If a system consists of just one component(e.g.: water) ,equilibrium of phases exists depicted one component system . The component may exist in different forms, thus variables here are–temperature and pressure.
the number of degrees of
freedom F is given by
F = C – P + 1 (C=1) F = 2 – P
Silica phase diagram(Silica System)
Many minerals are known that have the chemical composition SiO2 . The silica minerals include quartz, tridymite, cristobalite, coesite, stishovite, and several others. The silica minerals are different minerals with different structures, different symmetry, different physical properties, etc., but all with the same composition (SiO2 ). Two minerals that have the same chemical composition, but a different crystal structure are called polymorphs.
1- 1- At room temperature , the stable form of silica is ?-quartz.
2- At 573°C, ?-quartz will change to ?-quartz.
3- Cooling ?-quartz , will change ?-quartz.
4- At 870°C , ?-quartz will change to ?-Tridymite.
5- At high temperature , ?-quartz will change to ?- Cristobalite or to liquid silica.
(Phase Diagram for silica system)
.
Stability realitions in silica system) )
Titania phase diagram(Titania System)
1- At low temperature the stable form of titania is Anatase modification exists in two forms ?, and ? Anatase which change reversibly at 642° C .
2- At 1000° C change reversibly to Rutile.
3- Rutile melt at 1870° C .
4- At 650° C Brookite change to Rutile.
Stability realitions in titania system)
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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