Understanding the Growth Mechanism of Hematite Nanoparticles: The Role of Maghemite as an Intermediate Phase

2020 ◽  
Vol 21 (1) ◽  
pp. 16-22
Author(s):  
Suresh Bandi ◽  
Ajeet K. Srivastav
Keyword(s):  
Growth Mechanism ◽  
Intermediate Phase ◽  
Hematite Nanoparticles

Chemical Availability of Bromide Dictates CsPbBr3 Nanocrystal Growth

2019 ◽  
Author(s):  
Je-Ruei Wen ◽  
Benjamin Roman ◽  
Freddy Rodriguez Ortiz ◽  
Noel Mireles Villegas ◽  
Nicholas Porcellino ◽  
...  
Keyword(s):  
Reaction Time ◽  
Growth Mechanism ◽  
Chemical Control ◽  
Critical Role ◽  
Phase Evolution ◽  
Detailed Understanding ◽  
Semiconductor Nanocrystal ◽  
Nanocrystal Growth ◽  
Chemical Availability

Lack of detailed understanding of the growth mechanism of CsPbBr3 nanocrystals has hindered sophisticated morphological and chemical control of this important emerging optoelectronic material. Here, we have elucidated the growth mechanism by slowing the reaction kinetics. When 1-bromohexane is used as an alternative halide source, bromide is slowly released into the reaction mixture, extending the reaction time from ~3 seconds to greater than 20 minutes. This enables us to monitor the phase evolution of products over the course of reaction, revealing that CsBr is the initial species formed, followed by Cs4PbBr6, and finally CsPbBr3. Further, formation of monodisperse CsBr nanocrystals is demonstrated in a bromide-deficient and lead-abundant solution. The CsBr can only be transformed into CsPbBr3 nanocubes if additional bromide is added. Our results indicate a fundamentally different growth mechanism for CsPbBr3 in comparison with more established semiconductor nanocrystal systems and reveal the critical role of the chemical availability of bromide for the growth reactions.<br>

Further studies on the role of redox-active monolayer as intermediate phase of solid-state sensors

2007 ◽  
Vol 123 (1) ◽  
pp. 480-487 ◽  
Author(s):  
Ewa Grygolowicz-Pawlak ◽  
Kamila Plachecka ◽  
Zbigniew Brzozka ◽  
Elzbieta Malinowska
Keyword(s):  
Solid State ◽  
Intermediate Phase ◽  
Redox Active

Role of Oxygen on Growth Mechanism and Composition Change of Ba-Ferrite Films

1985 ◽  
Vol 1 (1) ◽  
pp. 41-43 ◽  
Author(s):  
Y. Matsuda ◽  
M. Matsuoka ◽  
M. Naoe ◽  
Y. Hoshi
Keyword(s):  
Growth Mechanism ◽  
Composition Change ◽  
Ferrite Films

The role of alumina in the growth mechanism of Bi(Pb)SrCaCuO whiskers

1995 ◽  
Vol 251 (1-2) ◽  
pp. 149-155 ◽  
Author(s):  
Sergey Lee ◽  
Ki-Jeong Kwon ◽  
Wan-Seon Kim ◽  
Sung-Ik Lee
Keyword(s):  
Growth Mechanism

scholarly journals Evaluation of the Role of the Bvg Intermediate Phase in Bordetella pertussis during Experimental Respiratory Infection

2005 ◽  
Vol 73 (2) ◽  
pp. 748-760 ◽  
Author(s):  
Nuria Vergara-Irigaray ◽  
Alberto Chávarri-Martínez ◽  
Juan Rodríguez-Cuesta ◽  
Jeff F. Miller ◽  
Peggy A. Cotter ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Bordetella Pertussis ◽  
Wild Type Strain ◽  
Intermediate Phase ◽  
Transcriptional Level ◽  
Wild Type ◽  
Environmental Signals ◽  
Time Point

ABSTRACT The BvgAS system of Bordetella pertussis was traditionally considered to mediate a transition between two phenotypic phases (Bvg+ and Bvg−) in response to environmental signals. We characterized a third state, the intermediate (Bvgi) phase, which can be induced by introducing a 1-bp substitution into bvgS (the bvgS-I1 mutation) or by growing B. pertussis under conditions intermediate between those leading to the Bvg+ and Bvg− phases. Like B. bronchiseptica, B. pertussis displays in its Bvgi phase a characteristic colony morphology and hemolytic activity and expresses a Bvgi-phase-specific polypeptide called BipA, whose synthesis is regulated by bvgAS at the transcriptional level. Based on our results, we hypothesize that the Bvgi phase of B. pertussis may be involved in facilitating transmission between hosts. Thus, a B. pertussis mutant carrying the bvgS-I1 mutation (GMT1i) persisted at wild-type levels only in the upper murine respiratory tract. Interestingly, a bipA deletion derivative of GMT1i displayed a reduced ability to colonize the nasal cavity of mice compared with GMT1i. However, in experimental mixed infections GMT1i expressing the Bvgi phase could establish an initial colonization in the nose and trachea of mice as efficiently as GMT1, but the wild-type strain outcompeted GMT1i at a later time point at all sites of the respiratory tract, suggesting that the Bvgi phase does not serve as a phenotypic phase specialized in colonization. Finally, even though B. pertussis expresses in vitro the Bvgi phase at the human nasal temperature, anti-BipA antibodies were undetectable in a large collection of sera from pertussis patients.

Synthysis of S Doped Y-Junction Carbon Nanotubes by CVD Method

2011 ◽  
Vol 183-185 ◽  
pp. 1731-1735 ◽  
Author(s):  
Xia Yuan ◽  
Xiao Juan Wu ◽  
Yu Liang An ◽  
Qing Yi Hou
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Carbon Disulfide ◽  
Growth Mechanism ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Processing Parameters ◽  
Structure And Morphology ◽  
Cvd Method

The sulfur-doped Y-junction carbon nanotubes (S-YCNTs) were prepared by chemical vapor deposition of carbon disulfide using Fe as catalyst. Sulfur can be incorporated into the nanotubes with an identifiable amount, forming sulfur-doped carbon nanotubes. The growth of asymmetrical Y-branches in the nanotubes may be related to the presence of sulfur from precursor. The structure and morphology of S-YCNTs can be controlled by processing parameters. The S-YCNTs were characterized by SEM, TEM, EDX, and XPS, respectively. The growth mechanism of S-YCNTs was discussed in terms of the role of sulfur from carbon feedstock.

The role of ion energy on the growth mechanism of cubic boron nitride films

2004 ◽  
Vol 447-448 ◽  
pp. 125-130 ◽  
Author(s):  
S. Eyhusen ◽  
H. Hofsäss ◽  
C. Ronning
Keyword(s):  
Boron Nitride ◽  
Growth Mechanism ◽  
Cubic Boron Nitride ◽  
Ion Energy ◽  
Boron Nitride Films
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