Uniform Crystals Research Articles

Directing Charge Carriers and Ferroelectric Domains at Lateral Interfaces in van der Waals Heterostructures.

Emergent phenomena in traditional ferroelectrics are frequently observed at heterointerfaces. Accessing such functionalities in van der Waals ferroelectrics requires the formation of layered heterostructures, either vertically stacked (similar to oxide ferroelectrics) or laterally stitched (without equivalent in 3D-crystals). Here, we investigate lateral heterostructures of the ferroelectric van der Waals semiconductors SnSe and SnS. A two-step process produces ultrathin crystals comprising an SnSe core laterally joined to an SnS edge-band, as confirmed by Raman spectroscopy, transmission electron microscopy (TEM) imaging, and electron diffraction. TEM shows a moiré pattern across the SnSe core due to coverage by an ultrathin SnS layer. The ability of the lateral interface (IF) to direct excited carriers, probed by cathodoluminescence, shows electron transfer over 560 nm diffusion length from the SnS edge-band. Large, thin flakes supporting ferroelectricity allow investigating domains and domain wall interactions in uniform crystals and lateral heterostructures. Polarized optical microscopy of sub-20 nm flakes consistently shows ⟨110⟩ oriented stripe domains with mirror-twin domain walls. Heterostructures adopt two domain configurations, with domains either constrained to the SnSe core or propagating across the entire SnSe-SnS flakes. The combined results demonstrate multifunctional van der Waals heterostructures with high-quality IFs presenting extraordinary opportunities for manipulating carrier flows and ferroelectric domain patterns.

Enhancing Mushroom Freezing Quality Using Microwave-Assisted Technology.

This study investigated the effects of microwave-assisted freezing on the quality attributes of button mushrooms (Agaricus bisporus). Four levels of microwave power (0, 10, 20, 30%) were applied to the mushroom samples during freezing. The quality attributes of the frozen and thawed mushrooms were then evaluated. The results suggested that higher microwave power produced the smaller and more uniform ice crystals. Moreover, the browning index of the mushroom samples increased with increasing microwave power. The textural properties (hardness) of the mushrooms were also affected by the microwave power, showing higher values as the power increased. Furthermore, the ratio of the microwave operating system's power to the freezer power was low and approximately 20% at the highest power level. Therefore, these findings confirm the potential of microwave-assisted freezing for reducing freeze damage to mushroom tissue and, thus, provide frozen mushroom with a better texture.

Large‐scale synthesis of nano‐ZIF‐90 from zinc chloride application orientation heat storage materials

AbstractThe paper presents the results of the first research on the synthesis of nano‐ZIF‐90 from zinc chloride. More specifically, the paper also introduces the results of large‐scale pure nano‐ZIF‐90 synthesis with a high specific surface, uniform cubic crystals, and good thermal strength. ZIF‐90 is synthesized from zinc chloride‐containing medium capillaries, which have both a weak acid center and a strong base center. The post‐synthetic ZIF‐90 was also evaluated for heat storage based on its ability to adsorb water, methanol, and ethanol. XRD, FTIR, SEM, TEM, N2 adsorption and desorption methods, TG mass thermal analysis, and NH3‐TPD/CO2‐TPD were used to study the ZIF‐90 crystallization process with modifications of precursors, solvents, additives, and reaction conditions. From this, a large‐scale synthesis of nano‐ZIF‐90 from high‐efficiency zinc chloride has been derived. DSC measurements are used to evaluate the enthalpy adsorption of water, methanol, and ethanol on ZIF‐90.

Effect of side chain ionizability of polycarboxylate superplasticizer on cement hydration

Although the side chain ionizability (the adsorption group density and adsorption space are changed) of polycarboxylate superplasticizer (PCE) serve as the key structural parameter in affecting the cement hydration, its effect on cement hydration is unclear. Based on PCE with nonionizable side chain (NSC-PCE) and the PCE with ionizable side chain (ISC-PCE), the influence of the side chain ionizability of PCE on the hydration behavior of cement was studied. Compared with NSC-PCE, ISC-PCE has a stronger ability to change the migration of water and ions, thus delaying the crystal nucleation and growth of cement hydration (better morphology and distribution, the crystal size was reduced by more than 20 %), increasing the crystal growth index (tendency toward spherical growth), prolonging the phase boundary reaction (reduce micro-cracks), which was conducive to the formation of more uniform and dense crystals (good strength, ISC-PCE: 50.0 MPa > NSC-PCE: 49.2 MPa > Blank: 48.7 MPa). These findings provide the design basis and theoretical guidance for the innovative development of PCE.

High-efficiency fabrication of uniform photonic crystals by a vertical deposition method from multiple glass slides of simple moulds and their application in isomer recognitions

Vertical deposition method is a simple, cheap and common method for fabricating photonic crystals (PCs). However, a majority of PCs are obtained based on the traditional vertical deposition method from one glass slide, the method is low efficiency. Herein, it is proposed to efficiently fabricate uniform PCs by an optimized vertical deposition method from double or multiple glass slides of simple moulds. Amounts of SiO2 spheres, distances of two glass slides of moulds, preparation temperatures and different diameters of SiO2 spheres are investigated for obtaining uniform PCs. And different types of PCs (the bottom-middle-top 3D PCs, bilayer 2D PCs and amorphous PCs) are also fabricated based on the optimized vertical deposition method. The above method is a simple, cheap and high-efficiency way for mass production of uniform PCs. Meanwhile, the chemicals with similar refractive indices (isomers and cis-trans isomers) can be easily distinguished under high humidity based on dynamic reflection spectra of the PCs. For example, the difference in the refractive indices of m-xylene and p-xylene is only 0.002, the difference of desorption balance time of PCs is 263 s. The PCs have potential applications in visual detections, isomer recognitions and monitoring of volatilization rates of trace liquids.

Effective degradation of organic pollutants by CuFe@C composite derived from bimetallic MOFs synthesized through stepwise feeding method

In this work, Cu-Fe bimetal-embedded carbonaceous CuFe@C materials were prepared by high-temperature pyrolysis of CuFe-MOFs precursors synthesized through a facile two-step feeding approach. Through adjusting the reaction time of each feeding step, CuFe-MOFs of uniform dispersed crystals with controlled sizes were obtained. The carbonized composites were then applied to activate persulfate (PMS) for Reactive Brilliant Red X-3B (RBRX-3B) degradation in water. The removal rate of RBRX-3B was up to 98% in 40 min in the CuFe@C600/PMS system, indicating that the CuFe@C600 catalyst showed excellent sulfate radical-based oxidation (SR-AO) activity in the degradation process. The effects of PMS dosage, initial pH, RBRX-3B concentration on the degradation efficiency were investigated in detail. Based on quenching experiments, a possible mechanism for the CuFe@C600/PMS system was proposed. The catalyst had good reusability, in which the removal rate of RBRX-3B could attain 82% after 5 times of repeated recycling. It also showed satisfactory removal effect on other organic pollutants, i.e. Congo red, Methyl orange, Reactive blue and p-nitrophenol. This study provided a valuable strategy for the treatment of wastewater containing organic pollutants using MOFs-derived materials.

High-Quality TiO2 Electron Transport Film Prepared via Vacuum Ultraviolet Illumination for MAPbI3 Perovskite Solar Cells.

The electron transport layer (ETL) plays an important role in determining the conversion efficiency and stability of perovskite solar cells (PSCs). Here, TiO2 thin film was prepared by irradiating diisopropoxy diacetylacetone titanium precursor thin film with 172 nm vacuum ultraviolet (VUV) at a low temperature. The prepared TiO2 thin film has higher electron mobility and conductivity. As it is used as an ETL for MAPbI3 PSCs, its band structure is better matched with the perovskite, and at the same time, due to the good interface contact, more uniform perovskite crystals are formed. Most importantly, a large number of hydroxyl radicals were formed during VUV irradiation of the precursor film, which made up for the oxygen defect present on the surface of the TiO2 thin film, and were adsorbed to the film surface. These hydroxyl groups form hydrogen bonds with methylammonium (MA) components on the MAPbI3 buried surface, thus promoting the transfer of photogenerated electrons at the MAPbI3/ETL interface. The power conversion efficiency of PSCs fabricated in air with the ETL prepared by VUV irradiation is 20.46%, which is higher than that of the contrast solar cell based on the sintered ETL (17.96%).

Investigation of the influence of minor components and fatty acid profile of oil on properties of beeswax and stearic acid-based oleogels

Understanding the impact of minor components and the fatty acid profile of oil on oleogel properties is essential for optimizing their characteristics. Considering the scarcity of literature addressing this aspect, this study aimed to explore the correlation between these factors and the properties of beeswax and stearic acid-based oleogels derived from rice bran oil and sesame oil. Minor oil components were modified by stripping the oil, heating the oil with water, and adding β-sitosterol. Oleogels were then prepared using a mixture of beeswax and stearic acid (3:1, w/w) at a concentration of 11.74 % (w/w). The properties of oils and oleogels were evaluated. The findings indicated that minor components and fatty acid composition of the oils substantially influence the oleogel properties. Removing minor components by stripping resulted in smaller and less uniformly distributed crystals and less oil binding capacity compared to the oleogels prepared from untreated oils. A moderate amount of minor components exhibited a significant influence on oleogel properties. The addition of β-sitosterol did not show any influence on oleogel properties except for the oleogel made from untreated oil blend added with β-sitosterol which had more uniform crystals in the microstructure and demonstrated better rheological stability when stored at 5 °C for two months. The oil composition did not show any influence on the thermal and molecular properties of oleogels. Consequently, the oleogel formulation derived from the untreated oil blend enriched with β-sitosterol was identified as the optimal formula for subsequent development. The findings of this study suggest that the physical and mechanical properties as well as the oxidative stability of beeswax and stearic acid-based oleogels are significantly affected by the minor constituents and fatty acid composition of the oil. Moreover, it demonstrates that the properties of oleogels can be tailored by modifying oil composition by blending different oils.

Micro/nanogroove-structured graphene-oxide-doped indium gallium yttrium oxide alignment layer with improved electrical characteristics

Graphene oxide (GO)-doped indium gallium yttrium oxide (InGaYO) alignment layers formed by a brush-based solution-coating process are reported in this study. The doping concentrations were adjusted to 0, 5, and 15 wt%. The alignment layers obtained thus showed anisotropic micro/nanogroove structures having induced by shear stress originating from the brush-hair movements. This structure enabled uniform and homogeneous liquid crystal (LC) alignment on the film surface with geometric constraints. The alignment state was verified by polarized optical microscopy and pretilt angle analysis. The GO-doped InGaYO alignment layer demonstrated enhanced 1.92 × 10−4 Jm−2 polar anchoring energy of the LCs and reduced hysteresis property, which aid in lower image-sticking effects. The LC device operation was verified with 1.7 V in a twisted-nematic LC system along with stable optical transmittance control. From these results, GO doping of the metal-oxide alignment layer shows the potential for functional LC device applications.

Droplet microfluidics for time-resolved serial crystallography.

Serial crystallography requires large numbers of microcrystals and robust strategies to rapidly apply substrates to initiate reactions in time-resolved studies. Here, we report the use of droplet miniaturization for the controlled production of uniform crystals, providing an avenue for controlled substrate addition and synchronous reaction initiation. The approach was evaluated using two enzymatic systems, yielding 3 µm crystals of lysozyme and 2 µm crystals of Pdx1, an Arabidopsis enzyme involved in vitamin B6 biosynthesis. A seeding strategy was used to overcome the improbability of Pdx1 nucleation occurring with diminishing droplet volumes. Convection within droplets was exploited for rapid crystal mixing with ligands. Mixing times of <2 ms were achieved. Droplet microfluidics for crystal size engineering and rapid micromixing can be utilized to advance time-resolved serial crystallography.

Crystal Facet Engineering on SrTiO3 Enhances Photocatalytic Overall Water Splitting.

Single-crystal semiconductor-based photocatalysts exposing unique crystallographic facets show promising applications in energy and environmental technologies; however, crystal facet engineering through solid-state synthesis for photocatalytic overall water splitting is still challenging. Herein, we develop a novel crystal facet engineering strategy through solid-state recrystallization to synthesize uniform SrTiO3 single crystals exposing tailored {111} facets. The presynthesized low-crystalline SrTiO3 precursors enable the formation of well-defined single crystals through kinetically improved crystal structure transformation during solid-state recrystallization process. By employing subtle Al3+ ions as surface morphology modulators, the crystal surface orientation can be precisely tuned to a controlled percentage of {111} facets. The photocatalytic overall water splitting activity increases with the exposure percentage of {111} facets. Owing to the outstanding crystallinity and favorable anisotropic surface structure, the SrTiO3 single crystals with 36.6% of {111} facets lead to a 3-fold enhancement of photocatalytic hydrogen evolution rates up to 1.55 mmol·h-1 in a stoichiometric ratio of 2:1 than thermodynamically stable SrTiO3 enclosed with isotropic {100} facets.

Effect of a Substrate’s Preheating Temperature on the Microstructure and Properties of Ni-Based Alloy Coatings

Laser cladding is a new technology to fabricate a coating on the surface of a metal substrate. The properties on copper substrates are usually not very good due to the high thermal conductivity and reflectivity. The appropriate preheating temperature is helpful to fabricate coatings with good quality and properties, especially for copper substrates. In order to investigate the effect of different preheating temperatures, four coatings with different preheating temperatures (100, 200, 300 and 400 °C) were fabricated via a laser on a copper substrate. The microstructures and properties of four coatings were investigated using SEM, XRD, EDS, a Vickers microhardness meter, a wear tester and an electrochemical workstation. The results show that the elements from Ni-based alloy powder were uniformly distributed among the binding region, which obtained a good metallurgical bonding. The microstructure was mainly composited of cellular, dendrite and plane crystals, and the main reinforced phases were γ (Fe, Ni), Cr0.09Fe0.7Ni0.21, WC and Ni3B. The values of average microhardness of the four coatings were 614.3, 941.6, 668.1 and 663.1 HV0.5, respectively. The wear rates of the four coatings were 9.7, 4.9, 12.5 and 13.3 × 10−5 mm3·N−1·m−1, respectively, which were less than that of the copper substrate (4.3 × 10−3 mm3·N−1·m−1). The decrease in wear rate was due to the existence of the reinforced phases, such as WC, Ni3B, M7C3 (M=Fe, Cr) and Cr0.09Fe0.7Ni0.21. The fine crystals in the coating preheated at 200 °C also improved the wear resistance. Additionally, the minimum values of corrosion current density were 3.26 × 10−5, 2.34 × 10−7, 4.02 × 10−6 and 4.21 × 10−6 mA·mm−2, respectively. It can be seen that the coating preheated at 200 °C had higher microhardness, lower wear rates and better corrosion resistance due to the existence of reinforced phases and fine and uniform crystals.

Microstructures and mechanical properties of nano-TiC/Ti-refined Al[sbnd]Mg alloys prepared by wire arc additive manufacturing

In the current study, an AlMg alloy refined with a nano-TiC/Ti grain refiner was successfully printed by cold metal transition wire arc additive manufacturing (CMT-WAAM). The effects of the nano-TiC/Ti grain refiner on the microstructure and mechanical properties of the CMT-WAAM-prepared AlMg alloy were studied. The results indicated that the nano-TiC/Ti grain refiner has a significant refining effect on AlMg alloy and refined the coarse columnar crystals into uniform fine equiaxed crystals. The average grain size of the CMT-WAAM AlMg alloy refined with the 0.6 wt% nano-TiC/Ti grain refiner decreased from 53.06 μm to 25.32 μm (yz plane), and the average grain size in the xy plane decreased from 52.00 μm to 25.80 μm. The excellent grain refinement effect of the nano-TiC/Ti grain refiner was attributed to the presence of TiC particles at the grain, which acted as heterogeneous nucleation sites and improved the nucleation rate. Moreover, TiC particles located at the grain boundary inhibited the growth of the grain boundary. The mechanical properties, i.e., the tensile and yield strength, were improved by 20–25%, and there was an increase in the microhardness (~9.5%) of the CMT-WAAM AlMg alloy refined with the 0.6 wt% nano-TiC/Ti grain refiner.

Exploring moisture adsorption on cobalt-doped ZnFe2O4 for applications in atmospheric water harvesting.

Sorption-based atmospheric water harvesting (SBAWH) is a highly promising approach for extracting water from the atmosphere thanks to its sustainability, exceptional energy efficiency, and affordability. In this work, ZnFe2O4 and Zn0.4Co0.6Fe2O4 were evaluated for moisture adsorption. The desired materials were synthesized by a surfactant-assisted sol-gel method. Synthesized samples were characterized using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometry (VSM), and point of zero charge (PZC). Crystallinity and phase composition were evaluated by XRD analysis. Several parameters were determined using XRD analysis: lattice parameter, unit cell volume, crystallite size, and bulk density. The morphology of synthesized materials was assessed via SEM, and unveiled the acquisition of consistent, homogeneous, and uniform crystals. Elemental composition was determined through EDX spectroscopy. Water adsorption on the surface was evaluated by FTIR spectroscopy. The magnetic properties of synthesized ZnFe2O4 and cobalt-doped ZnFe2O4 ferrites were investigated using VSM. The negative charge on the Zn0.4Co0.6Fe2O4 surface was explored using PZC. Adsorption studies on synthesized materials were conducted with the help of an atmospheric water harvesting (AWH) plant created by our team. Moisture adsorption isotherms of synthesized materials were determined using a gravimetric method under varying temperature and relative humidity (45-95%) conditions. The moisture content (Mc) of Zn0.4Co0.6Fe2O4 and ZnFe2O4 was 597 mg g-1 and 104 mg g-1, respectively. Key thermodynamic properties, including isosteric heat of adsorption (Qst), change in Gibbs free energy (ΔG), and change in sorption entropy (ΔS), were evaluated. Qst was negative, which confirmed the sorption of water vapors on the material surface. ΔG and ΔS indicated that water-vapor adsorption was spontaneous and exothermic. A second-order kinetics study was carried out on synthesized materials, demonstrating their chemisorption behavior. The latter was due to the oxygen defects created by replacement of Co2+ and Fe3+ at tetrahedral and octahedral sites. Water vapors in the atmosphere became attached to the surface and deprotonation occurred, and the hydroxyl ions were formed. Water vapor attached to these hydroxyl ions. A second-order kinetics study was carried out to confirm the chemisorption behavior of synthesized materials.

Structural and optical properties of cadmium selenide thin film growth with different substrate temperatures by spray pyrolysis deposition

In this work, cadmium selenide (CdSe) thin films were deposited successfully by spray pyrolysis at different substrate temperatures. The influence of the preparation technique on the optical, morphological, and structural properties of the different substrate temperature CdSe films were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Visible optical transmission. The XRD analysis reveals that CdSe thin film has hexagonal (wurtzite) and (cubic) crystal structures with different particle sizes depending on the substrate temperature. The SEM image shows uniform and adherent crystals. The optical energy gap was found to be in the range of 1. 70 – 2.59 eV with different temperatures.

Effect of stearic and oleic acid-based lipophilic emulsifiers on the crystallization of the fat blend and the stability of whipped cream.

Effect of stearic acid-based lipophilic emulsifiers (sorbitan monostearate (Span-60), sucrose ester S-170, and lactic acid esters of monoglycerides (LACTEM)) and oleic acid-based lipophilic emulsifiers (sorbitan monooleate (Span-80) and sucrose ester O-170) on the crystallization of fat blend and the stability of whipped cream were studied. Span-60 and S-170 possessed strong nucleation inducing ability and good emulsifying properties. Thus, tiny and uniform crystals were formed in fat blends, small and ordered fat globules were distributed in emulsions, and air bubbles were effectively wrapped in firmly foam structures. The crystallization of the fat blend and the stability of whipped cream were slightly modified by LACTEM due to its poor nucleation inducing ability and moderate emulsifying characteristic. Span-80 and O-170 had weak nucleation inducing ability and poor emulsifying properties, therefore, loose crystals were formed in fat blends and some big fat globules were separated in emulsions, thereby decreasing the stability of whipped creams.

Electrochemical synthesis of ultra-flexible PES/HKUST-1 composite membranes for wastewater treatment

Electrochemical synthesis of polymer/MOF composite membranes holds great potential for practical applications, yet the preparation of flexible and dense MOF layers remains a challenge, which is crucial for achieving practicality. Herein, a novel ultra-flexible polyethersulfone (PES)/Cu-based metal–organic framework (HKUST-1) composite membrane has been fabricated via an electrochemical synthesis method. Various reaction conditions, including voltage, stirring speed, and reaction time, were systematically investigated to elucidate their influence on crystal growth and the resulting membrane uniformity. The characterization results showed that high voltage and moderate stirring as well as are conducive to obtaining uniform fine crystals. Additionally, a relatively extended reaction time is advantageous for achieving a more continuous and denser MOFs membrane with outstanding flexibility. The optimized membrane possesses an excellent separation flux (2.81 × 103±32 L m−2 h−1·bar−1) and efficiency (99.7 ± 0.3%) for n-hexane/water mixtures, as well as excellent photodegradation efficiency (>99%) for methylene blue (MB). Remarkably, the optimized membrane exhibits remarkable scalability and stability, maintaining superior separation performance even after being rolled up 10 times with a curvature of 200 m−1. This suggests that it has great potential for practical applications in complex environments.

Piezoelectric, mechanical, and crystallographic properties of polyvinylidene fluoride‐hexafluoropropylene based composites reinforced by different dimensional carbon nanomaterials

AbstractPolymer based piezoelectric materials are increasingly used because of their lightweight and flexibility. To understand the effects of different dimensional carbon nanomaterials on the properties of polyvinylidene fluoride‐hexafluoropropylene (PVDF‐HFP) based composites, carbon black (CB), carbon nanotube (CNT), and few‐layer graphene (FLG) were used to reinforce PVDF‐HFP for preparing different composites, respectively. Their piezoelectric, mechanical, and crystallographic properties were tested. The results show that CB/PVDF‐HFP composite film has the best piezoelectric property, successively followed by FLG/PVDF‐HFP and CNT/PVDF‐HFP at 0.5%, 0.05%, and 0.1% contents of CB, FLG, and CNT, respectively. In the initial crystallization stage, CB better plays the best role of crystallization core, increasing the electroactive crystalline phase content and crystallization rate. The appropriate contents of CNT and FLG promote the formation of β crystalline phase. In the polarization stage, CB forms a uniform nonconductive network in the composite film and shows the best polarization effect. CNT tends to form connections and has the worst polarization effect. FLG forms a “microcapacitor” structure to enhance the local polarization effect. The effects of CB, CNT, and FLG on crystalline phase changes and piezoelectric property enhancements of PVDF‐HFP based composites are mainly due to their differences in size, morphology, and quantity.Highlights Effects of CB, CNT, and FLG on the piezoelectricity of PVDF‐HFP are investigated; CB more obviously increases the piezoelectricity of PVDF‐HFP than CNT and FLG; α, β, and γ crystalline phase changes in PVDF‐HFP based composites are understood; CB forms smaller and more uniform crystal cores in PVDF‐HFP than CNT and FLG; CB markedly increases the contents of electroactive crystalline phases in PVDF‐HFP.

Bismuth-magnesium-oxide-based graphene oxide hybrid film for liquid crystal device application

Hybrid films containing bismuth magnesium oxide (BiMgO) and graphene oxide (GO) are investigated in this study. Solution-processed brush coating is used to fabricate the hybrid films, with the graphene oxide weight ratios adjusted to 0, 5, and 15%. The hybrid films show more stable and higher optical transmittances than the pure BiMgO film. A directional micro/nanogroove structure is observed on the hybrid film surface, which is derived from the shear stress during the brush-coating process; this anisotropic structure is used as a uniform liquid crystal (LC) alignment layer. Uniform and homogeneous LC alignment is then demonstrated via polarized optical microscopy and pretilt angle analyses, along with perfect light-control performance. Enhanced LC polar anchoring energy and hysteresis-free characteristics are observed for the brush-coated hybrid film as the GO-doping concentration is increased. Based on this perspective, the BiMgO-based GO hybrid film achieved via brush coating has potential for applications in next-generation LC systems.

Highly hydrophobic zeolite ZSM-8 with perfect framework structure obtained in a strongly acidic medium

The synthesis of zeolites in a strongly acidic medium is a new and nearly unexplored chemistry field. In addition to the previously reported silicalite-1 and the several clathrasils, this paper elaborates that one more material of unique properties could be successfully crystallized in the strongly acidic fluoride medium. A pure-silica zeolite ZSM-8 has been obtained using tetraethylammonium ion as a structure-directing agent. Rietveld refinement proves that ZSM-8 is of the MFI topology, i.e., it is another silicalite-1 but different in framework distortions. Moreover, the discrete and uniform crystals of the acidic-medium synthesized pure-silica ZSM-8 possess a substantially perfect framework structure and thus hydrophobic surfaces. This remarkable character renders the material an ideal adsorbent for discriminating molecules on the polarity basis, which is desired in developing green separation processes. C3H8, CH4, and CO2 are chosen as examples respecting their different polarities and tested for the adsorptive parameters.