Charge ordering

TABLE 13.5 Electrostatic Charging Order of Filter Fibers... 

As well as charge-ordering in the system, out to two chloride shells, the specibc local structure shows strong interactions between the chloride and the ring hydrogens, as well as some interaction between the methyl groups of adjacent imidazoli-um cations. This is consistent with the crystal structure and implies that the molecular paclbng and interactions in the brst two or three coordination shells are similar in both the crystal and the liquid. 

Intermediate phases between these two extremes can be formed. The most stable of these are Sr5Mn50i3 and Sr7Mn7019. In both of these phases the structure consists of both square pyramids, containing Mn3+ and octahedra containing Mn4+ (Fig. 9.8c and 9.8d). These structures exhibit charge ordering, but the magnetic and spin states of the Mn ions has yet to be resolved. 

When the combined system of adatom and substrate is in its ground state, so that the lowest energy levels are each doubly occupied with an a- and a /2-spin electron, then, if two electrons are in a localized level, a localized surface bond will be formed. However, if the localized level is unoccupied, then an adbond formation will be achieved without localization of the bonding electrons (i.e., only delocalized electrons will be involved in the adbond). In the case of electron localization, the type of adbond is determined by the charge order of the adatom state, namely,... 

CHARGE ORDERING AND TILT MODULATION IN MULTIFERROIC FLUORIDES WITH TTB STRUCTURE BY ELECTRON DIFFRACTION AND SINGLE CRYSTAL XRD... 

Key words tetragonal tungsten bronze, charge ordering, electron diffraction... 

Charge Ordering and Tilt Modulation in Multiferroic Fluorides... 

S.Fabbrici, E.Montanaii, G.Calestani and A. Migliori Charge ordering and tilt modulation in multiferroic KxM"xM "i xF3 (0.4transition metal fluorides with tetragonal tungsten bronze structure Chem. Mater. 2004 16(16) 3007-3019... 

NMR time scale (ca. 10 s), the lithium spins see an average manganese oxidation state of 3.5 (i.e., Mn 5+ ions), and thus there is only one magnetically inequivalent lithium site (the 8a site). The NMR spectra are clearly sensitive to this hopping mechanism, and NMR spectroscopy may be used to follow the partial charge-ordering process that occurs just below room temperature in the stoichiometric material. 

Charge ordering below 220 K has also been found, in the organic conductor (DI-DCNQI)2Ag (Hiraki Kanoda, 1998). 

The switching or memory phenomena induced by electric field application or photo irradiation have been studied on Mott insulators, charge ordered insulators, and N-I transition systems and were found to be fast phase transitions in general. For the former two systems, the phase transitions caused a pronounced change in reflectance and conductivity from insulating to metallic features. The third system also exhibited a change in conductivity and dielectric response connected with the transports of solitons and/or domain walls, dynamic dimerization, and... 

Response temperature (operating temperature) may decrease in the foUowing order bond formation and cleavage —> molecular deformation lattice deformation —> electronic deformation such as SDW and charge-order melting. 

The phase transition consists of a cooperative mechanism with charge-ordering, anion order-disorder, Peierls-like lattice distortion, which induces a doubled lattice periodicity giving rise to 2 p nesting, and molecular deformation (Fig. 11c). The high temperature metallic phase is composed of flat EDO molecules with +0.5 charge, while the low temperature insulating phase is composed of both flat monocations... 

CO charge ordered threshold electric field Toper operating temperature No experiments... 

Laser irradiation onto the insulating (EDO)2PF6 crystal induces a phase transition to the highly conductive state within a few picoseconds [162, 180]. The crystal surface was excited by laser irradiation with a pulse width of 0.12 ps. The excitation photon energy (1.55 eV) was nearly resonant to the CT band at 11.1 x 10 cm (1.37 eV), directly reflecting the excitation of the charge ordered state. 

Fig. 13 Generalized phase diagram for the (TMTSF)2X and (TMTTF)2X by Jerome [195]. CL, SP, SDW, and SC refer to charge-localized (which corresponds to charge-ordered state), sprn-Peierls, spin density wave, and superconducting states, respectively, (a) (TlVrrTF)2PF6, (b) (TMTTF>2Br, (c) (TMTSF)2PF6, (d) (TMTSF)2C104...

Okamoto K, Tanaka T, Fujita W, Awaga K, Inabe T (2006) Low-field negative-resistance effect in a charge-ordered state of thiazyi-radical crystals. Angew Chem Int Ed 45 4516 518... 

Aoyagi S, Kato K, Ota A, Yamochi H, Saito G, Suematsu H, Sakata M, Takata M (2004) Direct observation of bonding and charge ordering in (EDO-TTF)2PFg. Angew Chem Int Ed 43 3670-3673... 

Tajima N, Sugawara N, Tamura M, Nishio Y, Kajita K (2006) Electronic phases in an organic conductor a-(BEDT-TTF)2l3 ultra narrow gap semiconductor, superconductor, metal, and charge-ordered insulator. J Phys Soc Jpn 75 051010/1-10... 

Kimura S, Suzuki FI, Maejima T, Mori H, Yamaura J, Kakiuchi T, Sawa H, Moriyama H (2006) Checkerboard-type charge-ordered state of a pressure-induced superconductor, j8-(OTe5 o-DMBEDT-TTF)2PF6. J Am Chem Soc 128 1456-1457... 

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