Some aspects of the growth of quartz crystals

Swinnerton, A. C.; Owen, G. E.; Corwin, James F.

doi:10.1039/df9490500172

Cited by 8 publications

(5 citation statements)

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“…temperature gradient between the bottom and top resulting from heating the bomb in a furnace at 380°to 400°C. Similar processes for growing quartz have been reported by other workers (78,79).…”

Section: Industrial Applicationssupporting

confidence: 89%

Crystallization.

Grove¹,

Gray²

1951

Ind. Eng. Chem.

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Few advances in theoretical correlation of crystallization phenomena have been reportedduring the past year. Emphasis has been placed on the effects of additions, as chemical ions, or physical treatments on both rate of crystallization and crystal habit. Much work has been reported on oriented growth of crystals on other crystalline or amorphous surfaces. A new field of application of crystallization has been opened up b y the use of crystalline complexes of urea and straight-chain hydrocarbons to separate straight-chain from branched and cyclic hydrocarbons. Processes for growing piezoelectric crystals have been improved. When ethylene glycol and ethyl alcohol are added to aqueous solutions of sodium sulfate, the deposition of solids on heating surfaces due to a lower solubility in water at higher temperature is avoided. theory and practice. It is stated that new nuclei may originate in situ in one or more of the following ways:1. By spontaneous n u c l e a t i o n from unseeded solution 2. By attrition of existing crystals 3. By mechanical impact 4. By formation of new crystals because of the inoculating influence of crystals already present 5. BY nucleation in restricting RYSTALLIZATION processes have continued to receive increased study and development. There have been c many investigations reported on the factors affecting the growth of crystals and the mechanisms involved in this growth. New techniques and improvements in industrial processes have been described. However, a satisfactory broad theoretical treatment of crystallization has not been reported. NUCLEATION AND RATE OF G R O W T HThe difficulty in formulating a complete theory describing the rates of formation of nuclei and growth of crystals is well expressed by Kirk and Othmer (47), who state:The mechanism of this process is very complex, as it involves the phenomena of diffusion, formation of nuclei, and crystal growth, all of which can take place a t the same time. No exact numerical calculations of the rates of any of these can be made at the present time so that, as a unit operation, crystallization is still highly empirfical in its methods. Because of this lack of any precise design calculations, the types of crystallizers have been numerous. To add to the designer's difficulty, it is frequently necessary t o produce crystals of a given shape, size, uniformity, and state of agglomeration as well as purity.However, the current status of crystallization theory and practice is summarized in some detail by these authors.Brown (IO) has pointed out that the problems concerning crystallization which are most frequently encountered deal with yields, purity, energy requirements, shape, size, and uniformity of the crystalline product, and rate of production of the desired crystals. Perry (61) has summarized in detail crystallization zones caked by local variations in th; concentration of the solution Umstatter and Hansen-Dannenitz (86) discuss the kinetics of precrystalline phases in liquids. They state that the inner friction of liquids is caused by ...

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Section: Industrial Applicationssupporting

confidence: 89%

Crystallization.

Grove¹,

Gray²

1951

Ind. Eng. Chem.

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“…3 In restricting themselves in this way they seem to have ignored the rather large body of quantitative data on the phase behavior of this two component system'-7 which in our opinion are quite conclusive in establishing the coexistence region for the two phases. 3 In restricting themselves in this way they seem to have ignored the rather large body of quantitative data on the phase behavior of this two component system'-7 which in our opinion are quite conclusive in establishing the coexistence region for the two phases.…”

Section: The Microwave Spectrum and Molecularmentioning

confidence: 98%

Concerning the Coexistant Phases in the System NaCl–H2O above 374°C

Fogo

Benson

Copeland

1954

The Journal of Chemical Physics

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“…) This suggests that the silica molecule is either present as such or as some hydrate that could be termed a silicic acid. Kennedy mentioned, as did Swinnerton et al (1949) that the molecule Si(OH)4 may be present in the gas phase and that this molecule might be expected to have properties analogous to SiF4 because of similar molecular weight, etc. (See Mosebach, 1955;Her, 1955.…”

Section: Systems Showing a Critical End Pointmentioning

confidence: 99%

Metamorphic Reactions and Metamorphic Facies

Fyfe¹,

Turner²,

Verhoogen³

1958

Geological Society of America Memoirs

230

111

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This book presents a detailed discussion of a few selected topics in metamorphism. Chapter I (Turner) is a historical account of the development of the facies concept. A new definition of metamorphic facies is formulated.Chapters II to IV (Fyfe and Verhoogen), each of which ends with a summary in nontechnical language, deal respectively with certain thermodynamic and kinetic aspects of metamorphic-reactions. In Chapter II, the authors consider successively the magnitude of the free energy of metamorphic reactions, methods for computing approximate values of the entropies of silicates, a definition of the pressure variables in metamorphism, the role of surface films, and structural aspects of metamorphic mineralogy. The conclusion of Chapter III, which is devoted to a study of kinetics, is that reaction rates in systems containing water are generally such as not to lead to difficulties or inconsistencies in the interpretation of metamorphic facies. The role of water in metamorphic reactions is stressed again. This leads to a closer study of systems containing water, which are discussed in Chapter IV. Some properties of water are evaluated, such as its dielectric constant and ionic product, at high pressures and temperatures. A model is set up by which thermodynamic functions for hydration-dehydration reactions can be evaluated. There follows a discussion of solubility in aqueous systems and of variations of pH under natural conditions. _ In Chapter V, Fyfe and Turner correlate field and experimental data on the stability of critical mineral assemblages in metamorphic rocks. They conclude that there are at present no major inconsistencies between field and experimental data. Metamorphic facies, defined by mineralogical and field criteria, can still be interpreted in terms of a few intensive physical variables.The role of water and heat in metamorphism is considered in Chapter VI (Fyfe and Verhoogen). Regional metamorphism is not a normal phenomenon, in the sense that it would occur wherever rocks are buried to sufficient depth. On the contrary, it appears that regional metamorphism can occur only where the heat flow is notably increased and where water, probably of juvenile origin, is abundant.Chapter VII (Turner) is a revision of individual metamorphic facies. In the light of new experimental and mineralogical data the limits of some facies and subfacies are redefined, and a few new divisions are proposed.

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Some aspects of the growth of quartz crystals

Cited by 8 publications

References 0 publications

Crystallization.

Crystallization.

Concerning the Coexistant Phases in the System NaCl–H2O above 374°C

Metamorphic Reactions and Metamorphic Facies

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