scholarly journals Changes in Dielectric Properties and Dispersion Parameters of ZnO with Surfactant and Temperature

2020 ◽  
Vol 3 (10) ◽  
pp. 41-46
Author(s):  
P. P. Sharmila
Keyword(s):  
Zinc Oxide ◽  
Dielectric Properties ◽  
Loss Tangent ◽  
Structural Characterization ◽  
Complex Permittivity ◽  
Semiconductor Nanoparticles ◽  
Precipitation Method ◽  
Dispersion Parameters ◽  
Capping Agents ◽  
Tan Δ

The semiconductor nanoparticles have recently attracted a lot of attention due to the possibility of their application in various devices. In the present paper, nanoparticles of Zinc oxide are prepared by precipitation method using two different (EDTA and DNA) capping agents to control the agglomeration. XRD and SEM technique was used for structural characterization. For the study of dielectric properties, complex permittivity (ε′ and ε″) and loss tangent (tan δ) with frequency is analyzed with frequency and temperature. The Dispersion parameters are calculated using Cole-Cole analysis and the results are compared.

Synthesis and Characteristics of MgO Coated BST-Mg2TiO4 Composite Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 1180-1183
Author(s):  
Qian Qian Jia ◽  
Hui Ming Ji ◽  
Shan Liu ◽  
Xiao Lei Li ◽  
Zheng Guo Jin
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Curie Temperature ◽  
Loss Tangent ◽  
Phase Shifters ◽  
Precipitation Method ◽  
Composite Ceramics ◽  
Low Dielectric ◽  
Dielectric Constant And Loss ◽  
Bst Ceramics

The (Ba, Sr)TiO3 (hereafter BST) ceramics are promising candidate for applying in tunable devices. MgO coated BST-Mg2TiO4 (BSTM-MT) composite ceramics were prepared to obtain the low dielectric constant, low dielectric loss, good dielectric constant temperature stability, and high tunability of BST ceramics. The Ba0.55Sr0.40Ca0.05TiO3 nanoparticles were coated with MgO using the precipitation method and then mixed with Mg2TiO4 powders to fabricate BSTM-MT composite ceramics. The morphologies, phases, elements, and dielectric properties of the sintered ceramics were investigated. The core-shell structure of BST powder wrapped with MgO was clearly observed from the TEM image. After sintered at 1100 °C for 2 h, the composite ceramics expressed dense microstructures from SEM images and two main phases BST and Mg2TiO4 were detected in the XRD patterns. The dielectric constant and loss tangent were both reduced after the coating. The reduced dielectric constant and loss tangent of BSTM-MT were 190, 0.0011 (2MHz), respectively. The ceramics exhibited the diffuse phase transition near the Curie temperature and the Curie temperature shifted from 10 °C to 5 °C after the coating. Since the continuous Ti-O bonds were disconnected with the MgO coating, the tunability was reduced to 15.14 % under a DC bias field of 1.1 kV/mm. The optimistic dielectric properties made it useful for the application of tunable capacitors and phase shifters.

Structural and Dielectric Properties of Zn1-xMoxO Nanoparticles

2020 ◽  
Vol 13 (2) ◽  
pp. 165-170
Keyword(s):  
Zinc Oxide ◽  
Dielectric Properties ◽  
Ac Conductivity ◽  
Hexagonal Wurtzite Structure ◽  
Dielectric Constants ◽  
Precipitation Method ◽  
Dielectric Parameters ◽  
Mo Doping ◽  
Lcr Meter ◽  
Co Precipitation

Abstract: In this work, samples of zinc oxide nanoparticles doped by molybdenum (Zn1-xMoxO with 0 ≤ x ≤ 0.1) were prepared by using the wet co-precipitation method. The characterization of the prepared samples was carried out by means of X-ray powder diffraction (XRD). The samples reserved their hexagonal wurtzite structure with Mo doping and showed a decrease in the crystallite size up to x = 0.04 followed by a further increase. On the other hand, dielectric measurements were performed using an LCR meter. The effect of frequency and temperature on the dielectric properties such as the real and imaginary parts of dielectric constant (ε^' and ε'', respectively), dielectric loss (tanδ) and ac-conductivity (σ_ac) of Mo-doped zinc oxide samples, was studied in the frequency range (100 Hz - 1 MHz) and at temperatures (300 - 773 K). The values of room temperature dielectric parameters were found to be strongly dependent on the Mo-doping. However, the increase in temperature caused an enhancement in the values of the dielectric parameters, particularly at 773 K. Keywords: Zinc oxide, XRD, Dielectric constants, Ac-conductivity.

AC CONDUCTIVITY AND DIELECTRIC PROPERTIES OF MANGANESE DOPED LAYERED Na1.89Li0.10K0.01Ti3O7 CERAMICS

2013 ◽  
Vol 28 (01) ◽  
pp. 1350200
Author(s):  
SHRIPAL SHARMA ◽  
RAKESH SINGH ◽  
GEETIKA
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
Chemical Synthesis ◽  
Loss Tangent ◽  
Relative Permittivity ◽  
Ac Electrical Conductivity ◽  
Conduction Mechanisms ◽  
Tan Δ ◽  
Electron Clouds ◽  
Derivatives Of

Manganese doped derivatives of polycrystalline Na 1.89 Li 0.10 K 0.01 Ti 3 O 7 bearing 0.01, 0.05 and 1.0 molar % of manganese have been prepared by chemical synthesis. The results of ac electrical conductivity studies in form of log (σT) versus 1000/T plots are reported in the frequency and temperature range of 10 kHz–1 MHz and 350–775 K, respectively. The corresponding plots have been divided into five temperature regions, I, II, III, IV and V. The various conduction mechanisms in different regions have been discussed. The nature of conductivity has been explained by proposing a model about the obtained conductivity σ(ω) which is the sum of three terms arising from three different mechanisms. Moreover, various Na–K–Li–O–Ti–O linkages in Na 2-x-y Li x K y Ti 3 O 7 materials may result special forms of electron clouds. Experimental results of the loss tangent ( tan δ) and relative permittivity (εr) versus temperature at different frequencies have been described. The results of tan δ and εr versus frequency plots at different temperature have also been given for these doped derivatives.

AN INVESTIGATION ON THE DIELECTRIC PROPERTIES OF POLYANILINE-BASED NANOCOMPOSITE

2010 ◽  
Vol 24 (15) ◽  
pp. 1669-1674
Author(s):  
J. JIANG ◽  
L. H. AI
Keyword(s):  
Dielectric Properties ◽  
Imaginary Part ◽  
Complex Permittivity ◽  
Room Temperature ◽  
In Situ Polymerization ◽  
Dissipation Factor ◽  
Frequency Range ◽  
The Real ◽  
Tan Δ

Polyaniline/ LiNi 0.5 Gd 0.08 Fe 1.92 O 4 nanocomposite was synthesized by an in-situ polymerization of aniline in the presence of LiNi 0.5 Gd 0.08 Fe 1.92 O 4 particles. The dielectric properties of the as-prepared polyaniline-based nanocomposite were investigated using an Agilent E4991A RF Impedance/Material Analyzer at room temperature in the frequency range from 1 MHz to 1 GHz. The real (ε') and imaginary part (ε″) of complex permittivity, and dissipation factor ( tan δ) were found to be frequency-dependent, which decreased with increasing of frequency. It was shown that ε', ε″ and tan δ of the nanocomposite were lower than those of pristine polyaniline. In order to investigate the dielectric process in detail, the complex electric modulii derived from the complex permittivity were analyzed as a function of the frequency.

Microstructure and Dielectric Properties of BaFe12O19 Hexaferrite Nanoparticles: Effect of Cobalt Addition and Calcination Temperature

2020 ◽  
Vol 13 (3) ◽  
pp. 211-219
Keyword(s):  
Dielectric Properties ◽  
Barium Hexaferrite ◽  
Hexagonal Structure ◽  
Dielectric Constants ◽  
Precipitation Method ◽  
Calcination Temperatures ◽  
Transmission Electron ◽  
Tan Δ ◽  
Co Addition ◽  
Co Precipitation

Abstract: M-type Barium Hexaferrite (BaFe12O19) is a promising compound for technological applications because of its high permeability, high saturation magnetization and excellent dielectric properties. In this study, the microstructure and dielectric properties of CoxBaFe12O19Hexaferrite were investigated. The co-precipitation method was employed to prepare CoxBaFe12O19 nanoparticles, with x = 0, 0.04, 0.06 and 0.1 wt. %, at two different calcination temperatures (900oC and 950oC). The microstructure of the samples was examined through X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The hexagonal structure of the prepared samples was confirmed from XRD results. TEM images reveal the formation of agglomerated nanoparticles with different size distribution. The dielectric properties of the samples were studied through HIOKI 3532-50 LCR-Hi TESTER as a function of frequency (100 kHz–3MHz) and temperature (25 °C–500°C). The effects of Co addition, frequency and temperature on the dielectric constants (ɛʹ and ɛʹʹ), loss tangent (tan δ) and ac conductivity (σac) have been explained on the basis of hopping of electrons between Fe2+ and Fe3+ ions. Keywords: BaFe12O19 Hexaferrite, Co-precipitation method, XRD, Dielectric properties.

DIELECTRIC PROPERTIES OF Li-Sb FERRITES

2005 ◽  
Vol 19 (18) ◽  
pp. 899-905 ◽  
Author(s):  
SHIVAJI CHONGTHAM ◽  
SUMITRA PHANJOUBAM ◽  
H. N. K. SARMA ◽  
RADHAPIYARI LAISHRAM ◽  
CHANDRA PRAKASH
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Room Temperature ◽  
Substitution Level ◽  
Higher Temperature ◽  
Tan Δ ◽  
Almost All ◽  
Frequency Curves

Dielectric properties such as dielectric constant (ε′) and dielectric loss tangent ( tan δ) of Li 0.5+x Fe 2.5-2x Sb x O 4 ferrites, 0.10≤ x ≤0.30 in steps of 0.05 have been investigated as a function of composition, frequency and temperature. The dielectric constant showed dispersion with frequency in the range of 100 Hz–1 MHz. Peaks were observed in the tan δ versus frequency curves for almost all the samples. The temperature variation of dielectric constant for the different samples was studied at 10 kHz in the temperature range from room temperature to 433 K. Peaks were observed for some of the samples. The peaks were seen to shift towards higher temperature region as the substitution level increases. The mechanisms involved in the processes are discussed in this paper.

Tuning the mechanical and dielectric properties of zinc incorporated hydroxyapatite

2020 ◽  
Vol 16 ◽  
Author(s):  
Alliya Qamar ◽  
Rehana Zia ◽  
Madeeha Riaz
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Bone Growth ◽  
Healing Process ◽  
Secondary Phase ◽  
Chemical Precipitation ◽  
Hexagonal Structure ◽  
Precipitation Method ◽  
Low Frequencies ◽  
A Minor

Background: Hydroxyapatite is similar to bone mineral in chemical composition, has good biocompatibility with host tissue and bone. Objective: This work aims to tailor the mechanical and dielectric properties of hydroxyapatite with zinc sudstitution, to improve wearability of implant and accelerate the healing process. Method: Pure and zinc incorporated hydroxyapatite Ca10(PO4)6(OH)2 samples have been successfully prepared by means of the chemical precipitation method. Results: The results showed that hydroxyapatite(Hap) having hexagonal structure was the major phase identified in all the samples. It was found that secondary phase of β-tricalcium phosphate (β-TCP) formed due to addition of Zinc resulting in biphasic structure BCP (Hap + β-TCP). A minor phase of ZnO also formed for higher concentration of Zn (Zn ≥ 2mol%) doping. It was found that the Zn incorporation to Hap enhanced both mechanical and dielectric properties without altering the bioactive properties. The microhardness increased upto 0.87 GPa for Zn concentration equal to 1.5mol%, which is comparable to the human bone ~0.3 - 0.9 GPa. The dielectric properties evaluated in the study showed that 1.5 mol% Zn doped hydroxyapatite had highest dielectric constant. Higher values of dielectric constant at low frequencies signifies its importance in healing processes and bone growth due to polarization of the material under the influence of electric field. Conclusion: Sample Z1.5 having 1.5 mol% Zn doping showed the most optimized properties suitable for bone regeneration applications.

Thermodynamic and anticancer properties of inorganic zinc oxide nanoparticles synthesized through co-precipitation method

2021 ◽  
Vol 330 ◽  
pp. 115602
Author(s):  
Seyyed Vahid Mousazad Goorabjavari ◽  
Fateme Golmohamadi ◽  
Saba Haririmonfared ◽  
Hosein Ahmadi ◽  
Soheil Golisani ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Zinc Oxide Nanoparticles ◽  
Precipitation Method ◽  
Oxide Nanoparticles ◽  
Anticancer Properties ◽  
Co Precipitation

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
Keyword(s):  
Dielectric Properties ◽  
Loss Tangent ◽  
Barrier Layer ◽  
Dielectric Response ◽  
High Resistivity ◽  
Low Loss ◽  
Rutile Tio2 ◽  
Complex Defect ◽  
Very High ◽  
Co Doped

(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.

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