X-ray Diffractometry Analysis Research Articles

Phase equilibria in Ho-Fe-Sn ternary system at 670 K

Interaction between the components in the Ho-Fe-Sn ternary system was studied using X-ray diffractometry, metallography and electron microprobe analysis. Isothermal section of the phase diagram was constructed at 670 K over the whole concentration range. Component interaction in the Ho-Fe-Sn system at 670 K results in the existence of one ternary compound HoFe6Sn6 which crystallizes in the YCo6Ge6 structure type (space group P6/mmm, a=0.53797(2), c= 0.44446(2) nm). The interstitial-type solid solution HoFexSn2 (up to 8 at.% Fe) based on the HoSn2 (ZrSi2-type structure) binary compound was found. Solubility of Sn in the HoFe2 binary (MgCu2 structure type) extends up to 5 at. %.

Characterization of electrodeposited Ni–Cr/hBN composite coatings

In this study, Ni–Cr/hBN composite coatings with different hBN content were deposited on AISI 1040 mild carbon steel using electrodeposition. The coatings were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD), cyclic voltammetry (CV), 2D surface profilometery, nano-indentation, corrosion and wear tests. While some cracks were observed in the Ni–Cr alloy coatings, more compact and crack-free surfaces were obtained in the Ni–Cr/hBN composite coatings under all deposition conditions. XRD analysis of the Ni–Cr/hBN layer revealed the presence of a predominant Ni phase with Cr, Cr2Ni3B6, (Ni2Cr23)0.16, and hBN phases in the structure. Depending on deposition parameters, the microhardness and nanohardness of the Ni–Cr and Ni–Cr/hBN coatings were found to range between 308 and 538 HV and 1,86–7,69 GPa respectively. hBN acted as a solid lubricant in the wear tests; the friction coefficient decreased and wear resistance was improved. Among the composite coatings, the corrosion resistance of the coating with 20 g/l hBN was found to be 12 and 3.3 times higher than the steel substrate and Ni–Cr alloy, respectively. The hBN additive provided better mechanical properties and corrosion resistance in the range of 5–20 g/l hBN, but after 20 g/l hBN agglomeration became a problem and impaired the mechanical properties. The highest corrosion and abrasion resistance was obtained with 20 g/l hBN.

Introducing the Newly Isolated Bacterium Aneurinibacillus sp. H1 as an Auspicious Thermophilic Producer of Various Polyhydroxyalkanoates (PHA) Copolymers-2. Material Study on the Produced Copolymers.

Aneurinibacillus sp. H1 is a promising, moderately thermophilic, novel Gram-positive bacterium capable of the biosynthesis of polyhydroxyalkanoates (PHA) with tunable monomer composition. In particular, the strain is able to synthesize copolymers of 3-hydroxybutyrate (3HB), 4-hydroxybutyrate (4HB) and 3-hydroxyvalerate (3HV) with remarkably high 4HB and 3HV fractions. In this study we performed an in-depth material analysis of PHA polymers produced by Aneurinibacillus sp. H1 in order to describe how the monomer composition affects fundamental structural and physicochemical parameters of the materials in the form of solvent-casted films. Results of infrared spectroscopy, X-ray diffractometry and thermal analysis clearly show that controlling the monomer composition enables optimization of PHA crystallinity both qualitatively (the type of the crystalline lattice) and quantitatively (the overall degree of crystallinity). Furthermore, resistance of the films against thermal and/or enzymatic degradation can also be manipulated by the monomer composition. Results of this study hence confirm Aneurinibacillus sp. H1 as an auspicious candidate for thermophilic production of PHA polymers with material properties that can be tuned together with their chemical composition by the corresponding adjustment of the cultivation process.

Development of mesh-type Fenton-like Cu/Fex/γ-Al2O3/Al catalysts and application for catalytic degradation of dyes.

The application of nanoparticle heterogeneous Fenton-like catalysts is limited due to the requirement of filtration after reaction and possible secondary pollution. In this work, a novel mesh-type monolithic Fenton-like Cu/Fex/γ-Al2O3/Al catalyst was developed for the degradation of dyes. The Cu and Fe species are uniformly dispersed on the mesh-type anodic monolithic γ-Al2O3 supports, and the results of scanning electron microscopy and X-ray diffractometry analysis show that Fe can reduce the particle size of Cu over γ-Al2O3. The activity results show that the degradation rate of rhodamine B (RhB) reached 99.5% within 1 h using 4 × 6 cm Cu12.0/Fe2.0/γ-Al2O3/Al catalyst with 1,200 ppm H2O2 at 50 °C. The important role of •OH as a reactive oxidant was confirmed through electron spin-resonance spectroscopy and radical scavenging experiment. The hydrogen temperature programmed reduction suggests the high redox ability of Cu/Fe bimetallic catalyst is beneficial to the production of •OH. The Cu/Fe bimetallic catalyst shows excellent recyclability in a 10-cycle experiment, the degradation rate of RhB was maintained at 98% and the leaching amount of metals was lower than 0.7 mg/L. The mesh-type catalyst will be easily applied for the continuous wastewater treatment because it does not need filtration for recovery.

Drifts (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) - a Way to Assess the Reactivity of Solid Electrolytes with Ambient Air

All-Solid-State-Batteries (ASSBs) are envisioned to be the next-generation lithium-ion batteries (LIBs). Replacing the inflammable organic electrolyte in conventional liquid electrolyte LIBs by a non-inflammable inorganic solid electrolyte (SE) is one of the concepts to increase battery safety. Moreover, ASSBs may offer higher gravimetric and volumetric energy density compared to liquid electrolyte based technology.[1,2] However, their high reactivity with ambient air is a major obstacle which prevents ASSBs from industrial scale processing, as production under inert atmosphere is not possible on this level.[3] Thus, industrial ASSB production would have to take place in dry-rooms, leading to the question whether SE handling in dry-room atmospheres containing O2 and CO2 and ppm-levels of moisture is possible.Therefore, we will examine the reactivity of the commercially available solid electrolyte Li10SnP2S12 (LSPS) with O2 and CO2 as well as with the typical H2O concentration in ambient air, followed by reactivity studies with a mixture of CO2 and H2O vapor. For this purpose, we used Diffuse Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS), a highly surface sensitive infrared technique.The hermetically sealed DRIFTS cell containing the SE powder was set up such that it could be purged with dry or humidified streams of inert gas (Ar), O2, and CO2, or mixtures thereof while monitoring in situ the chemical changes of the LSPS solid electrolyte and the formed gaseous species by DRIFTS. Figure 1 shows stacked IR spectra of LSPS after exposure to different gasses, stating no reactivity with O2 or CO2 but noticeable changes in the IR spectrum for exposure to moisture and a combination of CO2 and moisture, respectively, indicating decomposition reactions.The spectral analysis of the decomposition process is supported by ex situ X-Ray Diffractometry (XRD) analysis of the LSPS powder after exposure to the different gas streams. Concluding, the impact of exposing LSPS to the above mentioned gas mixtures on the ionic conductivity of the solid electrolyte will be demonstrated. Acknowledgements: This work was carried out as part of the research project ASSB coordinated by ZAE Bayern. The project is funded by the Bavarian Ministry of Economic Affairs, Regional Development and Energy.

A Comprehensive Study of a New 1.75 Hydrate of Ciprofloxacin Salicylate: SCXRD Structure Determination, Solid Characterization, Water Stability, Solubility, and Dissolution Study

One problem that often arises during the formulation of a dosage form is the solubility and dissolution of the active ingredients. This problem arises in ciprofloxacin, which is a BCS class IV fluoroquinolone antibiotic. A pseudopolymorph is a kind of polymorph in which the number of hydrates is different. In this study, a new pseudopolymorph comprised of ciprofloxacin and salicylic acid was found, namely the salt ciprofloxacin salicylate 1.75 hydrate form. This new solid phase was analyzed by Fourier-transform infrared spectroscope (FTIR), Raman spectroscopy, and thermal analysis and proven by Powder X-ray Diffractometry (PXRD) analysis. The crystal structure was successfully determined by Single Crystal X-ray Diffractometry (SCXRD) analysis. It was found that the piperazinyl group of ciprofloxacin is protonated by H+ from the carboxylic group of salicylic acid. In the unit cell, two ciprofloxacin and two salicylic acid molecules were independent with four water molecules, in which one water molecule had 0.5 occupancy due to inversion symmetry. Interestingly, this hydrate crystal dehydrated by grinding for 105 minutes forms an anhydrous crystalline phase, which was analyzed with FTIR, Raman spectroscopy, thermal analysis, and PXRD. The solubility and dissolution tests were carried out using UV-Visible spectrophotometry and a multiple linear regression method. This new hydrate solid phase has a better profile than the original ciprofloxacin crystal, according to the solubility and dissolution tests.

Investigations on the Doping Effects on the Properties of Piezoelectric Ceramics

In the present paper (1-x)Pb (Zr1-yTiy)O3 – xPb (Mn1/3Sb2/3)O3 – z at%E system, with E = Pr3+, Nd5+ and Gd3+ where x = 0.12; y = 0.48; z = 0 and 0.02 ceramic synthesized by solid state reaction technique is analysed. The investigation aims studying of the effect of dopants on the dielectric and piezoelectric properties of such piezoelectric ceramic. The prepared powders have been uniaxially pressed into discs with diameter of 10 – 12 mm and thickness of 1.2 mm. Sintering has been carried out in air atmosphere at temperatures of 1150°C and 1200°C, respectively, for 2 hours each, followed by a controlled cooling at a rate of 200°C /h. The piezoelectric properties have been investigated after a suitable preparation, including polishing, metallization. The structure of the samples has been determined by X-ray diffractometry (XRD), while the morphology and grains size have been investigated by the scanning electron microscopy (SEM). The piezoelectric properties have been studied by the resonance - antiresonance method. XRD analysis reveals a perovskite tetragonal structure and, as expected for ceramic materials, SEM analysis indicates that the average grain size increases as sintering temperature increases. The dielectric and piezoelectric properties have been determined measuring the ceramic discs, and properties, as dielectric permittivity (εr), dielectric loss (tg δ), and the electromechanical coupling factor (kp) have been obtained. The acquired results indicate a significant effect of the dopants on the dielectric and piezoelectric properties of such materials.

Effect of Heat Treatments on Wettability of Nacre

The surface wettability of biomaterials influences on osteoblast behavior and bone formation. In this research, the variation of wettability of nacre by heat treatments was examined. Plates of the nacre were fabricated from shells of the Akoya pearl oyster. The specimens were heated at 100, 200, 300, 400, 500, and 600 °C. Characterizations of the specimens during and after heat treatments were carried out using scanning electron microscopy, X-ray diffractometry, and thermogravimetry-differential thermal analysis. The water contact angle (WCA) of the specimen was measured to evaluate wettability. The color of nacre changed from iridescent color to brownish weak-iridescence by the heating at and over 300 °C. The nacre heated at and over 300 °C became brittle because organic substances in nacre, which acts as the glue between the aragonite platelets were evaporated by the heating. The WCA of the specimen was decreased with increasing heating temperature, which should be related to the decrease in the number of organic substances in nacre by the heating.

An eco-friendly degumming process of flax roving without acid pickling and NaClO2-bleaching

Flax fiber is an important textile material with excellent antibacterial activity and moisture wicking. Degumming of flax roving is essential in determining flax-fiber quality. Traditional degumming requires a large amount of chemicals to process flax roving. This study aimed to reduce the chemical usage and achieve cleaner production during this process by applying microbial treatment to degum flax roving. Microbial degumming instead of acid pickling and NaClO2-bleaching steps can no longer use H2SO4 and NaClO2, and the amount of alkali can be reduced by 50%. By analyzing the compositional changes of the main steps in traditional degumming processes and microbial-treatment sample, the application of Bacillus subtilis HR5 can achieve a good degumming effect. Results of environmental scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffractometry analyses showed that the gum was remarkably reduced, which can be confirmed by the gum components. Overall, the breaking tenacity and antibacterial activity of fibers degummed by microbial treatment were better than those treated by traditional degumming. These findings demonstrated the feasibility of microbial treatment as a solution for flax roving degumming.

Cocos nucifera Leaf Extract Mediated Green Synthesis of Silver Nanoparticles for Enhanced Antibacterial Activity

Antibiotic resistance is currently a global human health concern and insists on the importance of the production of new, alternative and most effective antibiotics. Nano-sized trace metals such as silver nanoparticles (AgNPs) is a potential material with antibacterial properties and hence the synthesis of this material is of considerable interest to the scientific community mainly for antimicrobial applications. In this work, we have successfully green synthesized the AgNPs using Cocos nucifera leaf aqueous extract as the natural reducing and stabilizing agent, and aqueous silver nitrate (AgNO3) solution as a precursor by a newly developed technique. The material was characterized by ultraviolet–visible (UV–Vis) spectrophotometry, X-ray diffractometry (XRD), Fourier transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM) analyses; and subsequently, evaluated their potential candidacy as antibacterial agents against some common human pathogens by the standard disc diffusion method. The synthesized AgNPs were identified by XRD analysis as a cubic crystal system with an average crystallite size of 14.2 nm. The aqueous colloidal suspension of AgNPs shows a UV–Vis absorption maxima of 380 nm indicating its formation. FT-IR analysis identified the C–N, –OH and N–H as the major and probable functional groups in the leaf extract responsible for the production of stable AgNPs. The results of antibacterial studies of the material showed the considerable zones of inhibition against both Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Salmonella typhimurium, Escherichia coli, Pseudomonas aeruginosa, and Citrobacter freundii) bacteria ranging from 10 to 20 mm with less inhibition for the former than the latter. The maximum (20 mm) and minimum (10 mm) inhibition zone was shown by C. freundii and Bacillus subtilis, respectively and P. aeruginosa shows the second-highest zone of inhibition (19 mm). The antibacterial performance of the material implies that the C. nucifera leaf extract mediated green synthesized AgNPs can be regarded as a potential candidate for antimicrobial application appreciably.

Microstructures and Tribological Properties of TiC Reinforced FeCoNiCuAl High-Entropy Alloy at Normal and Elevated Temperature

Recent studies have suggested that high-entropy alloys (HEAs) possess high fracture toughness, good wear resistance, and excellent high-temperature mechanical properties. In order to further improve their properties, a batch of TiC-reinforced FeCoNiCuAl HEA composites were fabricated by mechanical alloying and spark plasma sintering. X-ray diffractometry analysis of the TiC-reinforced HEA composites, combined with scanning electron microscopy imaging, indicated that TiC particles were uniformly distributed in the face-centered cubic and body-centered cubic phases. The room temperature hardness of the FeCoNiCuAl HEA was increased from 467 to 768 HV with the addition of TiC, owing to precipitation strengthening and fine grain strengthening effects. As the TiC content increased, the friction coefficient of the FeCoNiCuAl HEA first increased and then decreased at room temperature, due to the transition of the wear mechanism from adhesive to abrasive behavior. At higher temperature, the friction coefficient of the FeCoNiCuAl HEA monotonously reduced, corresponding well with the transition from adhesive wear to oxidative wear.

Characterization of spray deposited ternary ZnSxSe(1-x) thin films for solar cell buffers

This paper reports on cadmium free, environment friendly, industrially beneficial, chemically sprayed ZnSxSe(1-x) (ZSS) thin films with tunable band gap which is suitable for various optoelectronic applications including buffer layer in solar cells. Chemically sprayed ZSS thin films with x ranging from 0 to 1 were studied extensively by adopting the characterization techniques like X-ray diffractometry (XRD), Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDAX), Ultraviolet – visible (UV–VIS), Photoluminescence (PL) and Raman spectroscopies in order to assess the suitability of the formed thin film for the buffer layer applications. XRD analysis was done to determine various parameters like lattice constant, crystallite size, strain and dislocation density. From lattice constant, Vegard's law was also verified and compared the composition estimation with EDAX data. Refractive index was compared using Vandemme model with the values obtained using reflectance data. Photoluminescence and Raman spectra were analyzed to get an insight on structural defects, which have major role in deciding the electrical properties. Electrical properties were assessed by estimating carrier concentration, carrier mobility and electrical resistivity by adopting Van der Pauw technique. Based on structural, optical and electrical properties, sample with x = 0.4 is suggested for the buffer layer application in CIGS based solar cells, which produces minimum lattice mismatch with considerably high optical transmittance and electrical conductance.

A novel strategy for high color purity virescent Er3+-doped SrLaAlO4 nanocrystals for solid-state lighting applications

Unique down-conversion virescent SrLaAlO4:Er3+ nanocrystals were successfully fabricated by urea-assisted solution combustion route. Presence of tetragonal phase in doped samples [SrLa(1−x)ErxAlO4 (x = 0.1–4.0 mol%)] with a space group of 14/mmm (139) was investigated by powder X-ray diffractometry and Rietveld refinement analysis. Nanocubic crystals with their size ranging from 45 to 55 nm were displayed by scanning electron microscopy and transmission electron microscopy (TEM) techniques while high-resolution TEM highlighted the (105) crystallite plane by representing the resolved fringes of lattice. Nanocrystalline nature and the (101) crystal plane was depicted by selected area electron diffraction patterns of the powder sample. Qualitative as well as quantitative elemental composition of nanophosphors were investigated by mapping and spectra of energy dispersive X-ray analysis, respectively. On near UV excitation, photoluminescence emission spectra showed a prominent band of green color due to 4S3/2 → 4I15/2 transition (549 nm). Energy bandgap and refractive index of optimized sample were determined as 4.97 eV and 1.736, respectively, via diffuse reflectance spectra. Color chromaticity coordinates (0.1735, 0.6909) of SrLa0.98Er0.02AlO4 nanophosphors verified their virescent emission with a color purity of 100% and were found to be consistent with the standard values of European Broadcasting Unit (EBU) as well as International Telecommunication Union, thus reflected their important role as the green component in the solid-state lighting devices, especially red–green–blue pc-white light-emitting diodes.

Characterization of alkali treated new cellulosic fibre from Cyrtostachys renda

This study aims to explore the potential of the NaOH-treated Cytostachys renda fibre to be reinforced in the polymeric composites. The NaOH concentrations were prepared as 1, 3, and 5 wt% for soaking time of 1 and 2 h. The treated fibres were characterized in terms of density, chemical composition, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffractometry (XRD), and Thermogravimetric analysis (TGA). The results revealed that the density is improved with an increase in the concentration and soaking time. NaOH treatment has reduced the amorphous hemicellulose and lignin content. On the other hand, the improved crystallinity index by 6% was observed for fibre treated at 3% NaOH for 1 h, along with the enhancement of cellulose content as much as 0.27%. From the FTIR analysis, it was observed that the presence of CH stretching vibration from the ether in the treated fibre for 1 h soaking time would form a strong interaction with the polymeric matrix. The TGA results showed that fibre treated at 3% NaOH for 1 h exhibited the highest thermal stability compared to the untreated and other treated fibres. Therefore, it can be concluded that the fibre treated with 3% of NaOH for 1 h soaking time could act as a potential reinforcement in the polymeric composites for light weight applications.

Partially hydrolyzed polyvinyl alcohol for fusion-based pharmaceutical formulation processes: Evaluation of suitable plasticizers.

The present study evaluates the effect of several pharmaceutical plasticizers on the thermo-physical and physicochemical properties of partially hydrolyzed poly(vinyl alcohol) (PVA) used in fusion-based pharmaceutical formulation processes. Specifically, the effect of mannitol (MAN), sorbitol (SOR), sucrose (SUC), anhydrous citric acid (CA), triethyl citrate (TEC) and low-molecular weight polyethylene glycol (PEG400) on PVA's melting properties, physical state and thermal degradation was evaluated via differential scanning calorimetry (DSC), powder X-ray diffractometry (pXRD) and thermo-gravimetric analysis (TGA). Results showed that the use of MAN, SOR, SUC and PEG400 led to the reduction of PVA's melting onset temperature, while MAN, SUC, CA and SOR were amorphously dispersed within PVA's matrix, and the addition of SUC and CA resulted in significant reduction of PVA's crystallinity. TGA results showed the formation of thermally highly unstable PVA mixtures in the cases of CA and TEC (degradation started from ~150°C and ~125°C, respectively), while significant molecular interactions were identified by FTIR in the cases of PVA-MAN, PVA-SOR and PVA-SUC. Hot-stage polarized microscopy (HSM) revealed PVA's melt miscibility only with MAN and SOR, while melt flow index (MFI) measurements showed that the use of MAN, SOR and PEG400 resulted in a significant improvement of PVA's melt flow properties. Finally, MD simulations were in close agreement with the experimental observations, indicating that they can be considered as a promising tool for the theoretical modelling of such systems.

Preparation and characterization of rice husk based physical activated carbon

ABSTRACTActivated carbons (ACs) were successfully prepared from rice husk by physical activation method. In the present study, the ACs were prepared at different activation temperatures for a specified activation time interval of 1h in a flow of CO2 gas as an activating agent. The resulted product was analyzed by various characterization techniques, such as Brunauer, Emmett and Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravemetric analysis (TGA) and X-Ray Diffractometry (XRD). The maximum surface area of about 502 m2/g was obtained from the sample activated at 900°C for a time interval of 1h. The SEM microphotographs of the ACs exhibited a well-developed porous structure with different pore sizes. The TGA analysis confirmed the pyrolyzed rick husk (char) conversion that took place around 580°C. The XRD analysis of all the precursors and their resulted ACs were also performed. Wherein, the XRD results established the amorphous carbon structure of the product resulted. The FTIR analysis also confirmed the presence of various peak frequencies of functional groups before and after activation.

AFM Analyses of 3XXX Series Al Alloy Reinforced with Different Hard Nanoparticles Produced in Liquid State.

In the present work, nanocomposites-based 3XXX series Al alloy with three different types of hard nanoparticles, including TiO2, C, and CeO2, were produced employing two techniques such as mechanical milling and stir-casting method in order to evaluate the viability of integration of the reinforcement in the Al matrix. The integration and dispersion capability of the reinforcement into the Al alloy (3xxx Series) matrix was evaluated, using a phase angle difference and surface roughness analyses by atomic force microscopy operated in both the contact mode (CM-AFM) and tapping mode (TM-AFM), respectively. The distribution profile of both rugosity and the phase angle shift was used to statically quantify the integration and dispersion of the reinforcement into the extruded samples, by using the root mean square (RMS) parameter and phase shift coupled with the events number (EN) parameter. Results from Atomic Force Microscopy (AFM) analyses were corroborated by X-ray diffractometry and scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness tests were conducted to identify the mechanical properties of the composites in the extruded condition and their correlation with the microstructure. A close relationship was found between the microstructure obtained from the AFM and X-ray diffractometry (XRD) analyses and mechanical properties. Among all, the C reinforcement produced the major changes in the microstructure as well as the best integration and dispersion into the Al-alloy coupled with the best mechanical properties.

Isothermal section of the Ho-Cо-Sn system at 770 K

The phase equilibrium diagram of the Ho - Co - Sn ternary system was constructed over the whole concentration range at 770 K using methods of powder X-ray diffractometry, metallography and electron microprobe analysis. The alloys for investigation were prepared by direct arc melting the stoichiometric amounts of the constituent elements under high purity Ti-gettered argon atmosphere on a water-cooled copper bottom. The arc-melted ingots were then annealed at 770 K in evacuated quartz glass tubes for two months and subsequently cold water quenched. The synthesized and annealed samples are stable in atmospheric conditions. For the characterization of the annealed samples X-ray powder diffraction on DRON-2.0m diffractometer with Fe K α-radiation was performed. The chemical and phase compositions of the obtained samples were examined by Scanning Electron Microscopy REMMA-102-02 electron microscope. Interaction of holmium with nickel and tin at 770 K resulted in the formation of eight ternary intermetallic compounds: Ho 6 Co 2 Sn (Ho 6 Co 2 Ga-type), Ho 3 Co 8 Sn 4 (Lu 3 Co 7 . 77 Sn 4 -type), HoCoSn (TiNiSi-type), Ho 3 Co 6 Sn 5 (Dy 3 Co 6 Sn 5 -type), Ho 117 Co 57 . 3 Sn 111 . 5 (Dy 117 Co 57 Sn 112 -type), HoCo 6 Sn 6 (YCo 6 Ge 6 -type), Ho 5 Co 6 Sn 18 (Er 4 Rh 6 Sn 19 -type), and Ho 7 Co 6 Sn 23 (Ho 7 Co 6 Sn 23 -type). The Ho 3 Co 8 Sn 4 compound is characterized by small homogeneity range along isoconcentrate of Ho up to 4 at. % Sn. According to EPMA data the homogeneity range of the Ho 3 Co 8 Sn 4 compound is limited by Ho 20 .58 Co 52 . 3 1 Sn 27 .1 1 and Ho 21 .0 6 Co 5 6.7 8 Sn 2 2.1 6 compositions. Ho 7 Co 6 Sn 23 compound was checked using differential thermal analysis (LINSEIS STA PT 1600 device). The DTA curve measured in the heating regime shows the thermal peak at about 980 K which can be associated with the decomposition of the Ho 7 Co 6 Sn 23 phase. In the Ho–Sn, Co-Sn and Ho-Co systems a formation of the all binaries reported in the literature was confirmed. Additionally under used conditions the HoCo 5 binary with CaCu 5 -type was identified in the Ho-Co system. The formation of the interstitial-type solid solution HoCo x Sn 2 based on HoSn 2 (ZrSi 2 -type) binary compound was found up to 10 at. % Co ( а = 0.4382(2), b = 1.6193(4), с = 0.4291(2) nm for HoSn 2 ; а = 0.4393(2), b = 1.6273(7), с = 0.4334(4) nm for Ho 30 Co 10 Sn 60 sample. Solubility of the third component in other binary compounds is less than 1-2 at. %. With regard on the stoichiometry and crystal structure of the formed intermediate phases the investigated Ho-Co-Sn ternary system is similar to the Y-Co-Sn, Dy-Co-Sn and Er-Co-Sn systems. Keywords: intermetallics, ternary system, phase equilibria.

Characterization and concentration by selective flocculation/magnetic separation of iron ore slimes from a dam of Quadrilátero Ferrífero – Brazil

In this paper the results of size, chemical and mineralogical characterizations as well as the concentration tests performed with a slimes sample of iron ore from a dam at the Quadrilátero Ferrífero in the state of Minas Gerais, Brazil are presented. The sample was constituted by 75 % of slimes (particles –10μm). The main minerals identified by X-ray diffractometry and thermal analysis were: goethite, hematite, quartz and kaolinite. The sample grades were: Fe (∼51.4wt.%.), SiO2 (∼15.1wt.%), Al2O3 (∼3.4wt.%), P (0.097wt.%) and LOI (∼7wt.%). During the optimized bench testing condition of selective flocculation/magnetic separation (pH=10.5, sodium silicate and corn starch =50g/ton, magnetic strength =3575G) by experimental statistical planning design, the mass recovery was of 48.4 %. There was an increase of 8 % in Fe grade and a decrease of 50 % in both SiO2 and Al2O3 grades when compared with the feed. Agglomeration studies with the obtained concentrate will be performed in future.

Er-Cr-Ge Ternary System

The isothermal section of the phase diagram of the Er–Cr–Ge ternary system was constructed at 1070 K over the whole concentration range using X-ray diffractometry, metallography and electron microprobe (EPM) analysis. The interaction between the elements in the Er−Cr−Ge system results in the formation of two ternary compounds: ErCr6Ge6 (MgFe6Ge6-type, space group P6/mmm, Pearson symbol hP13; a = 5.15149(3), c = 8.26250(7) Ǻ; RBragg = 0.0493, RF = 0.0574) and ErCr1-хGe2 (CeNiSi2-type, space group Cmcm, Pearson symbol oS16, a = 4.10271(5), b = 15.66525(17), c = 3.99017(4) Ǻ; RBragg = 0.0473, RF = 0.0433) at investigated temperature. For the ErCr1-xGe2 compound, the homogeneity region was determined (ErCr0.28-0.38Ge2; a = 4.10271(5)-4.1418(9), b = 15.6652(1)-15.7581(4), c = 3.99017(4)-3.9291(1) Ǻ).