Non-destructive X-ray Diffraction Research Articles

Glancing-incidence focussed ion beam milling: A coherent X-ray diffraction study of 3D nano-scale lattice strains and crystal defects

This study presents a detailed examination of the lattice distortions introduced by glancing incidence Focussed Ion Beam (FIB) milling. Using non-destructive multi-reflection Bragg coherent X-ray diffraction we probe damage formation in an initially pristine gold micro-crystal following several stages of FIB milling. These experiments allow access to the full lattice strain tensor in the micro-crystal with ∼25 nm 3D spatial resolution, enabling a nano-scale analysis of residual lattice strains and defects formed. Our results show that 30 keV glancing incidence milling produces fewer large defects than normal incidence milling at the same energy. However the resulting residual lattice strains have similar magnitude and extend up to ∼50 nm into the sample. At the edges of the milled surface, where the ion-beam tails impact the sample at near-normal incidence, large dislocation loops with a range of Burgers vectors are formed. Further glancing incidence FIB polishing with 5 keV ion energy removes these dislocation loops and reduces the lattice strains caused by higher energy FIB milling. However, even at the lower ion energy, damage-induced lattice strains are present within a ∼20 nm thick surface layer. These results highlight the need for careful consideration and management of FIB damage. They also show that low-energy FIB-milling is an effective tool for removing FIB-milling induced lattice strains. This is important for the preparation of micro-mechanical test specimens and strain microscopy samples.

Non-destructive evaluation of Roman coin patinas from the 3rd and 4th century

Roman bronze coins from the 3rd and 4th century AD exhibit a wide variety of chemistries on their surfaces. This variation has been attributed to the variable methods used to produce the coins, a large number of mints producing bronze currency, and the periods of currency devaluation within the Roman Empire. Besides the base bronze metallurgy (Cu,Sn), Ag, Pb, and Zn were frequently used as coinage metals. Silver coatings were often applied to increase the apparent value of the coins. Over the centuries these surfaces corroded producing a range of patinas. Non-destructive X-ray diffraction and X-ray fluorescence methods were used to evaluate ancient bronze coins. These methods are limited by their half depth of penetration into the coins, so the focus was on the chemistry of the patina's and how they related to the current appearance. Several 3rd-century bronze coins exhibited a very dark patina that was often composed of CuCl, Cu2O (cuprite) and several forms of copper hydroxyl chloride, resulting from surface deterioration caused by corrosion and is often referred to as bronze disease. Coins of the latter 3rd century and 4th century often exhibit patinas that are corrosion products of lead, silver, and tin, as lead and tin preferentially oxidize relative to the bronze alloys.

Complex metallographic study on Gepid bronze and silver buckles from the Great Hungarian Plain (5-6th cent.)

ABSTRACTThis work presents a complex metallographic examination of bronze, silver and golden artefacts from early medieval German (Gepid) cemeteries of the Hungarian Plain, focusing on the finds from Tiszapüspöki.A newly developed non-destructive X-ray diffraction method was applied on the artefacts for the first time, as a novel approach, for sampling-free residual stress measurements. Other techniques such as optical microscopy and scanning electron microscopy combined with energy dispersive spectrometry has also been used. In addition to residual stress, crystallographic texture and properties of the reflections were analysed as well. The combined application of these methods was found to be an effective tool to deduce the production technologies of the examined artefacts. In addition to defining the characteristics of the material structures and compositions on the surfaces of the artefacts, the typical traces of several technological methods as casting, forming, coating were detected which are used for making various types of artefacts.

The X-ray diffraction beamline MCX at Elettra: a case study of non-destructive analysis on stained glass

<p class="Abstract"><span lang="EN-US">The MCX beamline at the synchrotron Elettra is the general purpose diffraction beamline that is well suited for non-destructive and innovative X-ray diffraction (XRD) experiments in the field of cultural heritage. The experimental station houses a large number of instruments facilitating a range of different types of analysis. Recently, a comprehensive study of the alteration products in grisaille paints was performed at the beamline. This type of analysis is very important to understand the complex processes involved in the deterioration of this type of glass decoration. An exhaustive characterization of these products and so a full understanding of the mechanism of their formation may lead to the development of new protective materials for conservation and restoration. XRD experiments at the MCX beamline allowed us to recognize the alteration products on the grisailles surface and to propose a mechanism for the formation of alteration patina. Here we present the beamline, its instrumentation and its capabilities by showing an example of the study on grisaille paints. </span></p>

Nondestructive X-ray diffraction measurement of warpage in silicon dies embedded in integrated circuit packages.

Transmission X-ray diffraction imaging in both monochromatic and white beam section mode has been used to measure quantitatively the displacement and warpage stress in encapsulated silicon devices. The displacement dependence with position on the die was found to agree well with that predicted from a simple model of warpage stress. For uQFN microcontrollers, glued only at the corners, the measured misorientation contours are consistent with those predicted using finite element analysis. The absolute displacement, measured along a line through the die centre, was comparable to that reported independently by high-resolution X-ray diffraction and optical interferometry of similar samples. It is demonstrated that the precision is greater than the spread of values found in randomly selected batches of commercial devices, making the techniques viable for industrial inspection purposes.

Evaluation of residual stresses present in spirally welded API grade pipeline steel using the hole drilling method

Abstract The mechanical and microstructural characterization of a material prior to its installation for the desired service is imperative to avoid material or structural failures. Of the several mechanical properties affecting the performance of a material, the residual stresses (RS) constitute an integral part of the material property and arise mostly during the manufacturing processes. They can be either beneficial or detrimental to material performance depending on their nature and magnitude. In this study, the microhardness, the tensile and the nature and magnitude of RS present in the weldment zones, base material (BM), heat affected zone (HAZ) and weld nugget (WN) of spiral welded (SWP) API grade line pipe steel, were determined. The microhardness and tensile responses were observed to have significant demarcation depending on the location where examined. The RS were measured using a nondestructive X-ray diffraction (XRD) and a semidestructive hole drilling (HD) technique. The results from both measurement techniques are found to be in good agreement. The BM microstructure consisted of ferrite and pearlite phases with ferrite constituting the dominant phase. The WN comprised of multi-passes, which consisted of root (hot) and the reinforcing (filling) pass. The microstructure of the reinforcing passes can be described as columnar grains/structure.

The Role of the Technological Residual Stress in Spiral Bevel Gears’ Degradation

The subjects of the examination were automotive components, spiral bevel gears, built up by two main parts, the axle, where the component is prone to fracture, and the head segment, where the working surface can be found. The occasional fracture occurs during the straightening process after the hardening heat treatment. Our aims were to monitor the evolution of the residual stress during the manufacturing processes and to reveal the role of the residual stress in the component’s fracture. The residual stress measurements were carried out via non-destructive X-ray diffraction. To reveal the component’s fracture hardness tests and microstructure measurements were also performed. Based on the results, the fracture of the components were connected to the stress asymmetry which was derived from the microstructure of the early stages of manufacturing.

Biomimetic deposition of carbonate apatite and role of carbonate substitution on mechanical properties at nanoscale

This work reports on the role of carbonate substitution on the mechanical properties of calcium deficient carbonate apatite which resembles closely the structure of bone apatite. The carbonate content determined using vibrational spectroscopy suggests two stage substitutions. The residual stress is evaluated using non-destructive X-ray diffraction procedure for these polycrystalline aggregates. The crystallinity increases with deposition time and increased carbonate substitution does not impede the crystal growth and no phase change is observed. A carbonate content of 6.34wt. % corresponds to a minimum residual stress without compromising the crystallinity of the films. The carbonate substitution might be associated with the calcium vacancy which is considered as the thermodynamically feasible mechanism for B-type carbonate apatite.

What Happens Structurally and Electronically during the Li Conversion Reaction of CoFe2O4 Nanoparticles: An Operando XAS and XRD Investigation

The need to identify lithium battery anodes consisting of new materials exhibiting high energy density and good cycling stability has intensified the research on reversible so-called conversion reactions between lithium and oxidic spinels such as, e.g., CoFe2O4. Operando nondestructive synchrotron X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) were applied to directly determine the complex reaction mechanisms occurring during discharge and charge processes. Distinct reaction mechanism steps related to different electrochemical features of nanosized CoFe2O4 as the anode material are elucidated. The different discharge steps include uptake of a small fraction of Li into an amorphous layer covering the particles, the transformation of the spinel structure into a NaCl-like structure, and the formation of nanosized metallic Co and Fe embedded in a Li2O matrix. The metals are oxidized to form Co2+ and Fe3+ during charging. The reaction Fe3+ ↔ Fe0 is observed for many discharge/charge processes,...

EPR Spectroscopy of Different Sol Concentration Synthesized Nanocrystalline-ZnO Thin Films

Nanocrystalline zinc oxide (nc-ZnO) thin films were grown on p-type silicon substrate through spin coating by sol-gel process using different sol concentrations (10 wt.%, 15 wt.%, and 25 wt.%). These films were characterized by high resolution nondestructive X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDS) attachment, and electron paramagnetic resonance (EPR) techniques to understand variations in structural, morphological, and oxygen vacancy with respect to sol concentration. The film surface morphology changes from nanowall to nanorods on increasing sol concentration. EPR spectra revealed the systematic variation from ferromagnetic to paramagnetic nature in these nc-ZnO films. The broad EPR resonance signal arising from the strong dipolar-dipolar interactions among impurity defects present in nc-ZnO film deposited from 10 wt.% sol has been observed and a single strong narrow resonance signal pertaining to oxygen vacancies is obtained in 25 wt.% sol derived nc-ZnO film. The concentrations of impurity defects and oxygen vacancies are evaluated from EPR spectra, necessary for efficient optoelectronic devices development.

Preliminary assessment of two non-destructive instrumental techniques for quality evaluation of Lobelia chinensis Lour.

Two non-destructive instrumental methods, infrared spectroscopy (IR) and X-ray diffraction (XRD), were studied for quality evaluation of Lobelia chinensis Lour. (L. chinensis). We obtained the IR spectra and XRD patterns of L. chinensis collected from different sources. The similarity of samples was analyzed by calculating the cosine coefficient. The cosine values were in the range of 0.83–0.90, indicating that the main components of L. chinensis samples are similar. Sample L1 and L6 showed a slightly lower similarity than that of L2, L3, L4, L5 detected by the two methods, which revealed that IR and XRD methods exhibited analogous detection ability for quality evaluation of L. chinensis. The two methods could be highly recommended as simple and rapid detection means for quality evaluation of L. chinensis.

Enhancement of two dimensional electron gas concentrations due to Si3N4 passivation on Al0.3Ga0.7N/GaN heterostructure: strain and interface capacitance analysis

Enhancement of two dimensional electron gas (2DEG) concentrations at Al0.3Ga0.7N/GaN hetero interface after a-Si3N4 (SiN) passivation has been investigated from non-destructive High Resolution X-ray Diffraction (HRXRD) analysis, depletion depth and capacitance-voltage (C-V) profile measurement. The crystalline quality and strained in-plane lattice parameters of Al0.3Ga0.7N and GaN were evaluated from double axis (002) symmetric (ω-2θ) diffraction scan and double axis (105) asymmetric reciprocal space mapping (DA RSM) which revealed that the tensile strain of the Al0.3Ga0.7N layer increased by 15.6% after SiN passivation. In accordance with the predictions from theoretical solution of Schrödinger-Poisson’s equations, both electrochemical capacitance voltage (ECV) depletion depth profile and C-V characteristics analyses were performed which implied effective 9.5% increase in 2DEG carrier density after passivation. The enhancement of polarization charges results from increased tensile strain in the Al0.3Ga0.7N layer and also due to the decreased surface states at the interface of SiN/Al0.3Ga0.7N layer, effectively improving the carrier confinement at the interface.

Changes of stress and luminescence properties in GaN-based LED films before and after transferring the films to a flexible layer on a submount from the silicon epitaxial substrate

Due to the lack of GaN substrates, hetero-epitaxial growth of GaN thin films is usually carried out on a foreign substrate. There are three kinds of substrate for GaN: sapphire, silicon carbide, and silicon; the sapphire substrate is the chief one, currently. Due to the availability of large scale and low cost of Si substrates, in recent years, extensive research has been devoted to the development of gallium nitride (GaN) optoelectronic devices on silicon substrates. Because of the large lattice mismatch and thermal-expansion cofficient difference between Si and GaN, it is difficult to grow thick enough crack-free GaN LED film on Si substrates. The two main kinds of methods for overcoming the crack problem are using the patterned Si substate and the thick AlGaN buffer layer. Although the two techniques could solve the problem of crack by cooling after growth, they will lead to an increase in tensile stress for GaN on Si. When making vertical-structured LED devices by transferring the GaN-based LED thin films from Si substrate to a new submount, this tensile stress will be partially released; but few researches have been made about the stress change before and after the transfer of the film, although the stress in GaN is an important factor that alters the energy band structure and may influence the vibrational properties. In this paper, we grow the crack-free GaN-based LED films on patterned Si(111), then light-emitting diode (LED) thin films are successfully transferred from the original Si (111) substrate to the submount with a flexible layer, and then the LED films without the influence of the submount and substrate are fabricated. In the following experiments, the strain-stress variation of the LED film is determined by using nondestructive high resolution X-ray diffraction (HRXRD) in detail, and the variation of photoluminescence (PL) properties of the film is studied too. Results obtained are as follows: 1) When the LED film is transferred to the flexible submount, the huge tensile stress will turn into compressive stress, and the latter in the InGaN layers will increase. 2) The In concentration in the (InGaN/GaN) MQW (multi-quantum well) systems can be evaluated with the help of reciprocal space maps (RSM) around the symmetric (0002) and asymmetric (1015) Bragg reflections. The In concentration in (InGaN/GaN) MQW will reduce when the GaN-based LED film is transferred to the flexible submount. 3) The PL spectra of the LED films will obviously appear red shift, after they are transferred to the flexible submount.

Tensile twin nucleation events coupled to neighboring slip observed in three dimensions

Low-symmetry crystals and polycrystals have anisotropic mechanical properties which, given better understanding of their deformation modes, could lead to development of next generation materials. Understanding how grains in a bulk polycrystal interact will guide and improve material modeling. Here, we show that tensile twins, in hexagonal close-packed metals, form where the macroscopic stress does not generate appropriate shear stress and vice versa. We use non-destructive high-energy X-ray diffraction microscopy to map local crystal orientations in three dimensions in a series of tensile strain states in a zirconium polycrystal. Twins and intragranular orientation variations are observed and it is found that deformation-induced rotations in neighboring grains are spatially correlated with many twins. We conclude that deformation twinning involves complex multigrain interactions which must be included in polycrystal plasticity models.

A powder X-ray diffractometry for detection of Tibetan medicine Zuotai

A robust, direct, rapid and non-destructive X-ray diffraction crystallography method for detecting the Tibetan medicine Zuotai is presented. Powder samples of Zuotai, cinnabar and calomel were unambiguously characterized using powder X-ray diffractometry (PXRD) by comparing a practical identification of metacinnabar in the analyzed material, which confirmed the present of metacinnabar in Zuotai. At the same time, 11 strong lines in the fingerprint of Zuotai were selected to indicate the effective constituents of Zuotai, which were listed in the form of d-( I/I0 )%: metacinnabar 3.356 4/100, 2.061 4/55.0, 2.911 8/35.0, 1.760 1/37.0, 1.339 5/12.0, 1.304 5/10.0, 1.192 0/10.0, 1.683 4/7.0, 1.458 0/5.6. sulfur 3.824 4/100, 3.197 5/40.2, 3.442 2/38.1, 3.095 6/19.7, 5.690 9/16.8, 2.851 0/16.3, 2.414 4/11.3. The results showed that mercury chemical state is metacinnabar with sulfur in Tibetan medicine Zuotai. This method should be supplemented to quality control of rare traditonal Chinese medicine.

Crystallographic services and technology support for industry.

The activities of CSEM's XRD Application Lab are oriented towards the analytical support of technology and product development in the fields of materials sciences, microtechnology, physics, chemistry, nanotechnology and life sciences. Non-destructive X-ray diffraction methods are used for the structural investigation of materials, components and systems. New developments are made with a focus on in situ techniques to 'watch the action' - structural transformations in dependence of applied external fields such as temperature, humidity, magnetic fields or mechanical stresses.

Non-destructive laboratory-based X-ray diffraction mapping of warpage in Si die embedded in IC packages

Reliability issues as a consequence of thermal/mechanical stresses created during packaging processes have been the main obstacle towards the realisation of high volume 3D Integrated Circuit (IC) integration technology for future microelectronics. However, there is no compelling laboratory-based metrology that can non-destructively measure or image stress/strain or warpage inside packaged chips, System-on-Chip (SoC) or System-in-Package (SiP), which is identified as a requirement by the International Technology Roadmap for Semiconductors (ITRS). In the work presented here, a triple-axis Jordan Valley Bede D1 X-ray diffractometer is used to develop a novel lab-based technique called X-ray diffraction 3-dimensional surface modelling (XRD/3DSM) for non-destructive analysis of manufacturing process-induced stress/warpage inside completely encapsulated packaged chips. The technique is demonstrated at room temperature and at elevated temperatures up to 115°C by in situ XRD annealing experiments. The feasibility of this technique is confirmed through the characterisation of die stress inside encapsulated commercially available ultra-thin Quad Flat Non-lead (QFN) packages, as well as die stress in embedded QFN packages at various stages of the chip manufacturing process.

Non-Destructive Inspection of Surface Integrity in Milled Turbine Blades of Inconel 738LC

Nickel super-alloys are widely used in aerospace as material for turbine blades. Unfortunately, their machining is difficult since mechanical hardening and, consequently, extreme tool wear occur. Casting can no longer meet the requirements for precision, hence, the castings are being ground or milled. In this contribution, a quality check of the milled surface by several surface integrity parameters is proposed with respect to the surface structural inhomogeneities caused by mutual effect of plastic deformations and thermal fields during the cutting process. Castings from Inconel 738LC were milled with cutting conditions chosen by Design-Of-Experiments method and the resulting surfaces were assessed by non-destructive X-ray diffraction methods in several areas corresponding to various cutter orientation and work-piece angle. Surface integrity was described by macroscopic residual stresses, microstrains, grain sizes and phase composition. Mostly, favourable compressive surface residual stresses were observed in the cutting direction, grain sizes were distinctively smaller when the tool axis was perpendicular to the machined surface.

Phosphorus compounds and their solubility in swine manure compost

Swine manure compost (SMC) contains a significant amount of phosphorus (P). In this study, the characteristics of P compounds in SMC were investigated by the nondestructive X-ray diffraction (XRD) method, chemical extraction, and a cultivation experiment. Only magnesium ammonium phosphate hexahydrate (MAP or struvite, MgNH4PO4·6H2O) was detected as crystal P compound by XRD in most SMC. Furthermore, MAP crystal was observed by scanning electron microscope (SEM) image. The amount of ammonium nitrogen in MAP (MAP-NH4-N) was 3.38 ± 2.24 mg-N g−1 on average, equivalent to 54% of total NH4-N (hydrochloric acid-extractable NH4-N) in SMC. The content of P in MAP (MAP-P) in SMC calculated backward from MAP-NH4-N was 7.5 ± 4.5 mg-P g−1. Sequential water extraction demonstrated that MAP in SMC was dissolved in water. The ratio of MAP-P to water-extractable P (WEP) was 66%, indicating that the amount of WEP was controlled by MAP existence in SMC. The amount of P uptake by the Japanese mustard spinach (Komatsuna; Brassica rapa var. perviridis) plant accorded with WEP content in SMC.

Microstructure of Ni/Al<sub>2</sub>O<sub>3</sub> Electrodeposited Coatings Studied with XRD and SEM Techniques

Our interests are focused on the Ni/Al2O3 nanocomposite coatings electrochemically deposited in modified Watt’s-type baths into which α-Al2O3 nanopowder is added on steel substrates. The effect of different amounts of α-Al2O3 phase in the electrolyte baths on microstructure of electrodeposited Ni/Al2O3 coatings is investigated. In order to study the coatings the non-destructive X-ray diffraction techniques are applied. As indirect techniques, they are supported by imaging methods, especially scanning electron microscopy.