scholarly journals Influence of Bi2O3 on microstructure and electrical properties of ZnO-SnO2 ceramics

2007 ◽  
Vol 39 (3) ◽  
pp. 229-240 ◽  
Author(s):  
T. Ivetic ◽  
M.V. Nikolic ◽  
M. Slankamenac ◽  
M. Zivanov ◽  
D. Minic ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Ball Mill ◽  
Energy Dispersive Spectrometer ◽  
Molar Ratio ◽  
Dc Resistivity ◽  
Impedance Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Scanning Electron

The effects of small amounts (0.5; 1.0 and 1.5 mol. %) of bismuth oxide on the microstructure and electrical properties of ZnO-SnO2 ceramics have been studied. Starting powders of ZnO and SnO2 were mixed in the molar ratio 2:1. After adding Bi2O3 this mixture was mechanically activated for 10 minutes in a planetary ball mill, uniaxially pressed and sintered at 1300?C for 2h. The phase composition of the sintered samples was analyzed by X-Ray Diffraction (XRD) and by Energy Dispersive Spectrometer (EDS). Morphologies were examined by Scanning Electron Microscopy (SEM). An Impedance/Gain Phase Analyzer (HP 4194A) was used to measure the impedance spectra (100Hz - 10MHz) at different temperatures. The electrical DC resistivity/conductivity at different temperatures was measured using a High Resistance Meter (HP 4329A).

scholarly journals Characterization of nanostructured spinel NiFe2O4 obtained by soft mechanochemical synthesis

2012 ◽  
Vol 44 (3) ◽  
pp. 331-339 ◽  
Author(s):  
Z.Z. Lazarevic ◽  
C. Jovalekic ◽  
D. Sekulic ◽  
M. Slankamenac ◽  
M. Romcevic ◽  
...  
Keyword(s):  
Mechanochemical Synthesis ◽  
Nickel Ferrite ◽  
Ball Mill ◽  
Energy Dispersive Spectrometer ◽  
Sintered Sample ◽  
Impedance Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures

Powdery nickel ferrite, NiFe2O4 has been obtained by soft mechanochemical synthesis in a planetary ball mill. Ni(OH)2 and Fe(OH)3 are used as initial compounds. This mixture was mechanically activated for 25h, uniaxial pressed and sintered at 1100?C for 2h. The phase composition of the sintered sample was analyzed by X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and Raman spectroscopy. Morphologies were examined by scanning electron microscopy (SEM). The electrical DC/resistivity/conductivity at different temperatures was measured using a Source Meter Keithley 2410. An Impedance/Gain-Phase Analyzer (HP-4194) was used to measure the impedance spectra (100Hz - 10MHz) at different temperatures.

scholarly journals Investigation of zinc stannate synthesis using photoacoustic spectroscopy

2007 ◽  
Vol 39 (2) ◽  
pp. 153-160 ◽  
Author(s):  
T. Ivetic ◽  
M.V. Nikolic ◽  
P.M. Nikolic ◽  
V. Blagojevic ◽  
S. Djuric ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Ball Mill ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
X Ray ◽  
Microstructure Characteristics ◽  
Amplitude Spectra ◽  
Scanning Electron

Mixtures of ZnO and SnO2 powders, with molar ratio of 2:1, were mechanically activated for 40, 80 and 160 minutes in a planetary ball mill. The resulting powders were compacted into pellets and non-isothermally sintered up to 1200?C with a heating rate of 5?C/min. X-ray diffraction analysis of obtained powders and sintered samples was performed in order to investigate changes of the phase composition. The microstructure of sintered samples was examined by scanning electron microscopy. The photoacoustic phase and amplitude spectra of sintered samples were measured as a function of the laser beam modulating frequency using a transmission detection configuration. Fitting of experimental data enabled determination of photoacoustic properties including thermal diffusivity. Based on the results obtained a correlation between thermal diffusivity and experimental conditions as well the samples microstructure characteristics was discussed. .

Molten Salt Synthesis of Mullite Whiskers from Silicon Carbide Precursor

2012 ◽  
Vol 724 ◽  
pp. 299-302 ◽  
Author(s):  
Wei Wang ◽  
Gui Wu Liu ◽  
Guan Jun Qiao ◽  
Jian Feng Yang ◽  
Hong Wei Li ◽  
...  
Keyword(s):  
Molten Salts ◽  
Energy Dispersive Spectrometer ◽  
Molten Salt Synthesis ◽  
Dissolution Mechanism ◽  
X Ray Diffraction ◽  
X Ray ◽  
System A ◽  
Different Temperatures ◽  
Mullite Whiskers ◽  
Scanning Electron

Mullite whiskers were prepared from SiC powders in molten Al2(SO4)3-Na2SO4 mixture salts at different temperatures. The morphology and phase composition of resulting whiskers were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) techniques. Mullite tiny fiber clusters with diameter about 50 nanometers and lengths of over several microns were obtained in 900°C mixture molten salts system. A new oxidation-dissolution mechanism was proposed for explanation mullite whiskers growth.

scholarly journals Extraction of Boron from Ludwigite Ore: Mechanism of Soda-Ash Roasting of Lizardite and Szaibelyite

Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 533 ◽  
Author(s):  
Xin Zhang ◽  
Guanghui Li ◽  
Jinxiang You ◽  
Jian Wang ◽  
Jun Luo ◽  
...  
Keyword(s):  
Sodium Carbonate ◽  
Energy Dispersive Spectrometer ◽  
Low Grade ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Selective Activation ◽  
X Ray ◽  
Shed Light ◽  
Soda Ash ◽  
Scanning Electron

Ludwigite ore is a typical low-grade boron ore accounting for 58.5% boron resource of China, which is mainly composed of magnetite, lizardite and szaibelyite. During soda-ash roasting of ludwigite ore, the presence of lizardite hinders the selective activation of boron. In this work, lizardite and szaibelyite were prepared and their soda-ash roasting behaviors were investigated using thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope and energy dispersive spectrometer (SEM-EDS) analyses, in order to shed light on the soda-ash activation of boron within ludwigite ore. Thermodynamics of Na2CO3-MgSiO3-Mg2SiO4-Mg2B2O5 via FactSage show that the formation of Na2MgSiO4 was preferential for the reaction between Na2CO3 and MgSiO3/Mg2SiO4. While, regarding the reaction between Na2CO3 and Mg2B2O5, the formation of NaBO2 was foremost. Raising temperature was beneficial for the soda-ash roasting of lizardite and szaibelyite. At a temperature lower than the melting of sodium carbonate (851 °C), the soda-ash roasting of szaibelyite was faster than that of lizardite. Moreover, the melting of sodium carbonate accelerated the reaction between lizardite with sodium carbonate.

Application of vermiculite and limestone to desulphurization and to the removal of dust during briquette combustion

2003 ◽  
Vol 67 (6) ◽  
pp. 1243-1251 ◽  
Author(s):  
A. Lu ◽  
D. Zhao ◽  
J. Li ◽  
C. Wang ◽  
S. Qin
Keyword(s):  
Electron Microscopy ◽  
Coal Combustion ◽  
Combustion Temperature ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Retention Ratio ◽  
X Ray ◽  
Major Factors ◽  
Chemical Reactant ◽  
Scanning Electron

AbstractSmall domestic cooking furnaces are widely used in China. These cooking furnaces release SO2 gas and dust into the atmosphere and cause serious air pollution. Experiments were conducted to investigate the effects of vermiculite, limestone or CaCO3, and combustion temperature and time on desulphurization and dust removal during briquette combustion in small domestic cooking furnaces. Additives used in the coal are vermiculite, CaCO3 and bentonite. Vermiculite is used for its expansion property to improve the contact between CaCO3 and SO2 and to convey O2 into the interior of briquette; CaCO3 is used as a chemical reactant to react with SO2 to form CaSO4; and bentonite is used to develop briquette strength. Expansion of vermiculite develops loose interior structures, such as pores or cracks, inside the briquette, and thus brings enough oxygen for combustion and sulphation reaction. Effective combustion of the original carbon reduces amounts of dust in the fly ash. X-ray diffraction, optical microscopy, and scanning electron microscopy with energy dispersive X-ray analysis show that S exists in the ash only as anhydrite CaSO4, a product of SO2 reacting with CaCO3 and O2. The formation of CaSO4 effectively reduces or eliminates SO2 emission from coal combustion. The major factors controlling S retention are vermiculite, CaCO3 and combustion temperature. The S retention ratio increases with increasing vermiculite amount at 950°C. The S retention ratio also increases with increasing Ca/S molar ratio, and the best Ca/S ratio is 2-3 for most combustion. With 12 g of the original coal, 1 to 2 g of vermiculite, a molar Ca/S ratio of 2.55 by adding CaCO3, and some bentonite, a S retention ratio >65% can be readily achieved. The highest S retention ratio of 97.9% is achieved at 950°C with addition of 2 g of vermiculite, a Ca/S ratio of 2.55 and bentonite.

Structural Evaluation of Ti-22.2Si-11.1B Powders Milled with PCA Addition

2008 ◽  
Vol 591-593 ◽  
pp. 147-153
Author(s):  
Gilbert Silva ◽  
Erika Coaglia Trindade Ramos ◽  
N.S. da Silva ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Electron Microscopy ◽  
Ball Milling ◽  
Ball Mill ◽  
Milling Process ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Evaluation ◽  
Equilibrium Structures ◽  
Scanning Electron

A large amount of the Ti6Si2B compound can be formed by mechanical alloying and subsequent heat treatment from the elemental Ti-22.2at%Si-11.1at%B powder mixture, but the yield powder after ball milling is reduced due to an excessive agglomeration of ductile particles on the balls and vial surfaces. This work reports on the structural evaluation of Ti-22.2at%Si-11.1at%B powders milled with PCA addition, varying its amount between 1 and 2 wt-%. The milling process was carried out in a planetary ball mill under argon atmosphere, and the milled powders were then heated at 1200oC for 1h under Ar atmosphere in order to obtain equilibrium structures. Samples were characterized by X-ray diffraction, scanning electron microscopy, and thermal analysis. Results revealed that the PCA addition reduced the excessive agglomeration during the ball milling of Ti-22.2at-%Si-11.1at-%B powders. After heating at 1200oC for 1h, the Ti5Si3, Ti3O and/or Ti2C phases were preferentially formed in Ti-22.2at%Si-11.1at%B powders milled with PCA addition, and the Ti6Si2B formation was inhibited.

Microstructure and Properties of Nanosemicrystalline Si3N4 Ceramics with Doped Sintering Additives: Part II. Phase Transformation and Microstructural Control

1998 ◽  
Vol 13 (9) ◽  
pp. 2588-2596 ◽  
Author(s):  
K. H. Ryu ◽  
J-M. Yang
Keyword(s):  
Electron Microscopy ◽  
Pressureless Sintering ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sintering Additives ◽  
Different Temperatures ◽  
Si3n4 Ceramics ◽  
Scanning Electron ◽  
Microstructural Control

The low temperature pressureless sintering of a nanosized Si3N4 powder with doped sintering additives was investigated. The microstructural evolution during sintering at different temperatures was analyzed using x-ray diffraction and scanning electron microscopy. The effect of using nanosized Si3N4 powder as a catalyst to accelerate the α→β–Si3N4 transformation of a commercial Si3N4 powder with larger particle sizes was also investigated. Finally, two stage sintering was used to study the feasibility of controlling the microstructure and the mechanical properties of the nanosized silicon nitride.

MICROSTRUCTURE AND BLUE PHOTOLUMINESCENCE OF HYDROGENATED SILICON CARBONITRIDE THIN FILMS

2019 ◽  
Vol 26 (04) ◽  
pp. 1850177 ◽  
Author(s):  
YINQIAO PENG ◽  
JICHENG ZHOU ◽  
GUIBIN LEI ◽  
YUANJU GAN ◽  
YUEFENG CHEN
Keyword(s):  
Thin Films ◽  
Network Structure ◽  
Energy Dispersive Spectrometer ◽  
Silicon Carbonitride ◽  
X Ray Diffraction ◽  
Hydrogenated Silicon ◽  
X Ray ◽  
Atomic Force ◽  
Scanning Electron ◽  
Blue Photoluminescence

Hydrogenated silicon carbonitride (SiCN:H) thin films were deposited by sputtering of silicon carbide target in hydrogen-doped argon and nitrogen atmospheres. The properties of the SiCN:H films were analyzed by scanning electron microscopy with energy dispersive spectrometer, atomic force microscope, Fourier transform infrared spectroscopy, X-ray diffraction and fluorescence spectrophotometer. No distinct crystal was formed in the SiCN:H films as-deposited and annealed at 600∘C and 800∘C. The SiCN:H films were mainly composed of Si–N, Si–C, Si–O, C–C, C–N, C[Formula: see text]N, N–Hn bonds and SiCxNy network structure. The strong blue photoluminescence observed from the SiCN:H film annealed at 600∘C was attributed to SiCxNy network structure.

High-performance electrical properties of La-based perovskite ceramics for the functional phase of thick film resistors

2020 ◽  
Author(s):  
Yongcheng Lu ◽  
Yuanxun Li ◽  
Daming Chen ◽  
Rui Peng ◽  
Qinghui Yang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electrical Properties ◽  
Thick Film ◽  
High Performance ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alternative Material ◽  
Perovskite Ceramics ◽  
Scanning Electron

Abstract In order to explore an economical functional phase alternative material for thick film resistors, the crystal structure, microstructure, and electrical properties of (1-x)LSCN + xLCNZ (x = 0.0–1.0) composite ceramics were studied through solid-state reaction experiments. The composite ceramics were characterized by x–ray diffraction, scanning electron microscopy, energy dispersive x–ray spectroscopy, and DC four–probe method. Results suggested that the main phases of LSCN and LCNZ were formed, along with a small part of impurity phases. The addition of LCNZ to LSCN decreased the electrical conductivity and changed the TCR from positive to negative. Zero TCR could be achieved around 0.6 < x < 0.8 and relatively low absolute TCR values could be obtained for the samples of 0.4 ≤ x ≤ 0.8. The ceramic of 0.6LSCN + 0.4LCNZ showed the optimal performances of conductivity = 1923 S/cm, TCR = 379.54 ppm/℃, and relative density = 95.05%.

Synthesis of Precipitate Calcium Carbonate with Variation Morphology from Limestone by Using Solution Mixing Method

2019 ◽  
Vol 966 ◽  
pp. 200-203
Author(s):  
Zaenal Arifin ◽  
Triwikantoro ◽  
Bintoro Anang Subagyo ◽  
Mochamad Zainuri ◽  
Darminto
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Carbonate ◽  
Molar Ratio ◽  
Mixing Process ◽  
X Ray Diffraction ◽  
Precipitate Calcium Carbonate ◽  
X Ray ◽  
Mixing Method ◽  
Scanning Electron

Abstract. In this study, the CaCO3 powder has been successfully synthesized by mixing CaCl2 from natural limestone and Na2CO3 in the same molar ratio. The mixing process of solutions was carried out by employing the molar contents of 0.125, 0.25, 0.375 and 0.5M at varying temperatures of 30, 40, 60 and 80ᴼC. The produced CaCO3 microparticles were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The highest content of aragonite phase with morphology rod-like of the samples is around 29 wt%, resulting from the process using solution of 0.125 M at 80 ᴼC. While at 30 ᴼC and 40 ᴼC produced 100 wt% calcite phase.

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