Ceramics density values

Colossal magnetoresistance studies of ceramics have demonstrated no significant influence of ceramic density on the magnetoresistance at H = 1.5T. However, ceramics obtained by the solid state synthesis method and containing inclusions of lanthanum-doped manganese oxide displayed substantially higher magnetoresistance values. This effect was later used for directed enhancement of low field... 

An important advantage of ULE (Coming) is the possibility to fabricate lightweight blanks because of the low density of 2.21 g.cm 3 of the glass itself (glass ceramics have values between 2.5 and 2,6 g.cm"3) and because of using special machined and fused core structures and bonding techniques [67]. 

In order to utilize the new high-temperature superconductors in large-scale applications, these materials must be able to carry large currents at high fields at the newly available temperatures. Bulk ceramic specimens of YBa2Cu3 07 presently show critical current density values of 10 and 10 A/cm, which are lower by a factor of 100 from those observed for the... 

Bar chart of room-temperature density values for various metals, ceramics, polymers, and composite materials. 

A more extensive comparison of many potential turbine blade materials is available (67). The refractory metals and a ceramic, sHicon nitride, provide a much higher value of 100 h stress—mpture life, normalised by density, than any of the cobalt- or nickel-base aHoys. Several intermetaHics and intermetaUic matrix composites, eg, aHoyed Nb Al and MoSi —SiC composites, also show very high creep resistance at 1100°C (68). Nevertheless, the superaHoys are expected to continue to dominate high temperature aHoy technology for some time. 

Fig. 95 shows the change in cell parameters, density and Curie temperature for ceramics with initial compositions of Li(Tai xMgx)03.3xF3x (where 0 < x < 0.2) versus x value. It should also be mentioned that the pyroelectric coefficient for x = 0.05 was found to be 4.0 nC cm 2 K l. 

Fig. 95. Change in cell parameters (an and cf), density of ceramics normalized by theoretical value and Curie temperature versus x value for Li(Tai.xMgf03.3XFsx system. Reproduced from [407], Z-G. Ye, R. Von Der Mtihll, J. Ravez, P. Hagenmuller, J. Mater. Res., 3 (1988) 112, Copyright 1988, with permission ofMRS Journal of Material Research.

Typical n-alkyl ligand densities that can be achieved with -alkylchlorosi lanes are within the range of 2.5-3.2pmolm-2, whilst with disilazanes, ligand densities approaching the limited values can be reached under optimized conditions, i.e. between 3.50 and 4.20 pmolm-2. Surface-modified zirconia or other metal oxide based RPC sorbents can be similarly prepared by either of the above two strategies. Compared to n-alkylsilicas, these ceramic RPC sorbents show different selectivities with synthetic peptides, as well as different chemical stability profiles. Consequently, RPC sorbents based on these types on surface-modified, porous metal oxide materials fulfill useful and complementary roles, but at this point in time, have achieved a more limited range of applications for the resolution of synthetic peptides due to their limited availability. 

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