scholarly journals Dilatometer Investigations of Reactive Sintering of Zinc Titanate Ceramics

2005 ◽  
Vol 494 ◽  
pp. 411-416 ◽  
Author(s):  
N. Obradović ◽  
Nebojsa Labus ◽  
Tatjana Srećković ◽  
Momcilo M. Ristić
Keyword(s):  
Mechanical Activation ◽  
Solid State Reactions ◽  
Molar Ratio ◽  
Formation Processes ◽  
X Ray Diffraction ◽  
Time Intervals ◽  
Zinc Titanate ◽  
X Ray ◽  
Sintering Time ◽  
Titanate Ceramics

Starting powder mixtures of ZnO and TiO2, at the molar ratio that is in accordance with the stoichiometry of zinc titanate Zn2TiO4, were mechanically activated using a planetary ball mill in different time intervals from 0 to 90 minutes. X-ray diffraction analysis, scanning electron microscopy and non-isothermal dilatometric measurements were performed in order to investigate zinc titanate formation. Processes occurring during mechanical activation led to the formation of a specific structure of obtained powders that promoted and accelerated solid-state reactions and densification during sintering. The main conclusion based on analysis is that mechanical activation enables better compaction of activated powders, i.e. possibility of achieving higher densities of green bodies without binders, but first of all that Zn2TiO4 ceramics can be obtained by mechanical activation after a certain time with appropriate thermal treatment, i.e. heating rate and sintering time, at temperatures lower than those when non-activated mixtures were used.

scholarly journals Synthesis of barium-zinc-titanate ceramics

2012 ◽  
Vol 44 (1) ◽  
pp. 65-71 ◽  
Author(s):  
N. Obradovic ◽  
M.V. Nikolic ◽  
N. Nikolic ◽  
S. Filipovic ◽  
M. Mitric ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Zinc Titanate ◽  
X Ray ◽  
Microstructure Characteristics ◽  
Amplitude Spectra ◽  
Titanate Ceramics

Mixtures of BaCO3, ZnO and TiO2 powders, with molar ratio of 1:2:4, were mechanically activated for 20, 40 and minutes in a planetary ball mill. The resulting powders were compacted into pellets and isothermally sintered at 1250?C for 2h with a heating rate of 10?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 correlation between thermal diffusivity and experimental conditions, as well the samples microstructure characteristics, was discussed.

Calcined Powder of the Sol-Gel Synthesis Hydroxyapatite

2013 ◽  
Vol 284-287 ◽  
pp. 41-45
Author(s):  
Chich Kuan Chen
Keyword(s):  
Sol Gel ◽  
Calcium Nitrate ◽  
Molar Ratio ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sintering Time ◽  
Bioactive Properties ◽  
Gel Preparation ◽  
Sol Gel Synthesis

The bioactive properties of hydroxyapatite [HA, Ca10(PO4)6(OH)2] have been demonstrated to be akin to osseous tissue, and provide quick fixation in prosthesis and orthopedics. In this study, sol-gel preparation of hydroxyapatite were arranged for Ca/P=1.67 molar ratio in calcium nitrate [Ca(NO)3.4H2O ] and triethylphosphate [TEP, C6H15PO4] and then dilute in the solvent of ethylene glycol mono-methyl ether [HOCH2CH2OCH3]. Consequently, sintering process was carried out at different temperature for various sintering time to materialize this inorganic polycrystalline phosphate. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) are applied to investigate the as dried amorphous and calcined hydroxyapatite. Results reveal calcinations at 1000oC prolonged for 30 minutes in air can exhibit crystalline hydroxyapatite.

Dielectric and Ferroelectric Behavior in 8/40/60 PLZT Ceramics

2014 ◽  
Vol 936 ◽  
pp. 119-122 ◽  
Author(s):  
Ladapak Chumprasert ◽  
Khem Chirapatpimol ◽  
Apichart Limpichaipanit ◽  
Komsanti Chokethawai ◽  
Athipong Ngamjarurojana
Keyword(s):  
Lead Zirconate Titanate ◽  
Lead Zirconate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ferroelectric Behavior ◽  
Sintering Time ◽  
Milling Method ◽  
Sintering Conditions ◽  
Titanate Ceramics ◽  
The Relationship

This paper describes the relationship between sintering time conditons, tetragonality from phase formation, dielectric and ferroelectric characteristics of tetragonal PLZT (lanthanum modified lead zirconate titanate) ceramics with the pressureless sintering conditions. Ferroelectric compounds of Pb0.92La0.08(Zr0.4,Ti0.6)0.98)O3, PLZT 8/40/60, were prepared using mixed-oxide synthetic route via a rapid vibro-milling method. X-ray diffraction, is used to observe the tetragonality characteristic and the presence of pyrochlore. When sintering time was increased (≥ 8 hours), pyrochlore was developed. It can be observed that with the increased sintering time, it were changed the structure and ferroelectric behavior of the PLZT ceramics.

scholarly journals Mechanical-chemical synthesis Ba0.77Sr0.23TiO3

2012 ◽  
Vol 44 (1) ◽  
pp. 47-55 ◽  
Author(s):  
D. Kosanovic ◽  
N. Obradovic ◽  
J. Zivojinovic ◽  
S. Filipovic ◽  
A. Maricic ◽  
...  
Keyword(s):  
Solid Phase ◽  
Phase Particle ◽  
High Energy ◽  
Solid State Reactions ◽  
Process Synthesis ◽  
X Ray Diffraction ◽  
Time Intervals ◽  
X Ray ◽  
Characteristic Temperatures ◽  
Barium Strontium

Barium-Strontium-Titanate Ba0.77Sr0.23TiO3 was prepared from starting materials BaCO3, SrCO3 and TiO2 through solid-state reactions. Mixtures of these oxides are mechanically activated in a high-energy planetary ball mill at different time intervals from 0 to 120 minutes. In order to obtain information on phase composition, crystal structure was determent by X-ray diffraction. It was observed that after 80 minutes in process synthesis Ba0.77Sr0.23TiO3 started Thermal analyzes were performed in order to determine the characteristic temperatures of the processes that occur in the solid phase. Particle size distribution, together with electron microscopy scanning has given us very useful information about the morphology of the powder.

TEM studies of solid-state reactions in sputter-deposited Nb/Al multilayer thin films

1996 ◽  
Vol 54 ◽  
pp. 1020-1021
Author(s):  
F. Ma ◽  
S. Vivekanand ◽  
K. Barmak ◽  
C. Michaelsen
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Stoichiometric Composition ◽  
Analytical Electron Microscopy ◽  
Grain Structure ◽  
Solid State Reactions ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sputter Deposited

Solid state reactions in sputter-deposited Nb/Al multilayer thin films have been studied by transmission and analytical electron microscopy (TEM/AEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The Nb/Al multilayer thin films for TEM studies were sputter-deposited on (1102)sapphire substrates. The periodicity of the films is in the range 10-500 nm. The overall composition of the films are 1/3, 2/1, and 3/1 Nb/Al, corresponding to the stoichiometric composition of the three intermetallic phases in this system.Figure 1 is a TEM micrograph of an as-deposited film with periodicity A = dA1 + dNb = 72 nm, where d's are layer thicknesses. The polycrystalline nature of the Al and Nb layers with their columnar grain structure is evident in the figure. Both Nb and Al layers exhibit crystallographic texture, with the electron diffraction pattern for this film showing stronger diffraction spots in the direction normal to the multilayer. The X-ray diffraction patterns of all films are dominated by the Al(l 11) and Nb(l 10) peaks and show a merging of these two peaks with decreasing periodicity.

Effect of Hydrated Metal Salts on the Coordination Product of Cobalt(II) halide and PNP Type Ligand, 2,6-bis(di-tertbutylphosphinomethyl) pyridine

2018 ◽  
Author(s):  
Tasneem Siddiquee ◽  
Abdul Goni
Keyword(s):  
Metal Salts ◽  
Molar Ratio ◽  
Pincer Complexes ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Pincer Ligand ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
Distorted Tetrahedral Geometry ◽  
Cobalt Center

Chemical treatment of CoX<sub>2</sub><b><sup>. </sup></b>6H<sub>2</sub>O (X = Cl, Br, I) with the potentially tridentate PNP pincer ligand 2,6-bis(di-<i>tert</i>-butylphosphinomethyl)pyridine in 1:1 molar ratio results in cobalt(II) halide-PNP pincer complexes. The effect of the hydrated metal source on molecular structure and geometry of the complexes was studied by single crystal X-ray diffraction analysis. The complexes are neutral and the cobalt center adopts a penta-coordinate system with potential atropisomerization. Within the unit cell there are two distinct molecules per asymmetric unit. One of the two phosphorus atoms in the PNP ligand was observed to be partially oxidized to phosphinoxide. Disorder in the structure reflects a mixture of square pyramidal and distorted tetrahedral geometry.

scholarly journals Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 346
Author(s):  
Sonam Goyal ◽  
Maizatul Shima Shaharun ◽  
Ganaga Suriya Jayabal ◽  
Chong Fai Kait ◽  
Bawadi Abdullah ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalyst Support ◽  
Oxidation Potential ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Optimum Parameters ◽  
Reduction Of Co2 ◽  
Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

scholarly journals Synthesis and Na+ Ion Conductivity of Stoichiometric Na3Zr2Si2PO12 by Liquid-Phase Sintering with NaPO3 Glass

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3790
Author(s):  
Yongzheng Ji ◽  
Tsuyoshi Honma ◽  
Takayuki Komatsu
Keyword(s):  
Solid State ◽  
Liquid Phase ◽  
Sintering Temperature ◽  
Liquid Phase Sintering ◽  
Ion Conductivity ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Sintering Time ◽  
Lower Activation

Sodium super ionic conductor (NASICON)-type Na3Zr2Si2PO12 (NZSP) with the advantages of the high ionic conductivity, stability and safety is one of the most famous solid-state electrolytes. NZSP, however, requires the high sintering temperature about 1200 °C and long sintering time in the conventional solid-state reaction (SSR) method. In this study, the liquid-phase sintering (LPS) method was applied to synthesize NZSP with the use of NaPO3 glass with a low glass transition temperature of 292 °C. The formation of NZSP was confirmed by X-ray diffraction analyses in the samples obtained by the LPS method for the mixture of Na2ZrSi2O7, ZrO2, and NaPO3 glass. The sample sintered at 1000 °C for 10 h exhibited a higher Na+ ion conductivity of 1.81 mS/cm at 100 °C and a lower activation energy of 0.18 eV compared with the samples prepared by the SSR method. It is proposed that a new LPE method is effective for the synthesis of NZSP and the NaPO3 glass has a great contribution to the Na+ diffusion at the grain boundaries.

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.

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