Thin Film X-ray Diffraction Analysis Research Articles

Structural properties, thicknesses, and qualities of plutonium oxide thin films prepared by polymer assisted deposition

Phase purity, morphology, and defect structures on plutonium oxide surfaces likely influence reactivity of plutonium, and high quality PuO2 crystalline substrates are needed to probe the effects of these properties on a model plutonium oxide surface. Indeed, different thin film thicknesses are required for conducting the range of state-of-the-art measurements available for studying these surfaces. In this Article, modification of a polymer-assisted deposition method is employed to grow various film thicknesses of PuO2 on yttria stabilized zirconia (YSZ) substrates, and measurements are carried out to characterize these films. Phase purity and epitaxial qualities of the films are assessed using thin film X-ray diffraction analysis, and the first Grazing Incidence Extended X-ray Absorption Fine Structure measurements carried out on a PuO2 thin film are reported, providing information about the short-range order of the lattice structure. Elemental purity is measured via X-ray photoelectron spectroscopy. Thicknesses and densities of the films are evaluated using neutron reflectivity, revealing that phase-pure PuO2 thin films of high epitaxial quality are formed. Micro-Raman spectroscopy suggests development of structural agglomerates of PuO2 on the surfaces, likely resulting from defects in the lattice match between the PuO2 film and the YSZ substrate.

Application of electroless plating process for multiscale Ni-La0.8Sr0.2Ga0.8Mg0.2O3-σ SOFC anode fabrication

An electroless plating process of nickel is introduced to solve the drawbacks of impregnation for developing the multiscale anode of a solid oxide fuel cell (SOFC). Impregnation is the conventional fabrication method of the electrode. The process is not favorable for depositing nanoscale metal catalysts due to severe problems including agglomeration of the catalysts while reducing metal oxides. Thus, as an alternative, we propose electroless plating of nickel to fabricate a multiscale nickel-based SOFC anode. A Ni-LSGM (La0.8Sr0.2Ga0.8Mg0.2O3-σ) anode is selected. The low chemical compatibility of LSGM with nickel emphasizes the advantage of the electroless plating process. First, nanoscale nickel particles are successfully applied as the main catalyst of the SOFC anode by plating nickel to the surface of the LSGM scaffold substrate near the triple phase boundary region. Thin film X-ray diffraction and image analysis confirm that pure nanoscale nickel particles form on the entire substrate, even at a low temperature (60 °C) without secondary phase formation. Electrochemical impedance spectroscopy analysis is then performed to verify the possibility of implementing an efficient Ni-LSGM anode through nickel electroless plating. As a result, the new Ni-LSGM anode shows ∼50 times higher electrochemical performance than that of an impregnated Ni-LSGM anode.

In Vitro Bioactivity of Binary Nepheline‐Fluorapatite Glass/Polymethyl‐Methacrylate Composite

In vitro bioactivity of stoichiometric nepheline‐fluorapatite glass/polymethyl‐methacrylate (PMMA (C5O2H8)n) composite was evaluated. Four glasses of nepheline/fluorapatite with different ratios (75/25, 80/20, 85/15, and 90/10 mole%) were added in 20 and 40 wt.% to PMMA. The composite samples were soaked in simulated body fluid (SBF) for 25 days. A scanning electron microscope with energy dispersive X‐ray microanalysis (SEM/EDX) and thin film X‐ray diffraction analysis was used to evaluate the composite materials after immersion in SBF. Inductively coupled plasma (ICP) and pH changes were used in the determination of the ions released and the alkalinity, respectively, after the immersion in Tris‐buffered solution. Effect of glass filler loading on compressive strength of the cements was also evaluated. The four binary nepheline‐fluorapatite glasses/PMMA cements composites are good potential bioactive materials. The compressive strength was between 70.36 ± 6.47 and 97.30 ± 3.90 MPa. In general, decreases of the compressive strength follow the increase of the glass ratio (i.e., 40 wt.%), but all meet that specified by the ASTM F‐451.

Surface Morphology and Phase Transitions of Anodic TiO<sub>2</sub> Films Induced by Hydrothermal Exposure

A dense TiO2 film was fabricated on the titanium surface using the anodization technique. Surface morphology and phase structure of anodic TiO2 film were investigated before and after the hydrothermal exposure at 160 °C for 24 h. The hydrothermal solution was 3.5 wt% NaCl solution and the films were either immersed in NaCl solution or exposed to water vapor during the exposure. It was found that the as-prepared anodic TiO2 film consisted primarily of amorphous oxides and exhibited a relatively smooth surface. After the hydrothermal exposure, lots of rod-like crystals were formed on the solution-immersed film, while aggregated fine nanoparticles emerged on the vapor-exposed one. Thin film X-ray diffraction analysis indicated that the hydrothermal exposure transformed amorphous oxides into crystalline anatase. The corrosion behavior investigation showed that the structural transition of anodic TiO2 film during the exposure reduced the corrosion resistance of anodized titanium greatly.

Porphycene dimer-based non-fullerene acceptor for organic solar cell

Porphycene dimers connected by [Formula: see text]-phenylene (DPc– m P) and 2,5-thienylene (DPc–T) linkages have been synthesized from 2,7,12,17-tetrahexyl-3-iodoporphycene by palladium-catalyzed cross-couplings. The crystal structures of porphycene dimers revealed that meta-phenylene linkage provides a highly twisted structure with the dihedral angel of 103° between two porphycene units, while thienylene linkage provides a nearly planar structure of two porphycene units. These porphycene dimers showed strong absorption thorough the visible to NIR regions and HOMO and LUMO energy levels of them are suitable as [Formula: see text]-type materials of organic solar cells (OSCs) in combination with P3HT as a [Formula: see text]-type material. The hole and electron mobilities of the blended films of the porphycene dimers and P3HT obtained by space-charge-limited-current (SCLC) method were 3.7 × 10[Formula: see text] and 0.26 × 10[Formula: see text] cm2.V[Formula: see text].s[Formula: see text] for DPc– m P :P3HT, and 3.2 × 10[Formula: see text] and 0.027 × 10[Formula: see text] cm2.V[Formula: see text].s[Formula: see text] for DPc–T :P3HT. Atomic force microscopy (AFM) and thin-film X-ray diffraction analysis (XRD) measurements indicated that the blended films of the porphycene dimers and P3HT formed amorphous films with smooth and low-roughness surfaces, whereas the blended film of porphycene monomer and P3HT created the highly crystalline film with huge domain structures. The OSCs composed of porphycene dimers and P3HT showed power conversion efficiencies of 0.08% was twice as high as that of monomer-based OSC.

Structural, Morphological, Optical And Electrical Properties Of PbSe Thin Films Grown By Chemical Bath Deposition

Lead selenide (PbSe) thin films were processed by chemical bath deposition (CBD) technique. To analyze the structure and the crystallite size of PbSe thin film X-ray diffraction (XRD) analysis was used. Using Scanning Electron Microscopy (SEM) the surface examination of the film was conducted. With the help of UV-visible absorption spectrum investigation of the optical properties were held. All the optical constants were determined from UV-visible absorption spectrum. The dielectric examination of PbSe thin films were analyzed for various frequencies and various temperatures. The AC electrical conductivity analysis brought to light that the conduction depended on both the frequency and the temperature. Photoconductivity analysis was carried out to the PbSe thin films.

Fluoride Conversion Coating on Biodegradable AZ31B Magnesium Alloy

A fluoride conversion coating was successfully prepared on AZ31B magnesium alloy by chemical reaction in hydrofluoric acid. Morphologies, composition, bonding strength, corrosion properties, in vitro cytotoxicity and antibacterial properties of the coating were investigated, respectively. The scanning electron microscopy observations revealed a dense coating with some irregular pores. The thin-film X-ray diffraction analysis indicated that the coating was mainly composed of MgO and MgF2. The electrochemical impedance spectroscopy results showed that the fluoride conversion coating significantly improved the corrosion resistance of AZ31B. The hydroxyapatite formed on the surface of the fluoride coated AZ31B after being immersed in the simulated blood plasma indicated the good bioactivity of the material. The in vitro cytotoxicity test showed that the fluoride coated AZ31B alloy was not toxic to BMMSCs (human bone marrow-derived mesenchymal stem cells). It was also found that the fluoride coated AZ31B alloy had antibacterial capability.

Effect of heat treatment on microstructures and mechanical behavior of porous Sr–Ca–P coatings on titanium

Titanium and its alloys are widely used in dental and orthopedic fields due to their excellent chemical stability. The micro-arc oxidation (MAO) technique is an effective method for coating strontium, calcium, and phosphorus onto titanium. In clinical application, the adhesion between the coating and the substrate is important factor for dental implants and artificial joint prosthesis. The present study investigates the effects of heat treatment on the properties of MAO coatings. The physicochemical characteristics are investigated using scanning electron microscopy (SEM) observation, thin film X-ray diffraction (TF-XRD) analysis, and the scratch test. After heat treatment, the TF-XRD results indicate that the tricalcium phosphate phase appears at a temperature of 800 °C. SEM results show that the surface morphology does not change. The scratch test results reveal that the adhesion strength between the coatings and the substrate increases with increasing heat treatment temperature. Consequently, all findings in this study indicated that MAO coatings with heat treatment have good mechanical properties for clinical applications.

Hydroxyapatite/diopside ceramic composites and their behaviour in simulated body fluid

In this work, diopside was introduced in hydroxyapatite matrix as a sintering aid and hydroxyapatite/diopside ceramic composites were fabricated by uniaxial hot-pressing. The biological activity of hydroxyapatite/diopside ceramic composites in simulated body fluid was assessed by means of scanning electron microscopy (SEM), thin-film X-ray diffraction (TF-XRD) and electron-probe micro analysis (EPMA). SEM micrographs showed an obvious bright mineral layer to form on the soaked composite surface, and the layer may be hydroxyapatite or NaCl crystals.

Silver ion-exchanged sodium titanate and resulting effect on antibacterial efficacy

Surface modification with silver ion is an effective way to reduce infections. In the present work, the effect of silver ion-exchanged sodium titanate on the titanium has characterized by thin film X-ray diffraction analysis (TF-XRD) and high resolution scanning electron microscopy (HR-SEM). Antibacterial activity of silver ion-exchanged sodium titanate on titanium was assessed by the plate-counting method using against Staphylococcus aureus. The results show that silver ion-exchanged samples improve the antibacterial activity depends on NaOH concentration in electrolyte while the titanium oxide layer shows a significant decline. It is also found that the apatite-forming ability of silver ion-exchanged samples was showed after 7 days by immersion in SBF. In conclusion, silver ion-exchange method to the sodium-titanate is favorable to increase the antibacterial activity of titanium surfaces as well as apatite-forming ability.

Characteristics and biological responses of novel coatings containing strontium by micro-arc oxidation

The modification of micro-arc oxidation (MAO) technique is an effective method to improve biocompatibility of titanium. This study aimed to investigate the coatings formed in the electrolytes with different strontium content, which is beneficial for biological performance. The physicochemical characteristics and cell behavior were assessed. The physicochemical characteristics were investigated using scanning electron microscope (SEM) observation, energy dispersive X-ray spectrometer (EDX), thin film X-ray diffraction (TF-XRD) analysis, electron spectroscopy for chemical analysis (ESCA) and surface roughness test. Cell behavior included morphology observation by SEM and number count by methylthiazoletetrazolium assay of hFOB cells. The TF-XRD results indicated that phase of coatings was anatase and rutile. The calcium, phosphorus, and strontium were detected in the coatings by EDX and ESCA. Using the SEM, the surface morphology exhibited uniform porous structure on titanium. Cell culture experiments demonstrate that MAO coating formed in the electrolytes with different strontium content would not alter initial cell morphology and 1-day and 7-day cell numbers. The cell proliferation of coatings containing 1% or 5% strontium content at 14-day culture was higher than coatings without strontium content at 14-day culture, but the higher strontium content (10%) could not be beneficial to cell growth. Consequently, this study indicates that strontium incorporated into MAO coatings did not change the physicochemical characteristics but exhibited an effect on biological responses.

Synthesis, Structures, and Properties of Fused Thiophenes for Organic Field‐Effect Transistors

A series of fused thiophenes composed of fused alpha-oligothiophene units as building blocks, end-capped with either styrene or 1-pentyl-4-vinylbenzene groups, has been synthesized through Stille coupling reactions. The compounds have been fully characterized by means of (1)H NMR spectrometry, high-resolution mass spectrometry, and elemental analysis. The molecules present a trans-trans configuration between their double bonds, which has been verified and confirmed by Fourier-transform infrared spectroscopy and single-crystal X-ray diffraction analysis. The X-ray crystal structures showed pi-pi overlap and sulfur-sulfur interactions between the adjacent molecules. The decomposition temperatures were all found to be above 300 degrees C, indicating that compounds of this series possess excellent thermal stability. The fact that no phase transition occurs at low temperature indicates that they should be well-suited for application in devices. Moreover, they possess low HOMO energy levels, based on cyclic voltammetry measurements, and suitable energy gaps, as determined from their thin-film UV/Vis spectra. Thin-film X-ray diffraction analysis and atomic force microscopy revealed high crystallinity on supporting substrates. In addition, as the substrate temperature has a significant influence on the morphology and the degree of crystallinity, the device performance could be optimized by varying the substrate temperature. These materials were found to exhibit optimal field-effect performance, with a mobility of 0.17 cm(2) V(-1) s(-1) and an on/off ratio of 10(5), at a substrate temperature of 70 degrees C.

Surface Treatments of Titanium Anodized in Phosphoric Acid Solution and in Vitro Cell Responses

TiO2 layer was fabricated on commercially pure titanium using an anodic spark oxidation technique with 1M phosphoric acid solution. Subsequent heat or water treatment was performed to improve the biocompatibility of oxide layers. Surface characteristics of oxide layers before and after subsequent treatments and their influence on the cell response were investigated. It was found that the oxide layer without subsequent treatments exhibited a porous surface structure with few nanometer features. Thin film X-ray diffraction analysis and electron probe microanalysis indicated that the oxide layer consisted of amorphous or poorly crystallized oxides with the incorporation of phosphorus. After heat treatment (500°C, 3 h), the crystallinity degree of oxide layer increased, but only slight change in the surface morphology was observed. In contrast, water treatment (80°C, 48 h) not only can significantly transform the amorphous oxides into crystalline anatase, but also result in a nanostructured surface. In vitro biocompatibility study of oxide layers demonstrated better cell response to water treated oxide layer than untreated one.

Surface characteristics and in vitro biocompatibility of titanium anodized in a phosphoric acid solution at different voltages

The surface of commercially pure titanium was modified by anodization treatment in a phosphoric acid solution at different voltages: 100 V, 200 V and 300 V. The surface characteristics of anodic TiO2 layers and their influence on the cell response were investigated. Micrographs by scanning electron microscopy revealed that the dense and uniform oxide layer obtained at 100 V exhibits a nanostructured surface which is similar to the surface of natural tooth cementum. In contrast, porous oxide layers without nanometer features were produced at higher voltages. Thin film x-ray diffraction analysis confirmed the existence of anatase in the oxide layer obtained at 300 V, but not in oxide layers obtained at 100 V and 200 V. The in vitro biocompatibility study of oxide layers demonstrated greater cell adhesion and proliferation of the oxide layer obtained at 100 V compared to the other two kinds of oxide layers.

Novel fabrication of nano-rod array structures on titanium and in vitro cell responses

Nano-scale rod arrays of titania were fabricated on titanium surface by a glass phase topotaxy growth (GPT) method, which was featured by an interfacial reaction between sodium tetraborate coating and the preheated metallic titanium at elevated temperature. The samples were characterized by thin-film X-ray diffraction (XRD), scanning electron microscope (SEM), profilometer and contact angle measurement. Thin-film XRD analysis indicated that the nano-rod arrays were composed of pure rutile titania phase. SEM images showed that these rutile rods were 100-200 nm wide and 1-2 microm long. The nano-rod arrays had significantly higher average roughness (P < 0.05) and greater hydrophilicity (P < 0.05) compared to the control. Human embryonic palatal mesenchymal (HEPM) cells were grown to evaluate in vitro cell responses to the nano-rod array structures in terms of cell attachment and proliferation. An equivalent high attachment rate of 94% was observed after 4-h incubation, but a lower proliferation rate was observed on the nano-rod array after 12-day culture compared to the control (P < 0.05).

Catalytic Activity of Zirconium Oxynitride Prepared by Reactive Sputtering for ORR in Sulfuric Acid

Zirconium oxynitride (ZrO x N y ) prepared by the reactive sputtering method under O 2 and N 2 atmosphere was evaluated as a nonplatinum cathode catalyst for polymer electrolyte fuel cells. The ZrO x N y prepared at p Ar = 0.886 Pa, p N2 = 0.41 Pa, and p O2 = 1.7 mPa with a substrate temperature of 800°C during the film formation had a superior catalytic activity for the oxygen reduction reaction (ORR) in sulfuric acid. The onset potential for the ORR had a maximum of 0.8 V vs a reversible hydrogen electrode. The thin-film X-ray diffraction analysis and ionization potential measurement revealed that the ZrO x N y with a high catalytic activity for the ORR contained the Zr 2 ON 2 crystalline structure.

In-Vitro Bioactivity Characterization of Sodium-Potassium Mica and Fluorapatite Containing Glass Ceramics

The aim of this study is to find out the crystallization behaviour and in-vitro bioactivity character of machinable glass ceramics having different ratios of Na/K mica and apatite phases, to ascertain the best machinable composition. In order to investigate the bioactivity behavior of the samples the simulated body fluid (SBF) was prepared. Samples were removed from the solution after 1 hour, 1 day, 1, 2, 3 and 4 weeks. FEG-SEM was used to characterize the morphology of precipitation HCA layer on the surface depending on time. Molecular bonding characterization of HCA layers were carried out by using Fourier Transform Infrared Spectroscopy (FTIR) technique. The thin film X-ray diffraction (TF-XRD) analysis was used to characterize the variation of chemical composition on precipitated layer by time. Optimum results were obtained by the composition, containing 70wt% Na/K mica and 30wt% fluorapatite which had an average mica size of 3-4 microns.

In Vitro Bioactivity of Injectable Ceramic Orthopaedic Cements

The objective of this paper is to investigate and compare the in vitro bioactivity of three injectable cements for orthopaedic applications. The cements were all based on chemically bonded ceramics technology; calcium phosphate (Norian SRS), and experimental versions of calcium silicate and calcium aluminate cements. The cements were mixed with their respective liquids and were after setting stored in phosphate buffered saline at 37 °C for time periods of 1h, 24 h, 7 days and 30 days. After storage the samples were analysed with scanning electron microscopy (SEM), thin film X-Ray diffraction (TF-XRD) and energy dispersive spectroscopy (EDS) for the presence of possible apatite on the sample surface. The SEM and EDX analyses showed that surface films containing Ca and P (along with the other atoms present in the materials) were formed on all materials. Thus reactions with the storage medium had occurred. The TF-XRD analysis confirmed the presence of apatite for the calcium phosphate cement and the calcium aluminate cement. On the calcium silicate cement most of the surface zone seemed to be amorphous with only broad peaks corresponding to apatite. Thus all the tested materials showed signs of in vitro bioactivity.

Influence of the Porosity of Starch-Based Fiber Mesh Scaffolds on the Proliferation and Osteogenic Differentiation of Bone Marrow Stromal Cells Cultured in a Flow Perfusion Bioreactor

This study investigates the influence of the porosity of fiber mesh scaffolds obtained from a blend of starch and poly(epsilon-caprolactone) on the proliferation and osteogenic differentiation of marrow stromal cells cultured under static and flow perfusion conditions. For this purpose, biodegradable scaffolds were fabricated by a fiber bonding method into mesh structures with two different porosities-- 50 and 75%. These scaffolds were then seeded with marrow stromal cells harvested from Wistar rats and cultured in a flow perfusion bioreactor or in 6-well plates for up to 15 days. Scaffolds of 75% porosity demonstrated significantly enhanced cell proliferation under both static and flow perfusion culture conditions. The expression of alkaline phosphatase activity was higher in flow cultures, but only for cells cultured onto the higher porosity scaffolds. Calcium deposition patterns were similar for both scaffolds, showing a significant enhancement of calcium deposition on cellscaffold constructs cultured under flow perfusion, as compared to static cultures. Calcium deposition was higher in scaffolds of 75% porosity, but this difference was not statistically significant. Observation by scanning electron microscopy showed the formation of pore-like structures within the extracellular matrix deposited on the higher porosity scaffolds. Fourier transformed infrared spectroscopy with attenuated total reflectance and thin-film X-ray diffraction analysis of the cell-scaffold constructs after 15 days of culture in a flow perfusion bioreactor revealed the presence of a mineralized matrix similar to bone. These findings indicate that starch-based scaffolds, in conjunction with fluid flow bioreactor culture, minimize diffusion constraints and provide mechanical stimulation to the marrow stromal cells, leading to enhancement of differentiation toward development of bone-like mineralized tissue. These results also demonstrate that the scaffold structure, namely, the porosity, influences the sequential development of osteoblastic cells and, in combination with the culture conditions, may affect the functionality of tissues formed in vitro.

Formation of Titania Submicron-Scale Rod Arrays on Titanium Substrate and In Vitro Biocompatibility

ABSTRACTTitania submicron-scale rod arrays were fabricated on metallic titanium (α-Ti) surfaces by coating a layer of sodium tetraborate on titanium substrates and subsequent thermal treatment. Thin-film X-ray diffraction analysis indicated that the sodium tetraborate gave rutile (TiO2: PDF# 21-1276) submicron-scale rod arrays. The rods in the arrays are parallel to each other in the grain of metallic titanium surface. The titania submicron-scale rod arrays deposited apatite within 7 days after being soaked in a simulated body fluid, indicating that the rod arrays exhibit in vitro bioactivity.