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Polyamorphism is also an important area in pharmaceutical science. The amorphous form of a drug typically has much better aqueous solubility (compared to the analogous crystalline form) but the actual local structure in an amorphous pharmaceutical can be different, depending on the method used to form the amorphous phase.
Amorphous phases are important constituents of thin films. Thin films are solid layers of a few nanometres to tens of micrometres thickness that are deposited onto a substrate. So-called structure zone models were developed to describe the microstructure of thin films as a function of the homologous temperature ( T h ), which is the ratio of ...
Amorphous solids are the opposite of crystalline. The atoms or molecules in amorphous substances are arranged randomly without any long-range order. As a result, they do not have a sharp melting point. The phase transition from solid to liquid occurs over a range of temperatures. [citation needed] Some examples include glass, rubber and some ...
One of the studies involving mineralized tissues in dentistry is on the mineral phase of dentin in order to understand its alteration with aging. These alterations lead to “transparent” dentin, which is also called sclerotic. It was shown that a ‘‘dissolution and reprecipitation’’ mechanism reigns the formation of transparent dentin ...
The reaction of acid with carbonates, most commonly found as the polymorph calcite and aragonite (CaCO 3), relates to the dissolution and precipitation of the mineral, which is a key in the formation of limestone caves, features within them such as stalactite and stalagmites, and karst landforms. Carbonates are most often formed as biogenic or ...
Mica-based clays result from a modification of the primary mica mineral in such a way that it behaves and is classed as a clay. [15] Most clays are crystalline, but some clays or some parts of clay minerals are amorphous. [16] The clays of a soil are a mixture of the various types of clay, but one type predominates. [17]
Solid-phase epitaxy (SPE) is a transition between the amorphous and crystalline phases of a material. It is usually produced by depositing a film of amorphous material on a crystalline substrate, then heating it to crystallize the film. The single-crystal substrate serves as a template for crystal growth.
Phase transitions (phase changes) that help describe polymorphism include polymorphic transitions as well as melting and vaporization transitions. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure."