Milled Samples Research Articles

Effect of precursor particle size of NiO-YSZ electrodes in its physico-chemical and electrical conductivity properties for solid oxide electrochemical cells

Electrodes play an important role in the overall performance of solid oxide electrochemical cells (SOC), such as for fuel cell or electrolysis cell applications. Desirable properties of the electrode include good morphological features with high electronic and ionic conductivity. In this study, in order to investigate the effect of precursor particle size on the microstructure and conductivity properties of nickel oxide and yttria-stabilized zirconia (NiO-YSZ), precursors were prepared with different particle sizes using a planetary ball mill via varying the milling speed and milling time. From the particle size analysis (PSA) of the milled samples based on the studied milling parameters, it was observed that the milling time had a significant effect on the resulting ball-milled samples compared to the effect of the milling speed. However, upon sintering to obtain the NiO-YSZ electrode composites, the effect of milling speed, in terms of grain size, can be observed. From the XRD patterns, major peaks can be attributed to cubic phases of NiO and YSZ; however, traces of ZrO2 impurity peaks can be seen for the precursor sample with higher milling speed. SEM-EDX analyses support the more agglomerated morphology for the sample with longer milling duration and larger grains for those with higher milling speed. The obtained total bulk conductivities for the sample milled at 400 rpm (10 h) is about 1.27x10-1 S/cm, and for the 400 rpm (20 h) is about 1.77x10-1 S/cm with Ea of 0.88 eV and 0.27 eV, respectively.

Crystallite size reduction of Cr doped Al2O3 materials via optimized high-energy ball milling method

α-Al2O3 based compounds have large crystals and it is very difficult to reduce the crystallite size because they are very stable and hard. One way of reducing the crystallite size of the materials is by using high-energy ball milling method. Pure and single-phase micron-sized α-Al2−xCrxO3 (x = 0.1, 0.2, 0.3) materials were successfully obtained via self-propagating combustion method. These materials were then subjected to a simple milling process from their microcrystalline powders. Comparisons between the micron-sized and milled samples in terms of their phase, structure, morphology and crystallite size were discussed. The XRD results reveal that all the milled samples were pure with no impurity or other phases present. Structural parameters are extracted via the Rietveld method, revealing that the cell constant, a, of the milled samples is higher than that of the micron-sized materials by 0.09 % to 0.11 %, resulting in a 0.28 % to 0.39 % increase in cell volume. FESEM results show a gradual decrease in crystallite size with increased milling time. Notably, the method successfully reduces the crystallite size without changing the phase of the materials and preserving the stoichiometry of the Al2−xCrxO3 materials which may offer improved properties in various applications.

Experimental Study on Mechanical Properties of Different Resins Used in Oral Environments.

Background and Objectives: Acrylic resins remain the materials of choice for removable prosthesis due to their indisputable qualities. The continuous evolution in the field of dental materials offers practitioners today a multitude of therapeutic options. With the development of digital technologies, including both subtractive and additive methods, workflow has been considerably reduced and the precision of prosthetic devices has increased. The superiority of prostheses made by digital methods compared to conventional prostheses is much debated in the literature. Our study's objective was to compare the mechanical and surface properties of three types of resins used in conventional, subtractive, and additive technologies and to determine the optimal material and the most appropriate technology to obtain removable dentures with the highest mechanical longevity over time. Materials and Methods: For the mechanical tests, 90 samples were fabricated using the conventional method (heat curing), CAD/CAM milling, and 3D printing technology. The samples were analyzed for hardness, roughness, and tensile tests, and the data were statistically compared using Stata 16.1 software (StataCorp, College Station, TX, USA). A finite element method was used to show the behavior of the experimental samples in terms of the crack shape and its direction of propagation. For this assessment the materials had to be designed inside simulation software that has similar mechanical properties to those used for obtaining specimens for tensile tests. Results: The results of this study suggested that CAD/CAM milled samples showed superior surface characteristics and mechanical properties, comparable with conventional heat-cured resin samples. The propagation direction predicted by the finite element analysis (FEA) software was similar to that observed in a real-life specimen subjected to a tensile test. Conclusions: Removable dentures made from heat-cured resins remain a clinically acceptable option due to their surface quality, mechanical properties, and affordability. Three-dimensional printing technology can be successfully used as a provisional or emergency therapeutic solution. CAD/CAM milled resins exhibit the best mechanical properties with great surface finishes compared to the other two processing methods.

75 Development of a rapid screening assay for monitoring the relative nutritional value of pasture samples

Pasture with a high biodiversity has the potential to provide a balanced diet and year-round forage availability for grazing equids. Monitoring the influence of biotic and abiotic factors on the relative proportions of key nutrients in pasture could help to inform grazing strategies. Traditional wet chemistry forage analytical methods are labor-intensive and require large sample amounts, thereby limiting their usefulness for high sample throughput. To develop a high throughput screening assay, 3 different hydrolysis methods were compared, each allowing the simultaneous extraction of total hydrolyzable carbohydrates (THC), protein, and phenolics for subsequent spectrophotometric quantification using established microassays. Three pasture samples were collected from mixed species grassland plots (3m x 2m, SRUC Aberdeen, UK). These samples represented a diverse range of THC, protein, and phenolic contents and included high- and low-sugar perennial ryegrass and forage herbs plots (collected in June 2021) and a herbal ley plot (collected in August 2021). Freeze-dried and milled samples were extracted in triplicate and subjected to a range of hydrolysis conditions (Method 1: 2.4% H2SO4, 2 h at 100°C; Method 2: 3M HCl, 14 h at 100°C; Method 3: 2M HCl, 0.5 h at 95°C) before spectrophotometric quantification (Lever assay for reducing sugars,Ninhydrin assay for proteins, Fast Blue assay for phenolics). Solvent-matched calibration curves of Bovine serum albumin (BSA), gallic acid, and glucose/fructose standards were used to quantify analytes and evaluate optimal hydrolysis conditions for each analyte to maximize yield. Extractions were repeated across 3 consecutive days to assess reproducibility of each hydrolysis method. All 3 hydrolysis methods demonstrated a reproducibility and reliability > 99% for THC and phenolics across all samples. ANOVA (using SPSS: significance level set at P < 0.05) showed significant differences between the means of phenolics and THC concentrations for method 2 vs. method 1 (P = < 0.001) and method 2 vs. method 3 (P = 0.015). Method 3 was identified as most optimal for the quantification of THC and phenolics, resulting in analyte concentrations reflective of the expected seasonal and grass species differences in the samples. However, the short hydrolysis time of this method was not sufficient for optimal protein quantification as achieved by Method 2. Therefore, a combination of Method 2 and 3 was subsequently established and is undergoing further optimization to evaluate performance in a greater range of pasture samples.

Potential Usage of Selected Agro-Residue as a Biofuel Production Sources: Physiochemical Evaluation Approach

This article present physiochemical characterization of commonly available agricultural waste residues on dry basis for: (Corn cob, Coconut shell, Cashew nut, Palm kernel shell and Cassava stem) with the view to evaluate their respective suitability for biofuel production using thermochemical conversion process. The investigated respective biomass feedstock milled samples was analyzed in the laboratory for fuel physiochemical characterization. The physiochemical characterization carried out on each biomass waste sample are Proximate Analysis, Ultimate Analysis, Elemental composition analysis and determination of their respective Higher heating Value(HHV). The obtained results revealed that of all the biomass samples characterized, the Coconut shell (CNS), Corn cob(CC) and Cassava stem(CS) samples proved to possess the most suitable characteristics for better bio-oil production. Palm kernel shell(PKS), Coconut shell(CNS) and Cashew nut(CN) due to their obtained low ash content, adequate hardness and fairly high fixed carbon content are generally regarded to be a potential source for making quality grade charcoal (bio-char) using Pyrolysis process. Gasification process is found desirable to producing high yield of bio-gas for Corncob(CC) and Cassava stem(CS) biomass samples due to their respectively obtainable high value of moisture content: (13.4%wt and 15.10%wt.) and fixed carbon contents of (67.94%wt and 74.13%wt) in this study. Moreover, among all other biomass sample investigated in this study, Coconut Shell(CNS) in comparison to all other samples characterized attained highest HHV of 31.2 MJ/kg. Negligible amount of Sulphur and Nitrogen which could resulted to lower emission of SO2 and NO2 if use directly for heating purposes aftermath application of any of the thermochemical conversion processes is also observed for the biomass waste samples analyzed independent of their types. These results show that the characterized biomass samples could be a suitable candidate for alternative energy fuels production in terms of quality and environment concern.

Analysis of Adsorbed Polyphosphate Changes on Milled Titanium Dioxide, Using Low-Field Relaxation NMR and Photoelectron Spectroscopy.

In this study, changes in the adsorbed amount and surface structure of sodium hexametaphosphate (SHMP) were investigated for aluminum-doped TiO2 pigment undergoing milling. Relaxation NMR was utilized as a potential at-line technique to monitor the effect of milling on surface area and surface chemistry, while XPS was used primarily to consider the dispersant structure. Results showed that considerable amounts of weakly adsorbed SHMP could be removed with washing, and the level of dispersant removal increased with time, highlighting destructive effects of sustained high-energy milling. Nonetheless, there were no significant chemical changes to the dispersant, although increases to the bridging oxygen (BO) peak full width at half-maximum (FWHM) suggested some chemical degradation was occurring with excess milling. Relaxation NMR revealed a number of important features. Results with unmilled material indicated that dispersant adsorption could be tracked with pseudo-isotherms using the relative enhancement rate (Rsp), where the Rsp decreased with dispersant coverage, owing to partial blocking of the quadrupolar surface aluminum. Milled samples were also tracked, with very accurate calibrations of surface area possible from either T1 or T2 relaxation data for systems without dispersant. Behavior was considerably more complicated with SHMP, as there appeared to be an interplay between the dispersant surface coverage and relaxation enhancement from the surface aluminum. Nevertheless, findings highlight that relaxation NMR could be used as a real-time technique to monitor the extent of milling processes, so long as appropriate industrial calibrations can be achieved.

Applying Material Science Principles to Chemical Stability: Modelling Solid State Autoxidation in Mifepristone Containing Different Degrees of Crystal Disorder

Ball-milling and harsh manufacturing processes often generate crystal disorder which have practical implications on the physical and chemical stabilities of solid drugs during subsequent storage, transport, and handling. The impact of the physical state of solid drugs, containing different degrees/levels of crystal disorder, on their autoxidative stability under storage has not been widely investigated. This study investigates the impact of differing degrees of crystal disorder on the autoxidation of Mifepristone (MFP) to develop a predictive (semi-empirical) stability model. Crystalline MFP was subjected to different durations of ambient ball milling, and the resulting disorder/ amorphous content was quantified using a partial least square (PLS) regression model based on Raman spectroscopy data. Samples of MFP milled to generate varying levels of disorder were subjected to a range of (accelerated) stability conditions, and periodically sampled to examine their recrystallization and degradation extents. Crystallinity was monitored by Raman spectroscopy, and the degradation was evaluated by liquid chromatography. The analyses of milled samples demonstrated a competition between recrystallization and degradation via autoxidation of MFP, to different extents depending on stability conditions/exposure time. The degradation kinetics were analyzed by accounting for the preceding amorphous content, and fitted with a diffusion model. An extended Arrhenius equation was used to predict the degradation of stored samples under long-term (25°C/60% RH) and accelerated (40°C/75% RH, 50°C/75% RH) stability conditions. This study highlights the utility of such a predictive stability model for identifying the autoxidative instability in non-crystalline/partially crystalline MFP, owing to the degradation of the amorphous phases. This study is particularly useful for identifying drug-product instability by leveraging the concept of material sciences.

Magnetic and optical properties of cobalt-doped hematite nanoparticles of logas natural sand for environmental application

The cobalt doped hematite (α-Fe2O3) nanoparticles have been prepared by ball milling method using Logas natural sand as a raw material. The milled hematite nanoparticles were doped using cobalt with concentration of 0, 5, 10, 15 and 20 wt. %. The optical, structural and magnetic properties were studied using Uv-Vis spectroscopy, X-ray diffractometer (XRD), and vibration sample magnetometer (VSM), respectively. The optical properties strongly depend on cobalt content and showed that the band gaps of cobalt doped hematite decrease with increasing cobalt content. The samples exhibited weak ferromagnetic behaviour with the coercivity ranged from 124 Oe to 299 Oe. The XRD measurements confirmed the formation of crystalline, rhombohedral crystal structure and hematite nanoparticles. The samples show cobalt-hematite nanoparticles as indicated through XRD measurement. The average crystallite size calculated using Scherrer formula found to be 38.51, 35.67, 33.75, 32.73 and 31.53 nm after being doped with cobalt 0, 5 and 10, 15 and 20 wt. %, respectively. Some other elements such as silicon and titanium and others elements were detected, which demonstrates that these milled samples are not purely hematite as confirmed by X-Ray Fluorescence Spectroscopy (XRF) results.

The Impact of Abrasive Grit Size on Roughness of Sanded Beech Wood Surface

The study assessed the changing of Ra, Rp, Rv and Rz roughness parameters of the sanded beech surface (Fagus sylvatica L.) as a function of different grit sizes and different measurement direction. The milled samples were ground with a belt sander BS-75 E-set from Festool with belt grit P60, P100 and P150. The sanding belts were Rubin 2 from Festool. Roughness was evaluated using a Keyence VHX-7000 digital microscope. The evaluation length of the roughness measurement was 12.5 mm (λc = 2.5 mm and λs = 8 mm). The R-parameters were measured in accordance with the latest standards ISO 21920 (2022) in the direction parallel to the grain, and in the direction perpendicular to the grain (profile). The paper proves the theoretical assumptions about the reduction of R-parameter values. The measurements showed that the sanded surface was less rough in the direction perpendicular to the grain at P150 sanding belt grit and in the grain direction at P100 grit.

Performance of clinoptilolite zeolite after milling as a pretreatment on hydration kinetics, shrinkage, and alkali-silica reaction of cementitious materials

Natural clinoptilolite zeolite has been a popular supplementary cementitious material (SCM) due to its acceptable pozzolanic performance and the overall lower environmental footprint. Previous research established that milling is an effective pretreatment technique to further increase the pozzolanic reactivity of zeolitic tuffs leading to an increased specific surface area and amorphous contents. Therefore, the present study characterized the zeolite particles after ball milling for 1 and 3 h using phase analysis by X-ray diffraction (XRD), particle size distribution by laser diffraction, microstructural analysis by scanning electron microscopy (SEM), moisture absorption rate, and relative chemical dissolution. The performance of milled clinoptilolite zeolite as a SCM with the replacement of up to 20% portland cement was evaluated through hydration kinetics (heat of hydration, setting time, chemical shrinkage, degree of hydration), workability, compressive strength, autogenous shrinkage, drying shrinkage, and alkali-silica reaction (ASR). Results revealed that 1 and 3 h of milling led to an increased specific surface area, moisture absorption capacity, and relative dissolution of particles, but had no visible effects on the crystalline structure of zeolite particles compared to the unmilled zeolite particles. For the hydrated system, both 1 and 3-h milled zeolite increased the overall heat of hydration leading to an increased silicate and aluminate reaction along with the acceleration effects in the setting time. The compressive strength of up to 20% milled (1 and 3 h) zeolite samples was increased by about 20 to 25% compared to the unmilled zeolite samples at an early age which suggested an increasing pozzolanic response of milled zeolite particles in the system due to an increased volume of hydrated phases and degree of hydration. Milling slightly decreased the workability by demanding a higher content of fresh water which was released at a later age leading to a higher drying and autogenous shrinkage. In addition, milling reduced the internal curing capacity leading to damage to the porous structure of zeolite particles. The use of up to 20% 3-h milled zeolite reduced the deleterious expansion by about 80% due to ASR compared to the control sample and the overall performance of milled clinoptilolite zeolite as the SCM was satisfactory in the hydrated system.

Tailoring the Band Gap of Carbon Nanoparticles in Carbon Soot by Ball Milling

Carbon nanoparticles (CNPs) in carbon soot have been ball milled in air for time durations of 1, 3, and 5 hours. A reduction of the average height of CNPs, measured using atomic force microscopy, with increase in ball milling time has been observed with values about 22.54 nm, 11.09 nm, 9.48 nm, and 7.25 nm for un-milled and ball milled samples for durations of 1, 3, and 5 hours, respectively. The optical band gaps of the CNPs have been estimated from the optical absorption data with values of about 5.06 eV, 3.77 eV, 2.08 eV, and 1.55 eV for the as-synthesized CNPs and 1, 3, and 5 hours of ball milled CNPs, respectively. Such observations of reduction of height and decrease in band gap of the CNPs are due to the mainly increase in in-plane graphitic ordering in the CNPs and simultaneous attachment of oxygen from the air ambient. The ball milling provided the required energy to acquire the in-plane graphitic order in the CNPs reducing the disorders in it. Also changes in the functional groups (formation of carbon and oxygen bonds) in the surfaces of the in-plane graphite in the CNPs can lead to the formation of graphene oxide (GO) leading to change in the surface states which can result in decrease in band gap of the CNPs. With increase in ball milling time, amount of GO has been increased resulted in further decrease in the band gap of the CNPs.

Valorisation of Water Potabilization Sludges as Precursors for Alkali-Activated Binders: Characterization and Feasibility Study.

Water potabilization sludges (WPS) are a heterogeneous waste generated from the coagulation-flocculation process of drinking water production, whose composition is highly dependent on the geological context of reservoirs, the composition and volume of treated water, and the types of coagulants used. For this reason, any feasible approach for reusing and valorising of such waste cannot be disregarded from the detailed investigation of its chemical and physical characteristics and they have to be evaluated at a local scale. In this study, WPS samples from two plants serving the Apulian territory (Southern Italy) were subjected for the first time to a detailed characterization with a view to evaluating their recovery and reuse at a local scale as a raw material for producing alkali activated binders. WPS samples were investigated by X-ray fluorescence (XRF), X-ray powder diffraction (XRPD) including phase quantification by the combined Rietveld and reference intensity ratio (RIR) methods, thermogravimetric and differential thermal analysis (TG-DTA), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Samples showed aluminium-silicate compositions with up to 37 wt% of Al2O3 and up to 28 wt% of SiO2. Small amounts of CaO were also found (6.8 and 4 wt%, respectively). The mineralogical investigation indicates the presence of illite and kaolinite as clayey crystalline phases (up to 18 wt% and 4 wt%, respectively), in addition to quartz (up to 4 wt%) and calcite (up to 6wt%) and a large amorphous fraction (63 wt% and 76 wt%, respectively). WPS were subjected to heating from 400 °C to 900 °C and mechanical treatment by high energy vibro-milling in order to determine the best pre-treatment condition in view of their use as solid precursors to prepare alkali-activated binders. Alkali activation (8M NaOH solution; room temperature curing) was attempted on untreated WPS, on 700 °C heated and on 10-minute high-energy milled samples, which were considered the most suitable based on the preliminary characterization. Investigations of alkali-activated binders confirmed the geopolymerisation reaction occurrence. Variations in gel features and compositions depended on the amount of reactive SiO2, Al2O3 and CaO available in the precursors. WPS heated at 700 °C led to the most dense and homogeneous microstructures, due to a greater availability of reactive phases. The results of this preliminary study demonstrate the technical feasibility of preparing alternative binders from the investigated Apulian WPS, paving the way for a local reuse of these waste products, leading to economic and environmental benefits.

Effect of the milling conditions on the decomposition kinetics of gibbsite

Synthetic gibbsite (Al(OH)3) was mechanically activated by attrition milling for 24h, with various grinding ball-to-powder weight ratios (0, 5, 10, and 20), and characterized by thermal analysis (TG-DSC). Further, we determined the corresponding kinetic parameters using the model-free and model-fitting methods from the Thermogravimetric Analysis (TG) data set. We found that the activation energies provided by both models agree very well. At temperatures higher than 350°C, the milled samples (GB5, GB10, and GB20) lose mass very slowly, while the unmilled sample (GB0) decomposes faster. In addition, we demonstrated that the decomposition mechanism of each sample engages multi-step reactions, and the corresponding activation energies change with the increasing milling conditions.

Roughness classification detection of Swin-Transformer model based on the multi-angle and convertible image environment

ABSTRACT Current machine vision methods for surface measurement rely excessively on feature design to quantify surface morphology and build predictive models, but metric design suffers from human intervention, and data acquisition is heavily dependent on light source environment and shooting angle. This paper uses the Swin-Transformer model to evaluate and classify roughness directly on colour images of milled samples acquired in a convertible image environment. The images used in the experiment are taken in a completely dark environment and in an environment disturbed by light sources, such as LED energy-saving lamps during the day. By using two kinds of lenses and combining custom light sources and ordinary light sources, respectively, and for different angles, it deeply simulates the environment of online inspection of industrial production. The roughness classification results prove that the method has very good robustness to light source environment and shooting angle, avoiding the artificial design and extraction of image features. The accuracy of the validation set of samples can reach 98.94%, while the accuracy of the test set can reach 97.54%. To wrap it up, the method provides an optimised strategy for visual roughness measurement in industrial production.

Effect of Post-synthesis Processing on the Electrochemical Performance of Y2W3O12

Lithium-ion batteries (LIBs) are enabling the uptake of electric vehicles and providing grid-scale storage solutions for renewable energy generation. However, it is vital to develop new and advanced electrode materials for lithium-ion batteries to meet various applied considerations such as cost, safety, toxicity, and performance. Here, solid-state synthesized Y2W3O12 is demonstrated as a high-rate active anode material in lithium-ion batteries, producing an initial discharge capacity of 637 mAh/g although with a very poor initial Coulombic efficiency of 35%. To improve the performance, simple post-synthetic milling and carbon coating are investigated. Carbon coating of the material leads to significant performance enhancement in both the unmilled and milled samples. For instance, the unmilled carbon coated electrodes maintained a high capacity of ∼140 mAh/g at 1600 mA/g after 2000 cycles with no capacity fading from cycle 200 to 2000. Such a remarkable rate performance and an excellent long-term cycling stability showcase the great potential of this unconventional electrode material in fast-charge and high-power applications. This facile post-synthesis process can be easily applied to other electrode material candidates to enhance their electrochemical performance.

Production of Hybrid Nanocomposites Based on Iron Waste Reinforced with Niobium Carbide/Granite Nanoparticles with Outstanding Strength and Wear Resistance for Use in Industrial Applications.

The main objective of this work is to recycle unwanted industrial waste in order to produce innovative nanocomposites with improved mechanical, tribological, and thermal properties for use in various industrial purposes. In this context, powder metallurgy (PM) technique was used to fabricate iron (Fe)/copper (Cu)/niobium carbide (NbC)/granite nanocomposites having outstanding mechanical, wear and thermal properties. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) examinations were used to investigate the particle size, crystal size, and phase composition of the milled samples. Additionally, it was investigated how different volume percentages of the NbC and granite affected the sintered specimens in terms of density, microstructure, mechanical and wear properties, and coefficient of thermal expansion (CTE). According to the findings, the milled powders included particles that were around 55 nm in size and clearly contained agglomerates. The results showed that the addition of 4 vol.% NbC and 8 vol.% granite nanoparticles caused a reduction in the Fe-Cu alloy matrix particle sizes up to 47.8 nm and served as a barrier to the migration of dislocations. In addition, the successive increase in the hybrid concentrations led to a significant decrease in the crystal size of the samples prepared as follows: 29.73, 27.58, 22.69, 19.95 and 15.8 nm. Furthermore, compared with the base Fe-Cu alloy, the nanocomposite having 12 vol.% of hybrid reinforcement demonstrated a significant improvement in the microhardness, ultimate strength, Young's modulus, longitudinal modulus, shear modulus, bulk modulus, CTE and wear rate by 94.3, 96.4, 61.1, 78.2, 57.1, 73.6, 25.6 and 61.9%, respectively. This indicates that both NbC and granite can actually act as excellent reinforcements in the Fe alloy.

Enhanced microwave absorption performances of FeCoNiCuCr high entropy alloy by optimizing particle size dehomogenization

FeCoNiCrCu high entropy alloy (HEA) powder was prepared by high energy ball milling mechanical alloying. The phase structure, microstructure, particle size, magnetic properties and electromagnetic parameters of the powder were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), laser scattering, vibrating sample magnetometer and vector network analyzer. The results show that the particle size can be controlled effectively by changing the grinding time, and the variation of particle size and uniformity induces the change of magnetic property and electromagnetic parameters, thus regulating the absorption performance of the powder. It is found that the smaller particle size and the worse uniformity of the powder correspond to the better microwave absorption performance. For the 50 h milling sample, the average particle size is 3.15 µm and the uniformity of the powder is the worst among the three 40 h, 50 h and 60 h milled samples. The minimum reflection loss (RLmin) is − 41.23 dB at 6.4 GHz, and when the thickness is 2.6 mm, the maximum effective absorption bandwidth (EAB) is 4.5 GHz (7.2 GHz∼11.7 GHz), covering the entire X band.

Nanocrystalline solid slabs of pure and CdS added KCl–KBr for energy storage application: Preparation and properties

The present study illustrates, for the first time, the possibility of preparing nanocrystalline solid slabs of pure and CdS (5 wt%) added KCl1−xBrx(with x = 0.0, 0.25, 0.5, 0.75 and 1.0) with good quality by using a melt quenching process. The ten samples prepared have been found to exhibit the halite crystal structure with reduced crystal grain size (average crystallite sizes observed in the range 43 to 97 nm), homogeneous morphology (cuboid shape) and phase purity. Optical measurements (absorption/reflectance and photoluminescence) show a significant difference between the melt quenched samples, precursors and ball milled samples (prepared for comparison); CdS addition leads to an extra photoluminescent peak at around 280 nm. The melt quenched samples exhibit much higher dielectric constants (indicating that they can be used as efficient energy storage materials) than the bulk (single/ poly) crystalline KCl–KBr (simple and mixed) systems, which could be due to their lower crystal grain/ crystallite sizes; for example, the ɛr value observed for the CdS added KCl0.5Br0.5 (with an applied AC field frequency of 1 kHz) increases from 2075 at 30 °C to 6188 at 190 °C, which is very interesting.

High energy mechanical-milling induced modifications in structural and microstructural properties of Gd2Zr2O7

A polycrystalline sample of gadolinium zirconate (Gd2Zr2O7) was synthesized through a solid-state reaction route (unmilled sample) and then subjected to high-energy ball-milling for 6 hrs and 18 hrs duration (milled samples). Interestingly, elemental analysis of the samples indicates the gradual reduction in the atomic percentage of Gd and Zr cations while significant enhancement in oxygen atomic percentage with the milling process. Rietveld refinement of X-ray diffraction patterns suggests that all samples possess defect fluorite structure and the values of the goodness-of-fit parameter improve from 3.88 for the unmilled sample to 1.85 for 18 hrs milled sample. The diffraction pattern of 18 hrs milled sample showed reflections from the ordered pyrochlore phase. The formation of the disordered fluorite phase is owing to the preparation temperature and the ionic radius ratio, r(Gd3+)/r(Zr4+) = 1. 46. Transmission electron micrographs, and selected area electron diffraction patterns analysis confirm the nanophasic nature of the milled samples, and particle size is found to reduce with increasing milling time. It was found that BET surface area continuously increases from 1.99 m2/g for an un-milled sample to 17.79 m2/g for 18 hrs milled sample. The BET isotherms exhibited type-II hysteresis loop and suggested that all the samples are macroporous with pore width greater than 50 nm.

DEVELOPMENT OF TECHNOLOGY OF BOILED SAUSAGES ENRICHED WITH SPELT FLOUR

DEVELOPMENT OF TECHNOLOGY OF BOILED SAUSAGES ENRICHED WITH SPELT FLOUR