More Like this

1. Photonic Crystal Enhanced Microscopy on a 2D Photonic Crystal Surface

   https://doi.org/10.1002/admt.202401837  

   Liu, Weinan; Li, Siyan; Chow, Edmond; Bhaskar, Seemesh; Fang, Ying; Cunningham, Brian T (January 2025, Advanced Materials Technologies)

   Abstract Digital‐resolution biosensing based on resonant reflection from photonic crystals (PC) has demonstrated significant potential for detection of proteomic and genomic biomarkers in serology, infectious disease diagnostics, and cancer diagnostics. An important intrinsic characteristic of resonant metamaterial surfaces is that enhanced electromagnetic fields are not uniformly distributed, resulting in spatially variable light‐matter interactions with nanoparticle tags that signal the presence of biomarker molecules. In this work, the spatial uniformity of resonantly enhanced, surface‐confined electromagnetic fields of a 1D PC is compared with a 2D PC with fourfold symmetry. When illuminated with unpolarized light, the simultaneously excited electromagnetic fields of transverse electric and transverse magnetic modes of the 2D PC present equally strong but complementary spatial distribution, leading to a >100% increased average near‐field intensity accompanied with a >50% compressed standard deviation compared to the 1D PC. Utilizing Photonic Resonator Absorption Microscopy (PRAM) to experimentally measure the absorption uniformity of ≈80 nm gold nanoparticles distributed upon the PC surface, a >100% improvement of the signal uniformity is observed when using the 2D PC. Overall, improvement in AuNP detection contrast, uniformity, and point spread function is demonstrated by PRAM performed upon a 2D PC surface. 

   more » « less
2. Liquid Crystal Colloids

   https://doi.org/10.1146/annurev-conmatphys-033117-054102  

   Smalyukh, Ivan I. (March 2018, Annual Review of Condensed Matter Physics)
3. Antiferroelectrics: History, fundamentals, crystal chemistry, crystal structures, size effects, and applications

   https://doi.org/10.1111/jace.17834  

   Randall, Clive_A; Fan, Zhongming; Reaney, Ian; Chen, Long‐Qing; Trolier‐McKinstry, Susan (May 2021, Journal of the American Ceramic Society)

   Abstract Antiferroelectric (AFE) materials are of great interest owing to their scientific richness and their utility in high‐energy density capacitors. Here, the history of AFEs is reviewed, and the characteristics of antiferroelectricity and the phase transition of an AFE material are described. AFEs are energetically close to ferroelectric (FE) phases, and thus both the electric field strength and applied stress (pressure) influence the nature of the transition. With the comparable energetics between the AFE and FE phases, there can be a competition and frustration of these phases, and either incommensurate and/or a glassy (relaxor) structures may be observed. The phase transition in AFEs can also be influenced by the crystal/grain size, particularly at nanometric dimensions, and may be tuned through the formation of solid solutions. There have been extensive studies on the perovskite family of AFE materials, but many other crystal structures host AFE behavior, such as CuBiP₂Se₆. AFE applications include DC‐link capacitors for power electronics, defibrillator capacitors, pulse power devices, and electromechanical actuators. The paper concludes with a perspective on the future needs and opportunities with respect to discovery, science, and applications of AFE. 

   more » « less
4. In situ observation of coalescence of nuclei in colloidal crystal-crystal transitions

   https://doi.org/10.1038/s41467-023-40627-w  

   Peng, Yi; Li, Wei; Still, Tim; Yodh, Arjun G; Han, Yilong (December 2023, Nature Communications)

   Abstract Coalescence of nuclei in phase transitions significantly influences the transition rate and the properties of product materials, but these processes occur rapidly and are difficult to observe at the microscopic scale. Here, we directly image the coalescence of nuclei with single particle resolution during the crystal-crystal transition from a multilayer square to triangular lattices. The coalescence process exhibits three similar stages across a variety of scenarios: coupled growth of two nuclei, their attachment, and relaxation of the coalesced nucleus. The kinetics vary with nucleus size, interface, and lattice orientation; the kinetics include acceleration of nucleus growth, small nucleus liquefaction, and generation/annihilation of defects. Related mechanisms, such as strain induced by nucleus growth and the lower energy of liquid-crystal versus crystal-crystal interfaces, appear to be common to both atomic and colloidal crystals. 

   more » « less
5. Crystal Shape Control on the Repacking and Jamming of Crystal‐Rich Mushes

   https://doi.org/10.1029/2022GL100040  

   Hoyos, Susana; Florez, Darien; Pec, Matej; Huber, Christian (October 2022, Geophysical Research Letters)

   Abstract The rheology of crustal mushes is a crucial parameter controlling melt segregation and magma flow. However, the relations between mush dynamics and crystal size and shape distribution remain poorly understood because of the complexity of melt‐crystal and crystal‐crystal interactions. We performed analog experiments to characterize the mechanisms that control pore space reduction associated with repacking. Three suspensions of monodisperse particles with different geometries and aspect ratios (1:1, 2:1, 4:1) in a viscous fluid were tested. Our results show that particle aspect ratios strongly control the melt extraction processes. We identify two competing mechanisms that enable melt extraction at grain scale. The first mechanism leads to continuous deformation and melt extraction and is associated with “diffuse” frictional dissipation between neighboring particles. The second is stochastic, localized, and nearly instantaneous and is associated with the development and destruction of force chains percolating through the granular assembly. 

   more » « less