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.

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.

Structure and Dielectric Properties of (Gd0.4Sm0.5Yb0.1)2(Zr1-xCex)2O7 Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 394-397
Author(s):  
Ling Liu ◽  
Qiang Xu ◽  
Fu Chi Wang
Keyword(s):  
Rare Earth ◽  
Dielectric Properties ◽  
Pyrochlore Structure ◽  
Microwave Frequency ◽  
Phase Region ◽  
Dielectric Constants ◽  
Precipitation Method ◽  
Low Dielectric ◽  
Pyrochlore Type ◽  
Co Precipitation

Complex rare-earth zirconates (Gd0.4Sm0.5Yb0.1)2(Zr1-xCex)2O7 (x=0, 0.3, 0.4) powders were synthesized by co-precipitation method. XRD and SEM results revealed that the complex rare-earth zirconates with single pyrochlore structure were prepared and no other phases existed among the grains. The dielectric properties of these compounds were investigated at low and microwave frequencies. It was found that they have intermediate dielectric constants and low dielectric loss in the whole frequency region, and they show the dielectric permittivity with weak frequency dependence. Substituting Zr4+ by Ce4+ leaded to smaller permittivity. Meanwhile, the dielectric contant values increase with increasing in the r(A3+)/r(B4+) value in the pyrochlore-type phase region, which can be explained by the increase in the degree of ordering of oxygen vacancy. This new series of pyrochlore type oxides would be potential candidates for electronic ceramic applications and microwave frequency components.

scholarly journals Dielectric Properties of (CdSe)1-X(ZnS)X Mixed Semiconductor Compounds

2012 ◽  
Vol 9 (2) ◽  
pp. 179-189 ◽  
Author(s):  
K. YADAIAH ◽  
J. KRISHNAIAH ◽  
VASUDEVA REDDY ◽  
M. NAGABHUSHANAM
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Relaxation Times ◽  
Dielectric Constants ◽  
Semiconductor Materials ◽  
Precipitation Method ◽  
Semiconductor Compounds ◽  
Optical Dielectric ◽  
Co Precipitation

Dielectric permittivity has been an important property of binary and mixed semiconductor materials as it is closely related to the studies on polarization and relaxation mechanisms. Therefore, dielectric properties of (CdSe)1-X(ZnS)X mixed semiconductors are studied at different frequencies. The mixed semiconductor samples used in the study are grown by controlled co-precipitation method. From these studies ac conductivity, static and optical dielectric constants, relaxation times and activation energy of dipole relaxation are determined. The variation of dielectric constant with frequency and composition of the sample was explained on the basis of Koops grain boundary mechanism.

scholarly journals PENGARUH TEMPERATUR KALSINASI DAN SUBSITUSI LOGAM NIKEL PADA PEMBENTUKAN FASA BARIUM M-HEXAFERRITTE (BaFe12-xNixO19) MENGGUNAKAN FTIR

2015 ◽  
Vol 10 (1) ◽  
Author(s):  
Susilawati Susilawati ◽  
Munib Munib ◽  
Aris Doyan
Keyword(s):  
Fourier Transform ◽  
Calcination Temperature ◽  
Barium Hexaferrite ◽  
Precipitation Method ◽  
Nickel Metal ◽  
Calcination Temperatures ◽  
Infra Red ◽  
M Phase ◽  
Materials Used ◽  
Co Precipitation

Abstrak: Sintesis Barium M-Hexaferrite (BaFe12-xNixO19) doping logam nikel telah dilakukan dengan metode korpresipitasi dan efeknya terhadap perubahan temperatur dan subsitusi dopan. Bahan dasar yang digunakan dalam sintesis BaCO3, FeCl3.6H2O dan logam nikel. Dalam penelitian ini digunakan variasi temperatur kalsinasi 80, 400, 600 dan 800°C selama 4 jam dengan variasi dopan 0; 0,4; 0,7 dan 0,9. Hasil sintesis dikarakterisasi dengan FTIR (Fourier Transform Infra Red Spectroscopy) merek Shimidzu tipe 8400 s. Hasil pembentuka fasa dari barium M-hexaferrite (BaFe12-xNixO19) diketahui melalui data FTIR seiring dengan meningkatkan temperatur kalsinasi yang digunakan diperoleh puncak yang muncul pada rentang bilangan gelombang 800 - 1650 cm-1 semakin sedikit, sehingga pembentukan fasa barium M-hexaferrite yang signifikan terbentuk pada temperatur kalsinasi 800 °C dan pada variasi dopan 0,7.Kata kunci:   Temperatur, dopan, barium M-hexaferrite, kopresipitasi Abstract: Synthesis of Barium M-Hexaferrite (BaFe12-xNixO19) nickel metal doping have been done with co-precipitation method and its effect on temperature changes and substitution dopants. Basic materials used in the synthesis of BaCO3, FeCl3.6H2O and nickel metal. This study used a variation of calcination temperature of 80, 400, 600 and 800°C for 4 hours with a variety of dopants 0; 0.4; 0.7 and 0.9. Synthesized characterized by FTIR (Fourier Transform Infra Red Spectroscopy) Shimidzu brand type 8400 s. Results of the phase formation of barium M-hexaferrite (BaFe12-xNixO19) known through the data FTIR along with increasing the calcination temperatures used were obtained peak appearing in the range of wavenumber 800 to 1650 cm-1 is getting a little bit, so the formation of M-phase barium hexaferrite significant formed at calcination temperature of 800 ° C and at variations of dopant  0.Key words: temperature, dopant, barium M-hexaferrite, co-precipitation

Magnetic and dielectric properties of BiFeO3 nanoparticles

2015 ◽  
Vol 7 (2) ◽  
pp. 1393-1403
Author(s):  
Dr R.P VIJAYALAKSHMI ◽  
N. Manjula ◽  
S. Ramu ◽  
Amaranatha Reddy
Keyword(s):  
Diffuse Reflectance Spectrum ◽  
Precipitation Method ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
Bifeo3 Nanoparticles ◽  
Transmission Electron ◽  
Multiferroic Bifeo3 ◽  
Pure Phase ◽  
Simple Chemical ◽  
Co Precipitation

Single crystalline nano-sized multiferroic BiFeO3 (BFO) powders were synthesized through simple chemical co-precipitation method using polyethylene glycol (PEG) as capping agent. We obtained pure phase BiFeO3 powder by controlling pHand calcination temperature. From X-ray diffraction studies the nanoparticles were unambiguously identified to have a rhombohedrally distorted perovskite structure belonging to the space group of R3c. No secondary phases were detected. It indicates single phase structure. EDX spectra indicated the appearance of three elements Bi, Fe, O in 1:1:3. From the UV-Vis diffuse reflectance spectrum, the absorption cut-off wavelength of the BFO sample is around 558nm corresponding to the energy band gap of 2.2 eV. The size (60-70 nm) and morphology of the nanoparticles have been analyzed using transmission electron microscopy (TEM).   Linear M−H behaviour and slight hysteresis at lower magnetic field is observed for BiFeO3 nanoparticles from Vibrating sample magnetometer studies. It indicates weak ferromagnetic behaviour at room temperature. From dielectric studies, the conductivity value is calculated from the relation s = L/RbA Sm-1 and it is around 7.2 x 10-9 S/m.

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.

Microstructure Characterization of Metal Mixed Oxides

MRS Advances ◽  
2017 ◽  
Vol 2 (64) ◽  
pp. 4025-4030 ◽  
Author(s):  
T. Kryshtab ◽  
H. A. Calderon ◽  
A. Kryvko
Keyword(s):  
Mixed Oxides ◽  
Profile Analysis ◽  
Atomic Resolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Reconstruction Procedure ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Co Precipitation

ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

Template Induced Synthesis of Nano-Hydroxyapatite by Co-Precipitation Method

2011 ◽  
Vol 311-313 ◽  
pp. 1713-1716 ◽  
Author(s):  
Yan Rong Sun ◽  
Tao Fan ◽  
Chang An Wang ◽  
Li Guo Ma ◽  
Feng Liu
Keyword(s):  
Electron Microscope ◽  
Chondroitin Sulfate ◽  
Aspartic Acid ◽  
Transmission Electron Microscope ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure And Morphology ◽  
Transmission Electron ◽  
Co Precipitation

Nano-hydroxyapatite with different morphology was synthesized by the co-precipitation method coupled with biomineralization using Ca(NO3)2•4H2O and (NH4)2HPO4 as reagents, adding chondroitin sulfate, agarose and aspartic acid as template. The structure and morphology of the prepared powders were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM).

scholarly journals Effect of Sintering Temperature on the Microstructure, Electrical and Magnetotransport Properties of La0.67Sr0.33MnO3 Compound

2014 ◽  
Vol 895 ◽  
pp. 319-322
Author(s):  
Lim Kean Pah ◽  
Abdul Halim Shaari ◽  
Chen Soo Kien ◽  
Chin Hui Wei ◽  
Albert Gan ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
Sintering Temperature ◽  
Measurement Range ◽  
Hexagonal Structure ◽  
Precipitation Method ◽  
Metal Insulator ◽  
Higher Temperature ◽  
Co Precipitation ◽  
Grain Surface

In this work, we report the effect of sintering temperature (900°C, 1000°C, 1100°C and 1200°C) on the electrical and magnetotransport properties of polycrystalline La0.67Sr0.33MnO3 (LSMO). Single phase of LSMO hexagonal structure (R-3c) accompanied with minor phases was successfully synthesized by co-precipitation method. With increasing sintering temperature, grain growth was promoted and grain connectivity was improved. It was found that an enhancement of resistivity on smaller grain size was due to larger grain surface over volume (grain boundaries effect). The shifting of the metal-insulator transition (TMI) to higher temperature was also responsible for observed changes in physical properties. TMI of 900°C, 1000°C and 1100°C were 232 K, 278 K and 298 K respectively however 1200°C was out of measurement range (higher than 300 K). In summary, CP900 with smaller grain size distribution (~200 nm) displayed the highest resistivity and MR% of -19.2% (at 80 K, 10 kG).

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