Basal Plane Research Articles

The Crystal Structure of a Mineral with the Composition Pd(Bi,Sb)

The Crystal Structure of a Mineral with the Composition Pd(Bi,Sb)

Mechanical properties of additively manufactured lattice structures composed of zirconia and hydroxyapatite ceramics

Ceramic lattices hold great potential for bone scaffolds to facilitate bone regeneration and integration of native tissue with medical implants. While there have been several studies on additive manufacturing of ceramics and their osseointegrative and osteoconductive properties, there is a lack of a comprehensive examination of their mechanical behavior. Therefore, the aim of this study was to assess the mechanical properties of different additively manufactured ceramic lattice structures under different loading conditions and their overall ability to mimic bone tissue properties.Eleven different lattice structures were designed and manufactured with a porosity of 80% using two materials, hydroxyapatite (HAp) and zirconium dioxide (ZrO2). Six cell-based lattices with cubic and hexagonal base, as well as five Voronoi-based lattices were considered in this study. The samples were manufactured using lithography-based ceramic additive manufacturing and post-processed thermally prior to mechanical testing. Cell-based lattices with cubic and hexagonal base, as well as Voronoi-based lattices were considered in this study. The lattices were tested under four loading conditions: compression, four-point bending, shear and tension.The manufacturing process of the different ceramics leads to different deviations of the lattice geometry, hence, the elastic properties of one structure cannot be directly inferred from one material to another. ZrO2 lattices prove to be stiffer than HAp lattices of the same designed structure. The Young’s modulus for compression of ZrO2 lattices ranges from 2 to 30GPa depending on the used lattice design and for HAp 200MPa to 3.8GPa. The expected stability, the load where 63.2% of the samples are expected to be destroyed, of the lattices ranges from 81 to 553MPa and for HAp 6 to 42MPa.For the first time, a comprehensive overview of the mechanical properties of various additively manufactured ceramic lattice structures is provided. This is intended to serve as a reference for designers who would like to expand the design capabilities of ceramic implants that will lead to an advancement in their performance and ability to mimic human bone tissue.

In-Plane Compression Properties of Continuous Carbon-Fiber-Reinforced Composite Hybrid Lattice Structures by Additive Manufacturing.

Continuous-fiber-reinforced composite lattice structures (CFRCLSs) have garnered attention due to their lightweight and high-strength characteristics. Over the past two decades, many different topological structures including triangular, square, hexagonal, and circular units were investigated, and the basic mechanical responses of honeycomb structures under various load conditions, including tension, compression, buckling, shear, and fatigue were studied. To further improve the performance of the honeycombs, appropriate optimizations were also carried out. However, the mechanical properties of a single lattice often struggle to exceed the upper limit of its structure. This paper investigates the effect of permutation and hybrid mode on the mechanical properties of CFRCLSs by comparing five structures: rhomboid (R-type), octagon orthogonal array (OOA-type), octagon hypotenuse array (OHA-type), octagon nested array (ONA-type), and rhomboid circle (RC-type), with the conventional hexagonal structure (H-type). CFRCLS samples are fabricated using fused filament fabrication (FFF), with carbon-fiber-reinforced polylactic acid (PLA) as the matrix. The in-plane compression properties, energy absorption characteristics, and deformation behaviors of the hybrid structures were studied by experimental tests. The results demonstrate that different permutation and hybrid modes alter the deformation behaviors and mechanical properties of the structures. Taking elastic modulus as an example, the values of H-type, R-type, OOA-type, OHA-type, ONA-type, and RC-type are, respectively, 6.08 MPa, 5.76 MPa, 19.0 MPa, 10.3 MPa, 31.7 MPa, and 73.2 MPa, while the ratio of their masses is 1:1:1.10:1.52:1.66. Furthermore, hybrid lattice structures exhibit significantly improved mechanical properties compared to single lattice structures. Compared to the single structure R-type, the RC-type increases elastic modulus, yield strength, and energy absorption, respectively, by 12.7 times, 5.4 times, and 4.4 times.

Effect of surface high-density twinned structure on the fatigue crack initiation of Ti–6Al–4V

Fatigue crack initiation sites would transfer from surface to subsurface of metal specimens through shot peening (SP) or laser shock surface strengthening. This phenomenon is typically attributed to the introduction of compressive residual stress on the surface of the specimen during the surface strengthening process. In this study, Ti–6Al–4V specimens featuring a high-density twinned structure on their surfaces, which eliminated compressive residual stress, were fabricated. Fatigue test result revealed that fatigue crack initiation sites in specimens with twinned structures were predominantly located in the subsurface, near the junction area between the twinned structure and the matrix. This phenomenon was accompanied by an increase in fatigue life. The microstructural features in the fatigue crack source were analyzed using focused ion beam (FIB) coupled with electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). It was observed that primary crack formed in badly oriented grains that are difficult to initiate dislocation slip according to the Schmid factor (SF). Nonetheless, TEM observations revealed the activation of basal <a> dislocations in these grains, potentially leading to crack nucleation along basal slip bands and subsequent propagation along the basal plane. Our results suggest that a high-density twin structure on the surface can enhance the fatigue strength of Ti–6Al–4V by transferring the fatigue crack source to the subsurface.

The effect of various crystalline forms of HFC 134a hydrate on the growth rate and desalination efficiency

Experimental studies on the synthesis of HFC 134a hydrate in the liquid HFC 134a – water system were performed. Despite today's lack of research on the use of HFC 134a hydrate for desalination of seawater and separation of harmful impurities by HFC 134a hydrate synthesis, this method has prospects for development: HFC 134a hydrate is synthesized at relatively high temperature and low pressure; it is poorly soluble in water, which simplifies gas hydrate separation from water–salt solution; it has high volumetric storage density and relatively high thermal conductivity. In spite of its low solubility in water, HFC hydrate exhibits relatively high growth rates. The growth of various crystalline forms and the peculiarities of their occurrence in pure water, aqueous salt solution, as well as with the addition of surfactant are considered. The use of SDS increases the HFC hydrate growth rate. For the first time, it was shown that the intensive growth of HFC 134a hydrate in the form of needles throughout the entire volume of the liquid allows increasing the efficiency of desalination. It is important to consider the desalination process comprehensively, taking into account the crystal forms, crystal growth rate, crystal defects, as well as taking into account the degree of salt removal. Simultaneously with the bubble growth, a thin gas hydrate film is shown to grow on the bubble surface. A detailed consideration of the stages of such hydrate growth is provided to explain the high-speed synthesis of porous HFC hydrate due to boiling of liquid HFC and vaporization.

On the effect of strain rate during the cyclic compressive loading of liquid crystal elastomers and their 3D printed lattices

Nematic liquid crystal elastomers (LCEs) are a unique class of network polymers with the potential for enhanced mechanical energy absorption and dissipation capacity over conventional network polymers because they exhibit both conventional viscoelastic behavior and soft-elastic behavior (nematic director changes under shear loading). This additional inelastic mechanism makes them appealing as candidate damping materials in a variety of applications from vibration to impact. The lattice structures made from the LCEs provide further mechanical energy absorption and dissipation capacity associated with packing out the porosity under compressive loading.Understanding the extent of mechanical energy absorption, which is the work per unit mass (or volume) absorbed during loading, versus dissipation, which is the work per unit mass (or volume) dissipated during a loading cycle, requires measurement of both loading an unloading. In this study, a bench-top linear actuator was employed to characterize the loading-unloading compressive response of polydomain and monodomain LCE polymers and polydomain LCE lattice structures with two different porosities (nominally, 62% and 85%) at both low and intermediate strain rates at room temperature. As a reference material, a bisphenol-A (BPA) polymer with a similar glass transition temperature (9°C) as the nematic LCE (4°C) was also characterized at the same conditions for comparing to the LCE polymers. Based on the loading-unloading stress-strain curves, the energy absorption and dissipation for each material at different strain rates (0.001, 0.1, 1, 10 and 90 s-1) were calculated with considerations of maximum stress and material mass/density. The strain-rate effect on the mechanical response and energy absorption and dissipation behaviors was determined. The energy dissipation ratio was also calculated from the resultant loading and unloading stress-strain curves. All five materials showed significant but different strain rate effects on energy dissipation ratio. The solid LCE and BPA materials showed greater energy dissipation capabilities at both low (0.001 s-1) and high (above 1 s-1) strain rates, but not at the strain rates in between. The polydomain LCE lattice structure showed superior energy dissipation performance compared with the solid polymers especially at high strain rates.

Biomimetic structural design and performance study of 3D-printed graded minimal surface bone scaffolds with enhanced bioactivity

Bone bionics and structural engineering have played a vital role in bone regeneration, with artificial scaffolds generating widespread interest. However, the mechanical properties and bone regeneration potential of biomimetic structures remain unclear. Herein, biodegradable polymer composites based on poly(butylene adipate-co-terephthalate)/poly(lactic acid) (PBAT/PLA) were 3D-printed into lattice structures as tissue engineering scaffolds. For structural design, graded diamond (D) minimal surfaces were proposed and designed to mimic the natural bone structure. The graded topologies were realized by designing gradient thickness either radially from center to edge or vertically from top to bottom. The mechanical performance of these graded samples displayed better load-carrying and energy absorption capacity than the uniform counterparts. No obvious damage was detected in the internal microstructure of the compressed samples using computed tomography. Subsequently, platelet-rich plasma (PRP), containing diverse cytokines, was loaded on the graded scaffolds. The PRP-loaded D-scaffold reported improved in vitro cell proliferation and osteoblast differentiation. Finally, femoral condyle defect repair results indicated that the PRP-loaded D-scaffold effectively promoted early-stage bone regeneration. Overall, this work provides insights into fabricating artificial scaffolds with bioactive factors and biomimetic lattice structures.

Mechanical and thermal property analysis and optimization design of hybrid lattice structure based on triply periodic minimal surfaces

Hybrid lattice structures have significant potential in engineering applications owing to their outstanding mechanical and thermal properties. In this paper, an innovative design strategy for hybrid lattice structures is proposed involving the integration of primitive surfaces with truss lattice configurations. This approach allows for the full exploitation of the mechanical and thermal properties inherent in each component, leading to the development of new hybrid lattice structures. Firstly, the quasi-static compression and fluid-solid coupling heat conduction analysis of the hybrid lattice structure is carried out by numerical simulation. Then the effects of surface wall thickness, and truss diameter on the mechanical and thermal properties of the lattice structure are discussed. Additionally, the mechanical performance of the array hybrid lattice structure is evaluated through quasi-static compression experiments. These experimental results are compared with those from the numerical simulations, validating the accuracy of the simulation model. Finally, a multi-objective optimization model targeting specific elastic modulus and heat dissipation performance (indicated by Nusselt number) is established, in response to the demand of aviation and aerospace industries for lightweight, load-bearing, and heat-dissipating multi-functional integrated lattice design. The non-dominated sorting genetic algorithm is utilized to solve the optimal model, and the distribution of feasible solutions and Pareto front are obtained. The results show that the interpenetrating hybrid lattice structure has a greater improvement in mechanical and thermal properties than the primitive surfaces. This research holds significant implications for the design of multi-performance hybrid lattice structures.

Mechanical characterization of lattice structures fabricated by selective laser melting via an image-based finite cell method with a damage model

Lattice structures fabricated by the selective laser melting (SLM) additive manufacturing process hold great potential for diverse applications. However, their actual mechanical behaviors often deviate from their counterparts with the as-designed geometries due to manufacturing defects. In this study, we presented an in-depth mechanical characterization of imperfect octet lattice structures via an image-based finite cell method (FCM) in combination with the multi-level hp refinement scheme for resolving the local defects and a Lemaitre damage model to conduct the damage analysis. Micro-computed tomography scanning was utilized to scan six SLM-fabricated octet lattice cells to obtain their as-built geometries. Based on the obtained geometry, the force-displacement curves and the damage distribution of the octet lattice cells and struts under given loads were predicted. The numerical results indicate that external defects significantly affect the struts' damage distribution, while internal voids have a lesser influence due to their low volume fraction. It is identified that the SLM-fabricated octet lattice cell presents better elastoplastic behavior along the loading direction perpendicular than parallel to its build direction. These insights into the mechanical performance of imperfect octet lattice cells underscore the defects' adverse effects and advance the understanding of their significance in SLM components.

Mechanical properties and failure behavior of additively manufactured Al2O3 lattice structures infiltrated with phenol-formaldehyde resin

The lightweight design and load-bearing capacity of underwater vehicles remain perennial focal points. Ceramic lattice structures (CLSs) offer significant weight reduction while maximizing structural strength; however, their inherent brittleness poses a limitation. To optimize the performance of CLSs for underwater vehicle applications, a biomimetic Al2O3/phenol-formaldehyde (PF) resin composite structure (APCS) was proposed and fabricated by infiltrating additive-manufactured Al2O3 lattice structures (ALSs) with PF. Comprehensive assessments of the quasi-static mechanical properties were conducted using both experimental and simulation methods. The specific compressive strength and specific energy absorption of the APCSs under quasi-static compressive loading exhibited remarkable improvements, with the maximum values achieved from the body-centered cubic (BCC)/PF structure increasing by ∼15.23 and ∼307.93 times, respectively. In contrast to ALSs, the failure process of APCSs was gradual, with the confining pressure introduced by the PF promoting transverse crack propagation and layer-by-layer failure, thereby strengthening the ceramic lattice. Toughing mechanisms (i.e., crack arrest, crack deflection, and branching) were also observed in the APCSs. Furthermore, the simulation results aligned well with the experimental results, providing an in-depth analysis of internal damage and crack propagation. The improvements introduced by the composite structure in this study provide a reliable approach for obtaining lightweight and strong materials, thereby accelerating the application of ceramic-based materials in underwater vehicles.

Structural, morphological, electrochemical and optical properties ZnS quantum dots: Influence of La3+ ions

The La-doped ZnS quantum dots were prepared by the facile co-precipitation technique. XRD patterns revealed the cubic structure of the ZnS crystal lattice. We measure the size of the synthesized nanoparticles at approximately 2 nm. Sulfur vacancies on the structure’s surface produce some defects. The HR-TEM and FE-SEM results also confirm the size, morphology, and other structural entities. The EDS and FTIR results confirmed the composition of the samples. We tested the electrochemical behaviors of the samples, and found that La 4 at% doped-ZnS offered a high specific capacitance. The enhancement of optical absorbance was observed by the UV–vis studies. A red shift was received in band gap due to incorporation of La ions. We observe high optical transmittance for La 2 at.% doped-ZnS quantum dots. PL emission results showed a weak emission in the UV region, and some defect-related emissions in the visible region.

Discovery of a giant lattice in Mg97Zn1Yb2 alloy

The Mg-rich corner of Mg–metal (M)–rare earth element (REE) ternary systems results in a long-period stacking-ordered (LPSO) phase that increases the strength and elongation of the Mg alloy. Using Yb at the REE position does not result in the LPSO phase; instead, it forms unique crystalline structures with intriguing properties. In this study, we found a new giant lattice belonging to the P6/mmc space group by quenching the Mg97Zn1Yb2 alloy at 723K. The giant lattice, which precipitates around the α-Mg matrix with a chemical composition of Mg75Zn7Yb18 (at.%), comprises a basic structure and a superlattice. We developed an atomic configuration model that expresses the basic structure as alternating stacking of three types of layers. The observed features indicate that the structure of the giant lattice is similar to that of the approximant quasicrystal reported for Mg–M–REE ternary systems.

Fatigue deformation behavior and fracture mechanism of high fatigue-resistant laser directed energy deposition fabricated titanium alloy: Effect of multi-scale microstructure

The application of the laser directed energy deposition (LDED) titanium (Ti) alloys has been severely impeded by their poor low cycle fatigue (LCF) properties in aerospace industry. Herein, we propose to improve the LCF properties of LDED-ed Ti6Al4V alloys via microstructure adjustment. A solid solution aging 850AA treatment is made to regulate the microstructure into a multi-scale composition dominated by discontinuous αGB and coarsened αP+(αS+β) phases. The LCF properties of LDED-ed Ti6Al4V with a multi-scale microstructure even outperform the wrought Ti6Al4V at high strain amplitudes. Furthermore, this multi-scale microstructure has special local plastic deformation behavior and dislocation activities under cyclic stress loading, which strongly affects the internal stress evolution and crack propagation. The fatigue softening behavior is attributed to the combined effect of back stress and friction stress. Fatigue cracks are deflected by the α/β boundary when the angle (φ) between the long axis of α lamellae and the crack direction is less than 35°. The transgranular fracture occurs when φ is close to 90° (70°-90°). Meanwhile, the fatigue crack usually propagates along the basal or prismatic planes with high Schmid factors. These findings provide novel insights into the microstructure design of LDED-ed Ti alloys with high fatigue damage tolerance.

Enhancing photocatalytic dye degradation efficiency through the utilization of shock wave effects on neodymium oxide (Nd2O3)

This article delves into the impact of shockwaves on neodymium oxide (Nd2O3) nanoparticles, aiming to evaluate their physical and chemical stability. Nd2O3 nanoparticles were subjected to varying sets of shock pulses (100, 200, and 300) in photocatalytic dye degradation. The nanoparticles crystallinity and unit cell volume after shockwave exposure were examined using powder X-ray diffraction (PXRD) analysis with unit-cell software. PXRD data revealed no alterations in the crystalline structure, lattice parameter and unit cell volume. Comparisons between pre- and post-shockwave field emission scanning electron microscopy (FE-SEM) portraying data demonstrate that repeated shockwave application causes a decrease in particle size. Raman spectroscopy, under ambient conditions, shows a high intensity after shock conditions intensity will decrease. Furthermore, FTIR spectroscopy revealed the characteristic strong and broad absorption band associated with metal-oxygen (Nd-O) groups in the Nd2O3 nanoparticles. UV–Vis diffuse reflectance spectroscopy (DRS) was used to investigate the bandgap of the Nd2O3 nanoparticles. Initially, the bandgap was measured at 5.96 eV under ambient conditions, but following the shockwave exposure, it was decreased to approximately 5.91 eV. Interestingly, the surface area of the shockwave-treated Nd2O3 nanoparticles is increased and exhibited an increased efficiency in photocatalytic dye degradation. This finding holds promising implications for environmental remediation applications.

Approaching the low thermal conductivity in layered oxychalcogenide Bi2-xPrxO2Se (0 ≤x≤ 0.15) via mass and strain field fluctuation for thermoelectric application

Bi2O2Se, a layered oxychalcogenide has gained much attention among the conventional oxides and chalcogenides based thermoelectric materials because of its high stability and less toxicity. Herein, Bi2-xPrxO2Se (0 ≤x≤ 0.15) is synthesized by ball milling followed by hot press densification technique, the x represents the replacement of atoms in atomic %. The influence of isovalent Pr substitution on the structural and thermal transport properties of Bi2O2Se were studied. The formation of tetragonal crystal structure with space group I4/mmm is confirmed by X ray diffraction (XRD) Pattern. HRTEM micrographs reveals the crystalline nature and lattice defects in the synthesized composition. The influence of 10 at % Pr substitution at Bi site reduces the thermal conductivity to 0.276 Wm−1K−1 at 653 K, originated from short phonon lifetime due to the effect of mass and strain field fluctuation. This result exhibits that the incorporation of Pr substitution in Bi2O2Se can dramatically enhance the thermoelectric performance of Bi2O2Se ceramic by reducing thermal conductivity.

Supramolecular architectures in multicomponent crystals of imidazole-based drugs and trithiocyanuric acid.

The structures of three multicomponent crystals formed with imidazole-based drugs, namely metronidazole, ketoconazole and miconazole, in conjunction with trithiocyanuric acid are characterized. Each of the obtained adducts represents a different category of crystalline molecular forms: a cocrystal, a salt and a cocrystal of salt. The structural analysis revealed that in all cases, the N-H...N hydrogen bond is responsible for the formation of acid-base pairs, regardless of whether proton transfer occurs or not, and these molecular pairs are combined to form unique supramolecular motifs by centrosymmetric N-H...S interactions between acid molecules. The complex intermolecular forces acting in characteristic patterns are discussed from the geometric and energetic perspectives, involving Hirshfeld surface analysis, pairwise energy estimation, and natural bond orbital calculations.

Synthesis and Characterisation of Biochar Activated Carbon for Oil Spills Removal

Activated carbon (AC) is an effective material for various environmental and industrial applications. The characteristics and performance of AC is a result of interaction between source and method of preparation. In the current work, AC has been prepared from date seed waste using microwave heating under nitrogen using basic medium such as potassium hydroxide and acidic medium such as sulfuric acid as chemical activating agents. The AC was characterised using X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) with differential scanning calorimetry (DSC). XRD patterns of the AC in both cases exhibited three peaks corresponding to the crystalline graphite form of carbon. Scanning electron microscopy (SEM) images of the freshly prepared carbons showed that the samples contained particles of various sizes including both nanoparticles as well as millimetre-range particles. DSC analysis showed that the samples exhibited endothermic reaction in low temperature ranges until 300°C and exothermic reaction above this temperature. SEM analysis of the AC, separated into three different size ranges, showed significant etching of the surface of the carbon to yield porous structures. The AC produced using sulfuric acid showed better adsorption capacity (9.2 g g−1) when compared to that produced using potassium hydroxide (7.7 g g–1). We conclude that the AC prepared from date seeds can find potential application in water purification and oil spill clean-up.

Fatigue Assessment of Inclined Film Cooling Holes in Nickel-Based Single-Crystal Superalloy

Fatigue tests of nickel-based single-crystal superalloys with inclined film cooling holes (FCHs) at 1000°C were conducted to investigate the effects of crystal orientation and to quantify the fatigue performance of the high-temperature structures. Fractographic analysis and computations of stress concentrations revealed competitive failure mechanisms between mode I crack nucleation and fatigue crack growth in crystallographic plastic slip systems, whereas crack nucleation around inclined FCHs can be characterized by the known fatigue criteria derived for smooth specimens. A life prediction model based on the crystal slip mechanism and the theory of critical distance was introduced to predict the fatigue life of FCH structures and provided reasonable accuracy for different FCH specimens.

Electronic and structural insights into boron nitride counterparts of Net-(Y,W)

Computational materials play a crucial role in comprehending various material classes and their properties, offering valuable insights for predicting novel structures and complementing experimental approaches. Net-(C,Y,W) has emerged as stable two-dimensional carbon allotropes of 4-6-8 carbon rings within this framework. This study uses density functional theory calculations and ab initio molecular dynamics simulations to explore the structural, electronic, optical, and mechanical properties of their boron nitride counterparts, named NetBN-W and NetBN-Y, with NetBN-C already investigated. The electronic analysis reveals an insulating characteristic for NetBN-W and a potential wide band gap semiconducting nature for NetBN-Y, with values of 5.12 eV and 3.71 eV, respectively. Optical properties examination indicates UV activity for these materials, accompanied by optical anisotropy between the x and y directions. Evaluation of mechanical properties also uncovers significant anisotropy in both materials, with Young’s moduli reaching 417.58 GPa for NetBN-W and 433.31 GPa for NetBN-Y when stretched in the y-direction of the basal plane. The nearly zero Young’s modulus for NetBN-Y in the x-direction signifies its substantial instability under tension due to nitrogen bonds parallel to the strain direction. These findings offer valuable insights into the fundamental properties of NetBN-W and NetBN-Y and their potential applications.

Surface energies control the anisotropic growth of [formula omitted]-Ni(OH)2 nanoparticles in stirred reactors

Nickel hydroxides are an important family of electrode materials in the field of batteries and electrochemical energy storage. Two polymorphs, α-Ni(OH)2 and β-Ni(OH)2 have been identified, with intermediate structures also reported. However, the synthesis of the β-phase precipitants that are ideal for electrochemical applications is not trivial. The growth and morphology of the final products can widely vary with the pH. The electrochemical performance of the β-phase is sensitive to its structure and morphology, which are also sensitive to the reaction conditions. In order to better understand the initial nucleation, growth and morphological evolution of the β-phase, we present a combined experimental and theoretical study including a multiscale phase-field model for the evolution of the morphology of β-Ni(OH)2. Surface indices and energies for the phase-field modeling were obtained from density functional calculations (DFT). The developed phase-field model can reproduce the growth of β-Ni(OH)2 phase in different conditions. The model shows that the basal planes of β-Ni(OH)2 can grow in high pH but at the same time its growth is limited by other high energy prismatic surfaces.