Effect of carbon on the growth of TaC crystal derived from organometallic precursors

2020 ◽  
Vol 58 (1) ◽  
pp. 62-68
Author(s):  
Yoonjoo Lee ◽  
Philjae Kang ◽  
Sooyong Jung ◽  
Seonggun Bae ◽  
Joungil Kim ◽  
...  
Keyword(s):  
Organometallic Precursors

TEM visualization of surface replicated acid and base catalyzed sol-gel glasses

1986 ◽  
Vol 44 ◽  
pp. 448-449
Author(s):  
George C. Ruben ◽  
Merrill W. Shafer
Keyword(s):  
Elevated Temperatures ◽  
Sol Gel ◽  
Basic Medium ◽  
Glass Transition Point ◽  
Structural Space ◽  
Acid And Base ◽  
Organometallic Precursors ◽  
New Processing ◽  
Gel Glasses ◽  
Physical Phenomena

Traditionally ceramics have been shaped from powders and densified at temperatures close to their liquid point. New processing methods using various types of sols, gels, and organometallic precursors at low temperature which enable densificatlon at elevated temperatures well below their liquidus, hold the promise of producing ceramics and glasses of controlled and reproducible properties that are highly reliable for electronic, structural, space or medical applications. Ultrastructure processing of silicon alkoxides in acid medium and mixtures of Ludox HS-40 (120Å spheres from DuPont) and Kasil (38% K2O &62% SiO2) in basic medium have been aimed at producing materials with a range of well defined pore sizes (∼20-400Å) to study physical phenomena and materials behavior in well characterized confined geometries. We have studied Pt/C surface replicas of some of these porous sol-gels prepared at temperatures below their glass transition point.

Friction and Wear Behavior of Silicon Carbonitride Processed From the Polymer-Derived Ceramic Route

2005 ◽  
Author(s):  
Tsali Cross ◽  
Somuri Prasad ◽  
Rishi Raj
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Friction And Wear ◽  
Wear Behavior ◽  
Silicon Carbonitride ◽  
Linear Wear ◽  
Polymer Derived Ceramic ◽  
Organometallic Precursors ◽  
Future Work ◽  
Contact Pressures

Polymer derived ceramics (PDC’s) are processed from liquid organometallic precursors by cross-linking the polymers into infusible solids, followed by controlled pyrolysis. No previous work regarding their tribology has been reported. Further, the synthesis of PDC’s as thin films, and the role that the nanostructure plays on the mechanical properties has not been reported. The objective of this research was to evaluate the fundamental tribological behavior of polymer derived SiCN in both bulk and thin film form. Friction and wear evaluations were made on bulk materials and thin films using a Si3N4 ballon-disk linear wear tester at various contact pressures and in different environments that contained various amounts of humidity. The micro/nanostructure was characterized by FTIR, microRaman, and scanning electron microscopy. Bulk SiCN gave a low friction coefficient and good wear resistance in humid environments but showed significant fracture and gouging in dry environments at higher contact pressures. Although there is ambiguity regarding the tribology of the thin films there seems to be a dependence upon the nitrogen content within the materials derived from the polymeric stage. The future work will focus on optimizing processing conditions of thin films and investigating the role that nitrogen plays in both bulk and thin film SiCN materials.

Organometallic precursors of nano-objects, a critical view

2013 ◽  
Vol 42 (35) ◽  
pp. 12546 ◽  
Author(s):  
Benoit Cormary ◽  
Frédéric Dumestre ◽  
Nikolaos Liakakos ◽  
Katerina Soulantica ◽  
Bruno Chaudret
Keyword(s):  
Critical View ◽  
Organometallic Precursors

Optic and Piezoelectric Coupling in the Sol-Gel PLZT Electroceramics

2012 ◽  
Vol 730-732 ◽  
pp. 129-134
Author(s):  
Lucjan Kozielski ◽  
Malgorzata Plonska
Keyword(s):  
Uv Light ◽  
Sol Gel ◽  
Light Illumination ◽  
Piezoelectric Effects ◽  
Piezoelectric Coupling ◽  
Wireless Device ◽  
Organometallic Precursors ◽  
Gain Adjustment ◽  
Piezoelectric Transformers ◽  
Sintering Method

PZT ceramic system with presence of La contents, have been proposed and prepared using sol gel sintering method for practical application of photostriction, which is the superposition of photovoltaic and piezoelectric effects. Such a ceramics produced by conventional mixing oxide method does not exhibit photostrictive properties due to the defects and inhomogeneous distribution of grains and pores. In this study, an investigated lanthanium(III) doped PZT ceramics were obtained by sol-gel technique from the organometallic precursors. It was found that fabricated material were effective in the enhancement of photovoltaic and photostrictive properties. Consequently, lanthanium influence deviation of piezoelectric parameters were studied as a function UV light illumination. For the determination lighting dependancy of the transformation parameters the resonant and antiresonant method was implemented. The improved Piezoelectric Transformer structure successfully changed gain characteristics proportionally to light intensity. The authors invention of a light driven output gain adjustment in Piezoelectric Transformers (PT) yields a novel “smart” multifunctional wireless device. This new created application area can be utilized in self-adopting shutters in photo cameras due to improved sensitivity to surrounding illumination conditions.

scholarly journals MOCVD deposition of zinc and bismuth chalcogenides films on the surface of silica optical fibres

2020 ◽  
Vol 59 (4) ◽  
Author(s):  
Peter Kuznetsov ◽  
Galina Yakushcheva ◽  
Evgeny Savelyev ◽  
Vasiliy Yapaskurt ◽  
Vasiliy Shcherbakov ◽  
...  
Keyword(s):  
Chemical Vapour ◽  
Organic Chemical ◽  
Optical Fibres ◽  
Transmittance Spectra ◽  
Bismuth Chalcogenides ◽  
Generation Mode ◽  
Metal Organic ◽  
Organometallic Precursors ◽  
Fibre Ring ◽  
Short Time

Metal organic chemical vapour deposition (MOCVD) technology is adapted for the deposition of thin zinc and bismuth chalcogenides films on the surface of silica optical fibres with short tapered sections. Growth runs were carried out in a special tubular quartz reactor at atmospheric pressure of hydrogen at 425°C temperature using ZnEt2, BiMe3, Et2Te and i-Pro2Se as organometallic precursors. During the deposition of chalcogenides, the transmittance spectra of the fibre were recorded in regular short time intervals. In the transmittance spectra of the fibre with a tapered section coated by ZnSe and ZnTe, lossy mode resonances (LMR) were observed at a diameter of the tapered waist below 30 μm. After the deposition of very thin Bi2Te3 and Bi2Se3 island films on the tapered waist with a diameter about 10 μm optical fibres were built into erbium fibre ring lasers. A pulsed generation mode was achieved in some of lasers due to resonator Q-factor modulation. These results can be applied for the design of LMR fibre sensors and passively Q-switch pulsed fibre lasers.

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