Double Crystal Research Articles

Investigation on induced smectic phases in double hydrogen bond liquid crystal complexes derived from aromatic carboxylic acids: Experimental and quantum chemical approaches

In the present study, double Hydrogen bond liquid crystal (HBLC) complexes in different mole ratio (1:1 and 1:2) have been isolated from symmetrical aromatic dicarboxylic acid of non-mesogenic compound 1,3-Phenylenediacetic acid (1,3-PDA) and mesogenic compound 4-n-dodecyloxybenzoic acid (12 OBA). Fourier transform infrared Spectroscopy (FTIR) explores the presence of functional groups in the title complexes. Formation of H-bond between 1,3-PDA and 12 OBA is experimentally confirmed by observing the FTIR peak at 3639 cm−1 (1:1 ratio). Induced mesophases and its textures along with transition temperatures are analyzed using polarizing optical microscope (POM) and differential scanning calorimetry (DSC). The layered structures (smectic phases) and their molecular mechanism has been analyzed using density functional theory (DFT). Further, the establishment of H-bond in the title complex has been investigated with the aid of optimized geomentry, molecular electrostatic potential (MEP) and reduced density gradient (RDG) analysis. The band gap energy of title complex (1:1) is calculated by UV–Vis spectrometer and the same has been justified by HOMO-LUMO studies. Maximum absorption in the UV region and moderate bandgap energy (Eg = 4.22 eV) of the title complex clearly indicates its potential application in NLO, optoelectronics and laser tuning devices. In addition to that, LC parameters and its effect on mesophase are reported using experimental and computational methods.

Evidence and engineering of x-ray luminescence in lead free perovskite Cs2AgInCl6 with Bi substitutions

Cs2AgInCl6 belongs to the family of lead-free halide double perovskites. Lead-free halide double perovskite appears as a viable contender for scintillator applications due to its inexpensive production costs, low intrinsic trap density, and nanosecond quick reaction. Perovskite crystals have a substantially lower trap density than lead halide and traditional oxide scintillator materials, according to thermo-luminescence measurements. Cs2AgInCl6 structure and dimensionality were engineered by Bi doping. Bi substitution reduces the bandgap, making it suited for scintillation applications. Bi substitution allows for easy tuning of Cs2AgIn(1−x)BixCl6 (0 ≤ x ≤ 50) due to its wide versatility in scintillation properties. For Cs2AgIn(1−x)BixCl6 (0 ≤ x ≤ 50), x-ray power dependent luminescence increases with increasing power. Because of their nontoxicity, sensitivity, reaction time, and stability, Cs2AgIn(1−x)BixCl6 (0 ≤ x ≤ 50) double perovskite crystals are promising for x-ray scintillation.

Responsive release of guest aqueous droplet in liquid crystal droplet assists the detection of organophosphorus using commercial pregnancy test strip

Here, we report a liquid crystal (LC) double-emulsion based system for organophosphorus (OPs) sensing by controllable release of guest aqueous droplets (GADs) cargo. First, double liquid crystal emulsion, water in liquid crystal in water (W/LC/W), with size between 4∼ 20 μm was prepared with GADs loaded at the center of liquid crystal droplet (LCD) through elasticity trap. The LCDs were monodispersed and response sensitively to amphiphilic surfactant with opposite charge. With the capability of ejecting GADs with human chorionic gonadotropin (hCG) as cargo located in LCD to continuous aqueous phase, responsive vehicles are obtained and applied in the repurposing of commercial pregnancy test strip (PTS). With hydrophobic alkyl chain and hydrophilic head, myristoylcholine (Myr) is a good amphiphilic surfactant to trigger the release of hCG, and substrate for the enzymatic hydrolysis of acetylcholine esterase (AChE). Provided with the inhibition effect of OPs to the hydrolysis ability of AChE, OPs correlate positively with the concentration of Myr, thus correlate well with the release of hCG in W/LC/W emulsion. Thus, OPs residue in river or food is readily visualized using commercial PTS.

Tunable multimode emissions of Yb3+/Er3+-doped rare-earth-based Cs2NaYCl6 double perovskite crystals for versatile applications

Lead-free halide double perovskite materials are gaining recognition because of their excellent optoelectronic performance. However, achieving multimode luminescence with tunable emission colors in single-component double perovskites remains a significant challenge. Understanding the mechanism of trivalent lanthanide-ion doping could provide a valuable solution. Herein, we report the synthesis of rare-earth-based Cs2NaYCl6 double perovskites using a hydrothermal method. Efficient visible to near-infrared down-shifting (DS) photoluminescence and green up-conversion (UC) emissions were realized by incorporating Er3+ ions with abundant energy levels into the hosts. Notably, the DS and UC emission colors could both be adjusted by further introducing Yb3+ ions that acted as sensitizers, and the photoluminescence was significantly enhanced due to the strong absorption at 980 nm. Spectral analysis revealed that the high compatibility of lanthanide ions with the rare-earth-based double perovskites and cross-relaxation processes played a key role in achieving modulated emission and multiple excitation modes. This study aimed to understand the photophysical mechanism of lanthanide-ion-doped double perovskites, as well as to highlight their ability to modulate emissions. Furthermore, this study expands the versatile applications of lanthanide-ion-doped double perovskites in the fields of high-security anti-counterfeiting, tissue imaging, and night-vision systems.

Facile synthesis, multimode and tunable luminescence, and multifunctional applications of rare earth ions activated lead-free double perovskite crystals

Lead-free double perovskites have gained recognition as top luminescent materials due to their environmental friendliness, high chemical stability, structural adjustability, and excellent photoelectric properties. However, the poor modulation of emission restricts their applications, and it is highly desirable to explore stable and efficient double perovskites with multimode luminescence and adjustable spectra for multifunctional photoelectric applications. Herein, the rare earth ions Ln3+ (Er3+ and Ho3+) doped Cs2NaYCl6:Sb3+ crystals were synthesized by a simple solvothermal route. The X-ray diffraction pattern (XRD), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and elemental mapping images demonstrate that the Sb3+, Er3+, and Ho3+ ions have been homogeneously incorporated into the Cs2NaYCl6 crystals. As anticipated, the emission spectra of Cs2NaYCl6:Sb3+/Ln3+ are composed of two bands. One broad blue band derives from self-trapped exciton (STE) in [SbCl6]3− octahedra while another group of emission peaks stems from the f-f transitions of Ln3+ ions. The emission colors of Cs2NaYCl6:Sb3+/Ln3+ phosphors can be tuned in a wide range by modulating the doping concentrations of Ln3+ ions. The efficient energy transfer from STE to Ln3+ is the key point to achieving the efficient and tunable emissions Cs2NaYCl6:Sb3+/Ln3+ samples. Interestingly, Cs2NaYCl6:Sb3+/Ln3+ can also exhibit characteristic up-conversion luminescence of Ln3+ under near-infrared (NIR) excitation besides the down-conversion luminescence, revealing that the materials may have potential applicability in multimode anti-counterfeiting and information encryption applications. Furthermore, the light emitting diodes (LEDs) assembled by Cs2NaYCl6:Sb3+ and Cs2NaYCl6:Sb3+/Ln3+ phosphors display dazzling blue, green, and red emissions under a forward bias current, which indicates that the as-obtained double perovskites materials may have great potential in solid-state lighting and optoelectronic devices.

Achieving multi-excitation in lanthanide-based Cs2NaTbCl6:Ce/Yb double perovskite single crystals for anti-counterfeiting

Lanthanide-doped inorganic perovskite luminescent materials have always been regarded as a good platform for multi-functional applications such as anti-counterfeiting and information encryption, owing to their good visibility, diverse colors and simple design. In this study, we design the Cs2NaTbCl6: Ce/Yb double perovskite single crystals, achieving visible green luminescence under various excitation sources such as ultraviolet, near-infrared (980 nm) and X-ray. The possible emission and energy transfer mechanisms between Tb3+ ions and Ce3+, Ce4+, Yb3+ ions under different excitations are discussed in detail. Our work skillfully takes advantage of the Tb3+ ions acquiring the transferred energy from non-luminescent Ce4+ ions and luminescent Ce3+ ions, broadening the ultraviolet response and improving its stability. The luminescence intensity of Cs2NaTbCl6 double perovskite single crystal was increased about 40 times under 343 nm excitation by doping Ce4+ and Ce3+ ions, which shows that Ce4+ and Ce3+ ions doping effectively introduces a new excitation band. Furthermore, diversified anti-counterfeiting modes are fabricated to highlight the promising applications of Cs2NaTbCl6 double perovskite systems with tunable luminescence in advanced anti-counterfeiting, paving the way for future research on the multi-light sources luminescent materials.

Error correction analysis of wavefront testing in quadriwave lateral shearing interferometry

Quadriwave lateral shearing interferometry (QWLSI) is based on double birefringent crystals of a beam displacer (DBCs-BD), which can generate the lateral shearing interference wavefront of four beams of overlapped replicas in the DBCs-BD orthogonal directions. When the replica waves are overlapped incident to the analyzer and the direction of the transmission axis is set as 45° or 135°, the QWLSI’s polarization interferogram can be obtained. This paper deduces the principle of QWLSI based on the DBCs-BD and presents the analysis of orthogonal error influence based on the DBCs-BD and the phase retrieval error of QWLSI when shear displacement by tilted incident on the DBCs-BD. In our investigation, we have established the correction range of the PBD’s orthogonal angle error is within −0.5∘−0.5∘, the maximum error in PV is 0.0012λ, and the maximum error in RMS is 1.3789×10−4λ in wavefront reconstruction. Moreover, when the testing light tilts to incident on the PBD in the range of −0.4∘−0.4∘, correction of the shear distance is used for wavefront reconstruction to achieve a high-precision wavefront testing result. Finally, the experiment shows that QWLSI based on the DBCs-BD exhibits feasibility and high precision.

High Stability and Corrosion-Resistant Gas of Recyclable and Versatile Manganese-Doped Lead-Free Double Perovskite Crystals toward Novel Functional Fabric and Photoelectric Device.

Lead-free halide perovskites possess excellent photoelectric properties, making them widely used in the photoelectric fields. Herein, lead-free double perovskite crystals (PCs) doped with manganese (Cs2NaInCl6:Mn2+) are successfully prepared by the more energy-efficient crystallization method. The crystals emit bright orange-red light under the ultraviolet (UV) lamp, showing unique optical properties. They have the highest photoluminescence quantum yield of 42.91%. The white light-emitting diodes (LEDs) are fabricated using these perovskite crystals, which show a color rendering index of 92 and external quantum efficiency (EQE) as high as 16.3%. Furtherly, perovskite-modified fiber paper made of aramid chopped fibers (ACFs) and polyphenylene sulfide (PPS) exhibited fluorescent properties under different conditions. This paper combines fiber composite technology with PPS fiber filter bags, which are widely used in environmental protection, for the first time and demonstrates functional fiber filter bags with fluorescent characteristics. This filter bag provides an idea for the automatic detection of industrial filtration. Meanwhile, after being exposed to industrial waste gas for 60h, the filter bag can maintain superior fluorescence performance. In this study, lead-free double perovskites are synthesized using an efficient method for preparing high-performance LEDs and high-stability fluorescent fibers. Concurrently, the application of perovskites in environmental protection is expanded.

A single-step crystallization process to remove potassium from sodium aluminate solution

The high concentration of potassium in sodium aluminate solution seriously threatens the seed precipitation process and reduces the quality of alumina products, but the separation of potassium is quite difficult due to the similar chemical properties between potassium and sodium ions. In this work, a novel single-step double salt crystallization (SDSC) process with low energy consumption was proposed to remove potassium from the concentrated sodium aluminate solution using sodium sulfate, and the corresponding removal performance, kinetics and mechanism were studied. The potassium concentration decreases with the increase of additive dosage and reaction temperature, while the high caustic alkali concentration hinders the potassium removal. At 70 °C, the SDSC process exhibits a rapid crystallization and reaches an equilibrium within 60 min because of the low activation energy and weak bonding of 3 K2SO4·Na2SO4·9H2O. Under the optimum conditions, the potassium removal efficiency can achieve 85.68 %, and the potassium concentration is reduced from 120 g∙L−1 to 24.54 g⋅L−1. Finally, a cyclic utilization pathway was obtained to economically and effectively remove potassium from the sodium aluminate solution.

Nano-optomechanical fiber-tip sensing

Nano-optomechanical sensors exploit light confinement at the nanoscale to enable very precise measurements of displacement, force, acceleration, and mass. Their application is hampered by the complex optical set-ups or packaging schemes required to couple light to and from the nano-optomechanical resonator. In this work, we present a fiber-coupled nano-optomechanical sensor that requires no coupling optics. This is achieved by directly placing a nano-optomechanical structure, a double membrane photonic crystal (DM-PhC), on the facet of a fiber, using a simple and scalable wafer-to-fiber transfer method. The device is probed in reflection and has a resonance at telecom wavelengths with a relatively broad spectral width of 3–10 nm, which is advantageous for a simple read-out and achieves a displacement imprecision of 10fm/Hz\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$10\\,{{\\rm{fm}}}/{\\sqrt{{\\rm{Hz}}}}$$\\end{document}. Using resonant driving and a ringdown measurement, we can induce and monitor mechanical oscillations with an nm-scale amplitude via the fiber, which allows for tracking the mechanical resonant frequency and the mechanical linewidth with imprecisions of 79 and 12 Hz, respectively, at integration times of 4.5 s. We further demonstrate the application of this fiber-tip sensor to the measurement of pressure, using the effect of collisional damping on the mechanical linewidth, leading to the imprecision of 9×10−4mbar\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$9\ imes {10}^{-4}\\,{\\rm{mbar}}$$\\end{document} with an integration time of 290 s. This combination of optomechanics and fiber-tip sensing may open the way to a new generation of fiber sensors with unprecedented functionality, ultrasmall footprint, and low-cost readout.

Bioinspired Colorimetric Double Inverse Opal Photonic Crystal Indicators for Ethanol Concentration Sensing in Fermentation Engineering.

Photonic crystal-based ethanol concentration indicators with rapid response and brilliant structural color output definitely take a place in colorimetric sensors. Here, based on the H-bond-regulated swelling of acrylate shape memory polymers (SMPs) and the solvent-induced structural color change of the double inverse opal photonic crystals (DIOPCs), new-type photonic crystals (PCs) colorimetric indicators were constructed, exhibiting a span of maximum reflection wavelength (λmax) up to ∼166 nm in response to alcohols with concentrations from 0 to 100 vol %. DIOPC indicators (DIOPCIs) show a rapid response to alcohols (<1.5 s) and output different structural colors (covering from blue to red). The colorimetric sensing mechanism includes the solvent-triggered recovery of the inverse opal skeleton, the cosolvency effect and H-bonds induced swelling/shrinkage of the polymer, the phase separation between polystyrene (PS) microsphere and polymer skeleton, and the light diffraction of DIOPCs. While ensuring a larger λmax span by regulating the H-bond interactions in polymer chains through acrylamide (AAm), AAm-modified DIOPCIs are sensitive to some specific ethanol concentrations. The real-time sensing of ethanol concentration during fermentation verified the practicability of DIOPCIs, thus establishing a visual model between structural color and corresponding fermentation kinetics. We envisage that the DIOPCIs will contribute to the intelligentization of the alcoholic fermentation and distillation industry.

Effectiveness study of recrystallisation method in pharmaceutical salt production from processed salt with zero waste concept

Indonesia's vast archipelago offers abundant seawater resources, holding the potential for salt production. Salt, a vital commodity in human life, typically contains sodium chloride and impurities like Ca2+, Mg2+, SO42−, and K+. Pharmaceutical salt is an industrial category adhering to pharmacopoeial standards regarding sodium chloride levels and impurity content, ensuring quality for drug preparations in Indonesia. Prior research indicates that recrystallisation, specifically evaporation crystallisation, enhances salt quality by increasing NaCl content. Chemical precipitating agents like NaOH and Na2CO3 can be introduced to improve salt purity further. This study aims to identify optimal conditions for pharmaceutical salt production from processed salt raw materials, considering crystallisation time, stirring speed, chemical additives (NaOH and Na2CO3), and double crystallisation stages. The method commences with pre-treatment, involving salt dissolution in distilled water to saturation, with the addition of precipitating agents as per designated variables. Precipitates formed from precipitating agents (NaOH and Na2CO3) are isolated through filtration. The filtrate undergoes evaporation crystallisation at 103 °C, varying between single and double crystallisation. Salt crystals are separated, dried, and weighed to calculate yield. Pharmaceutical salt is analysed for water content, NaCl, and impurities (Ca2+, Mg2+, SO42−, and K+). The optimal conditions for pharmaceutical salt production were double crystallisation with a 20 % excess of chemicals (NaOH and Na2CO3), 100 min of crystallisation time, and a stirring speed of 600 rpm. This yielded a 15 % NaCl content of 99.87 %, Mg2+ at 0 ppm, Ca2+ at 69.6 ppm, SO42− at 366 ppm, K+ at 370 ppm, and water content at 0.166 %. Notably, the pharmaceutical salt production process generates no waste, as byproducts like Mg(OH)2 and CaCO3 can be recycled and hold commercial value. However, it is essential to re-evaluate raw materials and technologies to address the market's high cost and competitiveness issues.

Er-doped Cs2AgBiCl6 double perovskite large single crystal for optoelectronics

Double perovskites have shown great potential in addressing the toxicity and instability concerns of lead halide perovskites for practical applications. However, the fabrication of high-quality double perovskite single crystals has remained challenging. Here, large Er-doped Cs2AgBiCl6 single crystals (SCs) with a maximum dimension of 8 mm were successfully prepared using a solution temperature-lowering (STL) method. The photoluminescence (PL) spectra were excited by the lasers with energies below and above the band gap, and the origin of the abnormal PL peaks changing with temperature is explored. The photodetector made from the Er-doped Cs2AgBiCl6 SCs shows a significantly enhanced light responsivity and detectivity in the wavelength range from 370 nm to 660 nm compared with the undoped one, with excellent environmental and radiation stability. It reveals that the Er ions can be successfully doped into double perovskite single crystal, benefiting the application to optoelectronic devices.

A Double Perovskite Single Crystal CsCuAgI3.

Eco-friendly halide double perovskites are attracting significant attention as potential substitutes for traditional lead-based halide perovskites. However, their typically wide or indirect band gap limits further technological advancement. This study presents a new, eco-friendly, all-inorganic millimeter-scale CsCuAgI3 single crystal (SC). The crystal exhibits a direct band gap of 2.02 eV at the G-point, markedly superior to that of traditional double perovskites. The absorption and photoluminescence spectra further corroborate its band gap attributes. Owing to the B-site Cu-Ag disorder, the crystal possesses a higher Urbach energy (119 meV), indicative of structural disorder. CsCuAgI3 exhibits a wide Stokes shift of 230 nm, a wide full width at half-maximum (fwhm) of 152 nm, a long fluorescence lifetime of 7.29 μs, and excellent stability. In addition, a photoelectric detection prototype was prepared using a CsCuAgI3 single crystal. Using a 375 nm laser as the excitation source, the device showed a very sensitive photoelectric response, clocking in at (0.37/0.21) seconds. This work offers new insights into developing novel lead-free double perovskite single crystals and exploring their potential applications.

Double Perovskite Single Crystals with High Laser Irradiation Stability for Solid-State Laser Lighting and Anti-counterfeiting.

Laser lighting devices, comprising an ultraviolet (UV) laser chip and a phosphor material, have emerged as a highly efficient approach for generating high-brightness light sources. However, the high power density of laser excitation may exacerbate thermal quenching in conventional polycrystalline or amorphous phosphors, leading to luminous saturation and the eventual failure of the device. Here, for the first time, we raise a single-crystal (SCs) material for laser lighting considering the absence of grain boundaries that scatter electrons and phonons, achieving high thermal conductivity (0.81 W m-1 K-1) and heat-resistance (575 °C). The SCs products exhibit a high photoluminescence quantum yield (89%) as well as excellent stability toward high-power lasers (>12.41 kW/cm2), superior to all previously reported amorphous or polycrystalline matrices. Finally, the laser lighting device was fabricated by assembling the SC with a UV laser chip (50 mW), and the device can maintain its performance even after continuous operation for 4 h. Double perovskite single crystals doped with Yb3+/Er3+ demonstrated multimodal luminescence with the irradiation of 355 and 980 nm lasers, respectively. This characteristic holds significant promise for applications in spectrally tunable laser lighting and multimodal anticounterfeiting.

High stability of robust anti-thermal-quenching lead-free double perovskite crystals for optoelectronic devices and functional fabric

Lead-free double perovskite is environmentally friendly, and good photoelectric efficiency has received widespread attention. However, the stability and efficiency of lead-free perovskites need to be further improved to meet the...

Enhanced photoelectric performance in Cu–Bi double halide perovskite single crystals

The low-dimensional structures of Bi-based perovskites severely restrict their optoelectronic performances. Here, a Cu–Bi double perovskite single crystal exhibits enhanced optical absorption, increased carrier mobility, and inhibition of defect recombination compared to Bi-only perovskite.

Tunable dual-emission of Sb3+, Ho3+ Co-doped Cs2NaScCl6 single crystals for light-emitting diodes

Lead-free halide double perovskites are considered as one of the most promising materials in optoelectronic devices, such as solar cells, photodetectors, and light-emitting diodes (LEDs), due to their environmental friendliness and chemical stability. However, the extremely low photoluminescence quantum yield (PLQY) of self-trapped excitons (STEs) emission from lead-free halide double perovskites impedes their applications. Herein, Sb3+ ions were doped into rare-earth-based double perovskite Cs2NaScCl6 single crystals (SCs), resulting in a large enhancement of PLQY from 12.57% to 87.37%. Moreover, by co-doping Sb3+ and Ho3+ into Cs2NaScCl6 SCs, the emission color can be tuned from blue to red, due to an efficient energy transfer from STEs to Ho3+ ions. Finally, the synthesized sample was used in multicolor LED, which exhibited excellent stability and optical properties. This work not only provides a new strategy for improving the optical properties of Cs2NaScCl6 SCs, but also suggests its potential application in multicolor LEDs.

Luminescence and Excited State Dynamics of Tb1-XEuxAl3(BO3)4 (x=0.01-0.20)

The room temperature luminescence spectra and emission decay curves of undoped and Eu3+-doped TbAl3(BO3)4 crystals, grown using the flux growth technique, are presented and discussed. The experimental results show that excitation of the Tb3+ excited states gives rise to 5D0 emission from the Eu3+ ion, and therefore non-radiative energy transfer involving the two ions is operative. Analysis of the experimental data indicates that the excitation of the Tb3+ donor ion gives rise to fast energy migration in the 5D4 level of the Tb3+ subset of cations, followed by the energy transfer process populating the 5D0 level of Eu3+. Upon increasing the Eu3+ acceptor concentration, the mainly green emission intensity and the decay time of the 5D4 level decrease, whilst the red emission of 5D0 becomes dominant. The experimental data are interpreted on the basis of the trigonal huntite-type structure of the double borate crystals under investigation.

In situ hydrothermal growth of Zeolite-A membrane on polysulfone hollow fibers

Zeolite-A hollow-fiber membranes with a high surface area are explored to address the present demands of high-productivity bioethanol manufacturing. Herein, we prepared Zeolite-A membranes on polymeric hollow-fiber support via double hydrothermal crystallization. The first hydrothermal crystallization from the solution yielded zeolite A crystals anchored on the polysulfone support. This transformation of the hollow fiber's skin layer into an organic-inorganic interface layer, as observed through SEM-EDX elemental analysis. This interface layer with penetrated Zeolite-A provides nucleation sites for further Zeolite-A membrane formation during the second hydrothermal crystallization and simultaneously enhanced interphase adhesion of Zeolite-A with the polymer support. The duration of the first and second cycles of hydrothermal crystallization was systematically studied to obtain continuous, crack-free, and pure Zeolite-A membranes on polysulfone hollow-fiber support. The membrane exhibited fluxes of 3.8 and 9.75 kg m−2 h−1 at 25 °C and 75 °C, respectively, with >99.9 wt% water separated through pervaporation of the 90/10 wt % ethanol/water mixture.