Phase Evolution and Crystallite Size of Ni0.25Zn0.75Fe2O4 at Different Calcination Temperatures

2014 ◽  
Vol 925 ◽  
pp. 290-294 ◽  
Author(s):  
Beh Hoe Guan ◽  
Hasan Soleimani ◽  
Noorhana Yahya ◽  
Noor Rasyada Ahmad Latiff
Keyword(s):  
Crystallite Size ◽  
Calcination Temperature ◽  
Temperature Increase ◽  
Spinel Structure ◽  
Sol Gel ◽  
Phase Evolution ◽  
Calcination Temperatures ◽  
Crystallite Sizes ◽  
Gel Technique ◽  
Scherrer Equation

The effects of calcination temperature varying from 700 to 1100°C on the phase evolution and crystallite size of Ni0.25Zn0.75Fe2O4 synthesized using Sol-Gel technique have been investigated. XRD results showed that the Fe2O3 phase was formed in Ni0.25Zn0.75Fe2O4 in the lower calcination temperature. The crystallization increased as the calcination temperature increased and the crystallite sizes of the Ni0.25Zn0.75Fe2O4 calculated from Scherrer equation were found to be ranged from 16 to 62 nm which increased when calcination temperature increase. Raman results further confirmed the presence of spinel structure in the samples.

scholarly journals Tuning the Pore Structures of Organosilica Membranes for Enhanced Desalination Performance via the Control of Calcination Temperatures

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 392
Author(s):  
Rong Xu ◽  
Qian Liu ◽  
Xiuxiu Ren ◽  
Peng Lin ◽  
Jing Zhong
Keyword(s):  
Calcination Temperature ◽  
Sol Gel ◽  
Great Promise ◽  
Oh Groups ◽  
High Salinity Water ◽  
Calcination Temperatures ◽  
Pore Structures ◽  
Salinity Water ◽  
Gel Technique ◽  
Acid Catalyzed

Microporous organosilica membranes based on 1,2-bis(triethoxylsilyl)ethane (BTESE) were fabricated via an acid-catalyzed sol-gel technique. In the preparation process, the calcination temperature plays a significant role in structural and surface properties of the organosilica networks. With an increase in calcination temperature, the surface hydrophilicity decreased due to the enhanced condensation of Si-OH groups in the networks. N2 adsorption results suggest that the pore structures of BTESE membranes was clearly dependent on the calcination temperature. The pore sizes of the membranes were quantitatively determined by using the Normalized Knudsen-based permeance (NKP) model. In pervaporation tests, the membranes with higher calcination temperatures showed higher salt rejections and lower water permeances, which was attributed to the changes in pore size and surface chemistry of pore walls. The BTESE membranes calcined at 200 °C exhibited superior hydrothermal stability in temperature cycles up to 70 °C and high reproducibility in concentration cycles with NaCl concentrations of 0.2–13 wt%, showing great promise for desalination applications of high-salinity water.

scholarly journals Effect of Calcination Temperature on Physical properties of Ni0.6Zn0.4Fe2O4  Ferrite nanoparticles

2021 ◽  
Author(s):  
sivakumar pendyala ◽  
G.k.Sivasankara Yadav
Keyword(s):  
Physical Properties ◽  
Crystallite Size ◽  
Calcination Temperature ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Ferrite Nanoparticles ◽  
Calcination Temperatures ◽  
Auto Combustion ◽  
Lcr Meter

Abstract The influence of Calcination temperature on the physical properties of Ni0.6Zn0.4Fe2O4 ferrite nanoparticles were investigated. These ferrite nanoparticles have been synthesized by sol-gel auto combustion method using citric acid as fuel agent at different calcination temperatures (4000C, 5000C and 6000C). The Morphological investigation, average crystallite size and microstructure of the material were examined by using X-ray diffraction (XRD) and confirmed by field emission scanning electron microscope (FESEM) and FTIR spectra. The Effects of calcination temperature on the dielectric and magnetic properties were calculated by using LCR meter and vibrating sample magnetometer (VSM). The XRD result shows a single-phase cubic spinel structure with average crystallite size increases from 27 to 29.5 nm, with an increase of temperature. The highest saturation magnetization was found at a calcination temperature 6000C with value 80.39 emu/g, and the value coercive field (Hc) was inverse with the crystallite size.

The effect of silver concentration and calcination temperature on structural and optical properties of ZnO:Ag nanoparticles

2015 ◽  
Vol 29 (01) ◽  
pp. 1450254 ◽  
Author(s):  
M. Shayani Rad ◽  
A. Kompany ◽  
A. Khorsand Zak ◽  
M. E. Abrishami
Keyword(s):  
Calcination Temperature ◽  
Sol Gel ◽  
Visible Emission ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
Zno Nps ◽  
Calcination Temperatures ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Average Size

Pure and silver added zinc oxide nanoparticles ( ZnO -NPs and ZnO : Ag -NPs) were synthesized through a modified sol–gel method. The prepared samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. In the XRD patterns, silver diffracted peaks were also observed for the samples synthesized at different calcination temperatures of 500°C, 700°C, 900°C except 1100°C, in addition to ZnO . TEM images indicated that the average size of ZnO : Ag -NPs increases with the amount of Ag concentration. The PL spectra of the samples revealed that the increase of Ag concentration results in the increase of the visible emission intensity, whereas by increasing the calcination temperature the intensity of visible emission of the samples decreases.

scholarly journals Crystal Structure, Lattice Strain, Morphology, and Electrical Properties of SnO2 Nanoparticles Induced by Low Calcination Temperature

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Panya Khaenamkaew ◽  
Dhonluck Manop ◽  
Chaileok Tanghengjaroen ◽  
Worasit Palakawong Na Ayuthaya
Keyword(s):  
Thin Films ◽  
Electrical Properties ◽  
Calcination Temperature ◽  
Tin Dioxide ◽  
Lattice Strain ◽  
Dielectric Constants ◽  
Precipitation Method ◽  
Calcination Temperatures ◽  
Sensing Applications ◽  
Crystallite Sizes

The electrical properties of tin dioxide (SnO2) nanoparticles induced by low calcination temperature were systematically investigated for gas sensing applications. The precipitation method was used to prepare SnO2 powders, while the sol-gel method was adopted to prepare SnO2 thin films at different calcination temperatures. The characterization was done by X-ray diffraction, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The samples were perfectly matched with the rutile tetragonal structure. The average crystallite sizes of SnO2 powders were 45 ± 2, 50 ± 2, 62 ± 2, and 65 ± 2 nm at calcination temperatures of 300, 350, 400, and 450°C, respectively. SEM images and AFM topographies showed an increase in particle size and roughness with the rise in calcination temperature. The dielectric constant decreased with the increase in the frequency of the applied signals but increased on increasing calcination temperature. By using the UV-Vis spectrum, the direct energy bandgaps of SnO2 thin films were found as 4.85, 4.80, 4.75, and 4.10 eV for 300, 350, 400, and 450°C, respectively. Low calcination temperature as 300°C allows smaller crystallite sizes and lower dielectric constants but increases the surface roughness of SnO2, while lattice strain remains independent. Thus, low calcination temperatures of SnO2 are promising for electronic devices like gas sensors.

Study of Nanocrystalline ZnAl2O4 and ZnFe2O4 with SiO2 on Structural and Optical Properties Synthesized by Sol-Gel Method

2015 ◽  
Vol 1119 ◽  
pp. 96-100
Author(s):  
Mohd Syafiq Zulfakar ◽  
Huda Abdullah ◽  
Wan Nasarudin Wan Jalal ◽  
Zalita Zainuddin ◽  
Sahbudin Shaari
Keyword(s):  
Optical Properties ◽  
Spinel Structure ◽  
Dielectric Material ◽  
Sol Gel ◽  
Zinc Aluminate ◽  
Gel Method ◽  
Sol Gel Method ◽  
Tauc Plot ◽  
Crystallite Sizes ◽  
Spinel Structures

Zinc aluminate (ZnAl2O4) and zinc ferrite (ZnFe2O4) nanocrystalline structures dispersed into SiO2 matrix were prepared by sol-gel method. Phase formation of ZnAl2O4 and ZnFe2O4 was confirmed by X-ray diffraction (XRD) analysis. The crystallite sizes was determine using Scherer’s equation from the broadening of dominant peak at (311) plane. It was found the crystallite size of both compound decreased due to the decrement compositions of Zn2+ ion and Al3+ / Fe3+ ions. The crystallite sizes for ZnAl2O4 and ZnFe2O4 was calculated to be around ~ 14.16 – 11.27 nm and ~ 11.27 – 4.72 nm, respectively. FTIR analysis was done to determine the formation of spinel structures. FTIR results analysis confirmed that the formation of spinel structure where it has been observed that the bands around 800 cm-1 was associated to the vibrations of aluminum-oxygen and metal-oxygen-aluminum bonds. This characteristic was identified to the formation of zinc aluminate spinel structure. The optical properties have been done to determine the energy bandgap of ZnAl2O4 and ZnFe2O4 samples. The Uv-Visible absorption spectra have been done within wavelength 300 – 800 nm and the graph was plotted into the Tauc plot. This new dielectric material was purposed to improve the value of dielectric permittivity with addition of SiO2 where it can be applied as microwave dielectric material without changing the original spinel structures.

Photoluminescence Properties Influenced by Calcining Condition and Doping Concentration of Nano-Sized ZnGa2O4: Cr3+

2009 ◽  
Vol 610-613 ◽  
pp. 616-620 ◽  
Author(s):  
Wei Wei Zhang ◽  
Jun Ying Zhang ◽  
Hui Wan ◽  
Zi Yu Chen ◽  
Tian Min Wang
Keyword(s):  
Spinel Structure ◽  
Doping Concentration ◽  
Sol Gel ◽  
Blue Shift ◽  
Maximum Height ◽  
Photoluminescence Properties ◽  
Phosphor Powder ◽  
Red Emission ◽  
Intrinsic Excitation ◽  
Gel Technique

Chromium-activated ZnGa2O4 nano-sized phosphor powder was prepared by the Sol-Gel technique using citric acid as chelator, and the microstructure and luminescent property were studied. The host ZnGa2O4 belongs to the spinel structure and the ZnGa2O4:Cr3+ phosphor powder exhibited bright red emission band. The excitation bands with peak of maximum height at about 250 nm, 410 nm and 560 nm were related to the charge transfer (CT) of Ga-O, 4A2-4T1 and 4A2-4T2 transitions of Cr3+, respectively. Different quenching concentrations of the CT state and intrinsic excitation were discovered originating from different energy transfer schemes. Meanwhile, with the increasing of the calcining temperature the PLE spectrum exhibited an obvious blue-shift which is attributed to the enhancement of the crystal field.

AN INVESTIGATION INTO MECHANOCHEMICAL SYNTHESIS OF NANOCRYSTALLINE HEXAFERRITE POWDER

2011 ◽  
Vol 25 (07) ◽  
pp. 987-993
Author(s):  
S. SADEGHI-NIARAKI ◽  
S. A. SEYYED EBRAHIMI ◽  
SH. RAYGAN
Keyword(s):  
Crystallite Size ◽  
Single Phase ◽  
Sol Gel ◽  
Milled Powder ◽  
Particle Morphology ◽  
Average Crystallite Size ◽  
Phase Evolution ◽  
High Energy ◽  
Strontium Hexaferrite ◽  
Electron Microscopes

Nanocrystalline strontium hexaferrite powder has been prepared by a new mechanochemical method in which the single phase hexaferrite was obtained via a sol–gel autocombustion process followed by an intermediate high energy milling step and subsequent annealing. The effects of the intermediate milling on the phase evolution, crystallite size and annealing behavior of the final products were investigated using the X-ray diffraction (XRD) technique. The single phase strontium hexaferrite was obtained at an annealing temperature of 800°C, while this temperature was 1,000°C for the powder synthesized without milling. It could be seen that an intermediate milling accelerates the formation of strontium hexaferrite during the calcination process. The results showed that in the milled powder, the average crystallite size of the ferrite was about 40 nm and much smaller than that of the nonmilled powder. Magnetic properties were also measured by a vibrating sample magnetometer (VSM). The particle morphology was then studied by scanning and transmission electron microscopes (SEM and TEM).

scholarly journals Highly Selective Syngas/H2 Production via Partial Oxidation of CH4 Using (Ni, Co and Ni–Co)/ZrO2–Al2O3 Catalysts: Influence of Calcination Temperature

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 141 ◽  
Author(s):  
Anis Hamza Fakeeha ◽  
Yasir Arafat ◽  
Ahmed Aidid Ibrahim ◽  
Hamid Shaikh ◽  
Hanan Atia ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Calcination Temperature ◽  
Partial Oxidation ◽  
Sol Gel ◽  
Analytical Techniques ◽  
Oxygen Storage Capacity ◽  
H2 Production ◽  
Oxygen Storage ◽  
Calcination Temperatures ◽  
Metal Support Interaction

In this study, Ni, Co and Ni–Co catalysts supported on binary oxide ZrO2–Al2O3 were synthesized by sol-gel method and characterized by means of various analytical techniques such as XRD, BET, TPR, TPD, TGA, SEM, and TEM. This catalytic system was then tested for syngas respective H2 production via partial oxidation of methane at 700 °C and 800 °C. The influence of calcination temperatures was studied and their impact on catalytic activity and stability was evaluated. It was observed that increasing the calcination temperature from 550 °C to 800 °C and addition of ZrO2 to Al2O3 enhances Ni metal-support interaction. This increases the catalytic activity and sintering resistance. Furthermore, ZrO2 provides higher oxygen storage capacity and stronger Lewis basicity which contributed to coke suppression, eventually leading to a more stable catalyst. It was also observed that, contrary to bimetallic catalysts, monometallic catalysts exhibit higher activity with higher calcination temperature. At the same time, Co and Ni–Co-based catalysts exhibit higher activity than Ni-based catalysts which was not expected. The Co-based catalyst calcined at 800 °C demonstrated excellent stability over 24 h on stream. In general, all catalysts demonstrated high CH4 conversion and exceptionally high selectivity to H2 (~98%) at 700 °C.

scholarly journals Synthesis and Characterization of Polystyrene/CuO-Fe2O3 Nanocomposites from Natural Materials as Hydrophobic Photocatalytic Coatings

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 31
Author(s):  
Ratnawulan Ratnawulan ◽  
Ramli Ramli ◽  
Ahmad Fauzi ◽  
Sukma Hayati AE
Keyword(s):  
Contact Angle ◽  
Calcination Temperature ◽  
Sessile Drop ◽  
Sol Gel ◽  
Basic Material ◽  
Copper Ferrite ◽  
Natural Materials ◽  
Hydrophobic Coating ◽  
Calcination Temperatures

This study reports on the synthesis, characterization of polystyrene(PS)/CuO-Fe2O3 nanocomposites, and their application as hydrophobic coatings. CuO and Fe2O3 materials were synthesized from natural materials by the milling method. Meanwhile, the PS/CuO-Fe2O3 nanocomposites were synthesized by the sol-gel method. Furthermore, the hydrophobic coating on the glass substrate was made by the spin-coating. To obtain highest value of contact angle, the composition of both CuO and Fe2O3 in nanocomposite as well as calcination temperatures were varied. Sample characterization was conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet visible (Uv-Vis) spectrophotometry analysis. The Sessile drop method was used to determine the contact angle of the layer. The results showed that PS/CuO-Fe2O3 nanocomposite was successfully obtained with a crystal size between 40–52 nm and grain size of 92 nm. In addition to the basic material of composites, hematite and tenorite, the presence of copper ferrite phase was also identified. The CuO-Fe2O3 composition and its large calcination temperature also plays an effective role in the magnitude of the contact angle. The highest value of contact angle obtained was 125.46° at 3:1 composition and calcination temperature of 200 °C. We found that the PS/CuO-Fe2O3 composite was hydrophobic, but the photocatalyst activity was very small at 0.24%.

Microstructural characteristics and photoluminescence performance of nanograined thermally treated CeO2-TiO2 xerogels

2007 ◽  
Vol 22 (5) ◽  
pp. 1182-1187
Author(s):  
Amita Verma ◽  
A.K. Srivastava ◽  
N. Karar ◽  
Harish Chander ◽  
S.A. Agnihotry
Keyword(s):  
Electron Microscopy ◽  
Crystallite Size ◽  
Sol Gel ◽  
Structural Features ◽  
X Ray Diffraction ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Crystallite Sizes ◽  
Thermally Treated

Nanostructured thermally treated xerogels have been synthesized using a sol-gel process involving cerium (Ce) chloride heptahydrate and titanium (Ti) propoxide mixed in different Ce:Ti molar ratios. Structural features of the xerogels have been correlated with their photoluminescence (PL) response. The crystallite sizes in the samples lie in the nanorange. The x-ray diffraction and transmission electron microscopy results have confirmed the coexistence of CeO2 and TiO2 nanocrystallites in these xerogels. In general, a decrease in the CeO2 crystallite size and an increase in the TiO2 crystallite size are observed in the xerogels as a function of Ti content. Scanning electron microscopy results have evidenced the evolution of ordered structure in the xerogels as a function of TiO2 content. Although both of the phases (CeO2 and TiO2) have exhibited PL in ultraviolet and visible regions, the major luminescence contribution has been made by the CeO2 phase. The largest sized CeO2 crystallites in 1:1 thermally treated xerogel have led to its highest PL response. PL emission in the xerogels is assigned to their nanocrystalline nature and oxygen vacancy-related defects.

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