Detailed Contents 3 Amorphous Materials

Spin-Lattice and Spin-Spin Relaxations. In order to determine the content of these crystalline and noncrystalline resonances, the longitudinal and transverse relaxations were examined in detail. It was first confirmed that the noncrystalline resonance of all samples is associated with Tic in an order of 0.45-0.57 s. Hence, the noncrystalline component of all samples comprises a monophase, in as much as judged only by Tic. However, it was found that the noncrystalline component of drawn samples generally comprises two phases with different T2C values amorphous and crystalline-amorphous interphases. The dried gel sample does not include rubbery amorphous material it comprises the crystalline and rigid noncrystalline components. However, the rubbery amorphous phase with T2C of 5.5 ms appears by annealing at 145 °C for 4 minutes. For the orthorhombic crystalline component, three different Tic values, that suggest the distribution of crystallite size, were recognized for each sample, as normal for crystalline polymers [17,54, 55]. The Tic and T2C of all samples examined are summerized in Table 6. 

A new class of siliceous microporous materials with varying metal contents and high porosities has recently been presented by Maier et al. [105,106]. These materials which are X-ray amorphous and where no crystalline structure can be seen in the transmission electron microscope are synthesized via a sol-gel-route under hydrothermal conditions without the use of template molecules. The simple reaction of silicon alcoholates and titanium alcoholates which are mixed in ethanol and the condensation of which is induced by the addition of hydrochloric acid, produces a gel that becomes solid after a few days. The following careful calcination process under inert atmosphere and milling of the resulting solid gives the porous material. Detailed analysis of the pore structure para-... 

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