Average density, green body

MgO ceramics. The MgO green bodies were sintered at 1400 for 2 h in ambient atmosphere. The as-sintered MgO ceramics had a relative density of 98.1 % with an average grain size of 6 pm and an average hardness of 6.8 GPa [3]. 

The density of the green bodies pressed at the pressure of 75 and 220 MPa, were 1.42 and 1.47 g/cm3, respectively. Taking into account the density of the starting materials, the average porosities of green bodies were found to be 55 and 53% under the pressures of 75 and 220 MPa, respectively. Also, the density of 1.52 and 1.62 g/cm and the porosity of 53% and 45% were measured respectively for samples sintered at 1100 and 1200 °C. The compressive strength of these samples were 16 3 and 25 3.5 MPa, respectively. 

The extent of fluorescence polarization at a time t following a brief excitation pulse is directly related to the time dependent, ensemble averaged probability that an excitation resides on the chrom-ophore where it was created at t = 0 [4,6,7]. This probability, which will be designated G (t), depends strongly on the density and distribution of chromophores, and can be obtained from a theoretical analysis of the many body EET problem in the polymeric system. A fit of transient fluorescence depolarization data to a theoretical expression for G (t) provides parameter values that are directly related to chromophore distribution. G (t) and G (t) are portions of the total Green function for excitation transport. 

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