Pressure-induced structural transitions

Pressure-Induced Structural Transition of Protein and Molecular Recognition... 

Fig. 10.8. Changes in the structure and in the volume components associated with the pressure-induced structural transition of ubiquitin. Solid ribbon representation of low-pressure (3 MPa) and high-pressure (300 MPa) structures. The data shown are the total change in the partial molar volume (V) and the changes in the van der Waals (Vw), void (W), thermal (VT), and interaction (Vi) volumes...

Benedict et al. (Benedict 1987 Benedict and Holzapfel 1993) reviewed the study of pressure-induced structural transitions in the actinide metals. High pressure is the most efficient and cleanest way of changing the interatomic distances in a lattice. 

Quadri SB, Yang J, Ratna BR et al (1996) Pressure induced structural transition in nanometer size particles of PbS. Appl Phys Lett 69 2205-2207... 

Shen LH, Li XF, Ma YM et al (2006) Pressure-induced structural transition in AIN nanowires. Appl Phys Lett 89 141903... 

Wang Z, Saxena SK, Pischedda V et al (2001) In situ X-ray diffraction study of the pressure-induced phase transformation in nanocrystaUine Ce02. Phys Rev B 64 012102 Liu H, Jin C, Zhao Y (2002) Pressure induced structural transitions in nanocrystaUine grained selenium. PhysicaB 315 210-214... 

The relation between the observed structural sequence in the lanthanides and the d-band occupancy can be examined qualitatively using the above values of the number of occupied d-electrons. The study of the pressure-induced structural transition of Lu above (Min et al. 1986c) shows that the dependence of the d-band oecupaney on the structure is small at the given lattice constant the differences obtained between struetures are only 0.02 or 0.03 electrons. Hence it is possible to relate, within a small uneertainty, the observed structures in the lanthanide metals with the absolute values of the d-band occupancy obtained in the fee structure. From fig. 6, the resulting ranges of d-band occupancy (JV ) for the stable structures are < 1.7 for hep and 1.75 [Pg.178]

Pressure-induced structural transitions in these metals will be reviewed in sect. 2. We will see that detailed studies of these materials under pressure have revealed clear systematic trends and a basic theoretical understanding. Nevertheless, some way remains to be gone before we really can say that the pressure behavior of these two series of metals is completely understood. 

Pressure-induced structural transitions in lanthanide pnictides and chalcogenides LnX of the B1 structure type. For each compound the table lists, from top to bottom the structure of the high-pressure phase, the pressure (range) of transition (GPa), the volume decrease on transition (%), and references. (x means compound unknown, - studied under pressure, but no phase transition observed, and -)- compound exists,... 

Pressure-induced structural transitions were observed for monopnictides of La and Ce, for the monochalcogenides of Eu, and for the monotellurides of Ce, Pr, Sm, Eu, and Tm (table 5). Not all of the remaining Ln monopnictides and monochalcogenides have been studied under pressure up to now. Compressibility data derived from high-pressure X-ray diffraction studies are listed in table 6 and plotted versus atomic number in fig. 18. Figure 16 gives an overview over all pressure-induced electronic and structural transitions observed up to now in LnX compounds. 

The B1-B2 phase transition is the prominent feature in the high-pressure structural behavior of these compounds. Although the interactinide distances reach the Hill transition zone (Hill 1970) under pressure in some of these compounds, the 5f electrons do not seem to have any link to this phase transition, since it is also the typical pressure-induced structural transition for the alkali halides. In addition, for a structural phase transition linked to 5f delocalization, one would in general expect that the high-pressure structure has lower symmetry than cubic. This assumption is based on an empirical correlation between itinerant f-states and low-symmetry structures, and is thought to be connected with strong directionality of the hybridized (s,p,d,f) orbitals. 

Data for pressure-induced structural transitions and isothermal bulk moduli of the ambient-pressure phases for lanthanide 4/3 compounds of the anti-ThjP4 structure type (Werner et al. 1981b). The high-pressure phase was assumed to be of a deficient Bl-type. 

Pressure-induced structural transitions in CeOj and actinide dioxides AnO ... 

Pressure-induced structural transitions to an orthorhombic structure, probably related to the PbClj type, in actinide compounds of the Fc2As-type structure. Data from Gerward et al. (1990c). 

The previous research opened the door to the possiblity of an accurate atomic scale investigation of the structural transformation of GeSc2 under high pressure. In the same sperit of FPMD, simulations were carried out covering a pressure ranging up to 16GPa. The resulting equation of state is displayed in Fig. 12.17. We refer to our paper by Wezka, Bouzid et al. [61] for details on the pressure-induced structural transition recorded therein and the peculiar role played by homopolar atoms. 

S.B. Qadii, J. Yang, B.R. Ratna, E.F. Skelton, J.Z. Hu, Pressure induced structural transitions in nanometer size particles of PbS. Appl. Phys. Lett. 69(15), 2205-2207 (1996)... 

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