We study the phase diagram of the triangular-lattice Q-state Potts model in the real (Q, v)-plane, where v = e J − 1 is the temperature variable. Our first goal is to provide an obviously missing feature of this diagram: the position of the antiferromagnetic critical curve. This curve turns out to possess a bifurcation point with two branches emerging from it, entailing important consequences for the global phase diagram. We have obtained accurate numerical estimates for the position of this curve by combining the transfer-matrix approach for strip graphs with toroidal boundary conditions and the recent method of critical polynomials. The second goal of this work is to study the corresponding A p−1 RSOS model on the torus, for integer p = 4, 5,. .. , 8. We clarify its relation to the corresponding Potts model, in particular concerning the role of boundary conditions. For certain values of p, we identify several new critical points and regimes for the RSOS model and we initiate the study of the flows between the corresponding field theories.
Lead zirconate titanate (PZT) thin film was formed on Pt/Ta/Si3N4/Si(100) substrate at 400 °C by sputtering and then annealed at 650 °C in air. The PZT film was 1 μm thick and had dielectric permittivity of 980, loss tangent of 0.05, remanent polarization of 31 μC/cm2, and coercive field of 110 kV/cm. Piezoelectric property of the film formed on silicon cantilever was estimated from the converse effect. Poling at 5 kV/mm increased the property by a factor of 1.2 to 3.4, resulting in converse piezoelectric constant (d31) varying from −84 to −102 pC/N.
Optically active novel N-propargylamides bearing azobenzene, (R)-HC⋮CCH2NHCOCH(CH3)O-1,4-C6H4−NN−C6H5 (1a), (R)-HC⋮CCH2NHCOCH(CH3)O-1,4-C6H4−NN-1‘,4‘-C6H4-n-hexyl (1b), (R)-HC⋮CCH2NHCOCH(CH2C6H5)O-1,4-C6H4−NN−C6H5 (2a), (R)-HC⋮CCH2NHCOCH(CH2C6H5)O-1,4-C6H4−NN-1‘,4‘-C6H4-n-hexyl (2b), and (R)-HC⋮CCH2NHCOCH(C6H5)O-1,4-C6H4−NN−C6H5 (3) were synthesized
and polymerized with [(nbd)RhCl]2 as a catalyst to obtain the corresponding polymers with moderate molecular
weights (M
n = 6900−44 000) in 46−99% yields. Polarimetric, CD, UV−vis, NOE−NMR, and IR spectroscopic
studies demonstrated that the resulting polymers took a helical structure with predominantly one-handed screw
sense stabilized by intramolecular hydrogen bonding between the amide groups in the side chains in various
solvents. The CD spectra simulated by molecular orbital calculation well agreed with the experimental ones, and
indicated the arrangement of azobenzene moieties in a mutual chiral geometry of one-handed screw sense. The
trans-azobenzene in the side chain isomerized into the cis form upon UV irradiation, while the helical structure
of the main chain was not affected so much. The cis-azobenzene reisomerized into the trans form upon visible-light irradiation, which induced a recovery of chiral geometry of azobenzene moieties in the side chain. Poly(1b)
formed a cholesteric liquid crystal.
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