti4O12) ceramics have been prepared by reactive sintering solid-state reaction where the powder was prepared from the elemental oxides by mechanochemical milling followed by conventional sintering in the temperature range 1000–1100 °C. The influence of sintering temperature on the structural and dielectric properties was thoroughly studied. X-ray diffraction analysis (XRD) revealed the formation of the cubic NSCTO phase. By using the Williamson–Hall approach, the crystallite size and lattice strain were calculated. Scanning electron microscope (SEM) observations revealed that the grain size of NSCTO ceramics is slightly dependent on the sintering temperature where the average grain size increased from 1.91 ± 0.36 μm to 2.58 ± 0.89 μm with increasing sintering temperature from 1000 °C to 1100 °C. The ceramic sample sintered at 1025 °C showed the best compromise between colossal relative permittivity (ε′ = 1.34 × 103) and low dielectric loss (tanδ = 0.043) values at 1.1 kHz and 300 K. The calculated activation energy for relaxation and conduction of NSCTO highlighted the important role of single and double ionized oxygen vacancies in these processes.

scholarly journals Co-Doping Effect of BiGaO3 and (Bi,Na,K,Li)ZrO3 on Multi-Phase Structure and Piezoelectric Properties of (K,Na)NbO3 Lead-Free Ceramics

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 886 ◽  
Author(s):  
Min-Ku Lee ◽  
Sang-Don Bu ◽  
Gyoung-Ja Lee
Keyword(s):  
Phase Structure ◽  
Room Temperature ◽  
Volume Fraction ◽  
Boundary Structure ◽  
X Ray Diffraction ◽  
Polymorphic Phase Transition ◽  
Co Doping ◽  
Lead Free Ceramics ◽  
Phase Transition Temperatures ◽  
Multi Phase

The phase boundary structure of (K,Na)NbO3 piezoelectric ceramic was modified by doping with Bi(Na,K,Li)ZrO3 and BiGaO3 through normal solid-state sintering. Rietveld refinements by X-ray diffraction revealed that the Bi(Na,K,Li)ZrO3/BiGaO3 co-doping in (K,Na)NbO3 led to a multi-phase structure at room-temperature, effectively moving the rhombohedral-orthorhombic (R-O) and orthorhombic-tetragonal (O-T) polymorphic phase transition temperatures close to the room temperature region. Increased levels of doping also generated a structural transition, i.e., triphasic R-O-T to diphasic R-T (T-rich) and finally to R-T (R-rich), contributing to shrinkage of the O phase as well as the increase of R phase fraction. A sensitive influence of the BiGaO3 doping (0.001 mole fraction level) on the structural properties such as the phase and microstructure was shown, resulting from the effect of the super-tetragonal structure of BiGaO3. The d33 property was strongly dependent on the phase and its volume fraction, in addition to the grain sizes. Eventually, enhanced and balanced properties of the piezoelectric coefficient and Curie temperature (d33 = 309 pC/N, TC = 343 °C) were obtained when the doped ceramic had a T-rich (86%) R-T structure.

Two-Step Sintering, Microstructure and Electrical Properties of (Ba, Ca)(Ti, Zr)O3 Lead-Free Ceramics

2015 ◽  
Vol 749 ◽  
pp. 79-83
Author(s):  
Pornsuda Bomlai
Keyword(s):  
Phase Transition ◽  
Grain Size ◽  
Electrical Properties ◽  
Piezoelectric Properties ◽  
Orthorhombic Phase ◽  
Lead Free ◽  
Lead Free Ceramics ◽  
Average Grain Size ◽  
Sintering Method ◽  
Dielectric And Piezoelectric Properties

In this work, the (Ba1-xCax)(Ti1-yZry)O3 lead-free ceramics were prepared by the two-step sintering method, and effects of Ca and Zr contents on phase structure, densification, microstructure, and electrical properties were investigated. It was found that all samples showed orthorhombic phase. The highest density of 5.84 ± 0.01 g/cm3 was achieved in x = 0.05, y = 0.05 sample. The average grain size, phase transition temperature, dielectric and piezoelectric properties significantly decreased by introducing of the Ca/Zr content. The ceramics with a small amount of Ca and Zr maintain good piezoelectric properties, and a lower dielectric loss. The composition with x = 0.05, y = 0.025 demonstrated optimum electrical properties of d33 ∼211 pC/N, TC ∼ 119 °C, εr ∼ 1788, and tanδ ∼ 0.04.

scholarly journals Boosted piezoelectricity with excellent thermal stability in tetragonal NaNbO3-based ceramics

2020 ◽  
Author(s):  
Lu Wang ◽  
Shengdong Sun ◽  
Huajie Luo ◽  
Yang Ren ◽  
Hui Liu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Temperature Stability ◽  
Lead Free ◽  
Excellent Thermal Stability ◽  
Lead Free Ceramics ◽  
Piezoelectric Performance

The realization of high piezoelectric performance and excellent temperature stability simultaneously in lead-free ceramics is the key for replacing Pb-containing perovskites in industry. In this study, large piezoelectric performance (d33...

Synthesis and Properties of Biodegradable Liquid Crystalline Poly(ester-Urethane)s Based on Poly(L-Lactic Acid)

2013 ◽  
Vol 652-654 ◽  
pp. 459-462
Author(s):  
Ya Tong Guo ◽  
Zhu Zheng ◽  
Zhen Qi Hou ◽  
Jie Du
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
Lactic Acid ◽  
Physical Properties ◽  
Liquid Crystalline ◽  
Degradation Rate ◽  
Hydrolytic Degradation ◽  
Hexamethylene Diisocyanate ◽  
Solution Polymerization ◽  
Phase Transition Temperatures

A series of biodegradable segmented liquid crystalline poly(ester-urethane)s were prepared by solution polymerization of poly(L-lactic acid) (PLLA), mesogenic diol prepolymer poly(butylene terephthaloyldioxy dibenzoates) (MD), and hexamethylene diisocyanate (HDI). The MD content was varied from 0 to 40 mol% so that the effects of the mesogen content on the thermal and physical properties, and hydrolytic degradation were examined respectively. It was found that introducing mesogens units could increase the thermal stability and the elastic properties, while reduced the phase transition temperatures and the hydrolytic degradation rate.

Effects of co-doping of Sr element and KNN group on the dielectric properties of BNT-BT ceramics

2021 ◽  
Vol 573 (1) ◽  
pp. 166-172
Author(s):  
Yongfeng Wang ◽  
Jing Cao ◽  
Zhao Li
Keyword(s):  
Dielectric Properties ◽  
Co Doping
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