What Do You Mean by Amorphous Form

Amorphous phases are important components of thin films, which are solid layers ranging from a few nanometers to tens of micrometers thick that settle on a substrate. So-called structural zone models have been developed to describe the microstructure and ceramics of thin films as a function of the homologous temperature Th, i.e. the ratio between the deposition temperature and the melting temperature. [6] [7] According to these models, a necessary (but not sufficient) condition for the appearance of amorphous phases is that Th must be less than 0.3, i.e. the deposition temperature must be less than 30% of the melting temperature. For higher values, surface diffusion of deposited atomic species would allow the formation of crystallites of large atomic order. Not in taxpayers` money, not in national resources, not even in the amorphous concept of a body count. The chemical and physical stability of amorphous pharmaceutical materials is controlled by the same fundamental factors as for crystalline materials (molecular structure, purity, molecular orientation and molecular mobility). For each sample of a given molecular structure and purity, there are more possible molecular orientations that occur in an amorphous sample than in a crystalline sample.

Thus, many other types of chemical and physical transformations could potentially take place. At a given temperature, molecular mobility in an amorphous material is also significantly higher than in any of the corresponding crystalline forms, which can result in greater chemical and physical reactivity in the amorphous sample. The material (which often contains silica) is slightly cooled from its liquid state when a glass is made, but does not solidify when its temperature drops below its melting point. The material is then cooled below the glass transition temperature to become an amorphous solid. Nevertheless, from a comparison of the properties of materials in the crystalline and amorphous state, the essential characteristics of the electronic structure and therefore also the macroscopic properties are determined in close order. Thus, these properties are similar for solids in the amorphous and crystalline state. But the character`s amorphous mix of character and motivation somehow turns into a plot. Amorphous solids have two determining properties. They create particles of strange surfaces, often twisted, when cracked or broken; And they have poorly described patterns when exposed to X-rays because their components are not organized in a typical order. A transparent and amorphous material is called wine. Some examples of amorphous solids are glass, rubber, pitch, many plastics, etc. Quartz is an example of a crystalline solid that has a regular order of arrangement of SiO4 tetrahedra.

When the quartz is melted and the melting cools fast enough to avoid crystallization, an amorphous solid called glass is obtained. “We`ve been here hours ago,” says a man with a footrest who has abandoned his place in the amorphous line to sit on a folding chair. The definition of amorphous should be easy to understand, accessible and provable for the purposes of infringement. Amorphous solids are similar to liquids in that they have no ordered structure, no ordered arrangement of atoms or ions in a three-dimensional structure. These solids do not have an acute melting point and conversion of solid to liquid occurs over a temperature range. The physical properties of amorphous solids are generally isotropic because they do not depend on the direction of measurement and are of the same size in different directions. In the pharmaceutical industry, amorphous drugs have been shown to have higher bioavailability than their crystalline counterparts due to the high solubility of the amorphous phase. In addition, some compounds can be precipitated in their amorphous form in vivo, and they can reduce the bioavailability of others when administered together.

[4] [5] As found natively, it is called corundum when it crystallizes ruby or sapphire when it is amorphous. An amorphous flexible silicon carbide, also formed in an electric furnace, was patented by B. Talbot in 1899. Data from one TSC study have been interpreted as indicating the existence of two amorphous regions (true and “rigid”) in a drug sample (28). If crystallization is avoided, many liquids of pharmaceutical importance vitrify at glass temperature Tg, about 2/3 to 4/5 of the crystalline melting point Tm. Tg is therefore a useful material descriptor because of its correlation with structural and thermodynamic properties. If a more stable crystalline state is present, an amorphous material can crystallize with sufficient molecular mobility. Important pharmaceutical examples are crystallization by freeze-drying and spray drying, from supercooled fusions and amorphous materials during storage, especially under the influence of heat and moisture.

In this context, factors influencing the rate of crystallization (temperature and plasticizers), the means of promoting or preventing crystallization, and the properties of crystals produced under conditions unfavorable to the growth of “high quality” crystals (the highly concentrated and highly viscous media that occur during freezing or spray drying) are of interest. For thermodynamic and kinetic reasons, the production of amorphous solids is easy for some materials (good glass-forming agents) but difficult for others (bad glass-forming agents). Thermodynamically, the ability to form glass comes from a crystalline state that is not significantly more stable than the amorphous state, which can be the case with molecules that weave poorly or contain many internal degrees of freedom. Kinetically, a slow crystallization rate allows a material to become a “frozen liquid” or to vitrify without crystallization. In many cases (free radical-initiated oxidation reactions), the stability of a compound is not significantly influenced either by its molecular mobility or by the orientation of the molecules; Thus, the amorphous form has a stability comparable to that of the crystalline material. In some cases (insulin), the more ordered structure of the crystalline material may actually increase the likelihood of certain intermolecular contacts and reduce the stability of the crystalline form. Amorphous metal layers played an important role in the discovery of superconductivity in amorphous metals by Buckel and Hilsch. [8] [9] The superconductivity of amorphous metals, including amorphous metallic thin films, is now understood to be due to phonon-mediated Cooper pairing, and the role of structural disorder can be rationalized based on the strongly coupled theory of Eliashberg superconductivity. [10] Optical coatings of TiO2, SiO2, Ta2O5, etc. and their combinations today consist mainly of amorphous phases of these compounds. A lot of research is underway on thin amorphous films as a membrane layer separating gases. [11] The most technologically important amorphous thin film is probably represented by a few thin layers of SiO2 nm, which serve as insulators on the conductive channel of a metal oxide semiconductor field-effect transistor (MOSFET).