Thermodynamics of metastable phase nucleation at the nanoscale

Progress in Ultrasonic Spray Pyrolysis for Condensed Matter Sciences Developed From Ultrasonic Nebulization Theories Since Michael Faraday

“…A number of previous review articles have been presented on different forms of CVD: thermal CVD [2][3][4][5][6][7][8][9][10][11], plasma enhanced PE-CVD [12][13][14][15][16][17][18][19], hot-wire or hot filament (HWCVD or HFCVD) [20][21][22][23][24][25][26][27][28] and not many of them have been as exhaustive in their respective areas. Pyrolysis, although classified under CVD in some text, has become a wide area of research and technology covering synthesis of new products, qualitative and quantitative spectroscopic analysis of fluids and, lately, alternative route to production of debri-free x-ray sources; these aspects are elaborated further in the sections that follow.…”

Gibbs Free Energy of Formation for Selected Platinum Group Minerals (PGM)

“…Using the equations of the HSC program, the calculated ∆ f G˝values in standard conditions (Table 1) were extrapolated to a wide range of temperature, up to 1300˝C (Table 4), and the variation of the free energy versus temperature is plotted (Figures 2-4). Since ∆H and ∆S are essentially constant with temperature unless a phase change occurs, the free energy versus temperature plot can be drawn as a series of straight lines, where ∆S is the slope and ∆H is the y-intercept [39,40]. Furthermore, since the ∆S values are always negative for these reactions, the ∆H-T∆S becomes larger with temperature, and the lines slope upwards (formation reactions are exothermic).…”

“…Since ∆H and ∆S are essentially constant with temperature unless a phase change occurs, the free energy versus temperature plot can be drawn as a series of straight lines, where ∆S is the slope and ∆H is the y-intercept [39,40]. Furthermore, since the ΔS values are always negative for these reactions, the ΔH-TΔS becomes larger with temperature, and the lines slope upwards (formation reactions are exothermic).…”

Oxidation Resistance of Nanocrystalline Alloys

“…The unique structure and high grain boundary fraction, enhances diffusion of impurities and alloying elements, and changes materials thermodynamic properties [31][32][33] which are expected to cause a considerable difference in the resistance of nanocrystalline materials to environmental degradation (oxidation) at high temperatures. For practical application of these nanocrystalline materials, an acceptable level of resistance to environmental degradation is required.…”