scholarly journals Characterization and properties of barium bismuth titanate

2009 ◽  
Vol 3 (1-2) ◽  
pp. 9-12 ◽  
Author(s):  
Jelena Bobic ◽  
Mirjana Vijatovic ◽  
Tadej Rojac ◽  
Biljana Stojanovic
Keyword(s):  
Mechanochemical Synthesis ◽  
Ball Mill ◽  
Room Temperature ◽  
Bismuth Titanate ◽  
Relaxor Ferroelectrics ◽  
X Ray ◽  
Air Atmosphere ◽  
Calcination Step ◽  
Barium Bismuth ◽  
Scanning Electron

BaBi4Ti4O15 (BBiT) was prepared from stoichiometric amounts of BaTiO3 (BT) and Bi4Ti3O12 (BIT) obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. BBiT ceramics were sintered at 1100?C, 1110?C and 1120?C for 1 h without pre-calcination step. The formation of phase and crystal structure of BT, BIT and BBiT were verified using X-ray analysis. The morphology of obtained powders and microstructure were examined using scanning electron microscopy. The electrical properties of sintered samples were carried out and BBiT shows behaviour typical for relaxor ferroelectrics and dielectric constant at room temperature is approximately 93. .

scholarly journals Study of barium bismuth titanate prepared by mechanochemical synthesis

2009 ◽  
Vol 41 (3) ◽  
pp. 329-335 ◽  
Author(s):  
Z.Z. Lazarevic ◽  
J. Bobic ◽  
N.Z. Romcevic ◽  
N. Paunovic ◽  
B.D. Stojanovic
Keyword(s):  
Mechanochemical Synthesis ◽  
Bismuth Titanate ◽  
Layer Structure ◽  
Layered Perovskite ◽  
Particle Analysis ◽  
Air Atmosphere ◽  
Calcination Step ◽  
Average Grain Size ◽  
Layered Perovskite Structure ◽  
Barium Bismuth

Barium-bismuth titanate, BaBi4Ti4O15 (BBT), a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure of BaBi4Ti4O15 ceramic forms at 1100 ?C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size.

scholarly journals Dielectric properties of bismuth titanate ceramics containing SiO2 and Nd2O3 as additives

2012 ◽  
Vol 6 (3) ◽  
pp. 117-122 ◽  
Author(s):  
Stanislav Slavov ◽  
Milena Krapchanska ◽  
Elena Kashchieva ◽  
Svetlin Parvanov ◽  
Yanko Dimitriev
Keyword(s):  
Room Temperature ◽  
Bismuth Titanate ◽  
Dielectric Materials ◽  
Dielectric Losses ◽  
X Ray Diffraction ◽  
Melt Quenching ◽  
X Ray ◽  
Quenching Method ◽  
Titanate Ceramics ◽  
Scanning Electron

Bismuth-titanate ceramics containing SiO2 and Nd2O3 as additives are synthesized by melt quenching method in the system Bi2O3-TiO2-Nd2O3-SiO2 in the temperature range of 1250-1500 ?C. The phase composition of the obtained materials is determined by X-ray diffraction analysis and energy dispersive spectroscopy. Using scanning electron microscopy different microstructures are observed in the samples depending on the composition. Different values of conductivity, dielectric losses and relative permittivity are obtained depending on the composition. It is established that all investigated samples are dielectric materials with conductivity between 10-9 and 10-13 (??cm)-1 at room temperature, dielectric permittivity from 1000 to 3000 and dielectric losses tg? between 0.0002 and 0.1.

The Influence of Tribophysical Activation on Non-Isothermal Sintering of BaTiO3 Ceramics

2006 ◽  
Vol 514-516 ◽  
pp. 1566-1570 ◽  
Author(s):  
Vera P. Pavlović ◽  
Maria V. Nikolić ◽  
V. Spasojević ◽  
Jovan Blanuša ◽  
Ljiljana Živković ◽  
...  
Keyword(s):  
Barium Titanate ◽  
Powder Diffraction ◽  
Ball Mill ◽  
Room Temperature ◽  
Diffraction Method ◽  
Heating Rates ◽  
Technological Parameters ◽  
Dilatometric Analysis ◽  
X Ray ◽  
Scanning Electron

In this paper the influence of tribophysical activation on non-isothermal sintering of barium titanate has been investigated. BaTiO3 powders were tribophysically activated in a planetary ball mill for 0, 60 and 120 min., pressed and non-isothermally sintered up to 1380oC. Dilatometric analysis was performed in air in the temperature range from room temperature to 1380oC with heating rates of 10, 20 and 30oC/min. The samples were analyzed by the X-ray powder diffraction method. Investigation of the morphology of microstructure constituents was performed using the scanning electron microsocopy method. With the purpose of optimizing technological parameters the results obtained by microstructure analysis were correlated with the results of quantitative dilatometric analysis.

scholarly journals Yttrium orthoferrite powder obtained by the mechanochemical synthesis

2017 ◽  
Vol 49 (3) ◽  
pp. 277-284 ◽  
Author(s):  
Zorica Lazarevic ◽  
Cedomir Jovalekic ◽  
Martina Gilic ◽  
Valentin Ivanovski ◽  
Ana Umicevic ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Crystallite Size ◽  
Mechanochemical Synthesis ◽  
Ball Mill ◽  
Room Temperature ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Yttrium Orthoferrite ◽  
Raman And Infrared Spectroscopy

Yttrium orthoferrite (YFeO3) powder was prepared by a mechanochemical synthesis from a mixture of Y2O3 and ?-Fe2O3 powders in a planetary ball mill for 2.5 h. The obtained YFeO3 powder sample was characterized by X-ray diffraction (XRD), Raman and infrared spectroscopy. The average crystallite size calculated by the Scherrer equation was 12 nm. The M?ssbauer spectroscopy at room temperature confirms the superparamagnetic character of YFeO3 orthoferrite sample.

MECHANOCHEMICAL SYNTHESIS OF SINGLE PHASE NANOCRYSTALLINE FORSTERITE POWDER

2010 ◽  
Vol 24 (03) ◽  
pp. 343-350 ◽  
Author(s):  
F. TAVANGARIAN ◽  
R. EMADI
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanochemical Synthesis ◽  
Ball Mill ◽  
Single Phase ◽  
Magnesium Carbonate ◽  
Subsequent Annealing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

Pure nanocrystalline forsterite ( Mg 2 SiO 4) powder was successfully synthesized by mechanochemical route and subsequent annealing. The starting materials were talc ( Mg 3 Si 4 O 10( OH )2) and magnesium carbonate ( MgCO 3) powders. To produce forsterite powder, first talc and magnesium carbonate powders were calcined at 1200°C for 1 h and 700°C for 2 h, respectively. After that the mixture of obtained powders was milled by a planetary ball mill, and then annealed at 1000°C and 1200°C for 1 h. Thermogravimetric (TG) analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques were utilized to characterize the initial and prepared powders. The results showed that a single phase nanocrystalline forsterite powder with a crystallite size of 49 nm was obtained after 40 h milling and subsequent annealing at 1000°C for 1 h.

ROOM TEMPERATURE PHOTOLUMINESCENCE OF POLYCRYSTALLINE SIC PREPARED FROM CARBON-SATURATED SI MELT

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1047-1051
Author(s):  
JIANPING MA ◽  
ZHIMING CHEN ◽  
GANG LU ◽  
MINGBIN YU ◽  
LIANMAO HANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Uv Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Composition And Structure ◽  
Light Excitation ◽  
Scanning Electron

Intense photoluminescence (PL) has been observed at room temperature from the polycrystalline SiC samples prepared from carbon-saturated Si melt at a temperature ranging from 1500 to 1650°C. Composition and structure of the samples have been confirmed by means of X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. PL measurements with 325 nm UV light excitation revealed that the room temperature PL spectrum of the samples consists of 3 luminescent bands, the peak energies of which are 2.38 eV, 2.77 eV and 3.06 eV, respectively. The 2.38 eV band is much stronger than the others. It is suggested that some extrinsic PL mechanisms associated with defect or interface states would be responsible to the intensive PL observed at room temperature.

Identification of Nd163 phase in melt-textured NdBa2Cu3O7−δ bulk samples

2003 ◽  
Vol 18 (9) ◽  
pp. 2050-2054 ◽  
Author(s):  
Marcello Gombos ◽  
Vicente Gomis ◽  
Anna Esther Carrillo ◽  
Antonio Vecchione ◽  
Sandro Pace ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Optical Microscopy ◽  
Room Temperature ◽  
Polarized Light ◽  
Energy Dispersive ◽  
X Ray ◽  
Spontaneous Formation ◽  
The Stability ◽  
Scanning Electron

In this work, we report on the observation of Nd1Ba6Cu3O10,5 (Nd163) phase of the NdBaCuO system in melt-textured Nd123 bulk samples grown from a mixture of Nd123 and Nd210 phase powders. The observation was performed with polarized light optical microscopy and scanning electron microscopy–energy dispersive x-ray analyses. Images of the identified phase crystals show an aspect quite different from Nd422 crystals. Unexpectedly, Nd163 was individuated, even in “pure” Nd123 samples. Moreover, after long exposure to air, Nd163 disappeared completely in samples synthesized from powders containing Nd210. Thermogravimetry analyses of powders show that the stability of this phase in air is limited to temperatures higher than 900 °C, so Nd163 is unstable and highly reactive at room temperature. Moreover, an explanation of the observation of Nd163 in Nd210 free samples, based on the spontaneous formation of Nd163 phase in a Nd123 melt, is proposed.

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.

Influence of Silicon Nitride on Properties of Corundum Based Castable

2013 ◽  
Vol 634-638 ◽  
pp. 2358-2361
Author(s):  
Jun Cong Wei ◽  
Li Rong Yang
Keyword(s):  
Electron Microscopy ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Cold Strength ◽  
X Ray ◽  
Refractory Castables ◽  
Shock Resistance ◽  
Scanning Electron

The effects of Si3N4 addition on the room temperature physical properties and thermal shock resistance properties of corundum based refractory castables were investigated using brown corundum, white corundum and alumina micropowder as the starting materials and pure calcium aluminate as a binder. The phase composition, microstructure, mechanical properties of corundum based castables were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that as the increase in Si3N4 addition, the bulk density decreased and apparent porosity increased, the cold strength deduced. However, the residual strength rate increased. That is, the thermal shock resistance was improved. This is because even though the introduction of Si3N4 inhibited the sintering of material and deduced the compactness, microcracks were produced in the materials due to a difference in thermal expansion coefficient. So the thermal shock resistance of corundum based castable was improved.

A Facile Fynthesis of ZnS Nanostructures via Liquid-Solid Reactions

2014 ◽  
Vol 979 ◽  
pp. 184-187
Author(s):  
Weerachon Phoohinkong ◽  
Thitinat Sukonket ◽  
Udomsak Kitthawee
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Inorganic Salts ◽  
Chloride Salt ◽  
X Ray ◽  
Commercial Grade ◽  
Transmission Electron ◽  
Salt Addition ◽  
20 Nm ◽  
Scanning Electron

Zinc sulfide (ZnS) nanostructures are important materials for many technologies such as sensors, infrared windows, transistors, LED displays, and solar cells. However, many methods of synthesizing ZnS nanostructures are complex and require expensive equipment. In this study, a liquid-solid chemical reaction without surfactant was used to synthesize ZnS at room temperature. In addition, commercial grade zinc oxide (ZnO) particles were used as a precursor. The effect of the addition of acids and inorganic salts were investigated. The products were characterized by field emission scanning electron microscopy (FESEM) coupled with energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). The results show that the nanoparticles of ZnS were obtained in hydrochloric acid and acetic acid addition. The diameters were in the range of 10 to 20 nm and 50 to 100 nm, respectively. In the case of a sodium chloride salt addition, a ZnS structure was obtained with a particle size of approximately 5 nm and a flake-like morphology.

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