scholarly journals Thermodynamic Analysis of Isothermal Crystallization of Amorphous Si-C-N Ceramics Derived from Polymer Precursors

2006 ◽  
Vol 114 (1335) ◽  
pp. 950-957 ◽  
Author(s):  
Jerzy A. GOLCZEWSKI
Keyword(s):  
Thermodynamic Analysis ◽  
Isothermal Crystallization ◽  
Polymer Precursors ◽  
Amorphous Si

Initial nucleation of amorphous Si–B–C–N ceramics derived from polymer-precursors

2019 ◽  
Vol 35 (12) ◽  
pp. 2851-2858
Author(s):  
Ling-yan Li ◽  
Hui Gu ◽  
Vesna Šrot ◽  
Peter van Aken ◽  
Joachim Bill
Keyword(s):  
Polymer Precursors ◽  
Initial Nucleation ◽  
Amorphous Si

Nucleation And Growth Rates in Isothermal Crystallization Op Amorphous Si50Ge50 Films

1993 ◽  
Vol 321 ◽  
Author(s):  
J. H. Song ◽  
James S. Im
Keyword(s):  
Growth Rate ◽  
Nucleation Rate ◽  
Growth Rates ◽  
Isothermal Crystallization ◽  
Nucleation And Growth ◽  
Crystal Nucleation ◽  
Two Dimensional ◽  
Transmission Electron ◽  
Amorphous Si ◽  
Si Films

ABSTRACTIsothermal crystallization behavior of as-deposited thin amorphous Si50Ge50 films (∼1000Å-thick) at 580°C has been investigated using transmission electron Microscopy (TEM). The crystal counting method was employed in order to obtain directly the two-dimensional steady-state crystal nucleation rate of 3.9×103 #/cm2sec (equivalent volumetric nucleation rate of 3.4×108 #/cm3sec). The Modified two-dimensional Johnson-Mehl-Avrami analysis, in which the growth rate of the crystals was the only adjustable parameter, and in which the time-dependent nucleation rate and the size effect associated with the onset of the observation are considered, was developed in order to extract the crystal growth rate of 16.5 Å/sec. When compared to the crystallization of a-Si films, these nucleation and growth rates confirm the observation that it is possible to achieve significantly faster crystallization at lower temperatures while producing substantially better Microstructures (i.e., > 5 μ grain-sized poly-Si50Ge50 obtained within two hours at 580°C vs. 1–2Μm grain-sized poly-Si obtained in about > 10 hours at 600°C).

Development of Crystallinity in Turbostratic Boron Nitride Derived from Polymeric Precursors

1991 ◽  
Vol 49 ◽  
pp. 954-955
Author(s):  
X. Qiu ◽  
A. K. Datye ◽  
T. T. Borek ◽  
R. T. Paine
Keyword(s):  
Thermal Treatment ◽  
Boron Nitride ◽  
Diffraction Pattern ◽  
Polymeric Precursors ◽  
Polymer Precursors ◽  
Diffuse Ring

Boron nitride derived from polymer precursors is of great interest for applications such as fibers, coatings and novel forms such as aerogels. The BN is prepared by the polymerization of functionalized borazine and thermal treatment in nitrogen at 1200°C. The BN powders obtained by this route are invariably trubostratic wherein the sheets of hexagonal BN are randomly oriented to yield the so-called turbostratic modification. Fib 1a and 1b show images of BN powder with the corresponding diffraction pattern in fig. 1c. The (0002) reflection from BN is seen as a diffuse ring with occational spots that come from crystals of BN such as those shown in fig. 1b. The (0002) lattice fringes of BN seen in these powders are the most characteristic indication of the crystallinity of the BN.

Growth of near noble metal Pd and Pt thin film silicides morphology and structure

1984 ◽  
Vol 42 ◽  
pp. 498-499
Author(s):  
E. I. Alessandrini ◽  
M. O. Aboelfotoh
Keyword(s):  
Noble Metals ◽  
Annealing Temperature ◽  
Chemical Compounds ◽  
Barrier Properties ◽  
Solid State Reactions ◽  
Transmission Electron ◽  
Stable Chemical ◽  
Metal Thickness ◽  
Amorphous Si ◽  
Si Films

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.

High-angle electron scattering from amorphous silicon

1995 ◽  
Vol 53 ◽  
pp. 162-163
Author(s):  
M. Libera ◽  
J.A. Ott ◽  
K. Siangchaew ◽  
L. Tsung
Keyword(s):  
Electron Scattering ◽  
Amorphous Material ◽  
Structural Defects ◽  
Constant Thickness ◽  
High Angle ◽  
Fast Electrons ◽  
Angle Scattering ◽  
Stem Image ◽  
Amorphous Si ◽  
Thermal Vibrations

Channeling occurs when fast electrons follow atomic strings in a crystal where there is a minimum in the potential energy (1). Channeling has a strong effect on high-angle scattering. Deviations in atomic position along a channel due to structural defects or thermal vibrations increase the probability of scattering (2-5). Since there are no extended channels in an amorphous material the question arises: for a given material with constant thickness, will the high-angle scattering be higher from a crystal or a glass?Figure la shows a HAADF STEM image collected using a Philips CM20 FEG TEM/STEM with inner and outer collection angles of 35mrad and lOOmrad. The specimen (6) was a cross section of singlecrystal Si containing: amorphous Si (region A), defective Si containing many stacking faults (B), two coherent Ge layers (CI; C2), and a contamination layer (D). CBED patterns (fig. lb), PEELS spectra, and HAADF signals (fig. lc) were collected at 106K and 300K along the indicated line.

Thermodynamic analysis of binding of p-substituted benzamidines to trypsin

2001 ◽  
Vol 268 (6) ◽  
pp. 1554-1560 ◽  
Author(s):  
Reinskje Talhout ◽  
Jan B. F. N. Engberts
Keyword(s):  
Thermodynamic Analysis
Sign in / Sign up

Export Citation Format

Share Document