Functional Properties of Donor (Al) and Acceptor (Cu) Codoped High Dielectric Constant ZnO Nanoparticles

In this work, we have synthesized donor-acceptor (Al-Cu) codoped ZnO nanoparticles with a doping concentration of 0%, 0.25%, 0.5%, and 0.75% by coprecipitation method. The synthesized samples were then annealed at 350°C and 600°C. All the samples showed wurtzite structure of ZnO with no secondary phase. The increase in doping concentration led to deterioration of crystalline quality, while improved crystallinity was observed at higher annealing temperature. The morphological study of these samples showed good grain-to-grain contact with less isolated pores. These samples were further characterized by impedance spectroscopy for analyzing dielectric properties. The values of the real part of dielectric constant and tangent loss showed decreasing trend with frequency. The appearance of semicircular arcs in the impedance complex plane plots indicates contribution of grains and grain boundaries and presence of different relaxation processes. 0.5% Al and Cu codoped ZnO showed the best dielectric response with a high value of dielectric constant and low tangent loss.

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Effect of Cu-Excess on the Microstructure and Microwave Dielectric Properties of CaCu3Ti4O12 Ceramics

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1087.50 ◽

2015 ◽

Vol 1087 ◽

pp. 50-54 ◽

Cited By ~ 2

Author(s):

Mohamad Johari Abu ◽

Julie Juliewatty Mohamed ◽

Mohd Fadzil Ain ◽

Zainal Arifin Ahmad

Keyword(s):

Dielectric Constant ◽

Microwave Dielectric Properties ◽

Secondary Phase ◽

Solid State Reaction Method ◽

Lattice Parameter ◽

Tangent Loss ◽

Conventional Solid State Reaction ◽

Microwave Dielectric ◽

Order Of Magnitude ◽

Grain Growth Behavior

CaCu(3+x)Ti4O12 (CCTO) ceramics with different Cu-excess (x = 0 – 0.6) were prepared by conventional solid-state reaction method. Characterization of the prepared ceramics with XRD and FESEM showed that lattice parameter and grain size are slightly increased, indicating Cu-excess to have the big impact on the both phase structure and microstructure. The XRD profiles indicated that the secondary phase (CuO or Cu2O) existed at edge/corner of CCTO grain, which promoted inhibited grain growth behavior. The CCTO ceramics exhibited two trends of dielectric constant related to frequency, which showed a flatter curve about ~50 in 1 – 25 GHz regions, and it’s dropped rapidly to ~35 in 25 – 50 GHz region. With Cu-excess, the dielectric constant of the ceramics was increased for an average of a quarter-order of magnitude, while the tangent loss also increased up to triple times than x = 0, for the same frequency range. Despite enormous increase of dielectric constant related to varying Cu-excess, the tangent loss also increased.

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Dielectric Properties of Li-Doped CaCu3Ti4O12 Ceramics

Materials Science Forum ◽

10.4028/www.scientific.net/msf.687.251 ◽

2011 ◽

Vol 687 ◽

pp. 251-256 ◽

Cited By ~ 1

Author(s):

Ying He ◽

Huai Wu Zhang ◽

Yuan Xun Li ◽

Wei Wei Ling ◽

Yun Yan Wang ◽

...

Keyword(s):

Dielectric Constant ◽

Dielectric Properties ◽

Dielectric Loss ◽

Secondary Phase ◽

Doping Amount ◽

Spectroscopy Analysis ◽

Low Dielectric ◽

Tan Δ ◽

High Dielectric ◽

Impedance Spectroscopy Analysis

CaCu3Ti4O12 ceramics doped with 0-2.0 wt% Li2CO3 were prepared by the solid-state reaction, and their electric and dielectric properties were investigated. It is found that these ceramics had the properties of high dielectric constant and comparatively low dielectric loss. At the doping amount of 0.5 wt%, the dielectric constant is kept to be 105 with weak frequency dependence below 105 Hz, and its loss tangent (tan δ) is suppressed below 0.1 between 300 Hz-5 kHz (with the minimum value of 0.06 at 1 kHz from 218 K to 338 K). The impedance spectroscopy analysis confirms that the decrease of dielectric loss is mainly due to the increase of resistance in the grain boundary, which may be related to the influence of Ti4O7 secondary phase. Our result indicates that doping Li2CO3 is an efficient method to optimize the dielectric properties of CaCu3Ti4O12.

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Very Thin Films of High Dielectric Constant Materials

MRS Proceedings ◽

10.1557/proc-446-309 ◽

1996 ◽

Vol 446 ◽

Cited By ~ 1

Author(s):

David B. Beach ◽

Catherine E. Vallet ◽

Mariappan Paranthaman

Keyword(s):

Thin Films ◽

Dielectric Constant ◽

Dielectric Layer ◽

Single Phase ◽

Annealing Temperature ◽

Bismuth Titanate ◽

High Dielectric Constant ◽

Electrical Measurements ◽

High Dielectric ◽

Alkoxide Route

AbstractAn all‐alkoxide route to SrBi2Ta2O9 (SBT) thin films and powders was developed. While stoichiometric gels transformed to single‐phase SBT, excess bismuth was required to obtain single‐phase SBT films on Pt substrates. An annealing temperature of 800 °C in O2 for 2 minutes was required to crystallize the films. Electrical measurements of SBT films produced under these conditions showed that films less than 2000 Å in thickness were shorted, while films of 3000 to 5000 Λ had a dielectric constant of~ 300. RBS measurements of a bismuth titanate film on Pt indicated that Pt diffuses into the dielectric layer when annealed at 700 °C in O2 for 1 minute, suggesting that interfacial reaction of these layered bismuth materials may be significant.

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Cobalt Alumino Silicate Ceramic(CASC) nanocomposite, a material with moderately high dielectric constant and low tangent loss at a critical concentration in high frequency range.

10.3390/mol2net-1-c005 ◽

2015 ◽

Author(s):

Sukhen Das ◽

Biplab Paul ◽

Smarajit Manna ◽

Debasis Roy ◽

Papiya Nandy

Keyword(s):

Dielectric Constant ◽

High Frequency ◽

High Dielectric Constant ◽

Critical Concentration ◽

Tangent Loss ◽

High Frequency Range ◽

Frequency Range ◽

Alumino Silicate ◽

High Dielectric ◽

Silicate Ceramic

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THE INTERACTION OF FRIEDEL–CRAFTS CATALYSTS WITH ORGANIC MOLECULES: I. THE CH3COCl:AlCl3 SYSTEM

Canadian Journal of Chemistry ◽

10.1139/v59-009 ◽

1959 ◽

Vol 37 (1) ◽

pp. 48-53 ◽

Cited By ~ 53

Author(s):

Denys Cook

Keyword(s):

Dielectric Constant ◽

Acetyl Chloride ◽

Organic Molecules ◽

Low Dielectric Constant ◽

Pure Liquid ◽

Infrared Study ◽

Low Dielectric ◽

Donor Acceptor ◽

High Dielectric ◽

Chlorine Bond

An infrared study of the liquid complex of aluminum chloride with acetyl chloride has been undertaken. The results indicate that the pure liquid complex is not a simple mixture, but consists of (1) the donor–acceptor complex [Formula: see text] and (2) the ions [CH3CO]+ and [AlCl4]−. A solution of the liquid complex in a solvent of high dielectric constant like nitrobenzene (ε = 36.1) contains both these species, but in a low dielectric constant solvent like chloroform (ε = 5.05) only (1) is present. The carbon–chlorine bond in (1) is modified. The mechanism of Friedel–Crafts ketone synthesis is briefly examined in the light of these results.

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Microstructural characterization of YBaCuO Films on LaAlO3 substrates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152872 ◽

1989 ◽

Vol 47 ◽

pp. 180-181

Author(s):

E. L. Hall ◽

A. Mogro-Campero ◽

N. Lewis ◽

L. G. Turner

Keyword(s):

Dielectric Constant ◽

Single Crystal ◽

Film Growth ◽

Microstructural Characterization ◽

Lattice Parameter ◽

Film Plane ◽

Substrate Material ◽

High Loss ◽

Amorphous Substrates ◽

High Dielectric

There have been a large number of recent studies of the growth of Y-Ba-Cu-O thin films, and these studies have employed a variety of substrates and growth techniques. To date, the highest values of Tc and Jc have been found for films grown by sputtering or coevaporation on single-crystal SrTiO3 substrates, which produces a uniaxially-aligned film with the YBa2Cu3Ox c-axis normal to the film plane. Multilayer growth of films on the same substrate produces a triaxially-aligned film (regions of the film have their c-axis parallel to each of the three substrate <100> directions) with lower values of Jc. Growth of films on a variety of other polycrystalline or amorphous substrates produces randomly-oriented polycrystalline films with low Jc. Although single-crystal SrTiO3 thus produces the best results, this substrate material has a number of undesireable characteristics relative to electronic applications, including very high dielectric constant and a high loss tangent at microwave frequencies. Recently, Simon et al. have shown that LaAlO3 could be used as a substrate for YBaCuO film growth. This substrate is essentially a cubic perovskite with a lattice parameter of 0.3792nm (it has a slight rhombohedral distortion at room temperature) and this material exhibits much lower dielectric constant and microwave loss tangents than SrTiO3. It is also interesting from a film growth standpoint since it has a slightly smaller lattice parameter than YBa2Cu3Ox (a=0.382nm, b=c/3=0.389nm), while SrTiO3 is slightly larger (a=0.3905nm).

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Enhanced performance of supercapacitors by constructing a “mini parallel-plate capacitor” in an electrode with high dielectric constant materials

Journal of Materials Chemistry A ◽

10.1039/d0ta04364h ◽

2020 ◽

Vol 8 (32) ◽

pp. 16661-16668

Author(s):

Huayao Tu ◽

Shouzhi Wang ◽

Hehe Jiang ◽

Zhenyan Liang ◽

Dong Shi ◽

...

Keyword(s):

Dielectric Constant ◽

Carbon Fiber ◽

Parallel Plate ◽

Sandwich Structure ◽

High Dielectric Constant ◽

Parallel Plate Capacitor ◽

Plate Capacitor ◽

Fiber Metal ◽

High Dielectric ◽

Mini Plate

The carbon fiber/metal oxide/metal oxynitride layer sandwich structure is constructed in the electrode to form a mini-plate capacitor. High dielectric constant metal oxides act as dielectric to increase their capacitance.

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