Titanates with layered structures

The Kagome lattice structure clearly explains the non-symmetric nature of the band structure of the C0O2 layer. When the effect of the Kagome lattice becomes dominant, the bottom band, i.e., the flat band as shown in Fig, 3(a) will play a crucial role on the electronic state. Mielke [32] has shown that the flat band with the Coulomb interaction has the ferromagnetic ground state at around half filling. A prospective system for the ferromagnet will be dl transition metal oxides, i.e., the layered titanates with iso-structure of the cobalt oxides. 

Figure 56 (a-d) Schematic interlayer structure of the intercalation compounds of the layered niobates and titanates with Ru(bpy)3+ ions. See text for more details. (From Ref. 109b. Copyright 1995 The American Chemical Society.)... 

High-quality, pore-free microstructures of PZ - PT piezoceramic, (b) and (c), are essential for reliable, high-performance applications, e.g. composites and arrays where very small elements are cut from larger pieces (e.g. see Fig. 6.36) (d) the layer-structured bismuth titanate ferroelectric (Bi4Ti3012) Tc 650°C the crystal structure consists of perovskite layers separated by bismuth oxide layers) is exploited in high-temperature applications, including accelerometers and flow-meters (reproduced with permission of Ferroperm Piezoceramics A/S, Denmark). 

Change in the selectivity patterns of transition metal ion/H+ systems has been encountered with the amorphous and anatase types of hydrous titanium oxides with different crystallinities [24]. Potassium titanate, KjO nXi02 (n = 2-4), in particular, exhibits a layered structure. Fibrous titanic acid, H2Ti409 nHjO, is obtained by acid treatment of fibrous K2Ti409 nH20 and shows higher selectivity for K, Rb and Cs than the amorphous titanic acid [206]. 

Titanates and titanoniobates of the general formula A2-vTi vNbv02 +1 (A = alkali metal) crystallize in layered structures possessing [Ti , vNbv02 +i sheets stacked with interlayer A ions [1, 2]. The sheets may be obtained from edge-connected layers of double-ReOr units by shearing every n-octahedron perpendicular to the sheets. Idealized structures of some of these oxides are shown in Figure 1. Several oxides in this family are known to exhibit interlayer chemistry... 

Figure 1 shows the two models which were calculated. The base structure was considered with another research group for improvement of the thermal conductivity, while three layered structure was adopted on the view point of shielding. The base structure was assumed to be a concentric cylinder of 60 cm height which was formed void, strontium titanate ( "SrTiOs, P 5.12g/cm 0 and boron nitride (BN, p 2.26g/cm3) from the inside. The weight of these two materials was made to be identical each other. 

The mesoporous structure, with high surface area could provide simple accessibility of guest molecules to the active sites and increase their chances to receive light. One research group fabricated mesoporous photocatalysts with delaminated structure. The exfoliated layered titanate in aqueous solution was reassembled in the presence of anatase Ti02 nanosol particles to make a great number of mesopores and increase the surface area of Ti02 [370] (see Table 6). 

Inorganic electroluminescent (EL) devices comprise a composite active layer of a zinc sulfide emitter and a dielectric such as barium titanate sandwiched between two conducting layers, one of which must be transparent. When an AC voltage of 100 V/400 Hz is applied, the zinc sulfide emits light, the hue of which can be tuned by the addition of appropriate doping agents. Figure 10.9 shows a schematic of the layered structure of typical EL device in which the transparent electrode is made with PEDT PSS. 

M. (1999) Possibility of superconductivity in new reduced tantalate and titanate with the layered perovskite structure. 

Yabuta, M., Takayama, T., Shirai, K., Watanabe, K., Kudo, A.. Sugimoto, T., and Matsumoto, Y. (2014) Effects of cocatalyst on carrier dynamics of a titanate photocatalyst with layered perovskite structure. /. Phys. Chem, C, 118,10972-10979. 

Saito N., Haneda H., Li D., Koumoto K. Characterization of zinc oxide micropatterns deposited on self-assembled monolayer template. J. Ceram. Soc. Jpn. 2002 110 386-390 Santos L.R.B., Santilli C.V., Pulcinelli S.H. Sol-gel transition in Sn02 colloidal suspensions viscoelastic properties. J. Non-Cryat. Solid 1999 247 153-157 Santos L.R.B., Craievich A.F., Santilli C.V., Pulcinelli S.H. Sol phase and sol-gel transition in Sn02 colloidal suspensions. J. Appl. Cryst. 2000 33 609-613 Sasaki T., Watanabe M., Michiue Y., Komatsu Y., Izumi F., Takeuchi S. Preparation of acid-base properties of a protonated titanate with the lepidocrocite-like layer structure. Chem. Mater. 1995 7 1001-1007... 

Experimental studies of the polyphase ceramics noted above demonstrate that hollandite is one of the most durable titanate phases in aqueous solutions. Pham et al. (1994) carried out experimental work on synthetic Ba-hollandite doped with Cs and containing Al on the B-site for charge balance. These authors suggested that, following the initial release of Cs and Ba from reactive surface sites the first few monolayers of the structure rapidly dissolved due to the release of Al and consequent precipitation of Al-OH species, driving solution pH to lower values. However, the alteration process was mediated via the formation of a continuous Al- and Ti-rich surface layer. Further evidence for selective removal of Ba and enrichment of Al and Ti on the surface of hollandite tested at 250-300 °C was presented by Myhra et al. (19886). These conclusions were largely based on the different release rates of Ba (10 g/m2/d), Al (7 x 10 3 g/m2/d), and Ti (<8 x 10 4 g/ m2/d) after 14 days of dissolution testing, combined with XPS analyses of the altered surfaces. 

Titanium Diiodide. Titanium diiodide is a black solid (p = 499(0) kg/m3 ) that has the cadmium iodide structure. Titaniums occupy octahedral sites in hexagonally dose-packed iodine layers, where a = 411 pm and c = 682 pm (144). Magnetic studies indicate extensive Ti—Ti bonding. Til2 reacts rapidly with water to form a solution of titanous iodide, Til3. 

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