The Brønsted acidity of isomorphously substituted ZSM-5 by B, Al, Ga, and Fe has been studied at the B3LYP level of density functional theory. On the basis of the calculated proton affinity, natural charge on the acidic proton, and the adsorption energy of NH3, the Brønsted acidity increases in the order:  B−(OH)−Si < Fe−(OH)−Si < Ga−(OH)−Si < Al−(OH)−Si, in agreement with the experiment. In both Al and Ga modified clusters, the adsorbed NH3 becomes ammonium (NH4 +) stabilized by two N−H···O hydrogen bonds, while the physisorbed NH3 is stabilized by one N···H−O hydrogen bond in Fe and B substituted clusters. It is also found that NH3 adsorption changes the B coordination sphere.

Ba ( Co x , Ti 1 − x ) O 3 thin films were prepared on fused quartz substrate by a sol-gel method. The results of x-ray diffraction showed that the films are perovskite phase and the change of lattice constant caused by different Co concentration is undetectable. Optical transmittance measurement indicated that Co doping has effect on the energy band structure. The energy gap of Ba(Cox,Ti1−x)O3 decreased linearly with the increase of Co concentration. It is inferred that the energy level of conduction bands decline with the Co content increasing. This result is similar to the phenomena found in binary semiconductor where the band gap decreases with the increasing of average atomic number.

Using synchrotron angle-dispersive X-ray diffraction and Raman spectroscopy techniques in a diamond anvil cell, we have examined the structural behaviors of the cubic (anti-C) Ca 3 N 2 at high pressures and room temperature. Two first-order phase transformations were observed at 9.6 and 19.5 GPa accompanied by large volume collapses of 7 and 9%, respectively. The two high pressure phases were identified as monoclinic (anti-B) and hexagonal (anti-A) structures by Rietveld refinement. With the pressure derivatives fixed at 4, the bulk modulus of anti-C, anti-B, and anti-A type structures were determined as 53.1(2), 61.6(4), and 83.9(2) GPa, respectively, indicating the increased incompressibility of Ca 3 N 2 under high pressure. The phase sequence observed in Ca 3 N 2 is in accordance with the systematic behavior of C f B f A phase transitions occurring in most sesquioxides.