Preparation and Dielectric Properties of Cr Doped Multiferroic BiFeO3

2012 ◽  
Vol 512-515 ◽  
pp. 1240-1243 ◽  
Author(s):  
Xi Wei Qi ◽  
Xiao Yan Zhang ◽  
Jian Quan Qi ◽  
He Ji Xu ◽  
Hai Feng Wang
Keyword(s):  
Dielectric Properties ◽  
Hydrothermal Method ◽  
Frequency Stability ◽  
Synthesis Temperature ◽  
Grain Structure ◽  
Main Peak ◽  
Second Phase ◽  
Hydrothermal Conditions ◽  
Cr Content ◽  
Multiferroic Bifeo

A series of Cr doped multiferroic BiFeO3 (BFO) with the composition of BiFe1-xCrxO3 have been prepared using hydrothermal method, in which x varies as 0, 0.05, 0.1, 0.2, 0.3, 0.4 and 0.5. The synthesis temperature is carried out as low as 230 °C under hydrothermal conditions. With the increase of the content of Cr, the second phase is gradually increased. When the value of Cr is 0.5, the main peak (110) and (104) of BFO tends to disappear, in which the structure of BFO is changed. The permittivity of as-prepared samples decreases with the increase of Cr content and excellent frequency stability is exhibited. Better grain structure can be obtained for samples sintered at 830 °C

Preparation and Dielectric Properties of La Doped Bi2Al4O9

2013 ◽  
Vol 423-426 ◽  
pp. 890-893
Author(s):  
Xiao Yan Zhang ◽  
Xi Wei Qi ◽  
Jun Fang Wei ◽  
Wen Shu Hu ◽  
Gui Fang Sun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Dielectric Properties ◽  
Sol Gel ◽  
Frequency Stability ◽  
Second Phase ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
La Doped ◽  
Scanning Electron

A series of (Bi1-xLax)2Al4O9(x = 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.40) ceramics were prepared by sol-gel method with sintering process. Doping dependent investigations were carried out to show the influence of La atom on the structural stability. The products were characterized using X-ray diffraction, scanning electron microscopy. This showed that the second phase is increased gradually by La doping. When the value of La is 0.4, the main phase tends to become LaAlO3. Details on dielectric properties are reported. The permittivity of as-prepared doped samples increases slightly compared to pure Bi2Al4O9and excellent frequency stability is exhibited.

Cetyltrimethylammonium bromide- and ethylene glycol-assisted preparation of mono-dispersed indium oxide nanoparticles using hydrothermal method

2014 ◽  
Vol 68 (8) ◽  
Author(s):  
Selvakumar Dhanasingh ◽  
Dharmaraj Nallasamy ◽  
Saravanan Padmanapan ◽  
Vinod Padaki
Keyword(s):  
Ethylene Glycol ◽  
Hydrothermal Method ◽  
Indium Oxide ◽  
Cetyltrimethylammonium Bromide ◽  
Oxide Nanoparticles ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Transmission Electron ◽  
Diffraction Patterns

AbstractThe influence of cetyltrimethylammonium bromide and ethylene glycol on the size and dispersion of indium oxide nanoparticles prepared under hydrothermal conditions was investigated. The precursor compound, indium hydroxide, obtained by the hydrothermal method in the absence as well as the presence of cetyltrimethylammonium bromide, was converted to indium oxide by sintering at 400°C. The formation of nanoscale indium oxide upon sintering was ascertained by the characteristic infrared adsorption bands and X-ray diffraction patterns of indium oxide. Transmission electron microscopy and band gap values confirmed that the cetyltrimethylammonium bromide facilitated the formation of indium oxide nanoparticles smaller in size and narrower in distribution than those prepared without the assistance of cetyltrimethylammonium bromide.

Dielectric properties of BaTiO3, Sr- and Pb-substituted BaTiO3ceramics synthesized through hydrothermal method

1994 ◽  
Vol 154 (1) ◽  
pp. 331-336 ◽  
Author(s):  
N. Yasuda ◽  
T. Kato ◽  
T. Hirai ◽  
M. Mizuno ◽  
K. Kurachi ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Hydrothermal Method

Hydrothermal Synthesis of Bi1.5ZnNb1.5O7 Nanopowders

2007 ◽  
Vol 561-565 ◽  
pp. 495-498 ◽  
Author(s):  
Jin Liang Huang ◽  
Xiao Wang ◽  
Liu Shuan Yang ◽  
Chun Wei Cui ◽  
Xing Hua Yang
Keyword(s):  
Reaction Time ◽  
Hydrothermal Synthesis ◽  
Hydrothermal Method ◽  
Pyrochlore Phase ◽  
Synthesis Temperature ◽  
Minimum Size ◽  
Hydrothermal Reactions ◽  
Prolonged Reaction Time ◽  
Scherrer Equation ◽  
Xrd Patterns

The cubic pyrochlore phase Bi1.5ZnNb1.5O7 nanopowder was successfully synthesized by the hydrothermal method (HTM) from the starting materials: Bi(NO3)3·5H2O, ZnO, Nb2O5 and the mineralizer: KOH. The XRD patterns prove that the cubic pyrochlore phase Bi1.5ZnNb1.5O7 nanopowder can be obtained by HTM, and TEM photographs show that the powders present the regularly granular shape, when the hydrothermal reactions were conducted at synthesis temperatures 140~220°C and reaction time for 6~48h. The crystalline sizes of the powders were calculated by the Scherrer equation to be about 43~49nm. The crystalline sizes decreased both with the increase in synthesis temperature and the prolonged reaction time until they reached to the minimum size about 43nm at 220°C for 24h.However, they tended to increase when the reaction time was above 24h.

A novel additive-free oxides–hydrothermal approach for monazite-type LaPO4nanomaterials with controllable morphologies

2010 ◽  
Vol 43 (5) ◽  
pp. 990-997 ◽  
Author(s):  
Jie Ma ◽  
Qingsheng Wu
Keyword(s):  
Electron Microscopy ◽  
Treatment Time ◽  
Synthesis Temperature ◽  
Molar Ratio ◽  
Hydrothermal Conditions ◽  
Typical Sample ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Hydrothermal Approach

A facile oxides–hydrothermal (O–HT) method is demonstrated to prepare high-purity monazite-type LaPO4nanomaterials. In this approach, La2O3and P2O5powder are first directly used as precursors under additive-free hydrothermal conditions. The as-prepared samples are characterized with X-ray diffraction, Fourier transform IR spectroscopy, thermogravimetry, scanning electron microscopy, transmission electron microscopy (high-resolution TEM, energy dispersive spectroscopy) and selected-area electron diffraction. The typical sample obtained at 433 K in 24 h comprises uniform single-crystal nanofibres with a diameter of ∼15–28 nm and an aspect ratio of 30–50. The influences of treatment time, synthesis temperature and P/La molar ratio are investigated. The phase transition from hexagonal hydrate to monoclinic anhydrous lanthanum phosphate and the growth process of nanofibres are revealed by the experimental results. The formation mechanism of the monoclinic LaPO4is discussed. The result indicates that the P/La ratio does not influence the composition and crystal phase but changes the morphology of the product in the O–HT system.

Depth Profile of Structure, Strain, and Composition in an Annealed Al-Cu-Fe-Cr Quasicrystalline Film

2001 ◽  
Vol 695 ◽  
Author(s):  
M.J. Daniels ◽  
D. King ◽  
J.S. Zabinski ◽  
Z.U. Rek ◽  
J.C. Bilello
Keyword(s):  
Residual Strain ◽  
Incident Angle ◽  
Rf Sputtering ◽  
Strain Analysis ◽  
Grazing Incidence ◽  
Grain Structure ◽  
Second Phase ◽  
Secondary Phases ◽  
Composite Target ◽  
X Ray

ABSTRACTQuasicrystalline films were formed by RF sputtering from a powder composite target onto Inconel substrates, which produces a polymorphic nanoquasicrystalline grain structure, ~2.5 - 10 nm. Subsequent annealing at 500°C for 4 hours, at base pressures of below 5*10-5 Torr, and with Ar flow to 5 - 10 mT, fully develops the quasicrystalline structure with decagonal phase predominating, except near the termination surface. Analysis by XPS indicated extensive oxygen incorporation and limited aluminum enrichment at the termination surface. These results are correlated with structure and strain analysis via synchrotron grazing incidence x-ray scattering (GIXS). By varying the incident angle, hence the x-ray penetration depth, the evolution of an amorphous and crystalline crystalline secondary phases at the surface of the film has been detected. Residual strain analysis shows that this second phase induces a compressive residual strain of 0.10% as measured from the displacement of the major quasicrystalline peaks in the surface layers of the film.

Preparation and Mechanical Properties of BiFeO3 Ceramics

2016 ◽  
Vol 697 ◽  
pp. 293-296
Author(s):  
Xiao Yang Zhang ◽  
Xi Wei Qi ◽  
Zhi Yuan Yang ◽  
Li Bao ◽  
Min Zhang
Keyword(s):  
Mechanical Properties ◽  
Hydrothermal Method ◽  
Perovskite Phase ◽  
Sol Gel ◽  
Cold Isostatic Pressing ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Three Point Bending ◽  
Multiferroic Bifeo ◽  
Sol Gel Process

Hydrothermal method and sol-gel process were used to synthesize multiferroic BiFeO3 ceramics. X-ray diffraction, scanning electron microscopy, vickers diamond indenter and three-point bending method were used to investigate the effects of methods on the phase structure, microstructures and mechanical properties. Cold isostatic pressing on the ceramics with two different loads (10 MPa, 200 MPa) was used to illustrate the influence of pressure in mechanical properties. The results show that all samples are crystallized in the perovskite phase. A few small traces of impurity are observed at a 2θ of ~28 o, which are found to be those of Bi2Fe4O9. The SEM images depict that samples prepared by sol-gel process are more uniform and the grain size is slightly larger than that of hydrothermal processed samples. The investigations on the hardness and flexural strength demonstrate the ceramics prepared by hydrothermal method have better mechanical properties than that of sol-gel process, and the mechanical properties can be obviously enhanced by increasing pressure.

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