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Browsing by Subject "X ray diffraction analysis"

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Wear behavior of flame-sprayed Al2O3 -TiO2 coatings on plain carbon steel substrates
(2005) Kusoglu I.M.; Celik E.; Cetinel H.; Ozdemir I.; Demirkurt O.; Onel K.
In this study, Al2O3-TiO2 powders were sprayed using a flame-spray technique after a NiCrMo bond layer was deposited on plain carbon steel substrate. The produced layers were characterized by X-ray diffraction (XRD), optical microscope, scanning electron microscope (SEM) including energy-dispersive spectroscopy (EDS), surface roughness and microhardness tester. Friction and wear behaviour of the coatings were also evaluated in the present study. The Al2O3-TiO2 coatings were subjected to sliding wear against AISI 303 stainless steel counter body under dry and acidic environments. A pin-on-plate type apparatus was used with normal loads in the range of 49-129 N. Wear resistance of the coatings in acid environment is better than that in dry conditions. © 2005 Elsevier B.V. All rights reserved.
Tribological behavior of PIII treated AISI 316 L austenitic stainless steel against UHMWPE counterface
(2006) Saklakoǧlu N.; Saklakoǧlu I.E.; Short K.T.; Collins G.A.
The aim of this work was to study the tribological benefits of PIII treated austenitic stainless steel by nitrogen ions and/or C ions in a ringer solution, which simulates the environment of the human body. This was achieved by hardness, wear and friction testing, and atomic force microscopy and XRD studies. The results showed that the samples, both treated and untreated, exhibited virtually no wear from contact with the ultra high molecular weight polyethylene (UHMWPE) pins, however, the pins themselves exhibited wear. The amount of wear of the pins was found to decrease with increasing PIII treatment temperature, but addition of C to the chamber caused some increase the amount of wear on the pins. Although C ions reduced to improve the hardness, friction characteristic was improved by formation of carbon-expanded austenite. © 2005 Elsevier B.V. All rights reserved.
Metal complexes of guanidine-substituted alkyl ligands: An unsolvated monomeric two-coordinate organolithium
(2007) Coles M.P.; Sözerli S.E.; Smith J.D.; Hitchcock P.B.
Single-crystal X-ray diffraction of MC(SiMe3) 2(SiMe2hpp) (M = Li, K; hppH = 1,3,4,6,7,8,-hexahydro-2H- pyrimido[1,2-a]pyrimidine) showed nonsolvated organometallic compounds in which the iminonitrogen of the guanidine forms strong intramolecular bonds to generate six-membered metallacycles. © 2007 American Chemical Society.
Luminescent, optical and color properties of natural rose quartz
(2007) Kibar R.; Garcia-Guinea J.; Çetin A.; Selvi S.; Karal T.; Can N.
Rose quartz is an interesting mineral with numerous impurities that have been studied by scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), cathodoluminescence (CL), ion beam luminescence (IBL), radioluminescence (RL), thermoluminescence (TL) and optical absorption (OA). After HF etching, rose quartz from Oliva de Plasencia (Caceres, Spain) shows under SEM the presence of other silicate phases such as dumortierite [Al6.5 - 7 (BO3) (SiO4)3 (O, OH)3]. The OA spectrum of rose quartz suggests that these inclusions are the cause of coloration of rose quartz. The luminescence (CL, IBL, RL, TL) spectra behavior, at both room temperature and lower, confirms that the ∼ 340 nm emission could be associated with Si-O strain structures, including non-bridging oxygen or silicon vacancy-hole centers; the observed ∼ 400 nm emission could be associated with recombination of a hole trapped adjacent to a substitutional, charge-compensated aluminum alkali ion center; the ∼ 500 nm emission could be associated with substitutional Al3 + and the ∼ 700 nm peak could be associated with Fe3 + point defects in Si4 + sites. These results suggest that, while defect properties of rose quartz are not greatly dissimilar to those of purer forms of quartz and silica, further research seems necessary to determine criteria for the evolution of the newly-formed self-organized microstructures in the rose quartz lattice under irradiation. © 2007 Elsevier Ltd. All rights reserved.
Thermal properties of gem-quality moganite-rich blue chalcedony
(2010) Hatipoǧlu M.; Tuncer Y.; Kibar R.; Çetin A.; Karal T.; Can N.
In this study, thermal properties and thermal decompositions of dehydration behaviour of gem-quality translucent blue chalcedonies, without banding or crystalline centre structure, from the Sarcakaya-Eskiehir region in Turkey were studied by means of X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-AES), Fourier transform infrared (FT-IR), thermoluminescence (TL), and simultaneously two thermal analyses of (DTA/TGA) spectroscopy. X-ray diffraction patterns of the blue chalcedony indicate the presence of two important chalcedonic silica phases with overlapped peaks at 4.26, 3.34, 2.28, 2.13, 1.82, 1.54, 1.38, and 137 . During heating from the room temperature to 300 °C, the thermoluminescence pattern of the blue chalcedony shows a characteristic peak at 210 °C. This peak may be due to unusually high traces of the impurities S, Th, Tl, U, and W. During heating from the room temperature to 1400 °C, the TGA pattern of the blue chalcedony indicates that the weight loss is due to the silanol water loss only, and that this loss occurs in a wide temperature range between about 170 and 954 °C. In addition, after making some corrections concerning the artefact mass gain, being due to the drift with buoyancy effect of the atmosphere in its TGA curve, the moganite-rich blue chalcedony shows a relatively lower mass loss of 0.202%. The DTA pattern of the blue chalcedony displays both endothermic and exothermic behaviours because of silica phase transformations. There are one distinctive sharp endotherm and three weaker endotherms at 806 °C. In addition, there is one distinctive sharp exotherm and one weaker exotherm at 1270 °C. © 2010 Elsevier B.V. All rights reserved.
Effects of heating on fire opal and diaspore from Turkey
(2010) Hatipoǧlu M.; Can N.; Karali T.
Fire opal (SiO2·nH2O) and diaspore [Al(OH)O] are two different precious and rare mineral species with high water content. While these species are being cut and polished to make gems, defect-induced weaknesses such as fragility, splintering, and cracking become apparent since the temperature of the mineral species may be increased to high temperatures during the process. These deformations may be broadly related to water loss (molecular (H2O) and hydroxyl (OH) group) and transformation of the base building components and/or inclusion minerals. In this study, thermal properties and thermal stability as dehydratial behaviors of both gem quality fire opal (SiO2·nH2O) from the Şaphane region (Kütahya, Turkey) and gem quality diaspore (AlOHO) from the Milas region (Muǧla, Turkey), including some associated mineral inclusions, were studied by means of X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform-Infrared absorption (FTIR) spectroscopy and thermal analysis (DTA/TGA). During heating to 1400 °C, DTA/TGA patterns indicated that the weight losses of the fire opal and diaspore were due to the water loss only, and that these losses occur in the temperature ranges between about 342 and 722 °C in fire opal, and between about 592 and 718 °C in diaspore. In addition, after making some corrections concerning the mass gain observed, being due to the drift with buoyancy effect of the atmosphere, in their TGA curves, the fire opal shows a mass loss of 7.942%, and one distinctive sharp endotherm at 1089.99 °C and seven weaker endotherms, whereas the diaspore shows a mass loss of about 13.826%, and one distinctive sharpest endotherm at 650.47 °C and four weaker endotherms. © 2010 Elsevier B.V. All rights reserved.
Production of ferroboron powders by solid boronizing method
(2010) Sahin S.; Meric C.; Saritas S.
Ferroboron is an iron-boron alloy containing 10-20% of boron by weight. Commercial ferroboron production is made by two main processes: carbothermic reaction and aluminothermic reaction. Ferroboron also occurs in steel surfaces due to boronizing, which is applied to increase surface hardness in steel. Boronizing is a thermo-chemical surface hardening treatment. The ferroboron phases like Fe2B, FeB form by diffusing of boron element into iron. These phases are very hard, wear strengths are high, and friction coefficients are low. In this study, ferroboron powder was obtained by boronizing ASC 100.29 iron powder that was used widely in powder metallurgy area. Solid boronizing method was preferred due to its advantages in applications and Ekabor-HM powder was used as the boronizing agent. The 80% ASC 100.29 and 20% Ekabor HM were mixed homogeneously and subjected to boronizing at 850-950 °C for 1-6 h. Formation and development of ferroboron phase on the samples was determined by metallographic studies depending on various treatment conditions. The X-ray diffraction analysis revealed that the Fe2B phase did form but FeB phase did not. Micro hardness distributions were measured on the powder grains. Eighteen GPa hardness was measured at Fe2B phase obtained by boronizing while hardness of non-boronized iron powders was 1.06 GPa. The thickness of ferroboron layer formed by boronizing changed with boronizing conditions. The thickness of ferroboron layer increased with boronizing temperature or boronizing time. Depending upon processing parameters, ferroboron layers was formed partially or throughout ferrous powder structure. Since boronizing can be applied to iron powders having any size or shape, ferroboron production with required shape and size is possible. Finally, a new method, namely solid boronizing method, was developed in ferroboron powder production. © 2010 The Society of Powder Technology Japan.
Reaction of [Cp*2W2O5] with mercaptocarboxylic acids: Addition rather than reduction. Isolation and characterization of Cp*WO2(SCH2CH2COOH)
(2011) Sözen P.; Daran J.-C.; Manoury E.; Demirhan F.; Poli R.
The reaction of Cp*2W2O5 with HS(CH2)nCOOH (n = 1, 2) in MeOH or in CH 2Cl2 solutions at room temperature proceeds in slightly different ways depending on the value of n. For n = 2, it selectively yields compound Cp*WO2(SCH2CH2CO 2H), which has been isolated and characterized by elemental analysis, NMR and single crystal X-ray diffraction. The reaction is equilibrated, being shifted to the product by absorption of water by anhydrous Na2SO 4 in CH2Cl2, and to the reactants by addition of water. Contrary to the Mo analogue, no products resulting from metal reduction are obtained. The corresponding reaction for n = 1 occurs similarly at low substrate/W ratios (<0.5), but proceeds further to several uncharacterized products for greater substrate amounts. The primary product could not be isolated, but its 1H NMR spectrum suggests a different, asymmetric structure. © 2010 Elsevier B.V. All rights reserved.
Spectral, electron microscopic and chemical investigations of gamma-induced purple color zonings in amethyst crystals from the Dursunbey-Balkesir region of Turkey
(2011) Hatipoǧlu M.; Kibar R.; Çetin A.; Can N.; Helvac C.; Derin H.
Amethyst crystals on matrix specimens from the Dursunbey-Balkesir region in Turkey have five representative purple color zonings: dark purple, light purple, lilac, orchid, and violet. The purple color zonings have been analyzed with optical absorption spectra in the visible wavelength region, chemical full trace element analyses (inductively coupled plasma-atomic emission spectroscopy and inductively coupled plasma-mass spectroscopy), and scanning electron microscopic images with high magnification. It can be proposed that the production of the purple color in amethyst crystals is due to three dominant absorption bands centered at 375, 530, and 675nm, respectively. In addition, the purple color zonings are also due to four minor absorption bands centered at 435, 480, 620, and 760nm. X-ray diffraction graphics of the investigated amethyst crystals indicate that these crystals are composed of a nearly pure alpha-quartz phase and do not include any moganite silica phase and/or other mineral implications. Trace element analyses of the amethyst crystals show five representative purple color zonings, suggesting that the absorption bands can be mainly attributed to extrinsic defects (chemical impurities). However, another important factor that influences all structural defects in amethyst is likely to be the gamma irradiation that exists during amethyst crystallization and its inclusion in host materials. This gamma irradiation originates from the large underlying intrusive granitoid body in the region of amethyst formation. Irradiation modifies the valence values of the impurity elements in the amethyst crystals. It is observed that the violet-colored amethyst crystals have the most stable and the least reversible coloration when exposed to strong light sources. This situation can be related to the higher impurity content of Fe (2.50ppm), Co (3.1ppm), Ni (38ppm), Cu (17.9ppm), Zn (10ppm), Zr (3.9ppm), and Mo (21.8ppm). © 2011 Taylor & Francis.
Luminescence behaviour and Raman characterization of dendritic agate in the Dereyalak village (Eskiehir), Turkey
(2011) Paral L.; Garcia Guinea J.; Kibar R.; Cetin A.; Can N.
Results are presented for the cathodoluminescence (CL), X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and simultaneously two thermal analyses of (DTA/TGA) spectroscopy of dendritic agate which occurs in the Pliocene polymictic conglomerates of the Höyüklü Formation, North West of the Dereyalak village (Eskisehir, Turkey). Micro-Raman measurements were performed on dendritic agate and then strong quartz and moganite peaks were identified at 465 and 501 cm -1, respectively. Thermal analysis shows the loss of water and hydroxyl units occurs in 2 distinct stages; at 796 and 808 °C. Spatially resolved CL results at room temperature were recorded for chosen 3 different areas. Grey area (100% SiO2) displays the lowest CL emission. Brown area (99.7% SiO2 and 0.3% Fe2O3) contains exsolved non-detected ironed phases such as goethite-lepidochrocite to explain the brown colour and the iron point substitutional defects attributed to the 643 nm CL emission. White outer (98.7% SiO2 and 1.3% Al 2O3) would be strongly disordered as observed in the amorphous Raman spectrum containing as inferred from the spectrum CL on the outer areas, particularly non-bridging oxygen hole centres (NBOHC) (317 nm) and [AlO4]°/H (380 nm) centres produced by large amounts of aluminium in the lattice (1.33% Al2O3). When it comes to collect the data in the time resolved CL spectrum, at least three broad emission bands were detected in: a green band of low intensity at about 496 nm, intense orange band at about 600 nm, and a red band at 670 nm. The CL emission at 670 nm shows some relationships between the hydroxyl or alkali content and the abundance of O2 (super 3-) centres and E′1 centres. Another conspicuous observed feature in the CL spectra of agates is the existence of an orange emission band centred at around 600 nm. The predominance of the yellow CL emission band and the high concentration of E′1 centres are typical for agates formed by acidic volcanism processes. © 2011 Elsevier B.V. All rights reserved.
Extraction and properties of Ferula communis (chakshir) fibers as novel reinforcement for composites materials
(2013) Seki Y.; Sarikanat M.; Sever K.; Durmuşkahya C.
The aim of this study is to examine the use of Ferula communis fibers as potential reinforcement in polymer composites. The fibers are extracted from the F. communis plant which grows in Selcuk, Izmir in western Turkey. The chemical composition of ferula fibers in terms of cellulose, lignin, and ash contents was determined. Surface functional groups of ferula fibers were obtained by fourier transform infrared and X-ray photoelectron spectroscopy. Crystallinity index and crystallite size were determined by X-ray diffraction analysis. The morphology of ferula fibers was investigated through scanning electron microscopy, the thermal behavior through thermogravimetric and differential scanning calorimetry analyses. The real density of ferula fibers was measured by means of Archimedes method with ethanol. The mechanical properties of F. communis were measured through single fiber tensile tests. The interfacial shear strength (IFSS) in a polyester matrix has been estimated from the pull-out test. © 2012 Published by Elsevier Ltd.
Determination of properties of Althaea officinalis L. (Marshmallow) fibres as a potential plant fibre in polymeric composite materials
(2014) Sarikanat M.; Seki Y.; Sever K.; Durmuşkahya C.
The mechanical, thermal, chemical, crystallographic and morphological properties of althaea fibres, extracted from Althaea officinalis L., was examined for the first time in this study. A. officinalis L. was obtained from Mordoǧan, Izmir (Turkey). After extraction process, lignin, cellulose and hemicellulose contents of althaea fibres were identified. Fourier transform infrared and X-ray photoelectron spectroscopy were utilized for surface functional groups of althaea fibres. By using X-ray diffraction analysis, CI value for althaea fibre is obtained to be 68%. The images of scanning electron microscopy were taken for observation of morphology of althaea fibres. The tensile modulus and tensile strength values of althaea fibre were obtained by single fibre tensile tests as 415.2 MPa and 65.4 GPa, respectively. Thermogravimetric analysis showed that thermal degradation of the fibre begins at approximately 220°C. Besides, by pulling out the althea fibre from the embedded high density polyethylene, interfacial shear strength value was determined to be 8.16 MPa. The results suggest that the althaea fibre can be used in composite applications as a natural reinforcement material. © 2013 Elsevier Ltd. All rights reserved.
Electrically conductive borate-based bioactive glass scaffolds for bone tissue engineering applications
(SAGE Publications Ltd, 2017) Turk M.; Deliormanll A.M.
In this study, electrically conductive, borate-based, porous 13-93B3 bioactive glass composite scaffolds were prepared using a polymer foam replication technique. For this purpose, a slurry containing 40 vol% glass particles and 0-10 wt% graphene nanoplatelets was prepared by dispersing the particles in ethanol in the presence of ethyl cellulose. Composite scaffolds were subjected to a controlled heat treatment, in air atmosphere, to decompose the foam and sinter the glass particles into a dense network. It was found that the applied heat treatment did not influence the structure of graphene in the glass network. Graphene additions did not negatively affect the mechanical properties and enhanced the electrical conductivity of the glass scaffolds. In X-ray diffraction analysis, the crystalline peak corresponding to hydroxyapatite was observed in all the samples suggesting that all of the samples were bioactive after 30 days of immersion in simulated body fluid. However, Fourier transform infrared spectroscopy analysis and scanning electron microscope observations revealed that hydroxyapatite formation rate decreased with increasing graphene concentration especially for samples treated in simulated body fluid for shorter times. Based on the cytotoxicity assay findings, the MC3T3-E1 cell growth was significantly inhibited by the scaffolds containing higher amount of graphene compared to bare glass scaffolds. Best performance was obtained for 5 wt% graphene which yielded an enhancement of electrical conductivity with moderate cellular response and in vitro hydroxyapatite forming ability. The study revealed that the electrically conductive 13-93B3 graphene scaffolds are promising candidates for bone tissue engineering applications. © The Author(s) 2017.
Microstructural and Radioluminescence Characteristics of Nd3+ Doped Columbite-Type SrNb2O6 Phosphor
(Springer New York LLC, 2017) Ekmekçi M.K.; İlhan M.; Ege A.; Ayvacıklı M.
Undoped and different concentration Nd3+ doped SrNb2O6 powders with columbite structure were synthesized by molten salt process using a mixture of strontium nitrate and niobium (V) oxide and NaCl-KCl salt mixture as a flux under relatively low calcining temperature. X-ray diffraction analysis results indicated that SrNb2O6 phases found to be orthorhombic columbite single phase for undoped, 0.5 and 3 mol% Nd3+ doping concentrations. Phase composition of the powders was examined by SEM-EDS analyses. Radioluminescence properties of Nd3+ doped samples from UV to near-IR spectral region were studied. The emissions increased with the doping concentration of up to 3 mol%, and then decreased due to concentration quenching effect. There is a sharp emission peak around 880 nm associated with 4F5/2 → 4I9/2 transition in the Nd3+ ion between 300 and 1100 nm. The broad emission band intensity was observed from 400 to 650 nm where the peak intensities increased by increasing Nd3+ doping concentration. All the measurements were taken under the room temperature. © 2017, Springer Science+Business Media New York.
Coordination entities of a pyrene-based iminopyridine ligand: Structural and photophysical properties
(Elsevier Ltd, 2017) Ayadi A.; Branzea D.G.; Allain M.; Canevet D.; Dinçalp H.; El-Ghayoury A.
A pyrene-based iminopyridine ligand L has been prepared and displays the absorption and emission properties expected for pyrene-based derivatives in solution. Ligand L, as well as two neutral and one monocationic coordination entities, respectively formulated as [ZnLCl2] 1, [ReLCl(CO)3] 3 and [CuL2](BF4) 2, have been crystallized and analyzed by single crystal X-ray diffraction analysis. The corresponding crystal structures indicate the formation of supramolecular architectures generated by offset π⋯π stacking between pyrene fragments and strong C–H⋯π interactions in coordination entity 1. For the cationic coordination entity 2, the crystal packing reveals the presence of C–H⋯F and C–H⋯π interactions and numerous C–H⋯π contacts interconnecting the molecules into a 3D network. As for coordination entity 3, hydrogen bonding and π⋯π stacking link the molecules in a three dimensional manner. Zinc(II) and copper(I) coordination entities have also been studied through isothermal titration calorimetry, which indicate a strong binding and a different stoichiometry for both coordination entities. Photophysical studies of the ligand and corresponding coordination entities show a monomer type pyrene emission and a higher fluorescence quantum yield for the zinc coordination entity 1 as compared with copper 2 and rhenium 3 coordination entities. © 2017 Elsevier Ltd
Structural characteristics of ashlar roman watchtowers in cilicia region, anatolia
(University of AEGEAN, 2019) Gençer F.
Depending on requirements of the building type, ashlar masonry (that is a masonry technique composed of rectangular blocks); varies in terms of dimension of blocks, staggering ratio, wall profile, etc. Determination of impact of these variables on resistance is critical for the intervention decision process and sustainability of integrity and authenticity of dry masonry constructions. Therefore, the aim of the study is to determine characteristics effecting structural resistance and failure mechanisms of ashlar Cilician dry masonry watchtowers under lateral loading by quasi-static tilt analysis. Thus, the towers were documented in detail by traditional documentation techniques, the type of stone material were determined by Scanning Electron Microscope (SEM) equipped with X-Ray Energy Dispersive System (EDS) and X-ray Diffraction (XRD) analysis to identify friction coefficient and density values of stones to be used in simulation. Then virtual towers designed based on caharacteristics of case study towers were analysed by quasi-static tilting method. The towers present differences in terms of staggering ratio, which is the ratio between horizontal distance between joints (s) and height of the related course (h), and proportional relationship between heigth (H) and length (L) of the tower. Consequently, it is seen that staggering ratio affected out-plane resistance of the towers, increase in staggering ratio increased structural resistance. High staggering ratio (s/bh=1.4) provided total behavior. When the H/L ratio increased (H/L ≥2), the collapse angle of the towers decreased and slenderness of the towers increased, bending was observed. These results demonstrate that ancient masons were probably aware of structural precautions for resistance, they tried to use these techniques within the limits of the sources of the area. © 2019, University of AEGEAN. All rights reserved.
Structural, theoretical and third order nonlinear optical properties of (E)-N’-(4-chlorobenzylidene)-4-fluorobenzohydrazide monohydrate
(Taylor and Francis Ltd., 2021) Latha N.; Barathi D.; Uthaya Kumar M.; Vennila K.N.; Vinitha G.; Mani R.; Louhi-Kultanen M.; Bardak F.; Atac A.; Kose E.
The title compound (E)-N’-(4-chlorobenzylidene)-4-fluorobenzohydrazide monohydrate (CBFBH) is a novel hydrazone Schiff base compound, synthesized and characterized by FTIR, 1H and 13C NMR, UV-Vis and single crystal X-ray diffraction analyses. Quantum chemical computations were performed by Density Functional Theory (DFT) with B3LYP/6-311G (d,p) level to study the structural and spectral properties of the synthesized compound. Reliability of the crystal structure was visualized by Hirshfeld surface analysis. Third-order nonlinear optical polarization coefficient was calculated by Z-scan technique. © 2021 Taylor & Francis Group, LLC.
Preparation and Magnetic Properties of NiFe2O4 Plate Nanoparticles
(Springer, 2021) Kocan F.
The aim of this study was to investigate nickel ferrite (NiFe2O4) plate nanoparticles synthesized by the co-precipitation method. The effects of parameters such as solution pH and Fe3+/Ni2+ mole ratio of nickel ferrite nanoparticles were analyzed. The nanoparticles synthesized by the co-precipitation method were calcined at 650°C. The samples were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), and Fourier-transform infrared spectroscopy (FTIR). The remanent magnetization, saturated magnetism, and coercivity properties of the samples were measured with a vibrating sample magnetometer (VSM). In a synthesis process with Fe3+/Ni2+ = 1 mole ratio, a Ni1.43Fe1.7O4 compound was formed where NiFe2O4 was expected to form. NiFe2O4 plate nanoparticles with 108-nm particle size were successfully synthesized using the Fe3+/Ni2+ = 2 mole ratio. © 2021, The Minerals, Metals & Materials Society.
Radioluminescence results, thermoluminescence analysis and kinetic parameters of Y2O3:Ln3+ (Ln: Dy, Nd, Sm) nanophosphors obtained by sol-gel method
(Elsevier Ltd, 2022) Keski̇n İ.Ç.
Dy3+, Nd3+, Sm3+ doped Y2O3 nanophosphors were produced with high homogeneity at low sintering temperature using the sol-gel method. To compare the structural and optical changes of different rare-earth ions included in the crystal lattice, the dopant ratio was chosen as constant 2 mol%. In the light of X-ray diffraction (XRD) analysis, the unit cell volume and average crystallite size of the doped nanophosphors and their pure Y2O3 sintered under the same heat treatment regime were calculated and compared. Scanning electron microscopy (SEM) techniques were used to describe their structures and morphologies; an average particle size histogram of nanostructures was generated. The Radioluminescence (RL) spectra of Y2O3:Ln3+ (Ln: Dy, Nd, Sm) nanophosphors were presented for the first time. Splittings were seen in detail in the emission spectra given the 200–1100 nm range. For Dy3+ 4F9/2 → 6H13/2, for Nd3+; in the visible region 4H11/2-4I9/2 in the NIR region 4F3/2-4I9/2, for Sm3+; in the visible region 4G5/2-6H7/2 in the NIR region 4G5/2-6F5/2 transitions were determined to have the most vigorous emission. It was observed that the optical band gap calculated from the absorption spectrum of Y2O3 was 4.97 eV; this value changed the most with Dy contribution and decreased to 4.77 eV. The thermoluminescence (TL) behaviors of nanophosphors were compared under both UV and X-ray excitation. The kinetic parameters were calculated by applying computerized glow curve deconvolution (CGDC), and various heating rate (VHR) methods to the glow curves obtained UV excitation. The obtained E (eV) values correlated with each other are highly compatible. © 2022 Elsevier Ltd and Techna Group S.r.l.
Electrochemical, mechanical, and antibacterial properties of the AZ91 Mg alloy by hybrid and layered hydroxyapatite and tantalum oxide sol-gel coating
(Walter de Gruyter GmbH, 2023) Albayrak S.; Gül C.; Emin N.; Gökmen U.; Karakoç H.; Uzun A.; Çinici H.
The corrosion and bacterial behavior of AZ91 magnesium alloy coated with sol-gel-deposited amorphous tantalum oxide and hydroxyapatite have been investigated. The objective was to assess the potential suitability of AZ91 for permanent prosthesis applications. The coatings were applied in layered and hybrid configurations and characterized using various techniques including X-ray diffractometry, Fourier transform infrared spectroscopy, scanning electron microscopy/energy dispersive spectrometry, and drop analyses. The antibacterial properties were evaluated through interactions with Staphylococcus aureus and Escherichia coli strains. Mechanical properties and adhesion were determined via linear scratch tests, and electrochemical corrosion tests were conducted in different media. The release of aluminum ions from the samples in Dulbecco's Modified Eagle's Medium was monitored over 28 days. The findings revealed that the amorphous tantalum oxide coating, particularly in combination with hydroxyapatite, improved antibacterial properties and positively influenced corrosion and scratch resistance. The layered and hybrid coatings demonstrated the highest corrosion resistance. The release of aluminum ions remained within acceptable levels in the tested medium. Overall, the study provides valuable insights into the potential of sol-gel coatings on AZ91 for prosthetic applications, considering antibacterial behavior, corrosion resistance, and aluminum release. © 2023 Walter de Gruyter GmbH, Berlin/Boston.

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