Liquid crystal mesophases beyond commensurate four-layer periodicity

Journal Article · Fri Jan 02 04:00:00 EST 2015 · Liquid Crystals Reviews

DOI:https://doi.org/10.1080/21680396.2015.1030462· OSTI ID:1354418

Huang, C. C.; Wang, Shun; Pan, LiDong; Liu, Z. Q.; McCoy, B. K.; Sasaki, Yuji; Ema, Kenji; Barois, P.; Pindak, Ron

For more than one decade, SMC*_d4, SmC*_d3, and SmC*_A were the only three confirmed commensurate SmC* variant phases with periodicities less than or equal four layers. In 2006, employing ellipsometry and resonant X-ray diffraction (RXRD), our research team first discovered a new liquid crystal mesophase having a six-layer periodicity in one ternary mixture which includes one sulfur-containing compound. From our ellipsometric results, this phase showed antiferroelectric-like optical response. This novel discovery inspired renewed interest to search for liquid crystal mesophases with commensurate periodicities greater than four layers. Soon after, another mesophase having a six-layer structure and showing a ferrielectric-like dielectric response, instead, was uncovered by RXRD measurements on a different binary mixture which has one bromine-containing compound. Meanwhile mesophases having a 5-, 8-, 12- or 15-layer periodicity were reported. However, numerous questions remain to be addressed associated with these unusual reported phases. Theoretical models giving rise to mesophases with periodicities greater than four layers have been developed; but, to date, none of them have provided satisfactory explanations of all the physical phenomena related to the mesophases exhibiting a six-layer structure. Moreover, the question “what is the source of long-range interactions between liquid-like smectic layers, which are responsible for establishing mesophases with long periodicities and mean-field behavior of the smectic-A–smectic-C transition?” remains unanswered for more than three decades.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• OSTI ID: 1354418
• Report Number(s): BNL--112935-2016-JA
• Journal Information: Liquid Crystals Reviews, Journal Name: Liquid Crystals Reviews Journal Issue: 1 Vol. 3; ISSN 2168-0396
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
SmC* variant phases
SmC*d6
null-transmission ellipsometry
resonant X-ray diffraction