Liquid-crystalline solid glass

In the case of two-ion systems, the coupled species is placed into the grouping that corresponds to that ion which has been sensitized. That is, in a system in which energy pumped into, say, gadolinium is fluoresced by, say, terbium, the system is placed into the terbium section. A further subdivision into crystalline solid, glass, and liquid hosts is also made. 

A crystalline solid is a solid in which the atoms, ions, or molecules lie in an orderly array called a lattice (Fig. 5.19). An amorphous solid is one in which the atoms, ions, or molecules lie in a random jumble, as in butter, rubber, and glass (Fig. 5.20). They have a structure like that of a frozen instant in the life of a liquid. Crystalline solids typically have flat, well-defined planar surfaces called crystal faces, which lie at definite angles to one another. These faces are formed by orderly layers of atoms (Box 5.1). Amorphous solids do not have well-defined faces unless they have been molded or cut. 

Fig. 6.4-5 Diagram of the transitions of food materials, which can be present as crystalline solids, glasses, rubbers, liquids, or in solution [B.108]...

F. 2.7 Density changes at on a first-order liquid-crystalline solid phase transition and on attaining the glass point by a liquid... 

Below Tg the material is hard and rigid with a coefficient of thermal expansion equal to roughly half that of the liquid. With respect to mechanical properties, the glass is closer in behavior to a crystalline solid than to a... 

Filtration. Filtration removes particulate impurities rapidly from liquids and is also used to collect insoluble or crystalline solids which separate or crystallise from solution. The usual technique is to pass the solution, cold or hot, through a fluted filter paper in a conical glass funnel. 

Of the oxide fluorides FIO3 has been prepared by the action of F2/liquid HF on HIO4. It is a white, crystalline solid, stable in glass but decomposing with loss of oxygen on being heated ... 

Inside ABCD, the crystalline solid is stable, above ABC the liquid, whilst to the right of CD the stable form is the amorphous glass. Roozeboom, however, holds a different opinion as to the latter part of the curve Heterogene Gleichge-u ichte, vol. I.). 

Supercooled liquids (glasses111) also have residual entropy at 0 Kelvin. As an example, glycerol supercools badly so that a glass is usually obtained at a low temperature. A crystalline solid can also be obtained if the liquid is cooled in a certain manner to initiate crystalization. Gibson and Giauque9 started with... 

Glasses typically are metastable substances. Like crystalline solids they exhibit macroscopic form stability, but because of their structures and some of their physical properties they must be considered as liquids with a very high viscosity. Their transition to a thermodynamically more stable structure can only be achieved by extensive atomic movements, but atom mobility is severely hindered by cross-linking. 

In contrast to crystalline solids characterized by translational symmetry, the vibrational properties of liquid or amorphous materials are not easily described. There is no firm theoretical interpretation of the heat capacity of liquids and glasses since these non-crystalline states lack a periodic lattice. While this lack of long-range order distinguishes liquids from solids, short-range order, on the other hand, distinguishes a liquid from a gas. Overall, the vibrational density of state of a liquid or a glass is more diffuse, but is still expected to show the main characteristics of the vibrational density of states of a crystalline compound. 

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