Order-disorder arrangement

Since actinide atoms (ions) usually have magnetic moments, magnetic transitions due to order disorder arrangement of magnetic spin have been observed in such uranium compounds as UO2 (267), US (268), UN (269), UP (270), but they usually occur at low temperatures. 

Order-disorder transition in the arrangement of defects is an interesting phenomenon in high temperature solid chemistry, but little work has been done in this domain except on the transitions of U409 and UjOg-, which will be described in the ensuing sections. Need is felt for further studies on transitions due to order-disorder arrangement of defects. 

In the ordered solution, the iron sites of the first species always occupy their specific sites, while atoms are ordered around the other sites, one out of every two sites is oeeupied by an iron atom and one out of two sites is oeeupied by an aluminum atom. One-third of the iron atoms and the aluminum atoms form a eubic crystal with centered faces such as NaCl. Thus, in this example, not all atoms are affected by the order-disorder arrangement. In the completely disordered solution, there are two types of sites those which are always oeeupied by iron and those whieh are randomly occupied by either iron or aluminum. In the ordered solution, again we have two types of sites those occupied by iron and those occupied by aluminum. In fact, because of their origin, we ean elearly see that the... 

This condition means that for f < 0.63 the disordered arrangement of molecules is thermodynamically unstable and the system is spontaneously reorganized into an ordered liquid crystalline phase of a nematic type (Flory called this state crystalline ). This result has been obtained only as a consequence of limited chain flexibility without taking into account intermolecular interactions. 

An A-B diblock copolymer is a polymer consisting of a sequence of A-type monomers chemically joined to a sequence of B-type monomers. Even a small amount of incompatibility (difference in interactions) between monomers A and monomers B can induce phase transitions. However, A-homopolymer and B-homopolymer are chemically joined in a diblock therefore a system of diblocks cannot undergo a macroscopic phase separation. Instead a number of order-disorder phase transitions take place in the system between the isotropic phase and spatially ordered phases in which A-rich and B-rich domains, of the size of a diblock copolymer, are periodically arranged in lamellar, hexagonal, body-centered cubic (bcc), and the double gyroid structures. The covalent bond joining the blocks rests at the interface between A-rich and B-rich domains. 

The disordered arrangement of the globuh and worm-hke species in combination with their uniform shape and diameter of 50 A demonstrates that the intramolecular self-assembly did not depend on intermolecular ordering. For both types of particles, the monolayer thickness was similar to the lateral diameter of the particles d = 50 5A. The topographic contrast of the images in Fig. 6 was enabled by strong molecular segregation and weak interpenetration of the particles. 

Diakonov, G.G. (1998) Thermodynamic properties ofiron oxides and hydroxides. II. Estimation of the surface and bulk thermodynamic properties of ordered and disordered arrangements (y-Fe203). Eur. J. Min. 10 17-29... 

That part of the entropy of a substance that is due to a disordered arrangement of the particles as opposed to a similar but ordered arrangement. The most clear-cut example is the order-disorder transition in binary alloys, in which virtually the whole entropy change is of this kind. The entropy change on fusion of a solid is largely due to entropy of disorder. 

M, and M2 — mesophases with translationally-ordered and disordered arrangement of the side groups in the layers... 

The columnar phases of oligobenzoate Hekates are most probably formed from -shaped conformers which pack disordered in hexagonal columnar phases and for symmetric mesogens they can tilt and aggregate in highly ordered helical arrangements to form the 3D columnar structures (see Fig. 10a, b). Indications... 

Students will explain why glasses have disordered particle arrangements and crystals have orderly particle arrangements. 

Morphology is the order or arrangement of the polymer structure. The possible order between a molecule or molecule segment and its neighbors can vary from a very ordered highly crystalline polymeric structure to an amorphous structure (i.e., a structure in greatest disorder or random). The possible range of order and disorder is clearly depicted on the left side of Fig. 1.14. For example, a purely amorphous polymer is formed only by the non-... 

Consider the A-B binary system. If A and B form a random solid solution with, say, 10 atom percent B, the probability of finding a B atom on any specific lattice site is just 0.1. Under certain conditions, however, B atoms may favour certain specific sites than die test. B atoms will then preferentially position themselves on these specific sites. The probability of finding B atoms in these sites will greatly increase. This type of arrangement is referred to as an ordered structure. The process in which a random disordered solid solution is rearranged into an ordered solid solution is called an order-disorder transition. 

Fig. 4a—d. Lamellar structures in thin films that are not considered further in detail in the present article a Thin film confined between inequivalent walls, where the lower one favors the B-rich domains and the upper one the A-rich domains. Then an arrangement where the interfaces run parallel to the walls requires that thickness D and wavelength X are related as D=(n+1/2)A, n=0,l, 2... b Thin film on a substrate that favors B-rich domains undergo at the order-disorder transition (ODT) of the block copolymer melt a phase separation into a fraction x of thickness nXh and a fraction 1-x of thickness (n+1) Xh, such that D=[xn+(l-x) (n+l)] K if the air also favors B-rich domains, c If the air favors A-rich domains instead, the phase separation happens in a fraction x of thickness (n-l/2)A and a fraction 1-x of thickness (n+ 1/2)X with n= 1,2,3... d If the block copolymer film undergoes dewetting at the substrate, droplets form with a step-pyramide like structure ( Tower of Babel [30]). 

From Flip-Flop Disorder to Ordered Homodromic Arrangements at Low Tbmperature... 

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