X-ray Diffraction Peak Intensity Research Articles

Evolution of structural and magnetic properties of Co-doped TiO2 thin films irradiated with 100 MeV Ag7+ ions

In continuation to our earlier studies where we have shown room temperature ferromagnetism observed in TiO2 and Co-doped TiO2 (CTO) thin films independent of their phase (Mohanty et al 2012 J. Phys. D: Appl. Phys. 45 325301), here the modifications in structure and magnetic properties in CTO thin films using 100 MeV Ag7+ ion irradiation are reported. Owing to the important role of defects in tailoring the magnetic properties of the material, we vary the ion fluence from 5 × 1011 to 1 × 1012 ions cm−2 to create post-deposition defects. While the film deposited under 0.1 mTorr oxygen partial pressure retains its crystallinity showing radiation-resistant behaviour even at a fluence of 1 × 1012 ions cm−2, films deposited under 1 to 300 mTorr oxygen partial pressure becomes almost amorphous at the same fluence. Using Poisson's law, the diameter of the amorphized region surrounding the ion path is calculated to be ∼4.2 nm from the x-ray diffraction peak intensity ((1 1 0) for rutile phase) as a function of ion fluence. The saturation magnetization (Ms) decreases exponentially similar to the decrease in x-ray peak intensity with fluence, indicating magnetic disordered region surrounding the ion path. The diameter of the magnetic disordered region is found to be ∼6.6 nm which is larger than the diameter of the amorphized latent track. Therefore, it is confirmed that swift heavy ion irradiation induces a more significant magnetic disorder than the structural disorder.

Hydrothermal growth of flower-like ZnO nanostructures on porous silicon substrate

Flower-like zinc oxide (ZnO) nanostructures were successfully synthesized on porous silicon substrates using a simple hydrothermal method. The characteristics of the ZnO nanostructures were investigated through field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and photoluminescence (PL). FESEM images revealed shape transitions from nanoflowers comprising nanoparticles to well-faceted hexagonal ZnO nanostructures when the precursor molarity increased from 0.01 to 0.20M. The strong intensity and narrow width of XRD peaks indicate that ZnO nanostructures with high molarities have good crystallinity. The PL spectra indicate that ultraviolet emissions shift slightly toward lower wavelengths with increasing precursor solution molarity and that the intensity increases with improvement in ZnO crystallization.

Improvement in crystallinity and electrical properties of TiN thin films deposited on ZnO underlayers

TiN single layers and double-layered ZnO/TiN thin films were deposited on soda-lime-silicate glass substrates by magnetron sputtering. The influence of ZnO underlayers on TiN thin films was investigated as a function of oxygen gas pressure during ZnO underlayer deposition. It was found from X-ray diffraction (XRD) measurement that the TiN single layers exhibited {111}-preferred orientation, whereas the {100}-oriented TiN thin films could be obtained on ZnO underlayers. Furthermore, when the oxygen gas pressure during ZnO underlayer deposition decreased, the XRD peak intensity due to TiN{100} increased. The X-ray reflectivity measurement revealed that the ZnO underlayers exhibited small roughness and high density as the oxygen gas pressure decreased during deposition. It can be concluded that the smooth and dense ZnO underlayers enhanced the crystal growth of TiN thin films.

Electrical investigation and ultraviolet detection of ZnO nanorods encapsulated with ZnO and Fe-doped ZnO layer

Encapsulated ZnO nanorod arrays were fabricated using a two-step method; hydrothermal followed by dip-coating. Intensity of X-ray diffraction peaks of ZnO nanorod films increased by encapsulation with ZnO and Fe doped ZnO layer. Encapsulation process increased diameter of the rods in a range of 20–40 nm. The optical studies indicated that the band-gap decreased with increment of the nanorod diameter, and increased with Fe doping in the ZnO layer. The electrical resistance of the samples demonstrated a remarkable reduction due to encapsulation, especially in the sample encapsulated with Fe doped-ZnO layer. The photoresponse behavior of ZnO nanorod films was investigated under different powers of ultraviolet illumination. The photoresponsivity was improved for encapsulated nanorods as compared to bare nanorods.

Optical and structural properties of Al-ZnO nanocomposites.

The optical and structural properties of aluminium-doped zinc oxide (AZO) films were investigated by photoluminescence (PL) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy. Pure zinc oxide (ZnO) and AZO composite films were deposited using vacuum evaporation method. The films exhibited different morphologies and crystallinity depending on the Al-doping. The SEM micrographs showed that a granular and compact structure could be seen for the ZnO film, while a nanoleaf structure with relatively porous nature was observed for the AZO composite film. The XRD patterns indicated that the crystalline growth orientation would be significantly affected by addition of Al. Compared with pure ZnO, the XRD peak intensity of the AZO composite was stronger and the line-width was narrower. Two-probe resistivity measurements showed that the AZO composites could be used as transparent conducting materials. The PL spectra revealed that the PL intensities of the AZO composites were stronger than that of the pure ZnO. The PL enhancement might be ascribed to the surface plasmon resonance of metal nanoclusters within the composite. Another possible reason of the PL enhancement would be the metal-induced crystallization caused by doping Al to ZnO matrix.

Structural and Magnetic Properties of Ni0.6Zn0.4Fe2O4Ferrite Prepared by Solid State Reaction and Sol-gel

Ni 0.6 Zn 0.4 Fe₂O₄ prepared using solid state reaction and sol-gel methods were compared for their structural and magnetic properties. Due to the much higher annealing temperature used in solid state reaction, the crystalline size was much larger than that of the nanoparticles prepared by sol-gel. The saturation magnetization of sol-gel nanoparticles was higher, and the coercivity was about 2 times larger, compared to the solid state reaction sample. By analyzing the integration intensity of x-ray diffraction peaks (220) and (222), we proposed that the difference in the saturation magnetization might be due to the inversion of cation distribution caused by the different preparation techniques used.

The analysis of magnetic controlled DC sputtering AZO films

The Al-doped zinc oxide (AZO) transparent conducting thin films were deposited by the use of magnetic controlled DC sputtering method. To obtain best process parameters, we compare and analyse different process parameters like working pressure and substrate temperature, and properties of AZO films with DC sputtering. The transmittance of AZO film is over 85% at visible region (380~800 nm). Blue shift effect was observed clearly within 350~390 nm, as the substrate temperature increases from 225oC to 325oC. This is primarily due to the Burstein-Moss shift effect. The FWHM of (002) orientation peak of the XRD decreased with increasing substrate temperature while the grain size, carrier concentration and carrier mobility increased with increasing substrate temperature. The resistivity decreases with the operating temperature due to the combined action of increasing carrier concentration and carrier mobility, and has a minimum resistivity of 0.34 mΩ-cm. The X-ray diffraction peak intensity increases with the increasing substrate temperature. As the substrate temperature increases from 225oC to 325oC, the increasing X-ray diffraction peak intensity of (002) is primarily due to the crystallisation of the AZO film. The crystalline size of various AZO films, as can be evaluated by Scherrer's Formula, is around 28–43 nm.

Thermoluminescence of Y2O3:Tb3+ thin films deposited by electron beam evaporation

Most thermoluminescent materials are created using crystal growth techniques; however, it would be of great utility to identify those few thermoluminescent materials that can be deposited using simpler methods, for example to be compatible with the early portions of a silicon integrated circuit or microelectromechanical fabrication process. In this work, thin films of yttrium oxide with a terbium impurity (Y2O3:Tb) were deposited on silicon wafers by electron beam evaporation. The source for the Y2O3:Tb was made by combining Y2O3 and Tb4O7 powders. The approximate thicknesses of the deposited films were 350nm. After deposition, the films were annealed at 1100°C for 30s to improve crystallinity. There is a strong correlation between the x-ray diffraction (XRD) peak intensity and the thermoluminescent glow curve intensity. The glow curve displays at least two peaks at 140°C and 230°C. The emission spectra was measured using successive runs with a monochromator set to a different wavelength for each run. There are two main emission peaks at 490nm and 540nm. The terbium impurity concentration of approximately 1mol% was measured using Rutherford backscattering spectrometry (RBS). The Y2O3:Tb is sensitive to UV, x-ray, and gamma radiation. The luminescent intensity per unit mass of UV irradiated Y2O3:Tb was about 2 times that of x-ray irradiated TLD-100.

In‐situ annealing effect of zinc‐blende MnAs thin films grown on InP substrates

AbstractMnAs thin films were grown by molecular beam epitaxy on InP substrates. The samples were in‐situ annealed at different temperatures of 340 °C, 380 °C and 420 °C in an As4 atmosphere. High‐resolution X‐ray diffraction (XRD) measurements showed that zinc‐blende type (zb‐) and NiAs type (n‐) MnAs co‐exist. The XRD peak intensities of zb‐MnAs increased with annealing temperatures up to 380 °C. Also, the in‐plane XRD results showed that the intensities of zb‐MnAs (400) and (220) increased after annealing. On the other hand, the peak intensities of n‐MnAs decreased with temperature up to 380 °C. The possible transition between zinc‐blende and hexagonal MnAs is estimated to be a temperature of 380 °C. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of annealing from traditional nixtamalisation process on the microstructural, thermal, and rheological properties of starch and quality of pozole

Eleven maize landraces were evaluated for pozole quality. The microstructural, thermal and rheological properties of annealed starch granules determine most of the quality of pozole. Annealed starch in traditional nixtamalisation has an important role in increasing gelatinisation onset (To), peak (Tp) and final (Tf) temperatures; peak, setback and final viscosity as well as the stability of the starch granule, all of which significantly affect pozole quality. Annealed starch in Cacahuacintle nixtamal (pozole end-use) increased temperatures To, Tp and Tf by >5.2, >3.8 and >4.1 °C respectively, and narrowed the range Tf − To from 13.78 to 12.62 °C. The enthalpy was reduced from 6.76 to 5.85 J/g, while the nixtamal starch in tortilla maize landraces presented fewer annealing effects. The annealing effect in nixtamal starch seems to stabilize the starch granules and avoid their collapse, compared to native starch, as shown by the X-ray diffraction peak intensity and pattern that is similar to unprocessed maize. Starch in nixtamal changes from Type A to Type V pattern in pozole. Kernel physical parameters, although important, affected the quality to a lesser extent, with the exception of the flotation index. Cacahuacintle maize landrace showed the best quality and yield as well as a short pozole cooking time.

Preparation and Characterization of Cu-Doped Zno Sol-Gel Derived Optical Thin Films

In this work, we report the preparation of Cu-doped ZnOthin films by sol-gel method based on zinc acetate dihydrate (CH3COO)2Zn·2H2O, Copper acetate dihydrate Cu3(CH3COO)2·H2O) and diethanolamine (HN(CH2OH)2, DEA). The precursor solution was prepared at various Cu composition ranging from 2-20 wt%. All films were spin-coated on borosilicate substrates for several coating repetition followed by annealing process at 550 °C for 4 h in an ambient air. The structural properties of the films were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD results indicate the domination of hexagonal wurtzite structure of ZnO with noticeable alternation in the XRD peak intensity upon Cu doping content. SEM results revealed the grain size shape and surface morphologies of as-prepared samples. Crucial optical properties of as-prepared films were scrutinized from their UV-Vis transmission spectra. The films are highly transparent in the visible region with more than 90 % transparency within 380 nm to 800 nm. Their corresponding band gaps indicate significant red shift with increasing Cu doping content. Overall results suggest that Cu additive play a vital role on relevant optical properties of ZnO that can be adjusted to meet the requirement for practical optoelectronics applications.

Properties of electrochemically deposited CdTe thin films: annealing effect

CdTe thin film have been deposited onto stainless steel and fluorine doped tin oxide coated glass substrates from aqueous acidic bath using electrodeposition technique. The different preparative parameters, such as deposition time, bath temperature, pH of the bath have been optimized by photoelectrochemical (PEC) technique get good quality photosensitive material. The deposited films are annealed at different temperature in presence of air. Annealing temperature is also optimized by PEC technique. The film annealed at 200 °C showed maximum photosensitivity. Different techniques have been used to characterize the as deposited and also annealed (at 200 °C) CdTe thin film. The X-ray diffraction (XRD) analysis showed the polycrystalline nature and a significant increase in the XRD peak intensities is observed for the CdTe films after annealing. Optical absorption shows the presence of direct transition with band gap energy 1.64 eV and after annealing it decreases to 1.50 eV. Energy dispersive analysis by X-ray study for the as-deposited and annealed films showed nearly stoichiometric compound formation. Scanning electron microscopy reveals that spherically shaped grains are more uniformly distributed over the surface of the substrate for the annealed CdTe film. Photovoltaic output characteristics and spectral response of the annealed film have been carried. The fill factor and power conversion efficiency (η) of the cell are found to be 71 and 3.89 %.

Sol‐gel undoped and Al‐doped ZnO films crystallized under an electric field and the ZnO/Si heterojunction characteristics

AbstractEffect of electric field on the crystallization of ZnO sol‐gel films was investigated by measuring x‐ray diffraction (XRD) patterns, photoluminescence (PL) spectra, and current‐voltage (I‐V) characteristics of n‐ZnO/p‐Si heterojunctions. When sol‐gel ZnO films (undoped and Al‐doped) were crystallized at 800 °C in air for 10 min, an electric field was applied between 0 and 2.0 kV/cm. As the electric field was increased, the XRD (002) peak intensity increased and had a maximum value at 1.5 and 2.0 kV/cm for the films on quartz and silicon substrates, respectively. The Hall carrier mobility increased and the carrier concentration decreased for the crystallized undoped and Al‐doped films when the electric field was 1.0 kV/cm and 1.5 kV/cm, respectively. As the electric field was increased from 0 to 2.0 kV/cm, the forward current increased and the reverse current decreased for n‐ZnO/p‐Si heterojunctions. These results indicated that application of electric fields was an effective means to reduce the defect density of ZnO sol‐gel films and to improve their heterojunction characteristics.

Effect of ALD surface treatment on structural and optical properties of ZnO nanorods

In this study, we report on the improvement of the optical and structural properties of ZnO nanorods using atomic layer deposition (ALD) on seed ZnO nanorods. After the initial growth of ZnO seed nanorods by hydrothermal synthesis for 1h, a ZnO layer with a thickness of 10nm was deposited on the initial ZnO seed nanorods using ALD. Then ZnO was further grown by hydrothermal synthesis for 4h. The samples were characterized using room temperature photoluminescence (PL), field emission-scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). From this experiment, it was found that the ZnO nanorods with the ALD surface treatment show improved optical and structural properties when compared with the ZnO nanorods grown only by hydrothermal synthesis. The ZnO nanorods with the ALD surface treatment show about 2.7 times higher XRD (002) peak intensity, about 2.64 times higher PL NBE peak intensity, and about 3.1 times better NBE/DLE ratio than the ZnO nanorods without an ALD surface treatment.

Orientation control of a seeding layer and its effect on structure, ferro- and piezoelectric properties of sol–gel derived Bi3.15Nd0.85Ti3O12 thin films

We report on the orientation control of a seeding layer for sol–gel derived Bi3.15Nd0.85Ti3O12 thin films by optimizing the layer thickness and processing parameters including annealing temperature and time. A 75-nm-thick seeding layer with (100) preferential orientation can be obtained on SiO2/Si substrate by annealing at 560 °C for 3 min. The Bi3.15Nd0.85Ti3O12 thin film grown on this optimized seeding layer exhibits a much higher relative intensity of (200) X-ray diffraction peak, which in turn results in more squared P–E hysteresis loops, larger remanent polarization (2Pr ~ 62 μC/cm2) and piezoelectric coefficient (d33 ~ 74 pm/V) compared to the film without the optimized first layer prepared using the conventional sequential layer annealing method.

Physical Properties of Nanostructured CdO Films from Alkaline Baths Containing Saccharin as Additive

Nanostructured cadmium oxide (CdO) films were fabricated on glass substrates from alkaline baths containing saccharin as an additive by a successive ionic layer adsorption and reaction (SILAR) method. The effects of saccharin concentration in the bath on the structural, morphological, and optical properties were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence, and Raman spectroscopy. The analyses showed that the surface morphologies, XRD peak intensities, Raman spectroscopy, and photoluminescence properties of CdO films changed with saccharin concentration. From the results, it can be said that morphological characteristic and optical properties of the films could be calibrated by adding various saccharin percentages in the growth bath.

Magnetic Orientation of Hexagonal Carbon Layers at High Temperatures

Abstract Coal tar pitch was treated at 773 K in a constructed furnace system used under a magnetic flux density (B) of up to 10 T. The (002) X-ray diffraction peak intensity of the treated pitches increased with increasing B to approach a saturation value over 6 T. The magnetic-field dependence of the intensity was fitted by the order parameter calculated by assuming the cooperative orientation of several thousand carbon crystallites. This suggests that the hexagonal carbon layers should be oriented in parallel to the magnetic fields.

Preparation and properties of polycrystalline silicon seed layers on graphite substrate

Polycrystalline silicon (poly-Si) seed layers were fabricated on graphite substrates by magnetron sputtering. It was found that the substrate temperature in the process of magnetron sputtering had an important effect on the crystalline quality, and 700 °C was the critical temperature in the formation of Si (220) preferred orientation. When the substrate temperature is higher than 700 °C, the peak intensity of X-ray diffraction (XRD) from Si (220) increases distinctly with the increasing of substrate temperature. Moreover, the XRD measurements indicate that the structural property and crystalline quality of poly-Si seed layers are determined by the rapid thermal annealing (RTA) temperatures and time. Specifically, a higher annealing temperature and a longer annealing time could enhance the Si (220) preferred orientation of poly-Si seed layers.

Precipitation of calcium carbonate during direct aqueous carbonation of flue gas desulfurization gypsum

The precipitation of calcium carbonate during the direct aqueous carbonation of flue gas desulfurization (FGD) gypsum, an industrial waste product, was investigated. For comparison, two-step carbonation was also attempted. Calcite was the dominating phase produced in the two-step carbonation, while the direct carbonation produced a mixture of vaterite and calcite phases under all conditions. The relative amounts of each phase were determined by comparing their X-ray diffraction peak intensities. The amount of vaterite phase in the mixture was found to increase with carbonation time for a fixed CO2 flow rate. An induction period before the precipitation of physically detectable calcium carbonate crystals was assessed using X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FE-SEM). For the CO2 flow rate of 1L/min, the C1s peak of CaCO3 became clear after carbonation took place for longer than 15min. Virtually impurity-free, single-phase calcite crystals were precipitated from the solution extracted during the induction period. The amount of calcite obtained was typically 5.3% of the amount that can be obtained in the case of the complete reaction. However, further elaboration of this method may allow for the preparation of pure calcite crystals from industrial by-product FGD gypsum.

Transparent conductive Ga-doped MgxZn1−xO films with high optical transmittance prepared by radio frequency magnetron sputtering

Transparent conductive Ga-doped MgxZn1−xO (GMZO) films were deposited on sapphire at room temperature using radio-frequency magnetron sputtering with different RF powers. The thickness of all films was controlled at 300nm, and the lowest resistivity was obtained at an RF power of 50W. This study investigates the influence of the post-annealing process on the structural, electrical, and optical properties of the films using X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), Hall measurement, optical transmission spectroscopy, photoluminescence (PL) spectra, and X-ray photoelectron spectroscopy (XPS) spectra. The XRD (002) peak intensity and the spectral linewidth enhanced monotonically as the annealing temperature rose to 700°C, indicating improved crystallinity in the GMZO thin films. A low thin film resistivity (ρ) of 5.69×10−4Ωcm was obtained, along with electron mobility (μ) and carrier concentrations (n) of 28.5cm2/Vs and 3.85×1020cm−3, respectively. XPS measurements were conducted to investigate the mechanism of the reduced thin-film resistivity after high-temperature annealing. The increased density of oxygen vacancies could contribute to the reduced resistivity after high-temperature annealing. Meanwhile, a high optical transmittance of over 96.6% was demonstrated in a wavelength range between 350 and 1100nm.