Crystal structure of lithium molybdenum purple bronze Li0.9Mo6O17

Structure determination of low-dimensional conductor sodium molybdenum purple bronze Na0.9Mo6O17

We present the EPR and NMR results on the quasi-one-dimensional conductor α'-Na x V 2 O 5 ( x =1.0, 0.9 and 0.78) in the temperature range from 12 K to 397 K. The spin susceptibility extracted from EPR measurements has a broad maximum around room temperature. The 51 V NMR line shift associated with the V 4+ ion increases with decreasing temperature below room temperature. The ground state of the V 4+ ion is spin-singlet and it is understood as bipolaronic state, which is the electron pairs of the adjacent V 4+ ions formed by the strong electron-phonon interaction. In the case of x =1.0, it is pointed out that there are the vanadium zigzag chains occupied by the only V 4+ ions, where the electron wave function overlaps directly.

Magnetic Resonance Studies of the Quasi-One-Dimensional Conductor α'–NaxV2O5

The term bronze, originally given to the NaxWO3 compounds by Wohler in 1825 [1], is now applied to a variety of crystalline phases of the transition metal oxides; usually ternary compounds of the type AxMzOy, but binary oxides with intense color and metallic luster, metallic or semiconducting properties, and resistance to attack by non-oxidizing acids also qualify. Ternary bronzes have been prepared in which M is Ti, V, Mn, Nb, Ta, Mo, W, or Re, and A is H, NH 4 + , alkali, alkaline earth, rare-earth, Group IB, IIB, or other metal ion.

Transition Metal Oxide Bronzes with Quasi Low-Dimensional Properties

Electro-Active Paper (EAPap) materials based on cellulose are attractive for many applications because of their low voltage operation, lightweight, dryness, low power consumption, bio-degradability. The construction of EAPap actuator has been achieved using the cellulose paper film coated with thin gold electrode layers. This actuator showed a reversible and reproducible bending movement. In order to improve both force and displacement of this, efforts are made to construct hybrid EAPap actuators using cellulose paper coated with carbon nanotubes (CNT). To coat the CNT, single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) are dispersed in polyaniline (PANI) matrix, and the solution is coated on the EAPap by using a spin coater. It is expected that the use of CNT can improve the force output by enhancing the stiffness of the hybrid EAPap actuator. Furthermore, the presence of the PANI may improve the actuation performance of the EAPap material. The performance of hybrid EAPap actuators is tested in an environmental chamber in terms of free displacement, blocked force and electrical power consumption. The performance of hybrid actuators is investigated for bio-mimetic applications.

Hybrid Electro-Active Papers of Cellulose and Carbon Nanotubes for Bio-Mimetic Actuators

The existence of the characteristic bound state of BIPOLARON (a dimerized electron pair of up and down spins on the near neighbour sites) was established by NMR and X ray diffraction measurements in the quasi-1-d conductor MxV205(M= Na,Ag,Li,Cu, and Pb). On the basis of the results of EPR and NMR relaxation, the observed high electrical conductivity along the 1-d axis is interpreted as the COLLECTIVE MOTION of BIPOLARONS. These characteristic properties are discussed with the strong electron-phonon interaction of the rather well localized small polarons in the 3d vanadium bronzes, which is different from the 4d. molybdenum bronzes.

Y. Kami

Papers

Mobile Bipolaron In Quasi-1-D Conductor Vanadium Bronzes