A new 1:1 mixed-stack organic charge-transfer crystal of 2,6-dimethyltetrathiafulvalene-p-chloranil (DMTTF-CA), which undergoes a temperature-induced neutral-ionic transition (TINIT), was reported.At a critical temperature of 65+5 K the molecular ionicity and the stack dimerization were found to change discontinuously.A most striking feature in the phase transition of DMTTF-CA was that a neutral-ionic coexisting phase did appear at lower temperatures, unlike the homogeneous ionic phase observed for the TINIT of tetrathiafulvalene-p-chloranil (TTF-CA). These transition characteristics were discussed by taking into account the structural differences between these two complexes composed of similar constituents.

A mixed-stack organic charge-transfer crystal of 2-chloro-5-methyl-p-phenylenediamine-2,5-dimethyldicyanoquinonediimine ͑ClMePD-DMeDCNQI͒, which undergoes a temperature-induced neutral-ionic transition ͑TINIT͒, is reported. From infrared spectroscopy, the molecular ionicity ͑͒ of ClMePD-DMeDCNQI was found to change continuously from ϭ0.3 at 300 K to ϭ0.6 at 100 K. The neutral-ionic interface was crossed without a discontinuity in at around 200 K, accompanied by stack dimerization. These features were quite different from the discontinuous change in observed for the TINIT of tetrathiafulvalene-p-chloranil ͑TTF-CA͒ and tetramethylbenzidine-tetracyanoquinodimethane ͑TMB-TCNQ͒. The transition characteristics in ClMePD-DMeDCNQI are discussed by drawing a comparison with those seen in TTF-CA and TMB-TCNQ.

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A new chemical vapor deposition technique has been developed for rapid (max. 24 µm/h) formation of the oxide superconductor film on a metal substrate. In this system, blended β-diketonate chelates of source materials were slowly fed to the vaporizer with carrier gas. The source gas from the vaporizer and O2 gas were introduced into the reactor. We realized a superconducting YBCO thin film that had a T c=87 K on a Hastelloy C-276 substrate.