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Phase transitions solid elements

Figure 8.9 is the phase diagram for Sn, a system that shows (solid + solid) phase transitions." Solid II is the form of tin stable at ambient conditions, and it is the shiny, metallic element that we are used to observing. Line ab is the melting line for solid II. Points on this line represent the values of p and T for which... [Pg.400]

Fullerene C70 molecules are more stable in nanotubes than in bulk crystals, collapsing to amorphous carbon at 51 instead of 35 GPa [186], Influence of the crystal size on the phase transitions in elemental solids has been studied on nanosamples of Pd [187] and Si [188]. While the/cc-structure of the bulk Pd is unchanged up to 77.4 GPa, its 9nm crystals transform to the/ct structure at 24.8 GPa. Similarly, nano-Si (60-80 nm) converts into the 3-Sn structure at 8.5-9.9GPa, which is 2 GPa less than for microcrystal samples. [Pg.427]

V. I. Levitas, A. V. Idesman, E. Stein. Finite element simulation of martensitic phase transitions in elastoplastic materials. Int J Solids Struct 55 855, 1998. [Pg.928]

In this second edition the text has been revised and new scientific findings have been taken into consideration. For example, many recently discovered modifications of the elements have been included, most of which occur at high pressures. The treatment of symmetry has been shifted to the third chapter and the aspect of symmetry is given more attention in the following chapters. New sections deal with quasicrystals and other not strictly crystalline solids, with phase transitions and with the electron localization function. There is a new chapter on nanostructures. Nearly all figures have been redrawn. [Pg.275]

Other features of interest in the phase diagram of 4He include triple points between various liquid and solid phases of the element. At point c in Figure 13.11, liquid I, liquid II and a body-centered cubic (bcc) solid phase are in equilibrium. The bcc solid exists over a narrow range of pressure and temperature. It converts by way of a first-order transition to a hexagonal close packed (hep) solid, or to liquid I or liquid II. At point d, liquid I and the two solids (bcc and hep) are in equilibrium liquid II and the two solids are in equilibrium at point e. [Pg.92]

The discussion of the high-temperature properties and thermal decomposition of carbonates in this chapter, a plan which will be followed for other classes of compounds in subsequent chapters, is given for each element. A brief discussion is followed by quantitative data on phase transitions, densities, and thermodynamic parameters for the carbonate, the corresponding oxide, and the decomposition reaction MC03 = MO + C02. If the carbonate and oxide are solids and form no solid solution, the equilibrium constant is the pressure of C02 which would be obtained if one begins with an evacuated container and lets the system come to equilibrium. In this case, the pressure is a unique function of the temperature. As pointed out in Chapter 1, this is no longer true... [Pg.31]

Recent advances in the techniques of photoelectron spectroscopy (7) are making it possible to observe ionization from incompletely filled shells of valence elctrons, such as the 3d shell in compounds of first-transition-series elements (2—4) and the 4/ shell in lanthanides (5, 6). It is certain that the study of such ionisations will give much information of interest to chemists. Unfortunately, however, the interpretation of spectra from open-shell molecules is more difficult than for closed-shell species, since, even in the simple one-electron approach to photoelectron spectra, each orbital shell may give rise to several states on ionisation (7). This phenomenon has been particularly studied in the ionisation of core electrons, where for example a molecule (or complex ion in the solid state) with initial spin Si can generate two distinct states, with spin S2=Si — or Si + on ionisation from a non-degenerate core level (8). The analogous effect in valence-shell ionisation was seen by Wertheim et al. in the 4/ band of lanthanide tri-fluorides, LnF3 (9). More recent spectra of lanthanide elements and compounds (6, 9), show a partial resolution of different orbital states, in addition to spin-multiplicity effects. Different orbital states have also been resolved in gas-phase photoelectron spectra of transition-metal sandwich compounds, such as bis-(rr-cyclo-pentadienyl) complexes (3, 4). [Pg.60]

What is so special about low-dimensional solids The key element here is the Mermin-Wagner theorem [2]. It states [3] that systems with short-range forces that are at finite temperature cannot undergo any phase transition to a state that breaks (1) a discrete symmetry in one dimension (d = 1) or (2) a continuous symmetry in one or two dimensions (d = 2). Why is this so ... [Pg.26]


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See also in sourсe #XX -- [ Pg.12 , Pg.13 , Pg.14 , Pg.15 , Pg.16 , Pg.17 , Pg.18 , Pg.20 ]

See also in sourсe #XX -- [ Pg.12 , Pg.13 , Pg.14 , Pg.15 , Pg.16 , Pg.17 , Pg.18 , Pg.20 ]




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Phase Transitions in the Solid Elements

Phase Transitions in the Solid Elements at Atmospheric Pressure

Phase element

Transition elements

Transitional elements

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