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Quasicrystal

A quasicrystal is a solid material whose atoms are arranged in an ordered pattern that exhibits long-range orientational order but lacks the translational periodicity of traditional crystals, resulting in a discrete pattern without repeating units. This structure allows for forbidden rotational symmetries, such as fivefold or tenfold, which were once considered impossible under classical crystallographic rules. The discovery of quasicrystals revolutionized when Israeli chemist observed a tenfold pattern in an using on April 8, 1982, while working at the National Institute of Standards and Technology (NIST) in the United States. Despite initial skepticism and controversy—Shechtman faced ridicule for challenging the prevailing definition of as materials with periodic atomic lattices—his findings were published in in November 1984, co-authored with Ilan , John W. Cahn, and Denis Gratias. For this breakthrough, Shechtman was awarded the in 2011, recognizing how quasicrystals expanded the understanding of solid-state order and prompted the International Union of Crystallography to redefine a in 1992 as any solid with a discrete diagram. Quasicrystals exhibit unique physical properties, including high hardness coupled with brittleness, low electrical and thermal conductivity, corrosion resistance, and low leading to non-stick behavior. Their atomic arrangements often correlate with the (approximately 1.618), manifesting self-similar patterns akin to Penrose tilings, and they can be modeled using higher-dimensional projections. Initially synthesized in metallic alloys through rapid cooling, quasicrystals have since been observed in diverse systems, including polymers, dendrimers, and nanoparticles, with natural examples identified starting with in 2009 from a in Russia's Khatyrka River, followed by additional extraterrestrial quasicrystals in the same in 2015 and 2016, and the first terrestrial example formed by in in 2023. These materials find practical applications in durable, low-friction coatings for blades, surgical instruments, and cookware, as well as potential uses in thermoelectric devices and advanced alloys.

Fundamentals

Definition and Characteristics

Quasicrystals are a of solid-state materials characterized by long-range orientational and quasiperiodic translational , which produces discrete sharp peaks indicative of atomic-scale organization without three-dimensional periodicity. This quasiperiodicity arises from arrangements where the positions of atoms follow a that repeats only after irrational multiples of certain lengths, distinguishing quasicrystals from both periodic crystals and disordered amorphous solids. Unlike amorphous materials, which exhibit diffuse due to the absence of long-range , quasicrystals display well-defined Bragg peaks, confirming their ordered nature despite the lack of a conventional repeating . A defining feature of quasicrystals is their possession of rotational symmetries that are incompatible with translational periodicity, such as five-fold, eight-fold, or ten-fold axes, which are forbidden in traditional under classical crystallographic restrictions. These symmetries manifest in specific s, including icosahedral quasicrystals with symmetry m35 (featuring six intersecting five-fold axes), decagonal phases with ten-fold along one axis, and octagonal phases with eight-fold symmetry. The icosahedral , for instance, requires a six-dimensional description to model its aperiodic structure, as its pattern cannot be indexed using three independent basis vectors alone. In comparison to conventional crystals, which combine translational periodicity with to form infinite lattices describable by 230 space groups, quasicrystals sacrifice translational repetition for enhanced rotational complexity, resulting in aperiodic tilings that fill space without gaps or overlaps. This structural distinction leads to unique physical behaviors, though quasicrystals retain the sharpness of diffraction signals typical of ordered solids.

Basic Physical Properties

Quasicrystals display distinctive mechanical properties arising from their aperiodic atomic arrangement, including high hardness and pronounced brittleness at room temperature. These materials often exhibit Vickers hardness values comparable to or exceeding those of conventional intermetallic compounds, often exceeding 5 GPa for icosahedral Al-Pd-Mn phases, making them promising for wear-resistant coatings. However, their brittleness limits plastic deformation, with bulk samples fracturing without significant yielding under tensile loads. This is accompanied by low fracture toughness, typically on the order of $0.8 \, \mathrm{MPa \cdot m^{1/2}} for Al-Cu-Cr icosahedral quasicrystals in composites, far below that of ductile metals like aluminum alloys (around 20-30 MPa·m^{1/2}}). Additionally, anisotropic elasticity emerges due to phason strains—diffusive rearrangements of atoms that couple to phonon modes—resulting in direction-dependent elastic moduli and wave propagation behaviors distinct from periodic crystals. In terms of thermal and electrical properties, quasicrystals generally show low conductivities relative to crystalline metals, a consequence of enhanced phonon and electron scattering by the aperiodic lattice. Thermal conductivity values are modest, often 1-5 W/m·K at room temperature for Al-based icosahedral phases, resembling amorphous glasses rather than ordered metals (which can exceed 100 W/m·K}), and it decreases with rising temperature above ambient conditions. Electrical conductivity is similarly reduced, with resistivities ranging from 100-5000 µΩ·cm—higher than pure metals (e.g., copper at ~1.7 µΩ·cm) but lower than semiconductors—leading to metallic yet inefficient charge transport. These traits stem from the lack of long-range translational symmetry, which disrupts mean-free paths for heat and charge carriers. Optically, quasicrystalline structures and their approximations demonstrate unique photonic bandgaps, frequency ranges where electromagnetic wave propagation is forbidden, due to their high rotational symmetries. Experimental realizations of icosahedral photonic quasicrystals, such as centimeter-scale structures fabricated via , reveal complete, spherically symmetric stop gaps in spectra, with gap widths up to several percent of the central frequency, outperforming some periodic photonic crystals in . These properties arise from the quasiperiodic ordering, enabling robust bandgap formation without the defects common in periodic lattices. Quasicrystals are predominantly metastable phases, requiring non-equilibrium conditions for formation and tending to transform into crystalline upon annealing. They typically nucleate under rapid cooling rates, such as 100 or higher, suppressing competing periodic phases. Natural examples, like in meteorites, form under extreme high pressures (above 5 GPa) and temperatures (over 1000°C) during shock events, stabilizing the aperiodic structure in otherwise unstable compositions. Stable quasicrystals exist in select systems like Al-Li-Cu, but most remain metastable, highlighting their kinetic rather than thermodynamic preference.

Historical Development

Discovery and Initial Controversy

In 1982, while working at the National Bureau of Standards (now NIST), Israeli materials scientist observed an unusual pattern during experiments on a rapidly solidified aluminum- containing approximately 14 atomic percent . The pattern displayed sharp peaks arranged in a tenfold , which violated the traditional crystallographic restriction that rotational symmetries in are limited to twofold, threefold, fourfold, or sixfold. Shechtman's colleagues, including his advisor Cahn, initially dismissed the result as an artifact, such as twinning of conventional or experimental error, leading Shechtman to spend two years seeking confirmation and facing professional isolation. The discovery sparked intense controversy within the community, as it challenged the foundational tenet that all solids with long-range order must exhibit . Prominent chemist , a two-time Nobel laureate, vehemently opposed the findings, publicly deriding them by stating, "There is no such thing as quasicrystals, only quasi-scientists," and attributing the patterns to multiple twinning of periodic crystals. Shechtman and his collaborators struggled to publish their work; the paper was rejected by Acta Crystallographica and other journals before being accepted by in November 1984, where it appeared under the title "Metallic Phase with Long-Range Orientational Order and No ." This publication introduced the term "icosahedral phase" and documented the forbidden symmetry, igniting a despite ongoing skepticism. Early independent confirmations began to emerge in , bolstering Shechtman's claims. For instance, researchers observed similar icosahedral patterns in other aluminum-based alloys, such as Al-Mn-Si, through electron microscopy and , ruling out artifacts in multiple laboratories. By 1987, further syntheses confirmed stable icosahedral phases, notably in the Al-Cu-Fe ternary system, where large single-domain samples were produced via , demonstrating thermal stability up to 800°C. These developments, including structural analyses by groups like those led by A.P. Tsai, shifted the debate toward acceptance, highlighting quasicrystals as a new class of ordered materials and prompting revisions in crystallographic theory.

Recognition and Natural Examples

The discovery of quasicrystals faced significant initial skepticism but gained formal scientific recognition over time, culminating in the 2011 awarded to for his pioneering observation of quasicrystalline order in an aluminum-manganese alloy, which challenged the long-held requiring translational periodicity in crystals. This accolade highlighted the paradigm shift from exclusively periodic crystal structures to aperiodic ones exhibiting long-range order and sharp diffraction patterns, validating quasicrystals as a new class of solids. The first naturally occurring quasicrystal was discovered in 2009 within fragments of the Khatyrka meteorite, a CV3 carbonaceous chondrite collected in Russia's Koryak Mountains, with the icosahedral phase named icosahedrite and composition Al63Cu24Fe13. Isotopic analysis confirmed its extraterrestrial origin, forming under high-pressure and high-temperature conditions in the early solar system approximately 4.5 billion years ago, and it remains embedded in a matrix of unusual aluminum-copper-iron alloys. Subsequent searches yielded additional natural examples under extreme terrestrial conditions, including an icosahedral quasicrystal (Si61Cu30Ca7Fe2) discovered in 2021 within red trinitite glass from the 1945 Trinity nuclear test site in New Mexico, formed by the intense heat and shock of the detonation. In 2023, a dodecagonal quasicrystal with 12-fold rotational symmetry was found in fulgurite—a glassy tube produced by a lightning strike—within a sand dune in Nebraska's Sand Hills region, composed primarily of silica (SiO2) and exhibiting aperiodic atomic arrangements impossible in conventional crystals. In 2024, researchers reported an icosahedral quasicrystal composed of Al-Cu-Fe-Si in a micrometeorite recovered from southern Italy, further evidencing their occurrence in extraterrestrial materials. These findings demonstrate that quasicrystals can form naturally via astrophysical impacts, explosive shocks, or electrical discharges, suggesting they may not be as rare as initially thought and could have played roles in processes. Recent analyses of micrometeorites, including Al-Cu alloys akin to those in Khatyrka, indicate potential prevalence in primitive solar system materials, hinting at broader distribution during the nebula's turbulent early phases.

Mathematical Foundations

Aperiodic Tilings and Order

The concept of aperiodic tilings originated with the work of , who in 1961 introduced square tiles with colored edges, known as , to explore decidability in logical systems and for theorem proving. conjectured that if a of such tiles could the plane without gaps or overlaps, it must admit a periodic tiling. This conjecture implied the domino problem—determining whether a given tile set tiles the plane—was decidable. In 1966, Robert Berger disproved Wang's conjecture by constructing the first aperiodic tile set, consisting of over 20,000 Wang tiles that tile the plane only non-periodically, thereby proving the undecidability of the domino problem. Berger's construction embedded simulations of Turing machines into the tiling rules, showing that no algorithm could universally determine tilability. This result established the existence of aperiodic sets, paving the way for simpler examples that enforce non-periodicity through local matching rules rather than undecidability proofs. Building on this foundation, developed two-dimensional aperiodic tilings in the 1970s. In 1974, Penrose introduced a set of two prototiles—a thin and a thick —with specific matching rules on their edges that forbid periodic arrangements while allowing complete coverage of the . These rules ensure that tiles must align in ways that generate fivefold , preventing translational repetition. By 1978, Penrose refined this to a pair of "kite" and "dart" prototiles, again with matching rules that enforce aperiodicity through hierarchical inflation rules, producing self-similar patterns at multiple scales. These Penrose tilings serve as prototypical models for quasicrystalline order in two dimensions, demonstrating long-range order without periodicity. For three-dimensional icosahedral quasicrystals, the projection method from higher-dimensional provides a generalization of aperiodic tilings. This cut-and-project approach, independently developed in 1985 by Michel Duneau and A. Katz, involves selecting a in a six-dimensional cubic and projecting the points onto a three-dimensional to the , followed by a to define atomic positions. The irrational orientation of the ensures dense, non-repeating packing with icosahedral , mimicking the atomic arrangement in quasicrystals. This method guarantees a well-defined and without periodic repetition, extending the principles of two-dimensional aperiodic sets to higher dimensions. Ideal quasicrystals are characterized by a pure point diffraction spectrum, meaning their consists solely of delta functions at positions, indicating perfect long-range order despite aperiodicity. This property arises from the model set structure in the projection method, where the diffraction intensities are determined by the higher-dimensional . Deviations from ideality introduce defects such as phason flips, which are local rearrangements of atoms corresponding to shifts in the internal of the higher-dimensional description. Phason flips act as dislocations in the perpendicular space, leading to phason strain that disrupts the pure point spectrum by broadening peaks or introducing diffuse scattering.

Diffraction Patterns and Symmetry Analysis

One of the defining experimental signatures of quasicrystals is their patterns, which display sharp, discrete Bragg peaks in , indicating long-range order, even though the real-space arrangement lacks translational periodicity. This quasiperiodic order results in a dense set of directions, with the of the module determining the dimensionality required for full description—typically higher than the physical . For instance, in icosahedral quasicrystals, the pattern consists of a of delta-function peaks forming a -6 module, densely filling without gaps or overlaps. These patterns reveal rotational symmetries forbidden in conventional crystals, such as five-fold (icosahedral), eight-fold (octagonal), and twelve-fold (dodecagonal) axes, which manifest as rings of spots or pentagonal arrangements in electron or diffraction. Analysis via transforms confirms these symmetries; for example, the in icosahedral quasicrystals exhibits icosahedral (m\bar{3}5), with peaks indexed to verify the absence of periodicity while preserving orientational order. In the original Al-Mn quasicrystal, ten-fold symmetry axes were observed, later refined to icosahedral, ruling out multiple twinning as an explanation. To index these peaks systematically, quasicrystal is modeled as a of a higher-dimensional periodic onto physical space, commonly six dimensions for icosahedral cases. The vector \mathbf{G} is then given by \mathbf{G} = \sum_{i=1}^6 h_i \mathbf{b}_i, where h_i are indices and \mathbf{b}_i are the basis vectors of the six-dimensional , often aligned with icosahedral directions and scaled by the \tau = (1 + \sqrt{5})/2. This approach, introduced in early theoretical models, allows precise assignment of observed peaks, such as in i-Al-Cu-Fe, where the six-dimensional is approximately 6.32 in primitive setting. For non-icosahedral quasicrystals, like decagonal, five or six dimensions suffice, with basis vectors rotated by multiples of $2\pi/n for n-fold . Structural analysis employs adapted crystallographic tools, including Patterson functions to map interatomic correlations in higher dimensions and Debye-Waller factors to account for thermal and phason fluctuations. The Patterson function in six dimensions reveals the autocorrelation of the electron density, deconvoluting "hyperatoms" into parallel and perpendicular components for refinement. Debye-Waller factors, extended to include phason strains, are expressed as T(\mathbf{H}_\parallel, \mathbf{H}_\perp) = \exp(-2\pi^2 \mathbf{H}^T \langle \mathbf{u} \mathbf{u}^T \rangle \mathbf{H}), where \mathbf{H} combines parallel (phonon) and perpendicular (phason) components, explaining intensity variations and peak broadening in experiments like those on i-Al-Pd-Mn. These methods have enabled high-resolution structure solutions, confirming the projected lattice model.

Synthesis and Materials

Production Techniques

Quasicrystals are primarily synthesized in laboratories through techniques that achieve rapid solidification or extreme conditions to stabilize their aperiodic structures, often requiring cooling rates on the order of 10^6 K/s to suppress the formation of competing crystalline phases. One of the earliest and most widely used methods is , where molten alloys are ejected onto a rotating chilled wheel to produce thin ribbons. This technique was instrumental in the initial discovery of icosahedral quasicrystals in Al-Mn alloys, enabling the formation of metastable phases through high cooling rates that prevent atomic rearrangement into periodic lattices. For example, in Al-Cu-Fe systems, melt spinning at rates of 5–7 × 10^4 °C/s yields ribbons containing significant fractions of icosahedral quasicrystalline phases embedded in an aluminum matrix. Alternative synthesis routes include mechanical alloying, which involves high-energy ball milling of elemental powders to induce solid-state reactions and form quasicrystalline phases without melting. This method has successfully produced icosahedral structures in Al-Cu-Fe and Al-Cu-Mn compositions by promoting atomic diffusion and disorder-to-order transitions during extended milling times. offers a vapor-phase approach, ablating quasicrystalline with pulsed lasers to deposit thin films or nanoparticles; for instance, KrF of Al-Pd-Mn results in quasicrystalline films when substrate temperatures are controlled to favor aperiodic growth. High-pressure synthesis, such as shock compression using explosive techniques or gas guns, mimics natural formation processes and has generated icosahedral Al-Cu-Fe quasicrystals under pressures exceeding 5 GPa and rapid quenching. Recent advances in 2024–2025 have explored additive , where laser-based of aluminum alloys inadvertently forms quasicrystalline lattices that enhance material strength, opening pathways for engineered aperiodic structures. A key challenge in quasicrystal production is their frequent , necessitating significant undercooling—often 100–200 K below the liquidus temperature—to nucleate the aperiodic before stable crystalline competitors emerge. diagrams for and systems, such as Al-Cu-Fe, reveal narrow compositional windows (e.g., around Al65Cu20Fe15) where the icosahedral is thermodynamically favored, but deviations require precise control to avoid during solidification. For scaling from nanoscale clusters to bulk materials, methods like the Bridgman technique are employed, where alloys are slowly pulled through a to grow large single-domain quasicrystals. This approach has produced centimeter-scale samples in systems like Zn-Mg-Ho, maintaining aperiodic order over extended volumes by minimizing .

Structural Composition of Known Quasicrystals

Quasicrystals exhibit diverse structural compositions, predominantly in metallic alloys where atomic arrangements achieve aperiodic order through cluster-based packing. Common icosahedral quasicrystals include ternary systems such as , where stable phases form around compositions like Al-20%Li-10%Cu, and Al-Mn, often with additions as in Al-Mn-Si for enhanced . Decagonal quasicrystals are exemplified by Al-Ni-Co alloys, typically with compositions near Al70Ni15Co15, which support tenfold along the axis perpendicular to decagonal planes. These structures often incorporate Frank-Kasper polyhedra, which enable efficient tetrahedral close-packing with coordination numbers of 12, 14, 15, or 16, contributing to the overall by minimizing local strain in the aperiodic . Atomic models of quasicrystals emphasize hierarchical arrangements that underpin their long-range . In icosahedral Al-Mn, Mackay icosahedra—55-atom s with icosahedral coordination—serve as building blocks, where a central atom is surrounded by shells of 12 and 42 atoms, facilitating patterns consistent with fivefold . Broader atomic models reveal coordination polyhedra ranging from 12 to 20 nearest neighbors, as seen in various systems, where these polyhedra tile space aperiodically while maintaining local icosahedral environments that enhance thermodynamic stability. Over 100 synthetic quasicrystals have been documented, primarily in metallic systems such as Al-Cu-Fe and rare-earth-based alloys like RE-Au-Al (RE = , ), which exhibit robust icosahedral or octadecagonal phases due to favorable electronic interactions. Natural quasicrystals, rarer still, include (Al63Cu24Fe13) from the Khatyrka , intergrown with khatyrkite (CuAl2) and other Al-Cu-Fe phases, demonstrating formation under high-pressure conditions that stabilize the aperiodic structure. Recent discoveries highlight compositional diversity beyond traditional alloys. In 2022, a dodecagonal quasicrystal with approximate composition Mn_{72}Si_{16}Cr_{10}Al_{2} (at.%) was identified in from a sand dune, formed via lightning-induced electrical discharge, marking the first natural example of dodecagonal on . By 2025, self-dual one-dimensional quasicrystal models, realized in arrays with quasiperiodic hoppings, have been adapted conceptually to solid-state systems, revealing critical phases with multifractal wavefunctions that parallel stability mechanisms in higher-dimensional metallic quasicrystals.

Advanced Phenomena

Electronic and Thermal Behaviors

Quasicrystals exhibit distinctive structures characterized by a pseudogap in the at the , particularly in icosahedral phases, which arises from strong interactions between the and the boundaries induced by the aperiodic lattice. This pseudogap, typically spanning 0.5–1.0 in width and reducing the by 30–50% relative to free-electron models, contributes to the thermodynamic stability of these materials by lowering energy. In icosahedral Al-based quasicrystals such as Al-Pd-Mn and Al-Cu-Fe, the pseudogap has been confirmed through bulk-sensitive hard , distinguishing it from surface-localized features. The presence of this pseudogap often positions these systems near a metal-insulator , where slight compositional tuning, as in Al-Pd-Re quasicrystals, can shift from metallic to insulating behavior at low temperatures, evidenced by tunneling and resistivity measurements. Certain quasicrystals display sp²-like bonding characteristics, stemming from p-d hybridization between aluminum 3p orbitals and d orbitals, which fosters covalent-like interactions within icosahedral clusters and enhances the pseudogap depth. This hybridization, observed in Al-TM systems like Al-Pd-Mn, promotes a metallic-covalent bonding conversion that underlies semimetallic properties and localization at low temperatures. Thermal transport in quasicrystals is markedly suppressed, with room-temperature thermal conductivities typically ranging from 0.5 to 5 W/m·K, far below those of conventional metals, due to extensive from the aperiodic structure and phason modes. Measurements on icosahedral Al-Pd-Mn reveal a positive for thermal conductivity, contrasting crystalline alloys, as dominates over boundary effects. Recent studies on sub-micrometer-scale quasicrystals demonstrate enhanced exceeding 50% strain at , which mitigates phonon scattering pathways and improves heat dissipation compared to bulk forms. Electron and heat in quasicrystals are modeled using a generalized Boltzmann that incorporates phason-electron coupling, accounting for the diffusive motion of phasons that scatters electrons and alters . This coupling term, gs(k1, k2), introduces relaxation-time approximations that explain the observed linear-in-T resistivity in systems like Ag-In-Yb. In the Au-Al-Yb icosahedral quasicrystal, properties exhibit quantum critical behavior with near unity (β ≈ 0.94–0.97) for resistivity and under pressure, indicating non-Fermi liquid characteristics without fine-tuning. A 2025 quantum-mechanical of quasicrystalline demonstrates their inherent through global energy minimization, revealing that aperiodic arrangements achieve lower total energies than competing crystalline phases via optimized electron-phonon interactions. This density functional theory-based approach confirms the pseudogap's role in stabilizing nanoparticle configurations, providing mechanistic insight into their formation and persistence.

Magnetic and Quantum Effects

In quasicrystals, magnetic order has long been considered challenging due to their aperiodic lattices, which frustrate conventional spin alignments. However, in 2025, researchers observed long-range antiferromagnetic order in the rare-earth-based icosahedral quasicrystal , marking the first definitive evidence of such ordering in a real quasicrystal. This discovery defies expectations for aperiodic structures, where geometric typically suppresses magnetic coherence, and was confirmed through showing a propagation vector consistent with icosahedral . The positive Curie-Weiss in this system suggests that rare-earth quasicrystals with specific compositions may preferentially stabilize , opening avenues for exploring in non-periodic environments. Quantum critical phenomena in quasicrystals further highlight their unique potential, with the Au-Al-Yb icosahedral quasicrystal exhibiting divergent at low temperatures, indicative of a without external tuning. This behavior arises from intermediate-valence Yb ions, leading to non-Fermi liquid properties and enhanced effective masses akin to heavy systems, despite the absence of periodicity. Such heavy -like characteristics persist in the quasicrystal's electronic structure, complementing the pseudogap observed in its charge transport. These findings underscore how aperiodicity can foster quantum criticality through frustrated interactions, distinct from periodic heavy materials. Recent advances in 2025 have expanded quantum effects in quasicrystals to photonic and other systems. In photonic quasicrystals, exciton-polaritons—hybrid light-matter quasiparticles—were realized in Penrose-tiled structures, enabling reconfigurable quantum fluids with topological protection against disorder. Additionally, self-dual one-dimensional quasicrystal chains were modeled with arbitrary-range hoppings, hosting multifractal critical phases protected by duality symmetries, as demonstrated in Rydberg-atom array simulations. Theoretically, a 2025 quantum-mechanical model resolved the 40-year debate on quasicrystal by showing that their aperiodic ground states exhibit degeneracy comparable to crystals, with barriers low enough for thermodynamic formation under realistic conditions. This framework attributes to minimized in quasiperiodic arrangements, explaining the persistence of both synthetic and natural quasicrystals despite their forbidden symmetries.

Applications

Engineering and Materials Uses

Quasicrystals, particularly Al-Cu-Fe alloys, are employed as coatings due to their low and high , providing low-friction and wear-resistant surfaces. These properties make them suitable for non-stick frying pans, where quasicrystalline coatings enhance durability and reduce adhesion compared to traditional materials. In diesel engines, quasicrystalline thermal barrier coatings help mitigate by matching the coefficient of of engine components like and aluminum, thereby improving efficiency and longevity. The high thermal stability and low thermal conductivity of quasicrystals enable their use in insulation applications. For LED dies, quasicrystalline layers provide effective heat management, preventing overheating and extending operational life. In building materials, they offer potential for energy-efficient by maintaining structural integrity at elevated temperatures. Emerging research in 2025 highlights light-matter quasicrystals for efficient , potentially revolutionizing optical devices through enhanced light manipulation. In composites, quasicrystals serve as reinforcements in metal matrices, imparting high without excessive due to their intrinsic low and structural integrity. Recent 2023-2024 studies on aperiodic inspired by quasicrystals demonstrate superior lightweight structures with optimized strength-to-weight ratios for and automotive applications. Despite these advantages, challenges in quasicrystal applications include high production costs from complex methods and issues for large-scale . Recent advances in , such as through aperiodic architected designs, have improved deformability, facilitating broader industrial adoption.

Theoretical and Non-Materials Roles

Quasicrystals have provided foundational models in for understanding disordered systems, bridging the gap between periodic order and chaotic disorder. In these models, quasicrystals serve as archetypes for quasiperiodic structures that exhibit long-range order without translational periodicity, offering insights into the electronic and energetic stability of amorphous materials. For instance, tight-binding approaches applied to binary alloys demonstrate how quasicrystalline arrangements can stabilize disordered configurations that mimic real-world and alloys, revealing universal behaviors in energy level correlations similar to those in weakly disordered metals. Beyond materials, quasicrystals inform by modeling lattices that interpolate between ordered and chaotic regimes, enabling the study of critical phases and self-dual potentials. One-dimensional self-dual quasicrystal models with arbitrary-range hoppings exhibit critical states that resist localization, providing a framework for simulating topological phases in processing. These structures highlight hidden symmetries in higher-dimensional projections, potentially enhancing stability in aperiodic lattices for fault-tolerant quantum computation. In biology, quasicrystals draw analogies to aperiodic structures observed in natural systems, such as the symmetry mismatches in viral capsids. Bacteriophages like HK97 exhibit 12-fold pores at five-fold icosahedral vertices, creating quasiperiodic arrangements that accommodate structural flexibility during DNA packaging and infection, akin to the forbidden rotational symmetries in quasicrystals. Similarly, collagen fibrils display quasicrystalline order, with their triple-helical motifs forming Boerdijk–Coxeter helices that exhibit irrational winding numbers, leading to non-periodic stacking and enhanced mechanical resilience in tissues. Second-harmonic generation microscopy confirms this quasi-crystalline alignment in type I collagen, where birefringence patterns reveal ordered yet aperiodic molecular packing. Interdisciplinary applications extend quasicrystals to optical metamaterials, where their aperiodic enables isotropic responses without compromising strength. Quasicrystalline metasurfaces, fabricated with cut-wire resonators arranged in Penrose-like patterns, exhibit rotationally electromagnetic properties, outperforming periodic lattices in light manipulation for applications like and superlensing. In , 2025 implementations using Rydberg-atom arrays simulate one-dimensional quasicrystals, observing discrete time quasicrystal phases with quasi-periodic oscillations that probe non-equilibrium and entanglement in driven chains. These Rydberg-based platforms allow precise of long-range interactions, facilitating the of localization transitions relevant to quantum simulation. Quasicrystals have inspired aperiodic designs in and , particularly through medieval Islamic tilings that predate discoveries. Girih patterns in 15th-century mosques, such as those in the Darb-i Imam shrine, employ decagonal quasicrystalline geometries with five- and ten-fold symmetries, achieved via strapwork tiles that approximate non-periodic order without repetition. These designs, rooted in affine transformations of decagons, influenced contemporary artists and architects, who adapt quasicrystal motifs for facades and installations to evoke infinite complexity, as seen in works drawing from Penrose tilings.

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