Polynitrohexaazaadamantanes (PNHAAs) have been the subject of much recent research because of their potential as high energy density materials (HEDMs). The B3LYP/6-31G method was employed to evaluate the heats of formation (HOFs) for PNHAAs by designing isodesmic reactions. The HOFs are found to be correlative with the number (n) and the space orientations of nitro groups. Detonation velocities (D) and detonation pressures (P) were estimated for PNHAAs by using the well-known Kamlet-Jacobs equations, based on the theoretical densities (rho) and HOFs. It is found that D and P increase as n ranges from 1 to 6, and PNHAAs with 4-6 nitro groups meet the criteria of an HEDM. When n is over 6, rho of PNHAAs slightly increases; however, the chemical energy of detonation (Q) decreases so greatly that both D and P decrease. The calculations on bond dissociation energies suggest that the N-N bond be the trigger bond during the pyrolysis initiation process of each PNHAA, and with increasing n, N-N bond dissociation energy (E(N-N)) decreases on the whole, that is to say, the relative stability of PNHAAs decreases. All E(N-N)(s) of PNHAAs are more than 30 kcal.mol(-1), which further proves that four PNHAAs with 4-6 nitro groups can be used as the candidates of HEDMs. Considering the synthesis difficulty and the performance as an energetic compound, we finally recommended 2,4,6,8,10-pentanitrohexaazaadamantane as the target HEDM for PNHAAs.
One-dimensional CL-20 chains have been constructed using CH 2 molecular bridges for the covalent bonding between isolated CL-20 fragments. The energy and electronic properties of the nanostructures obtained have been analyzed by means of density functional theory and nonorthogonal tight-binding model considering Landauer-Büttiker formalism. It has been found that such systems become more thermodynamically stable as the efficient length of the chain increases. Thus, the formation of bulk covalent CL-20 solids may be energetically favorable, and such structures may possess high kinetic stability comparing to the CL-20 molecular crystals. As for electronic properties of pure CL-20 chains, they are wide-bandgap semiconductors with energy gaps equal to several electron volts that makes their use in nanoelectronic applications problematic without any additional modification.
Green-emitting phosphor in glass (PiG) materials for high power blue laser lighting have been successfully synthesized by uniformly dispersing β-Sialon:Eu phosphor powders into the ZnO–B2O3–BaO–Al2O3 glass matrix.
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