Lattice Parameters Research Articles

Boosting photocatalytic H2 evolution in B-doped g-C3N4/O-doped g-C3N4 through synergistic band structure engineering and homojunction formation

Photocatalytic hydrogen production is a promising method to address the increasing energy demand and depletion of fossil fuels. Among various photocatalysts, g-C3N4 (CN) has attracted significant attention due to its favorable properties and tunable band structure. CN-based heterojunctions have been developed to enhance photocatalytic efficiency through improved charge separation via interfacial charge transfer. However, traditional heterojunctions formed between CN and other semiconductors often face challenges related to material compatibility and stability. In this work, we explored the formation of homojunctions, which involve identical semiconductors and offer superior charge separation and electron mobility due to perfect lattice matching. To further enhance individual oxidation and reduction capabilities, we employed band structure engineering through B doping and O doping. The homojunction between B-doped CN (BCN) and O-doped CN (OCN) was successfully synthesized using simple electrostatic self-assembly, resulting in significantly improved hydrogen production of 519.3 μmol g−1h−1 compared to BCN (34.7 μmol g−1h−1) and CN (167.2 μmol g−1h−1). This approach enhances visible light absorption, charge separation, and mobility, demonstrating the potential for developing advanced CN-based photocatalysts for various applications.

Heterogeneous nucleation of calcium sulfate whisker in polyamide 6 and its efficient reinforcement on tribology performance

AbstractFor traditional materials, a polymer composite with high performance and large‐scale production is still the goal pursued by researchers. In our work, polyamide 6/calcium sulfate whiskers (PA6/SCW) composites were fabricated via melt‐compouding method. The calcium sulfate whisker based on gypsum mineral was used as reinforcement. After grafting silane coupling agent on the whisker surface, the whiskers showed a significant reinforcing effect in polyamide. The mechanics and tribology performance of the samples had been significantly inhanced. Based on the nucleation mechanism of lattice matching, calcium sulfate whiskers have obvious heterogeneous nucleation effect in PA6 matrix, while the crystallization period was slightly prolonged. This was caused by the network structure formed by the whiskers in the matrix, which impeded the free movement of polymer chain segments. In combination with the orientation degree of the molecular chains measured by the interdigital electrode, the reinforcing effect of the oriented PA6 specimens was derived from the orientation arrangement of the whiskers and the efficient load transfer.Highlights Mechanical and tribological properties of composite were significantly improved. The composite could achieved large‐scale production due to simple preparation. The whiskers had obvious heterogeneous nucleation effect in matrix. The reinforcing effect was derived from efficient load transfer from whiskers.

Chemochromism and Tunable Acoustic Phonons in Intercalated MoO3: Ag-, Bi-, In-, Mo-, Os-, Pd-, Pt-, Rh-, Ru-, Sb-, and W-MoO3.

Intercalation of several elements (Ag, Bi, In, Mo, Os, Pd, Pt, Rh, Ru, Sb, and W) is used to chemically alter a wide range of properties of two-dimensional layered α-MoO3. Intercalation modifies acoustic phonons and elastic constants, as measured with Brillouin scattering. Intercalation alters electronic bandgaps, color, structure, Raman shifts, and electron binding energies. Optical chemochromism is demonstrated with intercalants changing the color of MoO3 from transparent to brilliant blue (In, Mo, Os, and Ru) and orange (Ag). Correlations are investigated among material properties. There is evidence that in-plane longitudinal stiffness c11 correlates with changes in the bandgap, while various Raman modes appear to be connected to a variety of properties, including shear modulus c55, Mo binding energies, lattice constants, and the preferred crystal structure of the intercalant. The results indicate a surprising degree of complexity, suggesting competition among multiple distinct mechanisms and interactions involving specific intercalant species.

Annealing Behavior of a Mg-Y-Zn-Al Alloy Processed by Rapidly Solidified Ribbon Consolidation

Mg-Y-Zn-Al alloys processed by the rapidly solidified ribbon consolidation (RSRC) technique are candidate materials for structural applications due to their improved mechanical performance. Their outstanding mechanical strength is attributed to solute-enriched stacking faults (SESFs), which can form cluster-arranged layers (CALs) and cluster-arranged nanoplates (CANaPs) or complete the long-period stacking ordered (LPSO) phase. The thermal stability of these solute arrangements strongly influences mechanical performance at elevated temperatures. In this study, an RSRC-processed Mg—0.9%, Zn—2.05%, Y—0.15% Al (at%) alloy was heated at a rate of 0.666 K/s up to 833 K, a temperature very close to melting point. During annealing, in situ X-ray diffraction (XRD) measurements were performed using synchrotron radiation in order to monitor changes in the structure. These in situ XRD experiments were completed with ex situ electron microscopy investigations before and after annealing. At 753 K and above, the ratio of the matrix lattice constants, c/a, decreased considerably, which was restored during cooling. This decrease in c/a could be attributed to partial melting in the volumes with high solute contents, causing a change in the chemical composition of the remaining solid material. In addition, the XRD intensity of the secondary phase increased at the beginning of cooling and then remained unchanged, which was attributed to a long-range ordering of the solute-enriched phase. Both the matrix grains and the solute-enriched particles were coarsened during the heat treatment, as revealed by electron microscopy.

Exploring changes in structural, electronic and elastic properties of TiO2 under pressure: A DFT investigation

Titanium dioxide (TiO2) is a semiconductor material that widely used in numerous applications due to its exceptional physical and chemical properties. This study explores the structural, electronic and elastic properties of TiO2 phases in rutile, anatase and brookite under hydrostatic pressure up to 100 GPa. At 0 GPa, the computed lattice parameters and volumes align closely with experimental data. The band structure reveals that rutile and brookite exhibit direct band gaps while anatase shows an indirect band gap. Elastic properties including bulk modulus, shear modulus, Young’s modulus, Cauchy pressure, Pugh ratio and Poisson’s ratio were calculated using the Voigt-Reuss-Hill approximation. Our findings confirm the mechanical stability of all TiO2 phases and offer insights that align with existing theoretical and experimental data. These findings provide a comprehensive understanding of behavior of TiO2 under high-pressure condition which is crucial for optimizing its applications in various fields such as photocatalysis and solar cells.

Mn-deficient ZnMn2O4/Zn0.5Mn0.5Fe2O4 cathode for enhancing structural reversibility and stability of zinc-ion batteries

Aqueous zinc-ion batteries have surfaced as a viable energy storage technology due to their safety, eco-friendliness, and cost-effectiveness. Binary zinc manganite oxide (ZnMn2O4 or ZMO) stands out as the potential cathode material owing to its considerable theoretical capacity and high operating voltage. However, high electrostatic repulsion of Zn2+ ions within ZMO leads to sluggish diffusion and poor reversibility of Zn2+ ions insertion/extraction that can reduce charge storage and overall cycling performance. This study addresses this challenge by introducing FeCl3 during the synthesis to form ZMO/Zn0.5Mn0.5Fe2O4 (ZMFO) cathode material. This cathode features Mn-deficient structures, which can reduce the electrostatic repulsion via low Mn occupancies and lattice parameters enlargement, thus facilitating Zn2+ ions diffusion. Ex-situ X-ray diffraction analyses further show that the cathode is able to maintain good structural reversibility during the charge-discharge cycles. Additionally, the ZMO/ZMFO cathode exhibits smaller particle sizes than pristine ZMO, providing a wider surface area. The presence of ZMFO with a large unit cell volume can also enhance Zn storage capacity and accelerate Zn2+ ions kinetics. Highlighting those advantages, aqueous zinc-ion batteries with ZMO/ZMFO cathode show a capacity of ~230 mAh g−1 at 0.05 A g−1 and retain 99 % of its initial capacity at 0.2 A g−1 after 200 cycles of charge-discharge.

Design and investigation of electrostatic doped heterostructure vertical Si(1-x)Gex/Si nanotube TFET

Researchers are inclining toward heterostructures suitable lattice matching, in Tunnel FETs to eliminate the difficulties of decreased On-Current, subthreshold swings, and ambipolar behavior. Nowadays, Electrostatic doping (ED) is a scrutinized substitute device for creating areas with a high electron or hole density to the conventional doped devices. This manuscript proposes an Electrostatic Doped Heterostructure Vertical Si(1-x)Gex/Si Nanotube Tunnel Field Effect with performance scanned by analyzing the different device parameters, considering the energy band diagram, concentrations of electrons, holes, potential, and electric field. In comparison to the Nanowire TFETs, the area, and rate of tunneling of the proposed device stand superior with a better ION/IOFF ratio of 1.56∗1013 and a lower OFF-current of about ∼10−18A/μm. The device exhibits a Drain current (IDS) of 2.39∗105A/μm. The architecture of the suggested device possessing Si(1-x)Gex/Si structure exhibits enhanced characteristics like improved steepness of the sub-threshold slope, ION/IOFF ratio, drain current, and lowered OFF-current.

Insights into effects of Fe doping on phase stability, martensitic transformation, and magnetic properties in Ni-Mn-Ti-Fe all-d-metal Heusler alloys

In this work, the effects of Fe doping on phase stability, martensitic transformation, and magnetic properties of Ni50Mn37.5-xTi12.5Fex (x = 3.125, 6.25, 9.375) all-d-metal Heusler alloys were systematically investigated by first-principles calculations. The results indicate a tendency for doped Fe atoms to aggregate within the Ni50Mn37.5-xTi12.5Fex alloys. As Fe concentration increases, a gradual reduction in both lattice constants and phase stability of austenite and martensite is observed. In the absence or presence of minimal Fe doping, both austenite and martensite exhibit antiferromagnetic behavior. However, at x = 9.375, a transition to a ferromagnetic state is observed in the austenite phase. This transition is attributed to the activation of the ferromagnetic coupling effect in the austenite phase induced by Fe doping in the Ni-Mn-Ti alloy. In contrast, the martensite phase maintains its antiferromagnetic characteristics throughout the doping range. A comprehensive analysis of the electronic structure elucidates the underlying physical mechanisms responsible for the martensitic transformation and magnetic property changes.

Mechanism of oxygen content on impact toughness of α + β powder metallurgy titanium alloy

Understanding the mechanism of oxygen on toughness of titanium alloys is crucial for popularizing powder metallurgy. In this work, the effect of oxygen content (1500, 3000 and 5000 ppm) on the impact toughness of powder metallurgically modified titanium alloys with fine equiaxed microstructures (∼1.5 μm) was systematically investigated. With increasing oxygen content, the c/a value of the α-phase lattice parameter increases to a maximum of 1.593 Å, and the hardness increases from 4.03 GPa to 5.05 GPa, resulting in an increase in strength of ∼150 MPa and a considerable decrease in the ability of the two phases to coordinate. The crack initiation energy is similar for different oxygen contents, whereas the crack propagation energy increases considerably with decreasing oxygen content; the impact energy of stable crack extension increases from 4 J to 13 J and 35 J, and the impact energy of unstable crack extension and crack collapse stages increases from zero to 14 J and 25 J, respectively, indicating that decreasing oxygen content can substantially improve the crack extension resistance. The activation of numerous dislocations within the two phases and the formation of subgranular boundaries at low oxygen contents promote the release of internal stresses in the grains, and simultaneously, the interfacial resistance to dislocation migration and the concentration of interfacial stresses are also reduced, which improves the coordination of the two-phase plastic deformation of the equiaxed microstructures; the crack extension paths in the impact process become more tortuous and finally achieve impact energies as high as 85–100 J.

Influence of Nd3+ on structural, electrical and magnetic properties of Ni-Cd nanoferrites

Here in we report the nanocrystalline Ni1-xCdxNdyFe2-yO4 (0 ≤ x ≤ 1.0 in steps of 0.2: y = 0.0; 0.1) ferrites were synthesized by novel solution combustion technique. The sintered powders have been characterized by X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Energy dispersive analysis by x-rays (EDAX) methods. DC electrical conductivity carried out by two probe method. Magnetic parameters were measured using vibrating sample magnetometer with an applied magnetic field up to 15 kOe at 300K. The XRD results confirmed the formation of single phase cubic spinel structure formation. It was found that the lattice parameter increased with increase in Cd2+ ion. The crystallite sizes have been found in the range of 44.24 nm–15.467 nm. Moreover, the formation of two prominent absorption bands confirmed the spinel structure. The SEM micrographs evidenced almost spherical shaped, agglomerated and grainy structure of nanoferrites. Moreover, the Curie temperature (TC) was decreased with increasing temperature and exhibit the semiconducting behaviour. Further, saturation magnetization (MS), remanence magnetization (Mr); coercivity (HC) were decrease with increase in the magnetic field. The magnetic parameters; MS, Mr, nB increases attain maximum thereafter decreases with increase in Cd2+ ion and Nd3+ ion content.

Epitaxial Growth of Monolayer WS2 Single Crystals on Au(111) Toward Direct Surface-Enhanced Raman Spectroscopy Detection.

The epitaxial growth of wafer-scale two-dimensional (2D) semiconducting transition metal dichalcogenides (STMDCs) single crystals is the key premise for their applications in next-generation electronics. Despite significant advancements, some fundamental factors affecting the epitaxy growth have not been fully uncovered, e.g., interface coupling strength, adlayer-substrate lattice matching, substrate step-edge-guiding effects, etc. Herein, we develop a model system to tackle these issues concurrently, and realize the epitaxial growth of wafer-scale monolayer tungsten disulfide (WS2) single crystals on the Au(111) substrate. This epitaxial system is featured with good adlayer-substrate lattice matching, obvious step-edge-guiding effect for the unidirectionally aligned nucleation/growth, and relatively weaker interfacial interaction than that of monolayer MoS2/Au(111), as evidenced by the evolution of a uniform Moiré pattern and an intrinsic band gap, according to on-site scanning tunneling microscopy/spectroscopy (STM/STS) characterizations and density functional theory calculations. Intriguingly, the unidirectionally aligned monolayer WS2 domains along the Au(111) steps can behave as ultrasensitive templates for surface-enhanced Raman scattering detection of organic molecules, due to the obvious charge transfer occurred at substrate step edges. This work should hereby deepen our understanding of the epitaxy mechanism of 2D STMDCs on single-crystal substrates, and propel their wafer-scale production and applications in various cutting-edge fields.

Lattice constant, bandgap energy, absorption coefficient and dielectric function of the antimony-rich InBixSb1-x alloy using first-principles calculations

So far, little is known about the electronic and optical properties of InBixSb1-x. In this work, the first-principles calculations are performed to research the lattice constant, the bandgap energy, the absorption coefficient and the dielectric function of the antimony-rich InBixSb1-x. The results show that the bowing coefficient for the lattice constant is merely −0.012 Å. According to the band structures, it is found that the Sb-rich InBixSb1-x possesses a direct bandgap at G point. Its bandgap reduction is due to the ascending of the valence band maximum (VBM) and the descending of the conduction band minimum (CBM). For the sake of providing a good description for the bandgap energy in the Sb-rich range, the modified valence band anticrossing (MVBAC) model plus a linear equation is utilized. The result shows that the predicted positive to negative bandgap transition occurs at x = 0.13. Besides, the valence band offset between InSb and InBi is identified to be 0.27eV. For the optical properties, it is found that the Bi component is effective in raising the static dielectric constant of InBixSb1-x. However, it has a minor effect on the transition ability of the electrons. In the Sb-rich component range, the critical point energies E0+Δ0E1, E1+Δ1E2 and E1′ are found to shift toward the low energy direction. The result of the absorption spectra supports this opinion as increasing Bi component leads to a redshift of the absorption spectra. The adjustable bandgap energy and the optical properties of InBixSb1-x demonstrate that it is a strong candidate for fabricating the photodetectors in the 8–12 μm spectral region.

The influence of nano structuring and combined doping (Ag and Sb) on the thermoelectric properties of PbTe thin films

Nanocrystalline PbTe and Ag & Sb co-doped PbTe thin films are prepared using an integrated physical-chemical approach by evaporating chemically synthesized PbTe and Ag & Sb co-doped PbTe nanopowders on glass substrates. The X-Ray Diffractogram (XRD) reveals that all samples are NaCl-type structure and the structural parameters such as crystallite size D, dislocation density δ, strain ε, lattice constant, volume of the cell and number of crystallites are calculated and reported the results. The crystallite size of the films is around 24 nm. The absolute value of the Seebeck coefficient of nanocrystalline PbTe and Ag and Sb co-doped PbTe thin films is 1.069 mV/K and 0.569 mV/K respectively and the positive values indicate their p-type conductivity of the film. The values of Seebeck coefficient and power factor are higher than that of bulk which implies an enhancement in the thermoelectric properties with a reduction in the particle size and co doping.

Impact of calcined temperatures on the crystalline parameters, morphological, energy band gap, electrochemical, antimicrobial, antioxidant, and hemolysis behavior of nanocrystalline tin oxide

To construct a battery, the precipitation-synthesized SnO2 products at 450 °C and 650 °C were separately taken and mixed with graphite as the anode and PbO2,V2O5, and graphite materials as cathode materials to make the pellets and examine their open circuit voltage (OCV) values. The microstrain, lattice parameter, and crystallite size values of the above-mentioned tin oxide compounds were obtained through Rietveld refinement-MAUD fit analysis. The microstrain and lattice parameter values of tin oxide were significantly varied at a higher calcined temperature. Surface particle grain growth was increased with the increased calcined temperature from 450 to 650 °C as evidenced by FE-SEM study. Particle size distributions of SnO2 and polycrystalline behavior have been discussed with the aid of TEM analysis. From the UV–visible spectra, optical band gap (Eg) values reduced from 3.73 to 3.69 eV for the SnO2 products with an increase in calcined temperatures from 450 to 650 °C. The antimicrobial responses of the two different calcined SnO2 samples at 450 °C and 650 °C against two different bacterial pathogens (gram-positive-S. aureus and gram-negative-E.coli) were investigated. From the microbicidal assessment, a relatively higher diameter of the zone of inhibition (DZOI) of tin oxide at 650 °C samples was measured to be 19 ± 2 mm and 21 ± 2 mm for S. aureus and E. Coli than the DZOI of SnO2 at 450 °C samples (15 ± 1 mm for S. aureus and 18 ± 1 mm for E. coli. DPPH scavenging activity at 100 μg/ml shows that SnO₂ calcined at 450 °C achieves 68 ± 1 %, while SnO2 calcined at 650 °C exhibits a significantly higher activity of 86 ± 1 %. A slight increase in hemolysis was observed for SnO2 calcined at 650 °C, reaching 1.3 % at higher concentrations, but overall, hemolysis remained below 5 %, indicating high hemocompatibility.

First principles study of the electronic structure and Li-ion diffusion properties of co-doped LIFex-1MxPyNy-1O4 (M=Co/Mn, N[dbnd]S/Si) Li-ion battery cathode materials

In this work, a first-principles method based on density functional theory was systematically employed to investigate the stability, electronic properties, lithium-ion migration rates, and capacity-voltage curves of the LiFex-1MxPyNy-1O4 (M = Co/Mn, NS/Si) system. The results indicate that the lattice constants of the LiFex-1MxPyNy-1O4 (M = Co/Mn, NS/Si) system show little variation, and the system exhibits low formation and binding energies. Among the investigated systems, LFP-Mn/S demonstrates the best structural and thermodynamic stability. The bandgap of the doped systems decreases, leading to enhanced electronic conductivity. The LiFe0.875Co0.125P0.875Si0.125O4 and LiFe0.875Mn0.125P0.875Si0.125O4 systems remain semiconductors, while the LiFe0.875Co0.125P0.875S0.125O4 and LiFe0.875Mn0.125P0.875S0.125O4 systems exhibit semi-metallic properties due to the introduction of sulfur. Differential charge density calculations reveal changes in the covalent bond strength of the doped systems, with the introduction of Si and S respectively increasing and decreasing the covalency of their bonds with surrounding oxygen atoms. Additionally, doping reduces the Li-ion diffusion energy barriers, with the LiFe0.875Co0.125P0.875Si0.125O4 system exhibiting the lowest migration energy barrier. The Li-ion diffusion rate is four orders of magnitude faster than that of the intrinsic system. This is attributed to changes in the average lengths of Li–O, Co–O, and Fe–O bonds. Finally, doping also alters the de-lithiation voltage, with values ranging from 2.69 V to 3.65 V for the doped systems, and the LiFe0.875Co0.125P0.875Si0.125O4 system shows the highest complete de-lithiation voltage of 3.65 V. The overall performance improvements of the doped system have significant implications for enhancing the performance of Li-ion batteries.

First-principles study on the stability and optoelectronic properties of the novel C6O2 nanostructure

This study presents the prediction of a novel 2D nanostructure, C6O2, characterized as a direct bandgap semiconductor with a rectangular atomic arrangement. Employing computational codes based on density functional theory (DFT), we optimized the lattice parameters, yielding (a = 6.26 Å and b = 2.43 Å). Stability analysis, including cohesive energy (with a value of −7.85 eV/atom) and phonon dispersion within the first Brillouin zone, confirms the acceptable stability of the C6O2 structure. Electronic properties in the ground state were investigated using both HSE06 and GGA approaches. Our results indicate that the predicted structure exhibits a direct bandgap with energy values of 0.108 eV (PBE), 0.11 eV (mBJ), and 0.415 eV (HSE06) at the M point. Furthermore, we explored the optical properties of this nanostructure using the HSE06 approach. Notably, the ground state exhibits moderate absorption across the visible light spectrum (around 3–5 eV) and a low reflection rate. These findings suggest that C6O2 holds promise for future experimental endeavors in designing electro-optical applications.

Modification of the Bose-Hubbard model parameters in an optical lattice by two-particle Wannier functions

Modification of the Bose-Hubbard model parameters in an optical lattice by two-particle Wannier functions

Effect of the chemical substitution on structural parameters and microwave properties of the Co–Ni–Zn spinels

Co0.3Ni0.7-xZn xFe2O4 (where x = 0.00–0.7 with step 0.1) spinels or CNZF with constant Co concentration and varying of the Ni/Zn concentration were obtained by the ceramic method from initial oxides. Based on X-ray diffraction data it was concluded that all samples are single-phase (SG: Fd-3m). Concentration dependences of the lattice constant and unit cell volume correlate well with Vegard's rule and the average value of the Zn2+ and Ni2+ ionic radii. The microwave permeability was measured in the frequency range of 0.1–20 GHz by a coaxial technique. Two resonances on frequency dependences were observed. Analysis of the microwave properties and magnetostatic data showed that low-frequency magnetic peak was caused by a resonance of domain boundaries; high-frequency peak was due to a natural ferrimagnetic resonance. Obtained results opens broad perspectives for practical application of such kind of materials and possibility for microwave parameters control by the external magnetic field.

Correlating Cu dopant concentration, optoelectronic properties, and photocatalytic activity of ZnO nanostructures: experimental and theoretical insights

The photocatalytic activity of photocatalysts can be enhanced by cation doping, and the dopant concentration plays a key role in achieving high efficiency. This study explores the impact of copper (Cu) doping at concentrations ranging from 0% to 10% on the microstructural, optical, electronic, and photocatalytic properties of zinc oxide (ZnO) nanostructures. The x-ray diffraction analysis shows a non-linear alteration in the lattice parameters with increasing the Cu content and the formation of CuO as a secondary phase at the Cu concentration of >3%. Density functional theory calculations provide insights into the change in the electronic structures of ZnO induced by Cu doping, leading to the formation of localizeddelectronic levels above the valence band maximum. The modulation of the electronic structure of ZnO by Cu doping facilitates the visible light absorption via O 2p → Cu 3d and Cu 3d → Zn 2p transitions. Photoluminescence spectroscopy reveals a quenching of the defect-related emission peak at approximately 570 nm for all Cu-doped ZnO nanostructures, indicating a reduction in the structural and other defects. The photocatalytic activity tests confirm that the ZnO nanostructures doped with 3% Cu exhibit the highest efficiency compared to other samples due to the suitable band-edge position and visible light absorption.

Printing of 3D photonic crystals in titania with complete bandgap across the visible spectrum.

A photonic bandgap is a range of wavelengths wherein light is forbidden from entering a photonic crystal, similar to the electronic bandgap in semiconductors. Fabricating photonic crystals with a complete photonic bandgap in the visible spectrum presents at least two important challenges: achieving a material refractive index > ~2 and a three-dimensional patterning resolution better than ~280 nm (lattice constant of 400 nm). Here we show an approach to overcome such limitations using additive manufacturing, thus realizing high-quality, high-refractive index photonic crystals with size-tunable bandgaps across the visible spectrum. We develop a titanium ion-doped resin (Ti-Nano) for high-resolution printing by two-photon polymerization lithography. After printing, the structures are heat-treated in air to induce lattice shrinkage and produce titania nanostructures. We attain three-dimensional photonic crystals with patterning resolution as high as 180 nm and refractive index of 2.4-2.6. Optical characterization reveals ~100% reflectance within the photonic crystal bandgap in the visible range. Finally, we show capabilities in defining local defects and demonstrate proof-of-principle applications in spectrally selective perfect reflectors and chiral light discriminators.