Easy Shaping Research Articles

Modelling and nondestructive quality prediction of Guanxi Honey Red Pomelo (<i>Citrus grandis</i> (L.) Osbeck) based on shape characteristics and bitterness

Currently, it is difficult to distinguish the inner quality of pachycarpous fruits using nondestructive instruments, and trace nutrients and flavor compounds are rarely considered in fruit sorting. In this study, the external features and internal quality indices of an extensively farmed citrus fruit, the Guanxi honey red pomelo, were measured. The correlation between the inner and external quality was analyzed using Pearson correlation, canonical correlation, and grey correlation analyses. This research innovatively introduced bitter substances and revealed that the height-diameter ratio could serve as a predictor for ultra-size fruits, which partially reflects inner quality indices. Several grey formulas were developed to express these correlations and were fitted to a matrix, which demonstrated accuracies at all level 1 (C < 0.35, P > 0.95). Based on the matrix, fruit quality analysis of white and red pomelo showed high prediction accuracy in TSS and bitter substance indices (R2 = 0.6 – 0.8) and indicated that mature and symmetrical pomelo (height-diameter ratio of 0.9 – 1.1) exhibit a similar quality pattern. This study achieved rapid quality assessment using easy measurable shape characteristics and explored the application of characteristic bitter substances in the quality evaluation model, providing theoretical references and potential application guidance for pachycarpous fruit sorting, as well as introducing a new idea to incorporating characteristic quality into modeling index.

A convenient analytical parametrization of a tokamak plasma last closed flux surface for use in shape and discharge design

Abstract An analytical parametrization of the last closed flux surface of a tokamak plasma is proposed, based on a reduced list of global shape parameters that are conveniently defined. This parametrization can reproduce a variety of shapes, from limited to diverted, lower and upper single null, double null, and diverted negative triangularity plasmas. The choice of the parameters is well suited to be used for easy shape and more generally discharge design, in view of fitting the coil currents that are required to form the desired shape.

Monolithically integrated multimode interference coupler-based master oscillator power amplifier with dual-wavelength emission around 830 nm

A monolithically integrated dual-wavelength multimode interference coupler-based master oscillator power amplifier is presented. It consists of two shallowly etched, laterally separated ridge waveguide laser cavities as master oscillators with individual distributed Bragg reflector gratings as cavity mirrors. A deeply etched coupling section containing S-bend shaped waveguides and a multimode interference coupler is used to couple the laser emission of the master oscillators into a shallowly etched single waveguide serving as power amplifier. Changing the etch depth for the coupling section enables a compact device layout. In addition, increased radiation angles of modes not coupled into the power amplifier help to suppress beam steering, otherwise indicated by laterally separated far-field intensity distributions. The device provides 0.5 W of dual-wavelength emission around 830 nm in individual and common operation. As designed, both emission wavelengths are separated by 0.5 nm with spectral widths below 20 pm, limited by the spectral resolution of the spectrometer. Both peak wavelengths remain within spectral windows of 50 pm within the available power range. This enables full flexibility selecting operating points for applications such as shifted excitation Raman difference spectroscopy and the generation of THz emission by photomixing. The emission wavelengths can additionally be non-continuously tuned by applying a heater current to resistors implemented next to the distributed Bragg reflector gratings. As an example, selected spectral distances of 0.5 nm, 1.0 nm, 1.5 nm, and 2.0 nm are demonstrated. Near field widths of 5 μm and far field angles of 17° result in beam propagation ratios of 1.4 (1/e2) in all operation modes and enable easy beam shaping or optical single-mode fiber coupling.

Mineralogical, geochemical and physical properties assessment of clay deposits in Umuoke Obowo Southeastern Nigeria for industrial applications

This study assessed the suitability of clay deposits from Umuoke, Obowo in southeastern Nigeria as local raw materials for industrial applications. Ten samples were collected from different mining pits across the locality. X-ray fluorescence, X-ray diffraction and physical property tests characterized the clays based on geochemical composition, mineralogy and key attributes. The clays showed high silica (56.41%) and alumina (32.82%) contents typical of aluminosilicate clays. Iron oxide levels were moderately elevated (3.34% Fe2O3). Clay minerals kaolinite (18.9-37.0%) and illite (0.5-4.15%) occurred predominantly alongside non-clay minerals like quartz, feldspars and metal oxides. The clays exhibited high plasticity (avg. plasticity index 26.61%) enabling easy moulding and shaping. Porosity averaged 21.33% appropriate for refractories. Firing shrinkage (6.5-19.2%) and density (1.54-1.76 g/cm3) were in acceptable ranges. Strength post-firing reached the 15 N/mm2 minimum standard. Estimated refractoriness was 1680.22°C. Overall, the Umuoke clays demonstrate favourable chemistry, mineralogy and physical properties for refractories and structural ceramics applications pending some processing adjustments. Locally exploiting these deposits can promote import substitution, rural industrialization and sustainable development in Nigeria. Further pilot testing can optimize formulations and processes for targeted ceramic products. Comprehensive nationwide clay deposit prospecting is also recommended. The clays are suitable for refractory bricks, ceramic tableware, architectural ceramics, wall tiles, pottery items.

Explicit Topology Optimization of Voronoi Foams.

Topology optimization can maximally leverage the high DOFs and mechanical potentiality of porous foams but faces challenges in adapting to free-form outer shapes, maintaining full connectivity between adjacent foam cells, and achieving high simulation accuracy. Utilizing the concept of Voronoi tessellation may help overcome the challenges owing to its distinguished properties on highly flexible topology, natural edge connectivity, and easy shape conforming. However, a variational optimization of the so-called Voronoi foams has not yet been fully explored. In addressing the issue, a concept of explicit topology optimization of open-cell Voronoi foams is proposed that can efficiently and reliably guide the foam's topology and geometry variations under critical physical and geometric requirements. Taking the site (or seed) positions and beam radii as the DOFs, we explore the differentiability of the open-cell Voronoi foams w.r.t. its seed locations, and propose a highly efficient local finite difference method to estimate the derivatives. During the gradient-based optimization, the foam topology can change freely, and some seeds may even be pushed out of shape, which greatly alleviates the challenges of prescribing a fixed underlying grid. The foam's mechanical property is also computed with a much-improved efficiency by an order of magnitude, in comparison with benchmark FEM, via a new material-aware numerical coarsening method on its highly heterogeneous density field counterpart. We show the improved performance of our Voronoi foam in comparison with classical topology optimization approaches and demonstrate its advantages in various settings.

PRODUCTION OF SELF-HEALING MORTAR USING BACTERIAL SPORES ENCAPSULATED WITH JUTE FIBRE

Cement-based composites have various advantages such as low cost, easy shaping, and high compressive strength. Therefore, they are widely used in the construction industry. However, their brittle structure makes them prone to cracking, which must be repaired promptly to avoid possible loss of strength and durability and ultimate structural failures. Microbially-induced calcite precipitation (MICP) offers an effective method for healing these cracks. Unlike other treatments, MICP method is a natural and environment-friendly option for self-healing of cracks. However, bacteria can be damaged by cement and mechanical impacts; therefore, encapsulation is necessary to protect them. Encapsulation in fibres is a simpler and more cost-effective method than the other techniques. This study tested the effectiveness of encapsulating Bacillus megaterium spores in jute fibres and added them to cement-based mortars. Different nutrient supplements were used, and physical analyses and compressive strength tests were conducted on 28-day cured cube specimens. Present findings revealed that Bacillus megaterium-type bacteria encapsulated in jute fibres improved the compressive strength recovery and healed the loading-induced cracks.

The influence of inelastic materials on freeform kerf structures

Kerfing or relief cutting is a fabrication approach to create moldable surfaces out of wood and metal panels. The kerf panels with pre-defined microstructural topology enable the creation of freeform kerf structures of complex geometries, which found many applications in building constructions. This study investigates the influence of inelastic materials, i.e., plastic deformation of stainless steel and viscoelastic wood, and microstructural topology on the overall moldability of kerf panels. Kerf unit cells fabricated from stainless steel (SS) and medium-density fiber (MDF) with different cut patterns, cut densities, and cell sizes are first studied. Experimental tests and mathematical models are used to examine the deformations of the kerf unit cells. Kerf panels of various microstructural topology, which depends on the cut patterns, cut densities, cell sizes, and cell arrangements, are then modeled to create freeform shapes. The effect of inelastic deformations, i.e., shape reconfiguration due to creep of MDF and utilizing inelastic deformations of SS to form the freeform shapes, are studied. When only an elastic deformation is considered, increasing the flexibility in kerf panels by increasing cut densities enables easy shape configurations. However, when a plastic deformation is utilized to form the shape, flexible kerf structures are less effective due to the relatively small stresses in the flexible SS kerf structures to induce plastic deformations. Flexible MDF kerf structures can experience significant creep deformations, inducing nonnegligible shape reconfigurations. To avoid shape reconfigurations due to the creep effect when using viscoelastic wood, one approach is to consider developable surfaces.

Conception of Hybrid Organic-Inorganic Membrane as New Electrolyte in All Solid-State Battery

All-solid-state lithium batteries (ASSBs) are considered like the next generation of electrochemical energy storage devices because of their safety and their high energy density up to 400Wh/kg. The all-solid-state battery is composed of a positive electrode (e.g., NMC (Li(Ni1∕3Mn1∕3Co1∕3)O2)), a negative one (Li), and a solid electrolyte, which is the critical component, composed of inorganic compound and/or solid polymer electrolyte (SPE) [1]. On the one hand, SPE have the advantage of an easy shaping with the technique already used in the manufacture of batteries and their flexibility allows obtaining a good interface with the electrode materials [2]. On the other hand, inorganic compounds generally have high ionic conductivity (10-3S/cm), they are stable electrochemically vs Li/Li+ and their transport number is close to 1 to promote the diffusion/migration of Li+ ions only. In order to combine the advantages of both types of materials, hybrid materials have been designed [3].First, a new adaptable polymer matrix based on PEO derivatives has been developed. A solvent-free synthesis has been designed from liquid and commercial precursors Poly(ethylene glycol) methyl methacrylate (PEGM) and Poly(ethylene glycol) dimethacrylate (PEGDM). These latter were copolymerized with Lithium 3-[(trifluoromethane)sulfonamidosulfonyl] propyl methacrylate (MTFSLi). The anion TFSI- is thus grafted to the PEO network, allowing exclusively the diffusion of the Li+ ion. This polymer matrix can be thus classified as single-ion conductor. In addition, the proportions between PEGM and PEGDM, acting as crosslinker, can be easily tuned. The PEGDM proportion controls the cross-linking density which modifies not only the glass transition temperature (Tg), but also the storage modulus (E’) and the free volume, and consequently the ionic conductivity of the polymer matrix which is the main property required for SPE. Finally, a ratio of PEGM:PEGDM (80:20) allows obtaining homogeneous SPE, self-standing and soft at room temperature, amorphous with a Tg of -41°C. The EO/Li ratio was then modulated in single-ion networks with the MTFSLi proportion, and an optimum in ionic conductivity of 2.10-7 S/cm @25°C has been measured for EO/Li ratio of about 20. The transport number measured by the Bruce and Vincent method [4] was t+=1,0 for the single ion conductor, demonstrating the effective grafting of the counter anion. This value has been validated by measuring the diffusion coefficients of 7Li and 19F in NMR. To our knowledge, this is the first time a real unity transport number is reported in the literature for a polymer electrolyte. Moreover, the electrochemical stability of this single ion system extends from 0 to 6V vs Li+/Li. These experiments suggest the interest of using the single-ion polymer in the formulation of composite positive electrode with high potential cathode materials, due to its stability in potential. Li metal is considered the ultimate anode for Li-batteries. The long-term electrochemical stability has been evaluated in symmetric Li/polymer electrolyte/Li cell. The cell is cycled at a constant current density of 0.2 mA/cm2. After 200 h of cycling the voltage reaches solely 2V. Accordingly, the grafting of the anion to the network limits an overpotential in the cell, allowing a more stable system over time.Second, the garnet Li6.4La3Zr2Al0.2O12 (LLZO) of the oxide family was associated to the previous polymer matrix. This garnet presents a high conductivity (10-4 S/cm @ 25°C), a good chemical stability not only against lithium metal but also against air and humidity, which is not the case of sulphides homologues. A 3D-fibrous network obtained by the electrospinning method was carried out with a solution containing the inorganic precursors, a polymer and an appropriate solvent [5]. Then this membrane is calcined at 850°C to obtain the 3D fibrous network of LLZO. The resulting self-standing porous inorganic material (~80% of porosity) exhibits a conductivity of the order of 10-6 S/cm @25°C. It was then impregnated with the polymer matrix precursors by capillarity and following by a polymerization. A self-standing membrane as thin as 80 µm containing 9%vol of LLZO was obtained. The conductivity of this hybrid membrane is comparable to that of the polymer (10-7S/cm @ 25°C). The resulting hybrid is mainly polymeric where the ionic conduction was realized by the polymeric matrix and the inorganic acts as a mechanical reinforcement. Preliminary results on high content of LLZO hybrid will also be presented, where a synergy of the both components is observed.[1] Janek. Nature Energy. 2016. Vol 1(9)p.16141. [2] Yue. Energy Storage Materials. 2016. Vol 5p.139-164. [3] Zheng. Chem Soc Rev. 2020. Vol 49p.8790-8839. [4] Bruce. Solid State Ion. 1988. Vol 28–30p.918–922. [5] A. La Monaca. Electrochemistry Communications. 2019. Vol 104p.106483. Figure 1

Additive Manufacturing of Advanced Ceramics Using Preceramic Polymers

Ceramic materials are used in various industrial applications, as they possess exceptional physical, chemical, thermal, mechanical, electrical, magnetic, and optical properties. Ceramic structural components, especially those with highly complex structures and shapes, are difficult to fabricate with conventional methods, such as sintering and hot isostatic pressing (HIP). The use of preceramic polymers has many advantages, such as excellent processibility, easy shape change, and tailorable composition for fabricating high-performance ceramic components. Additive manufacturing (AM) is an evolving manufacturing technique that can be used to construct complex and intricate structural components. Integrating polymer-derived ceramics and AM techniques has drawn significant attention, as it overcomes the limitations and challenges of conventional fabrication approaches. This review discusses the current research that used AM technologies to fabricate ceramic articles from preceramic feedstock materials, and it demonstrates that AM processes are effective and versatile approaches for fabricating ceramic components. The future of producing ceramics using preceramic feedstock materials for AM processes is also discussed at the end.

Flexible and conductive core-sheath fiber using multifunctional merocyanine as a smart electrolyte for a high-performance fibrous visible light sensor

Flexible conductive fibers have attracted significant attention in the wearable electronics field because of light weight, small size, and easy shape morphing. To date, there are few reports on multifunctional flexible conductive fibers. Finding a facile and effective solution for large-scale production of flexible conductive fibers is still a challenge. In this work, a flexible core-sheath fiber with excellent electrical conductivity (24.71 Ω·m) and visible light sensing is fabricated, which contains a merocyanine diol (MC(OH)2)/CrCl3·6H2O/ethanol aqueous solution core layer and a silicon rubber outer layer. The synthesized MC(OH)2 is an intelligent molecular switch with a visible light response that can reversibly convert from open-form MC(OH)2 to closed-form spiropyran diol (SP(OH)2) after short visible light irradiation. In the reverse process, the transition from SP(OH)2 to MC(OH)2 can occur gradually in the dark. This can be used to sense visible light in addition to electrical conductivity. The reversible change in the electrical resistance of the MC(OH)2/CrCl3·6H2O/ethanol aqueous solution reaches 15.59%. This fiber shows excellent electrical conductivity, good flexibility, a sensitive visible light response, good photochromism, a simple structure, low cost, easy preparation, and suitability for industrial large-scale production, offering promise for applications in the fields of flexible and wearable electronics.

Graphene-coated D-shaped terahertz fiber modulator

A terahertz (THz) fiber is of interest due to low loss and easy beam shaping. Graphene plays an important role in modulating the optical signal. In this paper, a graphene-coated D-shaped THz fiber modulator is proposed. The performance of the proposed modulator is investigated by the finite element method. The inference of geometric parameters of the structure on the proposed modulator is also analyzed, and an optimal structure is obtained. Simulation results show that the confinement loss and the full width at half-maximum (FWHM) can be tuned by adjusting the Fermi level of graphene. The proposed THz fiber modulator shows potential in future THz fiber communications.

A Quasi-Optimal Shape Design Method for Electromagnetic Scatterers Based on NURBS Surfaces and Filter-Enhanced GWO

This paper presents a quasi-optimal and efficient method for designing the shape of electromagnetic (EM) scatterers. Optimizing the EM scatterer shape to achieve satisfactory scattering properties is a crucial, yet challenging problem due to the complex geometry involved and the high non-linearity in the optimization. In this paper, the geometric complexity is to be handled by modeling EM scatterer shapes as non-uniform rational basis spline (NURBS) surfaces, which enables an easy and intuitive shape control. Using the surfaces’ control points as optimization variables, the shape optimization problem is to be solved with the heuristic optimization strategy, which can effectively handle non-linearity and the associated local optima. Specifically, the recently developed grey wolf optimizer (GWO) is employed. Although GWO can effectively avoid local optima and achieve quasi-optimal results, it requires repeated calls to time-consuming EM simulations. To solve this efficiency issue, a filter-enhanced version of GWO is proposed to reduce the times of calling EM simulations, and an efficient, adaptive remeshing method is proposed to accelerate the numerical analysis process within each EM simulation call. Altogether, they lead to a quasi-optimal and efficient method for optimizing EM scatterers. Its effectiveness has also been validated by several examples.

Clay/phosphate-based ceramic materials for thermal energy storage – Part I: Effect of synthetic phosphate content on microstructure, thermo-physical and thermo-mechanical properties

Fired clay ceramics are promising materials for TES, thanks to their thermal stability, availability worldwide, low cost and easy shaping and handling. However, their thermo-physical and thermo-mechanical properties have to be improved. For the first time, clay-phosphate ceramics, with synthetic calcium hydroxyapatite (TCP, Ca10(PO4)6(OH)2) as additive, were developed in view of TES application. A parametric study was carried out for different clay/TCP mixtures, wherein the TCP percentage varies from 0 to 16.7 wt%. The best material containing 4.7 wt% TCP allowed increasing up to 20% of the thermal conductivity and 23% of the mechanical strength. Moreover, it was thermally stable up to 1000 °C. These original results demonstrate the suitability of these new materials for heat storage in energy systems such as in a concentrated solar power (CSP) plant, or in a unit of heat recovery from an industrial waste heat source.

Sensorium

Sensorium

Temperature Effect on Corrosion Rate of Metal AA 5052 Using D-Galactose Inhibitors In Sulfuric Acid Media With Electrochemical Method

Aluminum Alloy 5052 (AA 5052) is a metal that can be used as a biopolar plate in proton exchange membrane fuel cell (PEMFC), because it has the advantages of being resistant to corrosion, high conductivity, easy shape and light weight. PEMFC produces electrical energy and the rest of the process in the form of hot water and steam. In a bipolar plate PEMFC environment corrosion can easily occur due to an acidic environment and high operating temperature around 40°C-80°C. For this reason, a treatment is needed to strengthen the corrosion-resistant properties of AA 5052. The coating of the material can be done using the technique of electrophoretic deposition (EPD) using green inhibitor to reduce the corrosion rate. The electrochemical method was carried out to see how much influence temperature had on the corrosion rate of AA 5052. In this study, d-galactose green inhibitor with a concentration of 0.5 g, EPD time of 20 minutes was used, in a PEMFC environmental simulation in 0.5 M H2SO4 sulfuric acid medium, with test temperatures of 25°C (room temperature), 40°C, 60°C, and 80°C. From the results of the analysis using the electrochemical method, there was an effect of temperature on the corrosion rate of AA 5052 without an inhibitor layer of 0.3610 mmpy at room temperature and increased at 80°C 3.9527 mmpy. While AA 5052 which was coated with a d-galactose inhibitor, had a corrosion rate of 0.1678 mmpy at room temperature and continued to increase at a temperature of 80°C 3.7745 mmpy. Inhibitor efficiency was 53.51% at room temperature and decreased with increasing temperature to 4.5% at 80°C.

Compact, Watt-class 785 nm dual-wavelength master oscillator power amplifiers

785 nm micro-integrated, dual-wavelength master oscillator power amplifiers with a footprint of 5 mm × 25 mm are presented. They are based on Y-branch distributed Bragg reflector ridge waveguide diode lasers and anti-reflection coated tapered amplifiers. In order to reduce the impact of potential optical feedback, devices with master oscillator front facet reflectivities of 5% and 30% as well as with an integrated miniaturized optical isolator have been realized. A comparison up to 1 W shows narrowband dual wavelength laser emission with a spectral distance of 0.6 nm (10 cm−1) and individual spectral widths <20 pm. As expected, a higher front facet reflectivity leads to a significant reduction of feedback related mode hops. Longitudinal modes corresponding to the master oscillator resonator length remain within spectral windows <0.15 nm (3 cm−1), suitable for applications such as Raman spectroscopy and especially shifted excitation Raman difference spectroscopy. Integrating a compact 30 dB optical isolator completely eliminates the observed optical feedback effects. Lateral beam propagation ratios of 1.2 (1/e2) enable easy beam shaping and fiber coupling. Outside of the experimental comparison, the developed MOPAs provide up to 2.7 W of optical output power available for applications.

Infill Microstructures for Additive Manufacturing

Additive Manufacturing (AM) is a well-known and rapidly advancing method, especially in the manufacturing of high-strength and lightweight microstructures. Utilizing AM, it is possible to fabricate any structure as complicated as it is. For an efficient and cost-effective printing, a critical parameter is the infill, which can be characterized from an easy 2D shape to high complexity. At the same time, Topology Optimization (TO) is an appropriate method to create high-strength and mass optimized microstructure lattices. In the current study, TO starts from a solid cubic volume of 15 × 15 mm, and different boundary conditions of two new cellular microstructures designed with 0.4 and 0.1 relative density are applied, respectively. The adopted TO method was Solid Isotropic Material with Penalization (SIMP), which predicts an optimal material distribution within a given design domain. TO methods do not check other characteristics of the structure, such as anisotropy. To evaluate and characterize the optimized microstructure, a general purpose homogenization method is utilized to calculate the Zener ratio and the elastic modulus. Using Fused Filament Fabrication (FFF), which is a material extrusion 3D printing method, lattice structure samples are fabricated and then tested in compression and tensile strength tests. The comparative results from the homogenization study showed that both microstructures have anisotropic behavior and an accepted response in the stress test similar to the homogenized material. The experimental results show that the mechanical behavior of the lattice structure changes significantly when the cell mapping angle differs.

Bioplastics / Biopolymers: How Aware Are We?

Today, polymers have found a wide range of uses from kitchen utensils to artificial heart valves, thanks to their lightness, easy shaping, corrosion resistance, and cheapness. A large number of polymers are used in the packaging of food, textiles, and machinery, and they are an important part of solid waste disposed of in landfills. In addition, microplastics, which are small particles under 5 mm, pose a major problem in the pollution of rivers, lakes, seas, and oceans and increase our carbon footprint. Many strategies are being developed in parallel with the Green Deal to reduce both all the negative effects caused by polymers and our carbon footprint. According to the European Green Deal, reducing waste, compensating for carbon footprint emissions, and protecting resources and sustainability are key priorities for the EU now and in the future. Reusability and biodegradable polymer production are important parts of these strategies. The scientific works demonstrated the opportunity for renewable, biodegradable biopolymers to replace their synthetic counterparts in a variety of /application. Biopolymer is a type of polymer and a biodegradable chemical compound that is produced by living beings in the ecosphere. Biopolymers obtained from natural materials (e.g. alginate, zein, gelatin, agar, and chitin/chitosan) are highly abundant but underexploited renewable biomasses. Besides their natural biological and structural functions, the biopolymers can be tailored to new biomaterials with novel functionalities. The roles of biopolymers in obtaining environmentally friendly materials are very important for the future of the world. &#x0D; So, are we aware of plastic pollution and ways to reduce it? Is there enough awareness in academia, industry, and society for biopolymers that are so important for a sustainable environment? In this study, the answers to these questions are researched and discussed.

Characterisation and ceramic application of clays from North Africa

ABSTRACT The mineralogical, chemical, physical and thermal analyses of the representative clays from North Africa (Algeria, Morocco and Tunisia) have been studied for their potential use in traditional ceramic industry. The clay fractions of the Moroccan and Algerian clays are essentially composed of illite (38 and 21%, respectively) and kaolinite (17 and 12%, respectively) as predominant minerals, with subordinate I/Sm mixed-layer (10 and 3%, respectively). The non-clay minerals are quartz, calcite, dolomite and occasionally plagioclase and haematite. Tunisian clays are composed of similar proportions of kaolinite (15%), smectite (15%), illite (12%) and palygorskite (9%), whereas their associated minerals are quartz (30%), calcite (15%) and rarely plagioclase (4%). The chemical data show agreement with estimated mineralogical compositions. All the samples contain large amounts of iron (>5.6%) and earth-alkaline oxides (>6.9%), and high values of LOI (>12%). Algerian clays show high plasticity (PI = 40%), requiring particular attention and careful temperature control during drying to avoid the deformation and the formation of cracks in the ceramic bodies, whereas the Tunisian and Moroccan clays (PI = 18% and 16%, respectively) show acceptable behaviour in shaping and drying. The average grain-size distribution demonstrates a substantial amount of the silt and clay fractions in raw materials which are therefore suitable for easy shaping of paste without any special need for further adjustments. Indeed, the amount of fraction upper 63 µm is lower less than 2%. The main transformations during firing are influenced by the abundance of components such as Fe2O3, CaO, MgO, K2O and Na2O and observed above 1000°C with the appearance of new crystalline phases, especially mullite, spinel, plagioclase, diopside and haematite. The technical parameters of fired pieces (firing shrinkage, water absorption and flexural strength) fall within the ceramic international standards (ISO).

Optical, scintillation and thermoluminescent properties of Eu2O3-doped K2O–La2O3–Ga2O3 glasses

Glasses are promising functional materials as phosphors with an aim to use in radiation measurements because of easy shaping, low fabrication cost and large volume fabrication possibility. In this study, Eu3+-activated gallate glasses having glass compositions of 20K2O–11La2O3–(69−x)Ga2O3–xEu2O3 (x = 0.1–1.0) were synthesized, and their photoluminescence, scintillation and thermoluminescent characteristics were investigated. Clear luminescence peaks at around 574, 591, 614, 653 nm ascribed to the electronic 4f-4f transitions of Eu3+ appeared when the Eu2O3-doped gallate glasses were irradiated by visible light and high energy X-ray. The photoluminescence and scintillation intensities of the 0.5% Eu2O3-doped gallate glass were found to be the highest. Furthermore, a thermoluminescent glow peak appeared at around 90 °C in the glow curve. The 0.1% Eu2O3-doped gallate glass showed the highest glow peak intensity unlike photoluminescence and X-ray induced scintillation spectra, suggesting that the Eu2O3-doped gallate glasses showed a complimentary relationship between scintillation and thermoluminescent intensities.