Size Dependent Dielectric Properties of TiO2 Nanoparticles

2020 ◽  
Vol 833 ◽  
pp. 147-151
Author(s):  
K.K. Anjali ◽  
A. Uma Maheswari ◽  
Manickam Sivakumar
Keyword(s):  
Dielectric Properties ◽  
Oxygen Vacancies ◽  
Surface Defects ◽  
Peak Shift ◽  
Chemical Precipitation ◽  
Space Charge Polarization ◽  
Precipitation Method ◽  
Bandgap Energy ◽  
Size Dependent ◽  
Mobility Of Charge Carriers

In this study, influence of nanoparticles size on optical and dielectric properties of TiO2 nanoparticles is investigated through thermal treatment of hydrous amorphous titania synthesized by chemical precipitation method at temperatures 300 °C and 600 °C. The average sizes of nanoparticles estimated respectively are ~ 8 nm and ~ 22 nm. Although the optical bandgap energy of both samples remains the same the Eg Raman mode observed at 144 cm-1 for bulk TiO2 is shifted to 150 cm-1 only for nanoparticles calcined at 300 °C. The shift is ascribed to the size as well as higher density of surface defects. Moreover, the presence of surface defects like oxygen vacancies which provide effective sites for catalytic reaction are confirmed by EPR and photoluminescence studies. The oxygen vacancies enhances space charge polarization and consequently results in higher dielectric constant. In addition, the peak shift of loss tangent which determines the mobility of charge carriers is found to be size dependent. Hence calcination temperature has significant influence on defect levels which in turn determine the optical and dielectric properties of TiO2 nanoparticles.

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.

Fluorescence Enhancement of ZnS Nanocrystals via Ultraviolet Irradiation

2014 ◽  
Vol 556-562 ◽  
pp. 27-31
Author(s):  
Ling Ling Peng ◽  
Bi Tao Liu ◽  
Tao Han
Keyword(s):  
Ultraviolet Irradiation ◽  
Surface Defects ◽  
Irradiation Time ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Photoluminescence Intensity ◽  
X Ray Diffraction ◽  
Zinc Blende ◽  
Transmission Electron ◽  
Zns Nanocrystals

ZnS nanocrystals were prepared via chemical precipitation method and characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) and photoluminescence (PL) spectra. The results indicated that the ZnS nanocrystals have cubic zinc blende structure and diameter is 3.68 nm as demonstrated by XRD. The morphology of nanocrystals is spherical measured by TEM which shows the similar particle size. The photoluminescence spectrum peaking at about 424 nm was due mostly to the trap-state emission, and a satellite peak at 480nm ascribed to the dangling bond of S in the surface of ZnS nanocrystals. The emission intensity of ZnS was enhanced after ultraviolet irradiation, the enhancement of the Photoluminescence intensity was due to the elimination of the surface defects after ultraviolet irradiation, for the growth of the coated shell on ZnS nonacrystals, the Photoluminescence intensity was increased as ultraviolet irradiation time growth, finally tends to be stable for the surface state of nanocrystals steady.

HIGH PRESSURE EFFECTS ON ELECTRICAL RESISTIVITY AND DIELECTRIC PROPERTIES OF NANOCRYSTALLINE SnO2

2006 ◽  
Vol 05 (04n05) ◽  
pp. 471-477 ◽  
Author(s):  
P. THANGADURAI ◽  
A. CHANDRA BOSE ◽  
S. RAMASAMY ◽  
R. KESAVAMOORTHY ◽  
T. R. RAVINDRAN
Keyword(s):  
High Pressure ◽  
Dielectric Properties ◽  
Complex Impedance ◽  
Chemical Precipitation ◽  
Pressure Effects ◽  
Precipitation Method ◽  
Grain Sizes ◽  
Electrical And Dielectric Properties ◽  
High Pressure Effects

Rutile structured nanocrystalline tin oxide (nano- SnO 2) was prepared by chemical precipitation method with different grain sizes. Its electrical and dielectric properties were studied using complex impedance spectroscopy under different hydrostatic pressures. These studies showed a transition in nano- SnO 2 under high-pressure. The transition pressures obtained from both the resistivity and dielectric measurements agree with each other and increase considerably with decrease in grain size. In order to find whether the transition under pressure is structural related or not, in situ high pressure Raman spectroscopy was done up to 3.38 GPa at room temperature. No structural change was observed and the transition may be due to the co-operative phenomenon of the change in band gap and better connectivity between grain boundaries.

scholarly journals Assimilation of Zinc Metal Ion With Hydroxyapatite for Impedance Studies

2021 ◽  
Author(s):  
POOVENDRAN K ◽  
K.S. Joseph Wilson
Keyword(s):  
Electrical Conductivity ◽  
Particle Size ◽  
Dielectric Properties ◽  
Metal Ion ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Wet Chemical ◽  
Particle Shapes ◽  
Wet Chemical Precipitation ◽  
Nanoscale Particle Size

Abstract The aim of the present work is to examine the doping outcome of Zn metal ions on hydroxyapatite for different concentrations (0.2, 0.4, 0.6, and 0.8). The samples for the pure and Zn doped HAp are synthesized by wet chemical precipitation method. The properties and the particle size are identified by using XRD. The functional bands of PO, CO and OH are analyzed through FTIR and the surface morphology and particle shapes are studied through SEM. The elemental analysis such as zinc, calcium and phosphates are analyzed by EDAX. All the designed elements are studied and confirm the (Ca+Zn)/PO ratio is nearly 1.67 and no other elements were identified in this study. The morphological particles of needle shape and the nanoscale particle size and shapes are studied by using TEM. The electrical conductivity of the synthesized ZnHAp ceramic is mainly related to width of the channel and the polarizability. The frequency dependence of the electric and dielectric properties was studied by using impedance spectroscopy.

scholarly journals Role of annealing temperature on the properties of SrO nanoparticles by precipitation method

2020 ◽  
Vol 1 (1) ◽  
pp. 18-23
Author(s):  
Suresh R ◽  
◽  
Indira Priyadharshini T ◽  
Thirumal Valavan K ◽  
Justin Paul M ◽  
...  
Keyword(s):  
Single Phase ◽  
Annealing Temperature ◽  
Surface Defects ◽  
Visible Region ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Crystalline Nature ◽  
Diffraction Peaks

Strontia nanoparticles are successfully prepared by chemical precipitation method. The SrO nanoparticles are characterized by XRD, UV-DRS and I-V analysis. X-ray diffraction peaks reveal the single-phase polycrystalline tetragonal structure with preferential orientation along (2 0 2) direction. Influence of annealing temperature strongly induce the growth of peak which indicates the increased intensity of (202) peak. The heat treatment strongly distresses the growth of triplet peaks (002), (101) and (110) whereas the same augment the growth of (202) and (310). Strontium oxide nanoparticles would allow more light for absorption in UV region due to its rough surface whereas the same would allow moderate light absorption in visible region due to its high packing density. The expansion and contraction of Sr-O bonds leads to a high crystalline nature with its purity at 322 nm. It is proposed that strain and surface defects in SrO nanocrystal take place due to different absorption edge.

Effects of Silver Doping in the Structural and Optical Properties of Hematite (α-Fe2O3) Synthesized via Chemical Precipitation Method

2021 ◽  
Vol 902 ◽  
pp. 113-118
Author(s):  
Aldrin A. Tan ◽  
Aldwin Christian T. Lacuesta ◽  
Mon Bryan Z. Gili ◽  
Rinlee Butch M. Cervera
Keyword(s):  
Environmental Remediation ◽  
Chemical Precipitation ◽  
Lattice Parameters ◽  
Chemical Precipitation Method ◽  
Precipitation Method ◽  
Bandgap Energy ◽  
Sem Images ◽  
X Ray ◽  
Optical Absorbance ◽  
Vis Spectroscopy

Hematite (α-Fe2O3) is a low-cost n-type semiconductor with significant absorption of visible light owing to its low bandgap energy of 2.1 eV. The wide applications of hematite in renewable energy and environmental remediation continuously entice more studies. However, the low absorbance of solar energy in the UV-range significantly limits the efficiency of many photocatalytic materials. In this study, we tried to dope α-Fe2O3 with silver via chemical precipitation method to lower the bandgap energy and widen its absorbance. The effects of doping hematite with Ag on the structure, morphology, elemental composition, and optical absorbance were determined by characterizing the samples via X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, and UV-Vis spectroscopy, respectively. It was observed from the XRD patterns that the α-Fe2O3 crystallizes in hexagonal structure with lattice parameters a = 5.0380 Å and c = 13.7720 Å for the pure α-Fe2O3. Doping with 0.1M and 0.2M AgNO3 leads to a greater value of the lattice parameters indicating successful doping. SEM images show that the hematite formed was composed of particles with irregular shapes that have sizes in the range 0.865-0.883 μm. Excess silver particles were deposited on the surface of hematite. UV-Vis spectra show that there is a red-shift in the absorption band of the Ag-doped hematite. A notable decrease in the bandgap energy of the undoped α-Fe2O3 was observed from ~2.2eV to ~2.0eV with the increase in the amount of the dopant in the hematite as determined using Tauc’s plot.

STUDY OF STRUCTURAL AND DIELECTRIC PROPERTIES OF COPPER OXIDE NANOPARTICLES PREPARED BY WET CHEMICAL PRECIPITATION METHOD

2013 ◽  
Vol 12 (05) ◽  
pp. 1350036 ◽  
Author(s):  
KIBRIYA SIDDIQUE ◽  
BHABESH KUMAR NATH ◽  
SANJIB KARMAKAR
Keyword(s):  
Electron Microscopy ◽  
Dielectric Properties ◽  
Copper Oxide ◽  
Chemical Precipitation ◽  
Cuo Nanoparticles ◽  
Chemical Precipitation Method ◽  
Precipitation Method ◽  
X Ray ◽  
Wet Chemical ◽  
Wet Chemical Precipitation

We report the synthesis of copper oxide ( CuO ) nanoparticles prepared by wet chemical precipitation method. The structural and dielectric properties are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and complex impedance spectroscopy as a function of frequencies from 40 KHz to 100 KHz in the range of temperatures (308–393K). Maximum value of dielectric constants are found to be in the order of 106 which increases with increase in temperatures. From XRD data it is found that the particle size increases with increase in calcination temperatures. SEM with energy dispersive X-ray fluorescence spectrometer (EDX) results show that only CuO is present in the prepared sample. The selected area electron diffraction (SAED) pattern by TEM shows that uniform size distributions of CuO nanoparticles are present in the sample.

scholarly journals Core-Shell Structure and Dielectric Properties of Ba0.6Sr0.4TiO3@ Fe2O3 Ceramics Prepared by Co-Precipitation Method

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 623
Author(s):  
Zhuo Li ◽  
Chenbo Wang ◽  
Zixuan Wang ◽  
Dandan Zhang ◽  
Yangxiao Qin ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Shell Structure ◽  
Ceramic Materials ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Core Shell ◽  
Reaction Conditions ◽  
Core Shell Structure ◽  
Co Precipitation ◽  
Different Content

Ba0.6Sr0.4TiO3 (BST) ceramic materials have been widely used in the field of multilayer ceramic capacitors. Surface modification through the surface coating to form a heterogeneous layer could effectively improve the dielectric properties. In this work, BST powders were prepared by a co-precipitation method. The effects of reaction conditions on the microstructure of the BST powder were investigated. The reaction temperatures significantly affected the morphology of BST powder, and the rhombic-type particles were obtained with the reaction temperature around 80 °C. Meanwhile, the BST@Fe2O3 was prepared by the chemical precipitation method using BST powders with rhombic-type microstructure as “core”, and the so-called “core-shell” microstructure was confirmed in the BST@Fe2O3 powder. Then, BST@x wt%Fe2O3 (x = 2.5, 5, 7.5, and 10, denoting the different content of Fe2O3) ceramics were further prepared, and the influence of “core-shell” structure on the phase structure, microstructure, and dielectric properties was investigated. With the increasing of Fe2O3 content, the ferroelectric–paraelectric phase transition temperature shifts toward lower temperatures, and dielectric peaks gradually become broad and frequency-dependent, which may be due to inconsistent chemical composition from core to shell.

Structural and morphological characterization of CdS nanoparticles

2020 ◽  
Vol 10 ◽  
Author(s):  
Manish Dwivedi ◽  
Vijay Tripathi ◽  
Dhruv Kumar ◽  
Dwijendra K. Gupta
Keyword(s):  
Blue Shift ◽  
Chemical Precipitation ◽  
Morphological Characterization ◽  
Precipitation Method ◽  
Cds Nanoparticles ◽  
Cubic Phase ◽  
Simple Chemical ◽  
Xrd Patterns ◽  
Average Size ◽  
Physical Tools

Aims: CdS nanoparticles are an attractive material having application in various field like as pigment in paints, biotag for bioimaging and many more optoelectronic as well as biological applications. Present study aims to synthesize and characterize the CdS nanoparticles to make it applicable in different areas Objectives: Preparation CdS nanoparticles by using simple and facile chemical methods and further physical and structural characterization using various physical tools Methods: In present work CdS nanoparticles has been synthesized by using rationally simple chemical precipitation method with some modi-fication on temperature and incubation time in existed methods. Characterizations were done by employing XRD, SEM, TEM, AFM tech-niques Results: Simple chemical method produces the CdS nanoparticles with the size about 100-200 nm in length and 5-10 nm in diameter. The SEM studies show that the CdS nanoparticles can agglomerate and form a continuous network like structure. The X-ray diffraction (XRD) measurements show the single-phase formation of CdS nanoparticles with the structure of cubic phase, and the broadening of XRD patterns indicates that the prepared samples are nanostructured. Our analysis on CdS nanoparticles by using transmission electron microscope and atomic force microscope (AFM) revealed that the nanoparticles form both spherical and nearly rod shaped with the average size applicable for biotagging. UV-Vis spectroscopic analysis reveals blue shift in the absorption peak probably caused by quantum confinement Conclusion: The observed CdS nanoparticles were appeared yellow in color. The XRD pattern of the CdS nanoparticles showed that the materials were of nanometric sized regime with a predominantly cubic phase along with the rod and round morphology. The study and char-acterization of CdS nanoparticles will bring us a new approach to understand biological problem by tagging nanoparticles with biomolecules and further suggests that the CdS nanoparticles formulate it more suitable biocompatible nanomaterial for biotagging and bioimaging

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