scholarly journals The Primary Origin of Excellent Dielectric Properties of (Co, Nb) Co-Doped TiO2 Ceramics: Electron-Pinned Defect Dipoles vs. Internal Barrier Layer Capacitor Effect

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3230
Author(s):  
Theeranuch Nachaithong ◽  
Narong Chanlek ◽  
Pairot Moontragoon ◽  
Prasit Thongbai

(Co, Nb) co-doped rutile TiO2 (CoNTO) nanoparticles with low dopant concentrations were prepared using a wet chemistry method. A pure rutile TiO2 phase with a dense microstructure and homogeneous dispersion of the dopants was obtained. By co-doping rutile TiO2 with 0.5 at.% (Co, Nb), a very high dielectric permittivity of ε′ » 36,105 and a low loss tangent of tanδ » 0.04 were achieved. The sample–electrode contact and resistive outer-surface layer (surface barrier layer capacitor) have a significant impact on the dielectric response in the CoNTO ceramics. The density functional theory calculation shows that the 2Co atoms are located near the oxygen vacancy, creating a triangle-shaped 2CoVoTi complex defect. On the other hand, the substitution of TiO2 with Nb atoms can form a diamond-shaped 2Nb2Ti complex defect. These two types of complex defects are far away from each other. Therefore, the electron-pinned defect dipoles cannot be considered the primary origins of the dielectric response in the CoNTO ceramics. Impedance spectroscopy shows that the CoNTO ceramics are electrically heterogeneous, comprised of insulating and semiconducting regions. Thus, the dielectric properties of the CoNTO ceramics are attributed to the interfacial polarization at the internal insulating layers with very high resistivity, giving rise to a low loss tangent.

RSC Advances ◽  
2021 ◽  
Vol 11 (40) ◽  
pp. 25038-25046
Author(s):  
Jakkree Boonlakhorn ◽  
Jedsada Manyam ◽  
Sriprajak Krongsuk ◽  
Prasit Thongbai ◽  
Pornjuk Srepusharawoot

Mg and Al atoms preferentially occupy Cu sites, creating liquid-phase sintering decomposition at grain boundary layers. This results in very high dielectric permittivity and a low loss tangent of the CaCu2.95Mg0.05Ti3.95Al0.05O12 ceramic.


Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6952
Author(s):  
Nateeporn Thongyong ◽  
Narong Chanlek ◽  
Pornjuk Srepusharawoot ◽  
Prasit Thongbai

The Mg2+/Ta5+ codoped rutile TiO2 ceramic with a nominal composition (Mg1/3Ta2/3)0.01Ti0.99O2 was synthesized using a conventional solid-state reaction method and sintered at 1400 °C for 2 h. The pure phase of the rutile TiO2 structure with a highly dense microstructure was obtained. A high dielectric permittivity (2.9 × 104 at 103 Hz) with a low loss tangent (<0.025) was achieved in the as-sintered ceramic. After removing the outer surface, the dielectric permittivity of the polished ceramic increased from 2.9 × 104 to 6.0 × 104, while the loss tangent also increased (~0.11). The dielectric permittivity and loss tangent could be recovered to the initial value of the as-sintered ceramic by annealing the polished ceramic in air. Notably, in the temperature range of −60–200 °C, the dielectric permittivity (103 Hz) of the annealed ceramic was slightly dependent (<±4.4%), while the loss tangent was very low (0.015–0.036). The giant dielectric properties were likely contributed by the insulating grain boundaries and insulative surface layer effects.


RSC Advances ◽  
2019 ◽  
Vol 9 (15) ◽  
pp. 8364-8368 ◽  
Author(s):  
Lanling Zhao ◽  
Jun Wang ◽  
Zhigang Gai ◽  
Jichao Li ◽  
Jian Liu ◽  
...  

Density functional theory calculations were conducted to investigate the electronic structures of rutile Ti16O32, Ti13Nb2InO32, and Ti13Nb2InO31 systems.


2017 ◽  
Vol 703 ◽  
pp. 139-147 ◽  
Author(s):  
Wattana Tuichai ◽  
Supamas Danwittayakul ◽  
Narong Chanlek ◽  
Prasit Thongbai ◽  
Santi Maensiri

2016 ◽  
Vol 06 (01) ◽  
pp. 1650003 ◽  
Author(s):  
A. Eršte ◽  
L. Fulanović ◽  
L. Čoga ◽  
M. Lin ◽  
Y. Thakur ◽  
...  

We have investigated dielectric properties of aromatic polythiourea (ArPTU, a polar polymer containing high dipolar moments with very low defect levels) thin films that were developed on Pt/SiO2 substrate. The detected response is compared to the response of commercially available polymers, such as high density polyethylene (HDPE) and polypropylene (PP), which are at present used in foil capacitors. Stable values of the dielectric constant [Formula: see text] (being twice higher than in HDPE and PP) over broad temperature and frequency ranges and dielectric losses as low as in commercial systems suggest ArPTU as a promising candidate for future use in a variety of applications.


1989 ◽  
Vol 155 ◽  
Author(s):  
Makoto Kuwabara

ABSTRACTA preliminary experiment was conducted to prepare semiconducting strontium titanate-based internal barrier layer capacitors with ferroelectric Pb(Fe, W)O3 forming insulating layers along the grain boundaries. Processing, microstructure and the dielectric properties of this new type of BL capacitors are described. The idea to obtain this type of BL capacitors with a very high dielectric constant may be realized when the ferroelectric materials can uniformly be diffused along the grain boundaries by using a more sophisticated processing of the second firing.


2000 ◽  
Vol 21 (9) ◽  
pp. 442-444 ◽  
Author(s):  
Y.H. Wu ◽  
A. Chin ◽  
K.H. Shih ◽  
C.C. Wu ◽  
C.P. Liao ◽  
...  

2013 ◽  
Vol 27 (06) ◽  
pp. 1350042 ◽  
Author(s):  
QING-SHOU LI ◽  
YUN-QIANG ZHANG ◽  
LI-BEN LI ◽  
GUO-ZHONG ZANG

The Ca 2 CuO 3– CaCu 2 O 3– CuO ceramics were synthesized by traditional solid-state sintering method. The complex dielectric response of the samples measured from 102–106 Hz and from 300–500 K reveals very high real part of ε > 104. The activation energy (being about 0.63 eV) calculated by the Arrhenius equation indicates that the oxygen vacancies may contribute to the high dielectric response. And the fitting to a Schottky barrier model of capacitance versus applied voltage suggests that the existence of Schottky barrier at the grain boundaries may be another important reason for the origination of good dielectric properties.


1958 ◽  
Vol 36 (12) ◽  
pp. 1672-1677
Author(s):  
A. G. Mungall

Measurement at millimeter wavelengths of the dielectric properties of low loss materials by a free space technique is described. The dielectric constant is determined from the Brewster angle, and the dielectric loss tangent from the attenuation coefficient measured at the Brewster angle of incidence. Results are given for bakelite at wavelengths between 5 and 10 mm. Details of the instrument, which was specifically designed for these measurements, are also given.


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