scholarly journals Free energy of formation of a crystal nucleus in incongruent solidification: Implication for modeling the crystallization of aqueous nitric acid droplets in polar stratospheric clouds

2017 ◽  
Vol 146 (13) ◽  
pp. 134709 ◽  
Author(s):  
Yuri S. Djikaev ◽  
Eli Ruckenstein
Keyword(s):  
Free Energy ◽  
Nitric Acid ◽  
Polar Stratospheric Clouds ◽  
Crystal Nucleus ◽  
Free Energy Of Formation ◽  
Stratospheric Clouds ◽  
Aqueous Nitric Acid ◽  
Energy Of Formation

Standard Gibbs free energy of formation of ZrOS

1990 ◽  
Vol 163 (1) ◽  
pp. 109-113 ◽  
Author(s):  
Zhi-Tong Sui ◽  
Xing-Yi Xiao ◽  
Ke-Qin Huang ◽  
Chang-Zhen Wang
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Standard Gibbs Free Energy ◽  
Free Energy Of Formation ◽  
Energy Of Formation

Thermodynamical study of (CaGa2S4)x(BaGa2S4)1−x solid solutions

2021 ◽  
pp. 2150469
Author(s):  
T. G. Naghiyev ◽  
R. M. Rzayev
Keyword(s):  
Free Energy ◽  
Solid Solutions ◽  
Calculation Method ◽  
Solid Phase ◽  
Ternary Compounds ◽  
Free Energy Of Formation ◽  
Concentration Dependences ◽  
Solid Phase Reactions ◽  
Two Phases ◽  
Energy Of Formation

The solid solutions of [Formula: see text] were synthesized by solid-phase reactions from powder components of CaS, BaS, and Ga2S3. The temperature-concentration dependences of the Gibbs free energy of formation of [Formula: see text] solid solutions from ternary compounds and phase diagrams of the CaGa2S4–BaGa2S4 were determined by a calculation method. It was revealed that continuous solid solutions are formed in these systems. The spinodal decomposition of [Formula: see text] solid solutions into two phases is predicted at ordinary temperatures.

scholarly journals Nucleation of nitric acid hydrates in Polar Stratospheric Clouds by meteoric material

2017 ◽  
Author(s):  
Alexander D. James ◽  
James S. A. Brooke ◽  
Thomas P. Mangan ◽  
Thomas F. Whale ◽  
John M. C. Plane ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Heterogeneous Nucleation ◽  
Ozone Depletion ◽  
Mode Of Action ◽  
Polar Stratospheric Clouds ◽  
Water Ice ◽  
Meteoric Smoke ◽  
Polar Stratosphere ◽  
Stratospheric Clouds ◽  
Meteoric Material

Abstract. Heterogeneous nucleation of crystalline nitric acid hydrates in Polar Stratospheric Clouds (PSCs) enhances ozone depletion. However, the identity and mode of action of the particles responsible for nucleation remains unknown. It has been suggested that meteoric material may trigger nucleation of nitric acid trihydrate (NAT), but this has never been directly demonstrated in the laboratory. Meteoric material is present in two forms in the stratosphere, smoke which results from the ablation and re-condensation of vapours, and fragments which result from the disruption of meteoroids entering the atmosphere. Here we show that analogues of both materials have a capacity to nucleate nitric acid hydrates. In combination with estimates from a global model of the amount of meteoric smoke and fragments in the polar stratosphere we show that meteoric material probably accounts for NAT observations in early season polar stratospheric clouds in the absence of water ice.

scholarly journals A closer look at Arctic ozone loss and polar stratospheric clouds

2010 ◽  
Vol 10 (17) ◽  
pp. 8499-8510 ◽  
Author(s):  
N. R. P. Harris ◽  
R. Lehmann ◽  
M. Rex ◽  
P. von der Gathen
Keyword(s):  
Nitric Acid ◽  
Climate Models ◽  
Empirical Relationship ◽  
Early Spring ◽  
Aerosol Formation ◽  
Polar Stratospheric Clouds ◽  
Ozone Loss ◽  
Relationship Analysis ◽  
Near Ultraviolet ◽  
Stratospheric Clouds

Abstract. The empirical relationship found between column-integrated Arctic ozone loss and the potential volume of polar stratospheric clouds inferred from meteorological analyses is recalculated in a self-consistent manner using the ERA Interim reanalyses. The relationship is found to hold at different altitudes as well as in the column. The use of a PSC formation threshold based on temperature dependent cold aerosol formation makes little difference to the original, empirical relationship. Analysis of the photochemistry leading to the ozone loss shows that activation is limited by the photolysis of nitric acid. This step produces nitrogen dioxide which is converted to chlorine nitrate which in turn reacts with hydrogen chloride on any polar stratospheric clouds to form active chlorine. The rate-limiting step is the photolysis of nitric acid: this occurs at the same rate every year and so the interannual variation in the ozone loss is caused by the extent and persistence of the polar stratospheric clouds. In early spring the ozone loss rate increases as the solar insolation increases the photolysis of the chlorine monoxide dimer in the near ultraviolet. However the length of the ozone loss period is determined by the photolysis of nitric acid which also occurs in the near ultraviolet. As a result of these compensating effects, the amount of the ozone loss is principally limited by the extent of original activation rather than its timing. In addition a number of factors, including the vertical changes in pressure and total inorganic chlorine as well as denitrification and renitrification, offset each other. As a result the extent of original activation is the most important factor influencing ozone loss. These results indicate that relatively simple parameterisations of Arctic ozone loss could be developed for use in coupled chemistry climate models.

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