Some Properties of Solids

We mentioned some properties of solids (for example, malleability, ductility) at the beginning of this text, and we will continue to consider additional properties. For now, we will comment on some properties that allow us to think of solids in relation to the other states of matter— liquids and gases. 

If we add heat uniformly to a solid-liquid mixture at equilibrium, the temperature remains constant while the solid melts. Only when all the solid has melted does the temperature begin to rise. Conversely, if we remove heat uniformly from a solid-liquid mixture at equilibrium, the liquid freezes at a constant temperature. The quantity of heat required to melt a solid is the enthalpy effusion, AfusH. Some typical enthalpies of fusion, expressed in kilojoules per mole, are listed in Table 12.7. Perhaps the most familiar example of a melting (and freezing) point is that of water, 0 °C. This is the temperature at which liquid and solid water, in contact with air and under standard atmospheric pressure, are in equilibrium. The enthalpy of fusion of water is 6.01 kj moP, which we can express as 

The broken-line portion represents the condition of supercooling that occasionally occurs. 

This curve traces the changes that occur as ice is heated from below the melting point to produce liquid water somewhat above the melting point. 

---

You have examined some properties of solids, liquids, and gases. You have seen how the motion of the particles affects these properties. Now you will examine how the particles affect each other. 

Table .1. Some properties of solid and liquid scintillators.

The first six years in this country were quiet and productive years for me. I taught at the University, worked with George Gamov on some relatively early question of nuclear physics and worked with a great number of other people on the physics of molecules, including some properties of solids. 

The constants e and o have been measured for the low-density noble gases. It is possible to estimate some properties of solid gases using only these values and the potential (15.11) [7]. 

Parkman, N., 1978, Some properties of solid-liquid composite dielectric systems, I.E.E.E. Trans El, EI-13 289. 

Intermolecular Forces 12-2 Some Properties of Liquids 12-3 Some Properties of Solids 12-4 Phase Diagrams... 

Electrostatic Properties of Solids in Suspension. Some solids in suspension will migrate from one pole to another when placed between direct current electrodes. The phenomenon of solids moving toward an electrode is known as cataphoresis. 

If the object of a synchrotron is to accelerate electrons to the highest possible energy, synchrotron radiation is a serious obstacle that limits the energy attainable. On the other hand, the electromagnetic radiation from a synchrotron can be useful for experiments on the properties of solids and for other purposes. For tins reason, some electron synchrotrons are built primarily for the synchrotron radiation they emit. 

We have, in this chapter, encountered a number of properties of solids. In Table 5-II, we found that melting points and heats of melting of different solids vary widely. To melt a mole of solid neon requires only 80 calories of heat, whereas a mole of solid copper requires over 3000 calories. Some solids dissolve in water to form conducting solutions (as does sodium chloride), others dissolve in water but no conductivity results (as with sugar). Some solids dissolve in ethyl alcohol but not in water (iodine, for example). Solids also range in appearance. There is little resemblance between a transparent piece of glass and a lustrous piece of aluminum foil, nor between a lump of coal and a clear crystal of sodium chloride. 

The milk and cream in ice cream contain butterfat, proteins, and milk sugars. Butterfat adds rich flavor, smooth texture, body, and good melting properties. The triglycerides in butterfat melt over a wide range of temperatures, so there is always some bit of solid and some liquid butterfat. Some of the butterfat almost turns into butter while the ice cream is being churned, adding to the unique texture of ice cream. 

Today, the term solid electrolyte or fast ionic conductor or, sometimes, superionic conductor is used to describe solid materials whose conductivity is wholly due to ionic displacement. Mixed conductors exhibit both ionic and electronic conductivity. Solid electrolytes range from hard, refractory materials, such as 8 mol% Y2C>3-stabilized Zr02(YSZ) or sodium fT-AbCb (NaAluOn), to soft proton-exchange polymeric membranes such as Du Pont s Nafion and include compounds that are stoichiometric (Agl), non-stoichiometric (sodium J3"-A12C>3) or doped (YSZ). The preparation, properties, and some applications of solid electrolytes have been discussed in a number of books2 5 and reviews.6,7 The main commercial application of solid electrolytes is in gas sensors.8,9 Another emerging application is in solid oxide fuel cells.4,5,1, n... 

The reciprocal lattice is useful in defining some of the electronic properties of solids. That is, when we have a semi-conductor (or even a conductor like a metal), we find that the electrons are confined in a band, defined by the reciprocal lattice. This has important effects upon the conductivity of any solid and is known as the "band theory" of solids. It turns out that the reciprocal lattice is also the site of the Brillouin zones, i.e.- the "allowed" electron energy bands in the solid. How this originates is explciined as follows. 

Some properties of the detectors most commonly used for transmission experiments are summarized in Table 3.2. Alternative counters are scintillation detectors based on Nal or plastic material that is attached to a photomultiplier, and solid-state detectors using silicon- or germanium-diodes. 

This chapter describes some of the properties of solids that affect transport across phases and membranes, with an emphasis on biological membranes. Four aspects are addressed. They include a comparison of crystalline and amorphous forms of the drug, transitions between phases, polymorphism, and hydration. With respect to transport, the major effect of each of these properties is on the apparent solubility, which then affects dissolution and consequently transport. There is often an opposite effect on the stability of the material. Generally, highly crystalline substances are more stable but have lower free energy, solubility, and dissolution characteristics than less crystalline substances. In some situations, this lower solubility and consequent dissolution rate will result in reduced bioavailability. 

Some properties of these ions make them particularly appealing as solid state spin qubits. The fact that they can be diluted into diamagnetic crystals offers a simple method to optimize their quantum coherence. Similarly to trapped ions, they are simple each qubit is embodied by a single atom. Yet, their immediate... 

In this and in the two following chapters, we shall describe in detail some measurements of the properties of solids at low temperatures. As we shall see, each measurement is a real experiment. This is due not only to the complex operations needed to reach and maintain the desired low temperature, but also to the number of parameters involved in a measurement. Such parameters are never perfectly reproducible in two nominally identical experiments a typical example is that of the thermal contacts (see Section 4.3). 

Although not one of the most frequently discussed properties of solids, hardness is an important consideration in many instances, especially in the area of mineralogy. In essence, hardness is a measure of the ability of a solid to resist deformation or scratching. It is a difficult property to measure accurately, and for some materials a range of values is reported. Because of the nature of hardness, it is necessary to have some sort of reference so that comparisons can be made. The hardness scale most often used is that developed by Austrian mineralogist F. Mohs in 1824. The scale is appropriately known as the Mohs scale. Table 7.11 gives the fixed points on which the scale is based. 

As with particle size, particle shape can influence the compaction properties of solids. While work in this area is limited, some work has been reported. Ridgway and Scotton [17], for example, investigated the effect of particle shape on die-fill weight and found that more angular materials had a greater weight variation. Also, Rupp [18] investigated the effects of particle shape on tablet... 

We shall briefly discuss the electrical properties of the metal oxides. Thermal conductivity, electrical conductivity, the Seebeck effect, and the Hall effect are some of the electron transport properties of solids that characterize the nature of the charge carriers. On the basis of electrical properties, the solid materials may be classified into metals, semiconductors, and insulators as shown in Figure 2.1. The range of electronic structures of oxides is very wide and hence they can be classified into two categories, nontransition metal oxides and transition metal oxides. In nontransition metal oxides, the cation valence orbitals are of s or p type, whereas the cation valence orbitals are of d type in transition metal oxides. A useful starting point in describing the structures of the metal oxides is the ionic model.5 Ionic crystals are formed between highly electropositive... 

Percolation models differ from the zone-refining model essentially by the absence of mixing in the liquid, giving the liquid position-dependent properties. A simplified account of these models was described in Chapter 8. We will now provide a reasonably comprehensive account which may prove useful to the demanding reader, and then examine some properties of the chromatographic effect in a simple configuration. Let

open volume porosity of the medium, pso, and pliq the density of the solid matrix and melt, respectively, vliq the liquid velocity relative to the matrix, and Cso, and CHq the concentration of element i in the matrix and melt, respectively. Let us rewrite equation (8.3.14) as... 

In application of this method to solubility data (8) in the KCl-KBr- O system at 25°C, it is found that equilibrium is in general not attained, though some mid-range compositions may be near equilibrium. As the highly soluble salts are expected to reach equilibrium most easily, considerable caution should be exercised before reaching the conclusion that equilibrium is established in other low-temperature solid solution-aqueous solution systems. It is not appropriate to derive thermodynamic properties of solid solutions from experimental distribution coefficients unless it can be demonstrated that equilibrium has been attained. 

Figure 3.3. Schematic representation of the diagrams for the alkali metals with a selected number of elements of the p-block. In each box the solid intermediate phases are represented in the positions approximately corresponding to their compositions (long bars congruent melting phases short bars non-congruent phases). In the top part of each box every mark corresponds to a characteristic composition of the liquid phase for which the formation of an associate ( liquid compound ) may be suggested, for instance by the presence of an extremum in the trend of some property of the liquid phase. The symbol 2 L shown for certain ranges of compositions in a few diagrams indicates the presence of a miscibility gap in the liquid state, that is two liquid phases.

Most scientists think of glass as an amorphous solid. Just to confuse matters, though, glass does have some properties of liquids, mainly its random arrangement of atoms, so there are some scientists who think of glass as its own state of matter, neither liquid nor solid. 

The photosensitive nature of selenium makes it useful in devices that respond to the intensity of light, such as photocells, light meters for cameras, xerography, and electric eyes. Selenium also has the ability to produce electricity directly from sunlight, making it ideal for use in solar cells. Selenium possesses semiconductor properties that make it useful in the electronics industry, where it is a component in some types of solid-state electronics and rectifiers. It is also used in the production of ruby-red glass and enamels and as an additive to improve the quality of steel and copper. Additionally, it is a catalyst (to speed up chemical reactions) in the manufacture of rubber. 

The metal-solution interface as the locus of the deposition processes. This interface has two components a metal and an aqueous ionic solution. To understand this interface, it is necessary to have a basic knowledge of the structure and electronic properties of metals, the molecular structure of water, and the structure and properties of ionic solutions. The structure and electronic properties of metals are the subject matter of solid-state physics. The structure and properties of water and ionic solutions are (mainly) subjects related to chemical physics (and physical chemistry). Thus, to study and understand the structure of the metal-solution interface, it is necessary to have some knowledge of solid-state physics as well as of chemical physics. Relevant presentations of these subjects are given in Chapters 2 and 3. 

---