The Role of MgCl2 in Preparation of SnO2, MgSnO3 and Mg2SnO4 Nanopowders

2011 ◽  
Vol 403-408 ◽  
pp. 640-645
Author(s):  
Ali Taherkhani ◽  
A.Taheri Asghari

Tin oxide (SnO2) ,MgSnO3and Mg2SnO4nanocrystals have been synthesized by one-step solid-state reactions. in the first step, The powder of SnCl4.5H2O was mixed with MgCl2and Mg(OH)2with weight ratio of Sn to Mg (1:1), (2:1) And (1:2) in an air atmosphere at room, and annealing temperature in this work were 200°C, 400°C ,600°C , 800°C and 1000°C . XRD patterns show the SnO2, MgSnO3and Mg2SnO4particle size of synthesized powders by MgCl2were 3 nm, 4nm and 27 nm respectively. In fact the excess amount of Mg role of crystallite growth inhibitor in SnO2. this method is a simple ,inexpensive ,efficient and economic preparation for SnO2, MgSnO3and Mg2SnO4nanoparticles with adjustable grain sizes in the range of 3-44nm in high yield. This article shows the role of mass MgCl2in producing of SnO2nanoparticles.

2013 ◽  
Vol 284-287 ◽  
pp. 193-197
Author(s):  
Cheng Fu Yang ◽  
Wen Cheng Tzou

Sr0.4Ba0.6Nb1.85Ta0.15O6 (SBNT) ceramic was used as a target and SBNT thin films were deposited at room temperature. After deposition, the SBN thin films were annealed in conventional furnace (CFA) and in an oxygen atmosphere for 1h by changing the temperature from 700oC to 900oC. The thicknesses of the SBN thin films were calculated by SEM and they were about 450nm independent on the annealing temperature. From the XRD patterns, the as-deposited SBNT thin films displayed amorphous phase, whereas as CFA-treatment was used, the SBNT thin films displayed smooth surfaces. The grain sizes also increased with increasing CFA-treated temperature. In addition, the remanent polarization and saturation polarization increased and coercive field decreased with increasing CFA-treated temperature. Finally, the lnJ-E1/2 curves of the SBNT thin films was developed to find that the linear variations of leakage current densities correspond either to the Schottky emission mechanism or to the Poole-Frenkel emission mechanism.


2020 ◽  
Vol 845 ◽  
pp. 59-64
Author(s):  
Wen Cheng Tzou ◽  
Hon Kuan ◽  
You Cheng Chang

Nb-doped TiO2 (TNO) thin films were prepared by a sol-gel spin coating method with Nb content of 5 at.%, and then annealed in the temperature range of 500-900 °C. The surface morphologies and the crystalline phases of the TNO thin films were investigated by using SEM and XRD patterns. The grain sizes increased with rising annealing temperature, and the crystalline phases were completely transformed from anatase into rutile when the annealing temperature was above 900 °C in air atmosphere. In addition, the optical band gap decreased and the average optical transmittance was between 75 and 70 % in the range of visible light. Furthermore, the better electrical properties were obtained at the annealing temperature of 600 °C.


2015 ◽  
Vol 1101 ◽  
pp. 238-241
Author(s):  
Wen Cheng Tzou ◽  
Hon Kuan ◽  
Kai Yang Chuang

In this study, HfO2 thin films were deposited onto the Si substrates by RF magnetron sputtering system. After deposition, the HfO2 thin films were then heated by a furnace thermal annealing process in air and at 400-700oC. The surface morphologies and crystalline characteristics of the HfO2 thin films were investigated by using SEM and XRD patterns. The grain sizes and crystalline phases increased with rising annealing temperature. In addition, the SiO2/HfO2 distributed bragg reflector (DBR) was used for improving the external quantum efficiency of the GaN-based LEDs. The output power of LEDs with 9-pair SiO2/HfO2 DBR and with Ag mirror+6-pair SiO2/HfO2 DBR were increased by approximately 10.6% and 7%, respectively, as compared with the LEDs without SiO2/HfO2 DBR.


2005 ◽  
Vol 475-479 ◽  
pp. 3741-3744
Author(s):  
Wan Li Zhang ◽  
Hong Chuan Jiang ◽  
Bin Peng ◽  
Wen Xu Zhang ◽  
Shi Qing Yang

In this paper, the influences of annealing temperature on TbFe magnetostrictive film magnetic and magnetostrictive characteristics were discussed. TbFe films were prepared by RF magnetron sputtering. XRD patterns indicate that polycrystalline films consisting mainly of a-Fe and TbFe2 Laves phase could be obtained through rapid cycle annealing process (RCAP) at higher annealing temperature. Grain sizes could be controlled through varying annealing temperature. From film hysteresis loops measured by VSM, it has been found that the annealing treatment can improve TbFe film in-plane magnetization at 1600 kA.m-1 external field, and decrease in-plane coercivity. Magnetostriction of annealed TbFe films measured by optical cantilever deflectometer is better than as-deposited films at 40 kA.m-1 external magnetic field.


2007 ◽  
Vol 336-338 ◽  
pp. 255-257
Author(s):  
X.H. Yu ◽  
Dong Xiang Zhou ◽  
Shu Ping Gong ◽  
Jun Zhao ◽  
X.L. Zhang

In order to study the effect of coexistence of Nd2O3 and Sm2O3 on phase development in Ba4 (Sm0.7Nd0.3)9.33Ti18O54 ceramics, the calcination process was applied in one-step and two-step way. From the XRD patterns of one-step calcinated powders, the solid-state reactions were deduced. And the results indicated the coexistence of Nd2O3 and Sm2O3 would be helpful to form secondary phase Nd2Ti2O7, which would worsen the properties. The final tested results of sintered samples confirmed the advantages of two-step calcination. The εr was improved from 72.1 to 82.4 and Q.f was improved from 7200 GHz to 8300 GHz, while τf was still near zero.


2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Yolanda Osuna ◽  
Karla M. Gregorio-Jauregui ◽  
J. Gerardo Gaona-Lozano ◽  
Iliana M. de la Garza-Rodríguez ◽  
Anna Ilyna ◽  
...  

Chitosan-coated magnetic nanoparticles (CMNP) were obtained at 50°C in a one-step method comprising coprecipitation in the presence of low chitosan content. CMNP showed high magnetization and superparamagnetism. They were composed of a core of 9.5 nm in average diameter and a very thin chitosan layer in accordance with electron microscopy measurements. The results from Fourier transform infrared spectrometry demonstrated that CMNP were obtained and those from thermogravimetric analysis allowed to determine that they were composed of 95 wt% of magnetic nanoparticles and 5 wt% of chitosan. 67% efficacy in the Pb+2removal test indicated that only 60% of amino groups on CMNP surface bound to Pb, probably due to some degree of nanoparticle flocculation during the redispersion. The very low weight ratio chitosan to magnetic nanoparticles obtained in this study, 0.053, and the high yield of the precipitation reactions (≈97%) are noticeable.


Author(s):  
E. I. Alessandrini ◽  
M. O. Aboelfotoh

Considerable interest has been generated in solid state reactions between thin films of near noble metals and silicon. These metals deposited on Si form numerous stable chemical compounds at low temperatures and have found applications as Schottky barrier contacts to silicon in VLSI devices. Since the very first phase that nucleates in contact with Si determines the barrier properties, the purpose of our study was to investigate the silicide formation of the near noble metals, Pd and Pt, at very thin thickness of the metal films on amorphous silicon.Films of Pd and Pt in the thickness range of 0.5nm to 20nm were made by room temperature evaporation on 40nm thick amorphous Si films, which were first deposited on 30nm thick amorphous Si3N4 membranes in a window configuration. The deposition rate was 0.1 to 0.5nm/sec and the pressure during deposition was 3 x 10 -7 Torr. The samples were annealed at temperatures in the range from 200° to 650°C in a furnace with helium purified by hot (950°C) Ti particles. Transmission electron microscopy and diffraction techniques were used to evaluate changes in structure and morphology of the phases formed as a function of metal thickness and annealing temperature.


2019 ◽  
Author(s):  
Bella Grigorenko ◽  
Igor Polyakov ◽  
Alexander Nemukhin

<p>We report a mechanism of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP) conversion by the mammalian type V adenylyl cyclase revealed in molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) simulations. We characterize a set of computationally derived enzyme-substrate (ES) structures showing an important role of coordination shells of magnesium ions in the solvent accessible active site. Several stable six-fold coordination shells of Mg<sub>A</sub><sup>2+ </sup>are observed in MD simulations of ES complexes. In the lowest energy ES conformation, the coordination shell of Mg<sub>A</sub><sup>2+ </sup>does not include the O<sub>δ1</sub> atom of the conserved Asp440 residue. Starting from this conformation, a one-step reaction mechanism is characterized which includes proton transfer from the ribose O<sup>3'</sup>H<sup>3' </sup>group in ATP to Asp440 via a shuttling water molecule and P<sup>A</sup>-O<sup>3A</sup> bond cleavage and O<sup>3'</sup>-P<sup>A</sup> bond formation. The energy profile of this route is consistent with the observed reaction kinetics. In a higher energy ES conformation, Mg<sub>A</sub><sup>2+</sup> is bound to the O<sub>δ1</sub>(Asp440) atom as suggested in the relevant crystal structure of the protein with a substrate analog. The computed energy profile initiated by this ES is characterized by higher energy expenses to complete the reaction. Consistently with experimental data, we show that the Asp440Ala mutant of the enzyme should exhibit a reduced but retained activity. All considered reaction pathways include proton wires from the O<sup>3'</sup>H<sup>3' </sup>group via shuttling water molecules. </p>


2017 ◽  
pp. 126-169
Author(s):  
S.E. Tariverdieva

The article deals with the development of the coregency system of Augustus and Agrippa from 29 to 18 BC: from formal and actual disparity of the coregents to their formal equality with the dominance of the princeps auctoritas. Particular attention is paid to the earlier stages of this development and to the crisis of 23 BC. The coregency system created by Augustus is often regarded by modern historians as means of ensuring uninterrupted succession of power. Agrippa as his coregent often is thought to have assumed the role of the regent who temporally replaces the princeps, just as it was in formal monarchies, or that of the tutor of the future rulers. However, the Roman system of state administration did not allow such type of regency. The princeps coregent, who was his equal in formal credentials but his inferior in terms of auctoritas, in case of the princeps death had to become the next princeps as his immediate successor. It is unlikely that later he was expected to voluntarily give up his power in favour of younger heir and to vanish from the political life altogether. The inheritance system under Augustus was like a ladder with the princeps at the top, the coregent who was also the immediate successor one step below, heirs of the next degree further down. In case of death of one of them, successors shifted one step up. The coregency had one more function: geographically it allowed Augustus and Agrippa to rule jointly the empire while staying in different parts of it.В статье исследуется развитие системы соправления Августа и Агриппы с 29 по 12 гг. до н. э.: от формального и фактического неравенства соправителей до их формального равенства при преобладании auctoritas принцепса, причём особое внимание уделяется раннему этапу этого развития и кризису 23 г. до н. э. Институт соправления, созданный Августом, часто рассматривается, как средство обеспечения бесперебойного перехода власти, причем Агриппе, как соправителю, НЕРЕДКО отводится роль регента, временно замещающего принцепса или воспитателя будущих правителей. Однако римская система государственного управления не предполагала регентства. Соправитель принцепса, равный ему по формальным полномочиям, но уступавший по auctoritas, в случае его смерти должен был СТАТЬ следующим принцепсом, ближайшим его наследником. Вряд ли предполагалось, что в будущем он должен добровольно уступить власть более молодому наследнику и исчезнуть из политической жизни. Система наследования при Августе представляла собой нечто вроде лестницы, на вершине которой стоял принцепс, на следующей ступени соправитель, он же избранный преемник, ниже наследники следующей очереди в случае смерти когото из них происходило продвижение наследников по ступеням вверх. Кроме того, соправление имело и иное значение позволяло Августу и Агриппе совместно управлять империей, находясь в разных ее частях.


2020 ◽  
Vol 17 (8) ◽  
pp. 628-630
Author(s):  
Vu Binh Duong ◽  
Pham Van Hien ◽  
Tran Thai Ngoc ◽  
Phan Dinh Chau ◽  
Tran Khac Vu

A simple and practical method for the synthesis on a large scale of altretamine (1), a wellknown antitumor drug, has been successfully developed. The synthesis method involves the conversion of cyanuric chloride (2) into altretamine (1) by dimethylamination of 2 with an aqueous solution of 40% dimethylamine and potassium hydroxide in 1, -dioxan 4in one step to give altretamine (1) in high yield.


Sign in / Sign up

Export Citation Format

Share Document