The dielectric properties and structural behavior of perovskite-related CaCu3Ti4O12 were studied at high temperatures. The dielectric constant increases gradually with increasing temperature and shows a shoulder-like round anomaly at approximately 630 K at 10 kHz. At 732 K, a new dielectric anomaly was found, where the peak value of the dielectric constant, εpeak≃2.8×106 at a frequency of 10 kHz. The lattice constant and X-ray intensity of the (880) reflection also exhibit an anomaly at 732 K. These findings indicate that CaCu3Ti4O12 undergoes a structural phase transition at 732 K.

The most anti-aromatic 16p porphyrin, an octaethylporphyrin (OEP) zinc(II) complex with no substituents at the meso-positions was generated as a highly unstable species from the reaction of the corresponding 18p porphyrin using strong oxidants such as AgSbF 6 /I 2 or SbF 5 . The porphyrin showed a significant blue-shift unique to 16p porphyrins in its UV-vis spectrum. 1 H NMR measurements revealed an evident high-field shift of the meso-protons of the porphyrin ring, thereby establishing that the novel 16p porphyrin has the strongest anti-aromaticity reported so far.

The dielectric behavior of the Bi-layered perovskite oxides Sr2Bi4Ti5O18 and Pb2Bi4Ti5O18 with five perovskite-like units (m=5) was studied. A new anomaly was found at T 1=428 K for Sr2Bi4Ti5O18 and 480 K for Pb2Bi4Ti5O18, in addition to the previously reported phase transition at T c. The dielectric constant does not show the Curie–Weiss behavior in both Sr2Bi4Ti5O18 and Pb2Bi4Ti5O18 crystals: the anomaly around T c is diffuse and broad, whereas those at T 1 are clearly shoulderlike. These two isomorphous layered-oxide ferroelectrics undergo a new intermediate phase transition at T 1. The transition temperatures show a linear dependence on the ionic radii of A-site ions in these layered perovskites.

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