scholarly journals Formation of nanocrystalline manganese oxide in flames: oxide phase governed by classical nucleation and size-dependent equilibria

CrystEngComm ◽  
2020 ◽  
Vol 22 (33) ◽  
pp. 5509-5521
Author(s):  
Shruthi Dasappa ◽  
Joaquin Camacho
Keyword(s):  
Manganese Oxide ◽  
Oxide Phase ◽  
Nucleation And Growth ◽  
Oxide Nanoparticles ◽  
Particle Nucleation ◽  
Manganese Oxide Nanoparticles ◽  
Size Dependent ◽  
Modelling Study

Particle nucleation and growth of crystalline manganese oxide nanoparticles was examined in a complementary experimental and modelling study.

scholarly journals Formation of nanocrystalline manganese oxide in flames: oxide phase governed by classical nucleation and size-dependent equilibria

2020 ◽  
Author(s):  
Joaquin Camacho ◽  
Shruthi Dasappa
Keyword(s):  
Manganese Oxide ◽  
Particle Temperature ◽  
Time History ◽  
Chemical Vapor ◽  
Oxide Phase ◽  
Oxide Nanoparticles ◽  
Particle Nucleation ◽  
Manganese Oxide Nanoparticles ◽  
One Dimensional ◽  
Size Dependent

Particle nucleation and growth of crystalline manganese oxide nanoparticles was examined in a complementary experimental and modelling study. Gas-to-particle conversion occured in a flame-assisted chemical vapor deposition process whereby a premixed stagnation flame drove the high-temperature synthesis. The structure of the stagnation flame was computed using pseudo one-dimensional and axisymmetric two-dimensional methods to assess the accuracy of using a faster similarity-based calculation for flame-deposition design. The pseudo one-dimensional computation performs reasonably well for the narrow aspect ratio stagnation flow currently studied as evidenced by reasonable agreement between the measured flame position and both computational methods. Manganese oxide nanoparticles having II, II-III, III or IV oxidation states were observed depending on the flame conditions. These observations may be explained by size-dependent equlibria between nano-scale manganese oxide and surrounding gas-phase oxygen. Local equibrium was assessed during the particle temperature-oxygen-time history to gain insight into oxide formation in the flame. Analysis of the saturation ratio for formation of condensed MnO in the flame indicates that nucleation may be limited by a thermodynamic barrier. This nucleation mechanism is supported by measured particle sizes smaller than what would be expected from a coagulation limited growth process. Nanocrystalline MnO, reported here for the first time by flame synthesis, was obtained in oxygen lean flames. MnO2 is the phase predicted to be thermally stable as the particles approach the deposition surface, yet other metastable oxide phases were produced in many of the flames examined. In fact, MnO2 was only observed in the smallest particle size conditions which may indicate that high cooling rates limit phase equilibrium to less massive particles.

scholarly journals Synthesis of Manganese Oxide Nanoparticles in Premixed Flames

2020 ◽  
Author(s):  
Shruthi Dasappa ◽  
Joaquin Camacho
Keyword(s):  
Manganese Oxide ◽  
Oxidation State ◽  
Flame Structure ◽  
Flame Synthesis ◽  
Oxide Nanoparticles ◽  
Particle Nucleation ◽  
Manganese Oxidation ◽  
Oxide Systems ◽  
Manganese Oxide Nanoparticles ◽  
One Dimensional

See also: CrystEngComm (2020) 22, 5509-5521"Formation of nanocrystalline manganese oxide in flames: oxide phase governed by classical nucleation and size-dependent equilibria" by Shruthi Dasappa and Joaquin CamachoSynthesis of manganese oxide nanoparticles was carried out in premixed stagnation flames. The deposition surface was stationary to enable rigorous comparison to flame structure computations using pseudo one-dimensional and full two-dimensional calculations. The pseudo one-dimensional assumption taken by OPPDIF to calculate the flame structure performs reasonably well for the narrow aspect ratio stagnation flow currently studied. Agreement between the measured flame position and both computational methods was within 0.25 cm. The variation in manganese oxidation state in the products observed here is shown to be caused by competing oxidation and particle nucleation processes. Complimentary experimental and modeling studies of flame synthesis were carried out under well-defined boundary conditions to examine this competition. Manganese oxide products having II, II,III, III and IV valence were observed depending on the flame conditions. Unlike iron oxide and titanium oxide systems, complete oxidation to MnO2 is only observed for the most oxidizing growth conditions. The first observation of phase pure MnO by flame synthesis is reported here. Manipulation of the balance between manganese oxidation and particle nucleation through control of the time-temperature-oxygen history may enable selective synthesis of manganese oxide nanoparticles with tailored morphology and oxidation state.

Size-Dependent Toxicity Differences of Intratracheally Instilled Manganese Oxide Nanoparticles: Conclusions of a Subacute Animal Experiment

2015 ◽  
Vol 171 (1) ◽  
pp. 156-166 ◽  
Author(s):  
Zsuzsanna Máté ◽  
Edina Horváth ◽  
Gábor Kozma ◽  
Tímea Simon ◽  
Zoltán Kónya ◽  
...  
Keyword(s):  
Manganese Oxide ◽  
Animal Experiment ◽  
Oxide Nanoparticles ◽  
Manganese Oxide Nanoparticles ◽  
Size Dependent

MnO2 nanoflowers as a multifunctional nano-platform for enhanced photothermal/photodynamic therapy and MR imaging

2021 ◽  
Author(s):  
Wanru Sun ◽  
Hui Yu ◽  
Deqiang Wang ◽  
Youjie Li ◽  
Baocheng Tian ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Mr Imaging ◽  
Manganese Oxide ◽  
Oxide Nanoparticles ◽  
Manganese Oxide Nanoparticles

Well-defined flower-shaped manganese oxide nanoparticles modified with 3-aminopropyltriethoxysilane (APTES) and loaded with Ce6 were achieved to realize synergistic PDT/PTT therapy and MR imaging.

Silica–F127 nanohybrid-encapsulated manganese oxide nanoparticles for optimized T1magnetic resonance relaxivity

Nanoscale ◽  
2014 ◽  
Vol 6 (1) ◽  
pp. 293-299 ◽  
Author(s):  
Benedict You Wei Hsu ◽  
Miao Wang ◽  
Yu Zhang ◽  
Vimalan Vijayaragavan ◽  
Siew Yee Wong ◽  
...  
Keyword(s):  
Manganese Oxide ◽  
Oxide Nanoparticles ◽  
Manganese Oxide Nanoparticles

scholarly journals Green synthesis of manganese oxide nanoparticles for the electrochemical sensing of p-nitrophenol

2017 ◽  
Vol 7 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Vineet Kumar ◽  
Kulvinder Singh ◽  
Shaily Panwar ◽  
Surinder Kumar Mehta
Keyword(s):  
Green Synthesis ◽  
Manganese Oxide ◽  
Electrochemical Sensing ◽  
Oxide Nanoparticles ◽  
Manganese Oxide Nanoparticles

Ceria associated manganese oxide nanoparticles: Synthesis, characterization and arsenic(V) sorption behavior

2011 ◽  
Vol 172 (1) ◽  
pp. 219-229 ◽  
Author(s):  
Kaushik Gupta ◽  
Sayan Bhattacharya ◽  
Dhrubajyoti Chattopadhyay ◽  
Aniruddha Mukhopadhyay ◽  
Harishankar Biswas ◽  
...  
Keyword(s):  
Manganese Oxide ◽  
Oxide Nanoparticles ◽  
Sorption Behavior ◽  
Manganese Oxide Nanoparticles ◽  
Nanoparticles Synthesis
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