Editing Liquid crystal (section)

====Blue phases====
Blue phases are liquid crystal phases that appear in the temperature range between a [[Chirality (chemistry)|chiral]] [[nematic]] phase and an [[Isotropy|isotropic]] liquid phase. Blue phases have a regular three-dimensional cubic structure of defects with [[Crystal structure|lattice]] periods of several hundred nanometers, and thus they exhibit selective [[Bragg's law|Bragg reflections]] in the wavelength range of visible light corresponding to the [[Cubic phase|cubic lattice]]. It was theoretically predicted in 1981 that these phases can possess icosahedral symmetry similar to [[quasicrystal]]s.<ref>{{cite journal | title = Lattice Textures in Cholesteric Liquid Crystals | vauthors = Kleinert H, Maki K | author-link = Hagen Kleinert | journal = Fortschritte der Physik | volume = 29 | issue = 5 | pages = 219–259 | date = 1981 | doi = 10.1002/prop.19810290503 | url = http://www.physik.fu-berlin.de/~kleinert/75/75.pdf | bibcode = 1981ForPh..29..219K | access-date = October 7, 2011 | archive-date = April 26, 2020 | archive-url = https://web.archive.org/web/20200426005943/http://users.physik.fu-berlin.de/~kleinert/75/75.pdf | url-status = live }}</ref><ref>{{cite journal|url=http://chemgroups.northwestern.edu/seideman/Publications/The%20liquid-crystalline%20blue%20phases.pdf|title=The liquid-crystalline blue phases|journal=Rep. Prog. Phys.|volume=53|date=1990|pages=659–705|bibcode=1990RPPh...53..659S|doi=10.1088/0034-4885/53/6/001|vauthors=Seideman T|issue=6|citeseerx=10.1.1.397.3141|s2cid=250776819|access-date=October 7, 2011|archive-date=March 30, 2012|archive-url=https://web.archive.org/web/20120330204736/http://chemgroups.northwestern.edu/seideman/Publications/The%20liquid-crystalline%20blue%20phases.pdf|url-status=live}}</ref>

Although blue phases are of interest for fast light modulators or tunable [[photonic crystal]]s, they exist in a very narrow temperature range, usually less than a few [[kelvin]]s. Recently the stabilization of blue phases over a temperature range of more than 60&nbsp;K including room temperature (260–326&nbsp;K) has been demonstrated.<ref>{{cite journal | vauthors = Coles HJ, Pivnenko MN | s2cid = 4307675 | title = Liquid crystal 'blue phases' with a wide temperature range | journal = Nature | volume = 436 | issue = 7053 | pages = 997–1000 | date = August 2005 | pmid = 16107843 | doi = 10.1038/nature03932 | bibcode = 2005Natur.436..997C }}</ref><ref>{{cite journal | vauthors = Yamamoto J, Nishiyama I, Inoue M, Yokoyama H | s2cid = 4432184 | title = Optical isotropy and iridescence in a smectic 'blue phase' | journal = Nature | volume = 437 | issue = 7058 | pages = 525–8 | date = September 2005 | pmid = 16177785 | doi = 10.1038/nature04034 | bibcode = 2005Natur.437..525Y }}</ref> Blue phases stabilized at room temperature allow electro-optical switching with response times of the order of 10<sup>−4</sup>&nbsp;s.<ref>{{cite journal | vauthors = Kikuchi H, Yokota M, Hisakado Y, Yang H, Kajiyama T | s2cid = 31419926 | title = Polymer-stabilized liquid crystal blue phases | journal = Nature Materials | volume = 1 | issue = 1 | pages = 64–8 | date = September 2002 | pmid = 12618852 | doi = 10.1038/nmat712 | bibcode = 2002NatMa...1...64K }}</ref> In May 2008, the first [[Blue Phase Mode LCD|blue phase mode LCD]] panel had been developed.<ref>{{cite news| url = http://www.physorg.com/news129997960.html| title = Samsung Develops World's First 'Blue Phase' Technology to Achieve 240&nbsp;Hz Driving Speed for High-Speed Video| access-date = April 23, 2009| archive-date = March 15, 2012| archive-url = https://web.archive.org/web/20120315124810/http://www.physorg.com/news129997960.html| url-status = live}}</ref>

Blue phase crystals, being a periodic cubic structure with a bandgap in the visible wavelength range, can be considered as [[Photonic crystal|3D photonic crystals]]. Producing ideal blue phase crystals in large volumes is still problematic, since the produced crystals are usually polycrystalline (platelet structure) or the single crystal size is limited (in the micrometer range). Recently, blue phases obtained as ideal 3D photonic crystals in large volumes have been stabilized and produced with different controlled crystal lattice orientations.<ref>{{cite journal | vauthors = Otón E, Yoshida H, Morawiak P, Strzeżysz O, Kula P, Ozaki M, Piecek W | title = Orientation control of ideal blue phase photonic crystals | journal = Scientific Reports | volume = 10 | issue = 1 | pages = 10148 | date = June 2020 | pmid = 32576875 | pmc = 7311397 | doi = 10.1038/s41598-020-67083-6 | bibcode = 2020NatSR..1010148O }}</ref>