ROOM TEMPERATURE CONTROLLABLE SYNTHESIS OF PEROXY NIOBATES CRYSTALLITES

2009 ◽  
Vol 23 (31n32) ◽  
pp. 3825-3834 ◽  
Author(s):  
MEINAN LIU ◽  
DONGFENG XUE
Keyword(s):  
Optical Properties ◽  
Room Temperature ◽  
Synthesis Process ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Controllable Synthesis ◽  
Electronic Microscopy ◽  
Temperature Synthesis ◽  
X Ray ◽  
Group Environment

A benign room temperature synthesis process has been developed to fabricate peroxy niobates with controllable composition and morphology. X-ray diffraction and scanning electronic microscopy were used to monitor the change of the phase composition and corresponding microstructure of the obtained niobates. Furthermore, UV/Vis spectra were used to study the optical properties of these ammonium and potassium peroxy niobates. The results showed that these peroxy niobates with { O 2} units present larger bandgap than those with { O 2 F } units. Photoluminescence results well demonstrated that the Nb group environment is sensitive to its optical properties, which offers a marvelous chance for its further applications, such as sensors.

Fabrication and Properties of La-Manganite/SnO2 Composites

2010 ◽  
Vol 123-125 ◽  
pp. 81-84 ◽  
Author(s):  
Geun Woo Kim ◽  
Yong Jun Seo ◽  
Jin Long Bian ◽  
Chan Gyu Lee ◽  
Bon Heun Koo
Keyword(s):  
Room Temperature ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Structure And Morphology ◽  
Low Field ◽  
Spin Polarized ◽  
Mr Effect ◽  
Spin Polarized Tunneling

Composites with compositions La0.7Ca0.3MnO3(LCMO) and La0.7Sr0.3MnO3(LSMO)/SnO2 were prepared by a standard ceramic technique. The structure and morphology of the composites have been studied by the X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The XRD and SEM results indicate that no reaction occurs between La based maganite and SnO2 grains, and that SnO2 segregates mostly at the grain boundaries of La based maganite. The variation in resistivity with temperature has been studied and shows a semiconducting behavior, furthermore the composites exhibit metallic percolation. It is interesting to note that an enhanced magnetoresisitance (MR) effect for the composites is found over a wide temperature range from low temperature to room temperature in an applied magnetic field of 0.5 Tesla. The spin-polarized tunneling and the spin-polarized tunneling may be attributed to the enhanced low-field magnetoresistance (LFMR) effect.

In Air Template-Free Synthesis of In2S3 Hierarchical Nanostructure from InCl3·4H2O and Thiourea

2010 ◽  
Vol 152-153 ◽  
pp. 63-66
Author(s):  
Shi Yin Li ◽  
Zhen Ni Du ◽  
Yong Cai Zhang
Keyword(s):  
Room Temperature ◽  
Band Gaps ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Hierarchical Nanostructure ◽  
Optical Band Gaps ◽  
Template Free

A novel template-free method, which was based on heating the mixture of InCl3•4H2O and thiourea in air from room temperature to 200 or 250 °C, coupled with a subsequent washing treatment using distilled water and ethanol, was proposed for the synthesis of In2S3 hierarchical nanostructure. X-ray diffraction and field emission scanning electronic microscopy demonstrated that the obtained products were pure cubic phase In2S3 urchin-like clusters built up by mainly nanoflakes (about 12–47 nm thick). UV-vis absorption spectra disclosed that the as-prepared In2S3 urchins had optical band gaps in the range of about 2.18–2.26 eV.

Synthesis and Characterization of ZIF-8 Mixed Matrix Membranes

2014 ◽  
Vol 625 ◽  
pp. 661-664
Author(s):  
Chen Chuang Lok ◽  
Yin Fong Yeong
Keyword(s):  
Room Temperature ◽  
Synthesis Method ◽  
Mixed Matrix Membranes ◽  
Inorganic Filler ◽  
X Ray Diffraction ◽  
Mixed Matrix ◽  
Temperature Synthesis ◽  
X Ray ◽  
Matrix Membranes

In the present work, ZIF-8/6FDA-durene mixed matrix membranes (MMMs) were synthesized and characterized. ZIF-8 nanocrystals, which were used as the inorganic filler, were synthesized using rapid room-temperature synthesis method whereas 6FDA-durene polyimide was synthesized by polycondensation method followed by chemical imidization. Pure and 6FDA-durene membranes loaded with 5 wt%, 10 wt% and 15 wt% of ZIF-8 were fabricated. The structural properties and morphology of the resultant membranes were characterized by using X-ray Diffraction (XRD) and Field emission scanning electron microscope (FESEM) . The EDX images showed that ZIF-8 particles agglomerated in the polymer matrix. However, no phase separation was observed for all resultant MMMs.

Characterization of Shivirtui Zeolite Modified with Aluminum Oxyhydroxide Nanofibers

2019 ◽  
Vol 942 ◽  
pp. 40-49
Author(s):  
Yulia Murashkina ◽  
Olga B. Nazarenko
Keyword(s):  
Chemical Properties ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Physical And Chemical ◽  
And Chemical Properties ◽  
Aluminum Oxyhydroxide

Natural zeolite of Shivirtui deposit (Russia) was modified with nanofibers of aluminum oxyhydroxide AlOOH. Aluminum oxyhydroxide nanofibers were produced at the heating and oxidation of aluminum powder with water. The properties of modified zeolite were investigated by means of X-ray diffraction, transmission electronic microscopy, scanning electronic microscopy, low-temperature nitrogen adsorption, thermal analysis, and Fourier transform infrared spectroscopy. It was found that water content in the modified sample of zeolite was about 15 %. Based on the study of the physical and chemical properties, shivirtui zeolite modified with nanofibers of aluminum oxyhydroxide can be proposed for use as a flame-retardant additive to polymers.

scholarly journals The Dehydrogenation Mechanism and Reversibility of LiBH4 Doped by Active Al Derived from AlH3

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 559 ◽  
Author(s):  
Qing He ◽  
Dongdong Zhu ◽  
Xiaocheng Wu ◽  
Duo Dong ◽  
Xiaoying Jiang ◽  
...  
Keyword(s):  
Reaction Products ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Scanning Calorimetry ◽  
Mass Spectral Analysis ◽  
X Ray ◽  
Mass Spectral ◽  
Al Composite ◽  
Dehydrogenation Mechanism

A detailed analysis of the dehydrogenation mechanism and reversibility of LiBH4 doped by as-derived Al (denoted Al*) from AlH3 was performed by thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD), scanning electronic microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results show that the dehydrogenation of LiBH4/Al* is a five-step reaction: (1) LiBH4 + Al → LiH + AlB2 + “Li-Al-B-H” + B2H6 + H2; (2) the decomposition of “Li-Al-B-H” compounds liberating H2; (3) 2LiBH4 + Al → 2LiH + AlB2 + 3H2; (4) LiBH4 → LiH + B + 3/2H2; and (5) LiH + Al → LiAl + 1/2H2. Furthermore, the reversibility of the LiBH4/Al* composite is based on the following reaction: LiH + LiAl + AlB2 + 7/2H2 ↔ 2LiBH4 + 2Al. The extent of the dehydrogenation reaction between LiBH4 and Al* greatly depends on the precipitation and growth of reaction products (LiH, AlB2, and LiAl) on the surface of Al*. A passivation shell formed by these products on the Al* is the kinetic barrier to the dehydrogenation of the LiBH4/Al* composite.

Study of the Synthesis of Mullite From Kaolin-α-Al2O3 and Kaolin-Al(NO3)3

2012 ◽  
Vol 1481 ◽  
pp. 11-17
Author(s):  
E. M. Lozada ◽  
O. Alanís ◽  
F. Legorreta ◽  
L. E. Hernández
Keyword(s):  
Combustion Method ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Crystallographic Study ◽  
Incomplete Reaction ◽  
Α Al2o3

ABSTRACTThe synthesis of mullite from kaolin clay and two precursors of aluminum: α-Al2O3 and Al(NO3)3 was investigated. In order to study the temperature effect, the system kaolin-α-Al2O3 was calcined in air in a range of 1200 to 1500°C, for 2 h. For the system kaolin-Al(NO3)3, the combustion method was employed, using urea as fuel, and calcined in air at 1500°C for 2 h. The products were characterized by X-ray diffraction, scanning electronic microscopy (SEM), energy dispersive spectroscopy and particle size analysis in order to analyze and compare their morphology and structure. The crystallographic study revealed an incomplete reaction between the kaolin and the α-Al2O3. Nevertheless, in the system kaolin-Al(NO3)3, it was obtained mullite with high purity and trace amounts of cristobalite.

Fabrication and Magnetic Properties of Fe3O4 Nanobranches via a Simple Solvothermal Method

2011 ◽  
Vol 335-336 ◽  
pp. 934-939
Author(s):  
Z. F. Zi ◽  
Y. N. Liu ◽  
Q.C. Liu ◽  
Jian Ming Dai ◽  
Yu Ping Sun
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Solvothermal Method ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
X Ray ◽  
Water Solvent ◽  
Phase Spinel ◽  
Antisite Defects

Magnetite (Fe3O4) nanobranches were synthesized using an improved solvothermal technique in mixed ethanol and water solvent. Structural and magnetic properties were systematically investigated. X-ray diffraction results showed that the sample was single-phase spinel structure. The results of scanning electronic microscopy exhibited that the grains were regular like-branch with sizes from 3 to 6 μm in length and in diameter between 50 and 200 nm. The composition determined by energy dispersive spectroscopy was very close to the stoichiometry of Fe3O4. The saturation magnetizations (Ms) at 10 and 300 K of the synthesized Fe3O4nanobranches were much lower than the theoretical values. On one hand, it could be explained by obstructive magnetizing along their non-easy magnetic axes by the shape anisotropy of Fe3O4nanobranches, on the other hand, lesserMscan also be understood by the existence of antisite defects.

Growth and Magneto-Optical Properties of CaTbAlO4 Crystal

2011 ◽  
Vol 306-307 ◽  
pp. 1722-1727 ◽  
Author(s):  
Man Mei ◽  
Li Li Cao ◽  
Yan He ◽  
Ru Ru Zhang ◽  
Fei Yun Guo ◽  
...  
Keyword(s):  
Optical Properties ◽  
Single Crystal ◽  
Room Temperature ◽  
Near Infrared ◽  
Visible Region ◽  
Czochralski Method ◽  
Optical Devices ◽  
X Ray Diffraction ◽  
X Ray ◽  
Infrared Spectral

The calcium terbium aluminate (CaTbAlO4) single crystal was grown by Czochralski method successfully for the first time.The structure of the crystal was determined by X-ray diffraction analysis.The transmission spectrum of the crystal was measured at room temperature at the wavelength of 400-1500nm.The specific Faraday rotation of the single crystal was surveyed at room temperature at the wavelength 532nm, 633nm, and 1064nm respectively.The Verdet constants of the CaTbAlO4 crystal are calculated and the results show that the Verdet constants of CaTbAlO4 are around 110% higher than that of TGG in the visible and near-infrared spectral region.Therefore,crystal CaTbAlO4 can be promising material for the fabrication of magneto-optical devices in the visible region.

scholarly journals The Dehydrogenation Mechanism and Reversibility of LiBH4 Doped by Active Al* Derived from AlH3

2019 ◽  
Author(s):  
Qing He ◽  
Dongdong Zhu ◽  
Xiaocheng Wu ◽  
Duo Dong ◽  
Xiaoying Jiang ◽  
...  
Keyword(s):  
Reaction Products ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Scanning Calorimetry ◽  
Mass Spectral Analysis ◽  
X Ray ◽  
Mass Spectral ◽  
Al Composite ◽  
Dehydrogenation Mechanism

A detailed analysis of the dehydrogenation mechanism and reversibility of LiBH4 doped by active Al* derived from AlH3 was performed by thermogravimetry (TG), differential scanning calorimetry (DSC), mass spectral analysis (MS), powder X-ray diffraction (XRD), scanning electronic microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show that the dehydrogenation of LiBH4/Al* is a five-step reaction: (1) LiBH4 + Al → LiH + AlB2 + “Li-Al-B-H” + B2H6 + H2; (2) the decomposition of "Li-Al-B-H" compounds liberating H2; (3) 2LiBH4 + Al → 2LiH + AlB2 + 3H2; (4) LiBH4 → LiH + B + 3/2H2; (5) LiH + Al → LiAl + 1/2H2. And the reversibility of LiBH4/Al* composite is based on equation as follows: LiH + LiAl + AlB2 + 7/2H2 ↔ 2LiBH4 + 2Al. The extent of dehydrogenation reaction between LiBH4 and Al* greatly depends on the precipitation and growth of reaction products (LiH, AlB2 and LiAl, etc.) on the surface of Al*. A passivation shell of Al* formed by these products is the kinetic barrier to the dehydrogenation of LiBH4/Al* composite.

scholarly journals Structure and composition of soils

2010 ◽  
Vol 4 (4) ◽  
pp. 259-263 ◽  
Author(s):  
Snezana Nenadovic ◽  
Milos Nenadovic ◽  
Ljiljana Kljajevic ◽  
Vladimir Pavlovic ◽  
Aleksandar Djordjevic ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Porous Structure ◽  
X Ray Diffraction ◽  
Scanning Electronic Microscopy ◽  
Electronic Microscopy ◽  
Characterization Methods ◽  
Soil Particles ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force

This paper presents a study of soils structure and composition using up to date technique, such as scanning electronic microscopy, atomic force microscopy, X-ray diffraction, X-ray fluorescence, as well as some other characterization methods. It was shown that soil particles have porous structure and dimensions in the range from several millimeters to several hundreds of nanometers and consist of different minerals such as kaolin, quartz and feldspate.

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