Synchrotron X-ray Diffraction Techniques Research Articles

Single-crystal structures of Zn2+-exchanged zeolite A: dependence on Zn2+ concentration of aqueous solution during exchange

To study the tendency of Zn2+ exchange into zeolite A, two single-crystals of fully dehydrated Zn2+-and Na+-exchanged zeolite A were prepared by the static ion-exchange method using a mixed ion-exchange solution whose Zn(NO3)2:NaNO3 mol ratios were 1:4 (crystal 1) and 3:2 (crystal 2), respectively, with a total concentration of 0.05 M, followed by vacuum dehydration at 623 K. Their single-crystal structures and chemical compositions were determined by single-crystal synchrotron X-ray diffraction techniques and electron probe microanalysis. Their structures were refined to the final error indices R 1/wR 2 = 0.0678/0.2154 and 0.0619/0.1938 for crystals 1 and 2, respectively. In both structures, the 4 Zn2+ ions are located in sodalite unit, whereas, the remaining 4 Na+ ions are located in large cavity. Unit-cell formula of two single-crystal structures is approximately |Zn4Na4|[Si12Al12O48]-LTA. This work shows that the degree of Zn2+ exchange by increasing the initial Zn2+ concentration and decreasing the initial Na+ concentration in given ion-exchange solution does not differ significantly.

Dynamic Lithium Intercalation/Deintercalation in 18650 Lithium Ion Battery by Time-Resolved High Energy Synchrotron X-Ray Diffraction

A time-resolved in situ high energy synchrotron X-ray diffraction (HESXRD) technique is employed to study the lithiation/delithiation of cathode/anode in a commercial 18650 battery under real working condition (current rate is 4 C). The phases and their changes in both the cathode and anode are identified simultaneously. For the anode component, during the charge process, as well as the LixC6 phase, a lithium-rich phase close to LiC6 phase and a series of intermediate phases between the Li0.5C6 and LiC6 phases are observed. A distinct lithium intercalation/deintercalation mechanism is proposed for the cathode. The transforms of LiFePO4 into the FePO4 consists three periods with different components of phases, i.e., LiFePO4 + lithium-deficient solid solution phases (period I), FePO4 + LiFePO4 phases (period II), and FePO4 + lithium-rich solid solution phases (period III). The changes in both the andode and cathode during the discharge process are just inversed to those occurrs during the charge process. The present work indicates that dynamic lithiation/delithaition process under real working condition is different from those at the thermodynamic state, and the in situ HESXRD is one of the most promising technique to monitor such kind of dynamic lithium behavior.

In situ synchrotron X-ray diffraction analysis of deformation behaviour in Ti-Ni-based thin films.

Deformation mechanisms of as-deposited and post-annealed Ti50.2Ni49.6, Ti50.3Ni46.2Cu3.5 and Ti48.5Ni40.8Cu7.5 thin films were investigated using the in situ synchrotron X-ray diffraction technique. Results showed that initial crystalline phases determined the deformation mechanisms of all the films during tensile loading. For the films dominated by monoclinic martensites (B19'), tensile stress induced the detwinning of 〈011〉 type-II twins and resulted in the preferred orientations of (002)B19' parallel to the loading direction (∥ LD) and (020)B19' perpendicular to the LD (⊥ LD). For the films dominated by austenite (B2), the austenite directly transformed into martensitic variants (B19') with preferred orientations of (002)B19' ∥ LD and (020)B19' ⊥ LD. For the Ti50.3Ni46.2Cu3.5 and Ti48.1Ni40.8Cu7.5 films, martensitic transformation temperatures decreased apparently after post-annealing because of the large thermal stress generated in the films due to the large differences in thermal expansion coefficients between the film and substrate.

Customizing properties of β-chitin in squid pen (gladius) by chemical treatments.

The squid pen (gladius) from the Loligo vulgaris was used for preparation of β-chitin materials characterized by different chemical, micro- and nano-structural properties that preserved, almost completely the macrostructural and the mechanical ones. The β-chitin materials obtained by alkaline treatment showed porosity, wettability and swelling that are a function of the duration of the treatment. Microscopic, spectroscopic and synchrotron X-ray diffraction techniques showed that the chemical environment of the N-acetyl groups of the β-chitin chains changes after the thermal alkaline treatment. As a consequence, the crystalline packing of the β-chitin is modified, due to the intercalation of water molecules between β-chitin sheets. Potential applications of these β-chitin materials range from the nanotechnology to the regenerative medicine. The use of gladii, which are waste products of the fishing industry, has also important environmental implications.

Determination of the phase boundary of the omega to beta transition in Zr using in situ high-pressure and high-temperature X-ray diffraction

The high-pressure behavior of zirconium has been examined using the synchrotron X-ray diffraction technique to a pressure of 38GPa and a temperature of 800K employing a hydrothermal diamond anvil cell technique. The structural transition from the ω to the β phase was observed. This transition has a negative dP/dT gradient, which is in general agreement with those reported in previous studies. The transition boundary was determined to be, P (GPa)=41.2–0.025×T (K). The negative slope of the transition, dP/dT, determined in our study using the diamond anvil cell technique was less than half that estimated by the previous study using a large press apparatus.

Correlation of ferrite formation to creep properties of Cr-Mo steel welds

A factor of four decreases from 16.0 × 10−4 to 4.1 × 10−4 %/h in steady state creep rate was observed in the fine-grained heat-affected zone (FGHAZ) of a Cr-Mo steel weld, by reducing the pre-weld tempering temperature from 760 to 650 °C. The current study used electron backscatter diffraction and synchrotron x-ray diffraction techniques to characterize the microstructure in the FGHAZ of the two tempering temperature conditions. The results showed carbide-free ferrite that formed in the FGHAZ of weldments that were pre-weld tempered at 760 °C, contributed to void formation resulting in lower creep strength. It is proposed that the formation of ferrite in the FGHAZ is due to the incomplete dissolution of Cr23C6 carbide at heating process during welding, which results in Cr enrichment adjacent to the undissolved Cr23C6 carbide. Dictra simulation confirmed ferrite formation at the carbide/austenite boundaries during Cr23C6 carbide dissolution.

Effects of TiCl3-decorated MWCNTs addition on the dehydrogenation behavior and stability of LiAlH4

A complex catalyst for enhancing the dehydrogenation kinetics of LiAlH4 was developed by using an impregnation process to decorate TiCl3 on multiwall carbon nanotubes (MWCNTs). The effects of these composite catalysts on the dehydrogenation behavior were investigated by using thermal gravimetric analysis (TGA) and in-situ synchrotron X-ray diffraction (XRD) technique. The experimental results showed that the initial dehydrogenation temperature could be lowered by adding the appropriate amount of TiCl3–MWCNTs composite. LiAlH4 became unstable and decomposed even at room temperature when 20 wt% TiCl3–MWCNTs was added.

Possible contribution of low shear modulus C44 to the low Young's modulus of Ti-36Nb-5Zr alloy

Despite the importance of single-crystal elastic constants of β-phase titanium alloys in understanding their low Young's modulus—a property crucial for many applications, such data are often difficult to obtain when the alloy composition is close to the instability limit of the β phase, where the presence of α" martensite precludes the fabrication of β-phase single crystal. In the present study, we extracted the single-crystal elastic constants of such a β-phase titanium alloy with low Young's modulus, Ti-36Nb-5Zr (wt. %), from polycrystalline specimens by using an in-situ synchrotron X-ray diffraction technique. It is indicated that the low Young's modulus of the alloy originates from the anomalously low shear modulus C44 as well as the low shear modulus C′, which is different from a common viewpoint that the Young's modulus of β-phase titanium alloys is dominantly controlled by the C′. This suggests that low C44 is an important contributor to low Young's modulus for instable β-phase titanium alloys.

Comparative study of the mechanical properties of nanostructured thin films on stretchable substrates

Comparative studies of the mechanical behavior between copper, tungsten, and W/Cu nanocomposite based on copper dispersoïd thin films were performed under in-situ controlled tensile equi-biaxial loadings using both synchrotron X-ray diffraction and digital image correlation techniques. The films first deform elastically with the lattice strain equal to the true strain given by digital image correlation measurements. The Cu single thin film intrinsic elastic limit of 0.27% is determined below the apparent elastic limit of W and W/Cu nanocomposite thin films, 0.30% and 0.49%, respectively. This difference is found to be driven by the existence of as-deposited residual stresses. Above the elastic limit on the lattice strain-true strain curves, we discriminate two different behaviors presumably footprints of plasticity and fracture. The Cu thin film shows a large transition domain (0.60% true strain range) to a plateau with a smooth evolution of the curve which is associated to peak broadening. In contrast, W and W/Cu nanocomposite thin films show a less smooth and reduced transition domain (0.30% true strain range) to a plateau with no peak broadening. These observations indicate that copper thin film shows some ductility while tungsten/copper nanocomposites thin films are brittle. Fracture resistance of W/Cu nanocomposite thin film is improved thanks to the high compressive residual stress and the elimination of the metastable β-W phase.

Equation of state of a synthetic ulvöspinel, (Fe1.94Ti0.03)Ti1.00O4.00, at ambient temperature

Using a diamond-anvil cell and synchrotron X-ray diffraction, the compressional behavior of a synthetic ulvospinel (Fe1.94Ti0.03)Ti1.00O4.00 has been investigated up to about 7.05 GPa at 300 K. The pressure–volume data fitted to the second-order Birch–Murnaghan equation of state yield an isothermal bulk modulus (K T ) of 147(4) GPa (K′ T fixed as 4). This value is slightly larger than that previously determined by an ultrasonic pulse echo method (121(2) GPa; Syono et al., J Phys Soc Jpn 31:471–476, 1971), but substantially smaller than that recently determined by a synchrotron X-ray diffraction technique (251(3) GPa; Yamanaka et al., Phys Rev B 80:134120, 2009; Am Mineral 98:736–744, 2013). Combined with the K T of magnetite (Fe3O4; ~182(3) GPa), our finding suggests that the bulk modulus of the solid solutions Fe3−x Ti x O4 (0 ≤ x ≤ 1) along the join magnetite–ulvospinel decreases by ~20 %.

A correlation between the magnetic and structural properties of isochronally annealed Cu-free FINEMET alloy with composition Fe72B19.2Si4.8Nb4

In this paper, structural changes in Cu-free FINEMET alloy (Fe72B19.2Si4.8Nb4) invoked by isochronal thermal annealing were investigated by synchrotron X-ray diffraction (SXRD) and X-ray absorption near-edge spectroscopy techniques. Detailed radial distribution function analysis of SXRD data showed that the first coordination shell in the amorphous matrix is preserved for annealing up to 400 °C (1 h), whereas changes were observed in the second coordination shell. Annealing at 600 °C (1 h) showed crystalline phase emanating over the amorphous background in SXRD data and a corresponding large decrease in the width of the first coordination shell. The width of the second coordination shell decreased with increasing annealing temperature. The magnetic properties such as remanence field, saturation magnetization and loss were found to have a positive correlation with the changes in the structural parameters of the second coordination shell, for all the samples (as quenched as well as annealed at various temperatures). We propose that the rearrangement of magnetic amorphous matrix on annealing also contributes to modifying the exchange interaction between ferromagnetic nanocrystalline domains and hence changes magnetic parameters, in addition to the growth of these domains, on annealing.

The dependence of Co2+-exchange into zeolite FAU on its Si/Al ratio

Three single crystals of fully dehydrated, largely Co2+-exchanged zeolites X and Y were prepared by the exchange of Na80-X (|Na80|[Si112Al80O384]-FAU, Si/Al = 1.40), Na75-Y (|Na75|[Si117Al75O384]-FAU, Si/Al = 1.56), and Na71-Y (|Na71|[Si121Al71O384]-FAU, Si/Al = 1.70) with aqueous streams 0.05 M in Co(NO3)2, pH = 5.1, at 294 K for 3 days. This was followed by vacuum dehydration at 673 K. Their crystal structures were determined by synchrotron X-ray diffraction techniques in the cubic space group Fd $$\overline{3}$$ m at 100(1) K. In all three crystals Co2+ ions occupy the 6-ring sites I, I’, and II; Na+ ions occupy sites II’ and II. The number of Co2+ ions exchanging into the zeolite was about 30 per unit cell for all three crystals. The number of residual Na+ ions, however, decreased sharply as Si/Al ratio increased, and the number of H+ ions co-exchanging into the zeolite decreased nearly to zero. Some dealumination of the zeolite framework was seen in the first crystal (initial Si/Al = 1.40).

Depth profile of oxide volume fractions of Zircaloy-2 in high-temperature steam: An in-situ synchrotron radiation study

To study the steam oxidation behavior of Zircaloy-2, a high-energy synchrotron X-ray diffraction technique was applied to perform an in-situ oxidation measurement. The depth profiles of oxide volume fractions were obtained at both 600 and 800°C. Multiple layers, including ZrO2 scale, (α+β) Zr matrix with ZrO2 incursions, and (α+β) Zr matrix, were mapped according to the volume fraction of each phase. The volume fractions of these phases were observed to change gradually with different distances to the surface, without a sharp edge distinguishing each of the layers. The ZrO2 consisted of tetragonal and monoclinic crystal structures, which were observed to coexist with different ratios of volume fractions in depth. The higher amount of tetragonal ZrO2 observed in the very inner region of the oxidizing Zircaloy sample indicates that the tetragonal crystal structure is the ab initio phase type, in which new oxide molecules form at the metal–oxide interface.

Non-crystalline samples under high-pressure conditions

Taking advantage of synchrotron x-ray diffraction, PDF and tomographic techniques, the P-V curve of non-crystalline samples were studied under high-pressure conditions. Two element and several metallic glass cases were performed. The procedure of crystallization of amorphous Se upon compression at room temperature, which was studied in diamond anvil cell combined synchrotron x-ray PDF and 3D imaging techniques; the melting and solidification procedure of Ga in large volume press at room and high temperature; and complicated crystallization, re-rystalization, melting behavior of Ce-based metallic glass, will be presented to show the capability of revealing structure and dynamics behaviors in P-V-T-t domains using these advanced techniques.

Relaxor ferroelectrics materials under high pressure

The rich phase diagrams from both relaxor and normal ferroelectrics under high pressure, stimulate us to study the pressure effect on the relaxor-PbTiO3 (PT) systems, to check whether the high pressure cubic structure will turn to low symmetry structure upon strong compression is the common behaviors for relaxor ferroelectrics materials. Furthermore, a complete phase diagram study of pressure-temperature effect on structure will allow us to explore the limitation on applications of relaxor-PT material devices under harsh environment involving in high pressure and high temperature conditions. Structure evolution and phase transition of several solid solution ferroelectrics, such as Pb(YbNb)O3-PT (PYN-PT), have been studied using in situ synchrotron X-ray diffraction (XRD) and Raman spectroscopy techniques under high pressure and high temperature conditions. XRD results show pressure induced phase transitions to a cubic phase, while the persistence of Raman spectroscopy in the full pressure range indicates its local distortion. A pressure-temperature phase diagram is further constructed to determine the stability region of the ferroelectric phase. The results provide useful guidance for the applications of this kind of high Curie temperature ferroelectric crystal under extreme conditions, and extra clue to synthesis of ferroelectric materials with tailored properties.

Two types of adjacent dimer layers in the low-temperature phase of BaCuSi2O6

The low-temperature crystal structure of BaCuSi2O6has been investigated with high-resolution synchrotron x-ray and neutron powder diffraction techniques and has been found to be on average (ignoring the incommensurate modulation) orthorhombic, with the most probable space group Ibam. The Cu-Cu dimers in this material are forming two types of layers with distinctly different interatomic distances. Subtle changes also modify the partially frustrated interlayer Cu-Cu exchange paths. The present results corroborate the interpretation of low-temperature nuclear magnetic resonance and inelastic neutron scattering data in terms of distinct dimer layers. The experimentally determined low-temperature crystal structure of BaCuSi2O6is discussed in terms of its relation to the newer findings of theory and of the complementary experiments.

Synchrotron X-ray diffraction techniques for in situ measurement of hydride formation under several gigapascals of hydrogen pressure

The high-pressure technique is a fundamental tool for realizing novel phase transitions, chemical reactions, and other exotic phenomena. Hydrogenation is one example of a high-pressure reaction; at high pressures of several gigapascals, hydrogen becomes chemically active and reacts with metals and alloys to form hydrides. This paper covers a high-pressure study of the hydrogenation process and the synthesis of hydrides using a cubic-type multi-anvil apparatus. The experimental details of a hydrogenation cell assembly, high-temperature and high-pressure generation, and an in situ observation technique are presented. These experiments are conducted with the aid of in situ synchrotron radiation X-ray diffraction measurements operated in an energy-dispersive mode in the conventional manner for time-resolved measurements and a newly developed angle-dispersive mode for observation of the crystal growth process during formation of metal hydrides. Two successful cases of high-pressure hydrogenation are presented: aluminum hydride, AlH3, and an aluminum-based alloy hydride, Al2CuH x , which are potential candidates for hydrogen storage materials.

Growth of arrays of oriented epitaxial platinum nanoparticles with controlled size and shape by natural colloidal lithography.

We developed a method for production of arrays of platinum nanocrystals of controlled size and shape using templates from ordered silica bead monolayers. Silica beads with nominal sizes of 150 and 450 nm were self-assembled into monolayers over strontium titanate single crystal substrates. The monolayers were used as shadow masks for platinum metal deposition on the substrate using the three-step evaporation technique. Produced arrays of epitaxial platinum islands were transformed into nanocrystals by annealing in a quartz tube in nitrogen flow. The shape of particles is determined by the substrate crystallography, while the size of the particles and their spacing are controlled by the size of the silica beads in the monolayer mask. As a proof of concept, arrays of platinum nanocrystals of cubooctahedral shape were prepared on (100) strontium titanate substrates. The nanocrystal arrays were characterized by atomic force microscopy, scanning electron microscopy, and synchrotron X-ray diffraction techniques.

Preparation and structural study of fully dehydrated, highly Mg2+-exchanged zeolite Y (FAU, Si/Al = 1.56) from undried methanol solution

Single-crystal of fully dehydrated, Mg2+-exchanged zeolite Y, |Mg34.5Na6|[Si117Al75O384]-FAU (Si/Al = 1.56), was successfully prepared from undried methanol solution (water concentration 0.02 M). A crystal of Na-Y was treated with 0.05 M MgCl2 ·6H2O in the solvent at 333 K, followed by vacuum dehydration at 723 K and 1 × 10−6 Torr for 2 days. Its structure was determined by single-crystal synchrotron X-ray diffraction techniques, in the cubic space group $$Fd\overline{3} m$$ at 100 K. It was refined to the final error indices R 1/wR 2 = 0.0587/0.2210 with 1,294 reflections for which F o > 4σ(F o). In the structure of |Mg34.5Na6|[Si117Al75O384]-FAU, 34.5 Mg2+ ions per unit cell are found at four different crystallographic sites: 15 per unit cell are located at site I at the center of the hexagonal prism [Mg–O = 2.216(2) A], two are at site I’ in the sodalite cavity near the hexagonal prism [Mg–O = 2.20(3) A], only one is located at site II’ in the sodalite cavity [Mg–O = 2.197(23) A], and the remaining 16.5 are at site II near single 6-oxygen rings in the supercage [Mg–O = 2.103(3) A]. The residual 6 Na+ ions per unit cell are found at site II [Na–O = 2.218(7) A]. No water molecules are found in this structure.

Single-Crystal Structures of Sr2+ and Cs+-Exchanged Zeolites X and Y, |Sr40Cs12|[Si100Al92O384]-FAU and |Sr29Cs17|[Si117Al75O384]-FAU

Two single-crystals of fully dehydrated, Sr2+-and Cs+-exchanged zeolites X (|Sr40Cs12|[Si100Al92O384]-FAU (Si/Al = 1.09, crystal 1)) and Y (|Sr29Cs17|[Si117Al75O384]-FAU (Si/Al = 1.56, crystal 2)) were prepared by the flow method using a mixed ion-exchange solution whose Sr(NO3)2:CsNO3 mol ratio was 1:1 with a total concentration of 0.1 M. The crystals were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $$Fd\overline{ 3}$$ and $$Fd\overline{ 3} m,$$ respectively, and were refined to the final error indices R 1/wR 2 = 0.070/0.209 and 0.052/0.155 for crystals 1 and 2, respectively. In the structure of |Sr40Cs12|[Si100Al92O384]-FAU, 40 Sr2+ ions per unit cell occupy three different equipoints; 16, 1.5, and 22.5 are at sites I, II′, and II, respectively. The 12 Cs+ ions per unit cell occupy three equipoints; 1, 6, and 5 are at sites II′, II, and IIIa, respectively. In the structure of |Sr29Cs17|[Si117Al75O384]-FAU, 29 Sr2+ ions per unit cell occupy four equipoints; 15, 1.5, 2.5, and 10 are at sites I, I′, II′, and II, respectively. The 17 Cs+ ions per unit cell are found at four different sites; 2.5, 9, 4, and 1.5 are at sites II′, II, IIIa, and IIIb, respectively. The Sr2+ ions occupy smaller pore size such as the centers of the double 6-rings and the positions near the center of single 6-rings planes, whereas, Cs+ ions preferentially occupy large-cavity sites in the supercage. Two single-crystals of fully dehydrated, Sr2+-and Cs+-exchanged zeolites X (|Sr40Cs12|[Si100Al92O384]-FAU (Si/Al = 1.09, crystal 1)) and Y (|Sr29Cs17|[Si117Al75O384]-FAU (Si/Al = 1.56, crystal 2)) were determined by single-crystal synchrotron X-ray diffraction techniques.