Structure tunnel

The maximum voltage drop in the tunnel is approximately (neglecting current flow from the tunnel structure into the surrounding soil) [6] ... 

Table 1. Crystallographic data for manganese oxides with tunnel structures... 

The presence of the foreign cation stabilizes the crystal structure of a - Mn02 compounds. This manganese dioxide modification (more exactly it is not a real MnOz modification, since the structure contains a considerable proportion of foreign atoms) can be heated to relatively high temperatures (300 - 400 °C) without destruction of the lattice. Although Thackeray et al. reported the synthesis of cation-and water- free a - MnOz [49, 50J, which is reported to be stable up to 300 °C without destruction of the [2 x 2] tunnel structure, it is commonly believed that a small,... 

T(2,2) tunnel structure T(2,3) tunnel structure T(3,3) tunnel structure... 

Effect of Tunnel Structures of BaTi409 and Na2TieOi3 on Photocatalytic Activity and Photoexcited Charge Separation... 

Since BaTi40g and Na2TieOi3 have a pentagonal prism tunnel and a rectangular tunnel structure, respectively, we have paid attention to the role of the tunnel structures in photocatalysis. A barium titanate, Ba4Tii303o, in a series of Ba-Ti titanates was chosen as a representative with non-tunnel structure, and we have compared the photocatalytic activity and the ability for the production of surface radical species with uv irradiation between the tunnel and the non-tunnel titanates. 

Figure 6(b) shows schematic projection of NagTieOis and the rectangular tunnel structure[9]. Na2TieOi3 has three kinds of TiOe units, each of which is distorted to produce different dipole moments. The directions of the dipole moments are... 

Figure 6. Schematic projection and tunnel structure of BaTi40g(a) and NagTieOiaCb). O.oxygen atom .titeinium atom barium or sodium atom X. center of gravity of six oxygen ions. The arrows indicate the dipole moments.

Table 1 demonstrates the distance of displacement from the center of gravity and the magnitude of the dipole moments. The dipole moments of BaTi40g were D=5.7 and D=4.1 and those of NazTigOig were D=5.3, D=5.8 and D=6.7, whereas all the moments of Ba4Tii303o was below D=5.0. It is to be noted that there is a clear difference in the dipole moment between tunnel structure titanates(D>5.0) and non-tunnel structure Ba4Tii303o (D<5.0). The ESR spectra of BaTi40g showed... 

The micrographs, Figures 6 and 7, show a side view of a 50/50 extruded blend, and a 70/30 blend after base hydrolysis. The porous, tunneling structure can clearly be seen. 

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