INCOMMENSURATE PHASE-TRANSITION IN 4,4'-DICHLORODIPHENYL SULFONE

The structural phase transition in a 4,4'-dichlorodiphenyl sulfone single crystal was investigated by means of X-ray diffraction. It has been found that the crystal shows the normal-incommensurate phase transition at 150 K with the modulation wavevec-tor q=a* ±(1/5+δ)b*, where a* and b* represent the reciprocal lattice vectors in the normal phase and δ represents the small misfit parameter in the incommensurate phase. No lock-in phase transition was confirmed within the temperature range 20-150 K. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.