Benchtop X-ray diffraction (XRD) instrument

Powder X-ray diffractometers can readily measure bulk samples provided techniques are devised for sample preparation. In the case of samples in sheet form, such as paper or film, a diffraction pattern with no angular error can be obtained, as shown in Fig. 1, by: (1) Cut the sample to the same size as the aluminum sample plate, (2) Stacking the sample and sample plate, and (3) Set the sample plate into the sample clip. If the sample has enough rigidity and thickness, it should be placed directly onto the sample clip, without using the aluminum sample plate.

In polymer materials processed into the shape of fibers or films, the molecular axes align in the direction of stretching. Therefore, when these types of material are measured, diffraction lines due to crystal faces in specific orientations are observed to be large (preferred orientation). By using this characteristic, and measuring while varying the placement of the sample relative to the scan axis, it is possible to investigate the direction of the molecular axes with respect to the material. In this case, the transmission method is used together with the reflection method.

X-ray diffraction (XRD) in the food and candy industry is crucial to producing a quality product. You would not want to have coconut flavoring in your plain dark chocolate bar or a sweet chocolate to be too bitter. Below is a diffractogram of the milk chocolate specimen shown at the right. The first set of peaks in red is sucrose. The second set in blue is lactose hydrate (essentially dehydrated milk). Finally a few peaks in purple down at 2-7° 2θ can be identified corresponding to the chocolate.

Aluminum oxide or corundum is a commonly available material. However, trace levels of contaminates in the crystal structure of aluminum oxide, can result in priceless gems, such as rubies, sapphires, and emeralds. Rubies are corundum with chromium contaminates. It's the chromium that produces the deep red color. Next to diamonds, rubies are the most precious gems. Sapphires come in many different colors, yellow, red, pink, and the more traditional color, blue. The blue color is only possible when titanium and iron are both present in the structure.

The width of the standard incident and receiving Soller slits of the MiniFlex300/600 is 5°, but to obtain high-resolution it is possible to select a width of 2.5° (incident/receiving Soller slits) or a width of 0.5° (receiving Soller slit only). Fig. 1 shows a comparison of the X-ray diffraction profiles of LaB₆ powder when the Soller slit is changed, and Table 1 shows the intensity ratios, and the full width at half maximum (FWHM), which varies proportionally with resolution.

X-ray diffraction (XRD) is an effective method for determination of the phase composition of unknown crystalline and amorphous materials. The analysis is performed by comparing diffraction peak positions and intensity values with the reference patterns of known compounds maintained in the ICDD Powder Diffraction File (PDF). Routine characterization is completed quickly with a minimum of operator involvement. Subsequent analyses, including quantitative analysis of identified phases, are easily accomplished.

Fig. 1 shows the appearance of the MiniFlex600 main unit. The main unit dimensions are 560(W) x 460(D) x 700(H) mm. With a newly developed X-ray generator, it is possible to obtain measurement data with 1.5 times the X-ray diffraction intensity of the previous model, the MiniFlex II. This makes it possible to obtain diffraction intensity approaching that of full-sized models. Fig. 2 shows an intensity comparison between the MiniFlex600, MiniFlex300 and the previous MiniFlex II model.

Forensic laboratories are frequently asked to verify vehicle types or to corroborate eye-witness testimonies. With a sample of the automobile paint and the MiniFlex benchtop X-ray diffractometer, this becomes an achievable assignment! Automobile manufacturer use slightly different paint components and pigments for every model of their vehicles. Every year, the paint formulas change. Using X-ray diffraction, the paint and pigment compositions can be to identified.

X-ray diffraction (XRD) is an excellent analysis technique for identifying unknown solid materials. The XRD pattern can act as a fingerprint to identify unknown materials in crystalline and semi-crystalline samples.

Materials that have a large unit cell with large open space such as zeolites and meso-porous silica are often used as filters, sensors, catalysts, drug delivery devices, etc. because of their cage like crystal structures. X-ray diffraction is one of the techniques often used to study those structures.

The MiniFlex300/600 can be equipped with the D/teX Ultra high-speed 1-dimensional detector to obtain greater intensity. By using this detector, it is possible to obtain intensity a few tens to roughly 100 times greater than a scintillation counter. Using this feature, it is possible to greatly reduce measurement time, detect trace components, and measure micro-samples with high sensitivity. Fig. 1 shows the diffraction profiles obtained with a scintillation counter and the D/teX Ultra high-speed 1-dimensional detector.

The MiniFlex300/600 can be equipped with the D/teX Ultra high-speed 1-dimensional detector to obtain greater intensity. This detector energy resolution, so fluorescent X-rays can be removed from the diffraction pattern without using a diffracted beam monochromator. Fig. 1 shows the X-ray diffraction patterns from measuring hematite in the standard energy range (standard mode) and the energy range enabling removal of fluorescent X-rays due to iron (fluorescent X-ray reduction mode).

For industrial samples, quality control or failure analysis is vital to future product improvements. This polypropylene coated metal sample failed quality control tests due to poor coating adhesions. A section of the coating was removed and the entire sample was inserted in the MiniFlex for testing.

Phase identification using X-ray diffraction (XRD) works much like fingerprint analysis. XRD patterns are collected on unknown samples and compared to patterns obtained from known materials. The primary database for these XRD patterns is compiled and maintained by the International Center for Diffraction Data (ICDD). In some industrial cases the preferred XRD patterns for optimal analysis of a specific process may not be present in the ICDD database.

The oil drilling industry can encounter a wide variety of samples, including rocks, scales, cements, cuttings, and muds throughout the drilling process. X-ray diffraction (XRD) is an essential tool for phase identification analysis of these commonly identified solids in the oil field. Three phases are identified in the figure below; the major is a barite phase and the two minor phases consist of calcite and quartz. The primary goal of this application is to quickly identify the phases contained within the sample material.

A common marketing approach in the cosmetics industry today is the branding of natural products. These natural cosmetics claim to use natural ingredients for effects such shine, whitening, and sun protection. X-ray diffraction (XRD ) is an excellent technique to identify the composition of materials in the cosmetics industry. As an example four brands of so called "natural" cosmetic foundations were analyzed for composition using the MiniFlex benchtop diffractometer. The scans and phase identification results can be seen in figures 1 through 4.

Ensuring quality control can be a daunting task in industrial processes. The key to a quality product is to maintain that quality throughout the entire process and having the appropriate materials is essential to this accomplishment. The wrong materials could alter the properties of the desired product. It could even change the product and everyone would certainly want the finished product to be able to function with its desired task. Observe the white powder in Figure 1.

Zeolites are commonly used in a vast variety of industrial applications, including environmental clean-up, petroleum cracking, filtering/separations and cation exchange. These materials can be mined from natural sources or can be commercially synthesized. A basic structure of five silicon and aluminum tetrahedra result in a cage-like structure with large open spaces or "pores". These pores have charged regions which attract or exchange cations. For effective activity and specific cation incorporation, the zeolites need to be very specific and pure.

Crystalline silica is a very common, naturally occurring mineral consisting of silicon and oxygen. Differences in temperatures and pressures can cause the atomic structure to change creating polymorphs of silica. These are commonly known as alpha quartz, beta quartz, cristobalite and tridymite. Damage to lungs and respiratory systems, known as silicosis, can be traced to exposure to very small particles of crystalline silica and acidic reactions within the human body.

TiO₂ is widely used in white pigments, electronics materials, optical catalysts and UV absorbents. It exists in three polymorphs: rutile, anatase and brookite. The efficiencies of rutile and anatase as optical catalysts are different, so a method to determine the rutile:anatase ratio is needed. The quickest way to do quantitative XRD analysis is to determine the RIR (Relative Intensity Ratio). Data from the MiniFlex, profiled below, is of a prepared mixture of rutile and anatase in a 3:1 ratio.

Shale and slate are sometimes use interchangeably, but the materials are not the same. Many of the items sold today for landscaping (flagstones, retaining walls) and construction (chalkboards, roofing tiles, pool tables, etc.) uses as "slate " is actually the much more inferior form—shale. Shale is sedimentary rock, lightly compacted into thin, crumbly layers. It may contain high concentrations of quartz, feldspars, pyrites amorphous silica, and clay minerals: illite, kaolinite, chlorite and smectite (montmorillionite).

With the MiniFlex300/600, it is possible to select Soller slits with small widths in order to obtain high resolution. In particular, the 0.5° receiving Soller slit and the 5 mm or 2 mm incident high limiting (DHL) slits can suppress the axial divergence, or umbrella effect which is prominent on the low-angle side. Fig. 1 shows a comparison of the X-ray diffraction profiles of zeolite-A when the receiving Soller slit and DHL are changed (the incident Soller slit is 2.5°). Intensity is normalized, and the actual intensity ratios are as shown in Table 1.

XRD can be used to validate minting ages of coins. A 2005 US penny has a zinc metal core and a combination Cu/Nickel alloy coating. Before 1986, the US pennies were comprised entirely of a copper and zinc alloy. When looking at the diffraction patterns from a MiniFlex in the figures it can be seen that no zinc core was discovered in the 1985 penny.

What do greenhouse gases, pearls, antacids, lasers, cement and sea shells have in common? They are all related to calcium carbonate phases. Calcium carbonate is one of the most commonly occurring natural minerals. It can be observed in three different forms, calcite, aragonite and vaterite. Figure 1 shows the calcite and aragonite forms. These forms share the exact same chemical formula, but have a slightly different crystal structure and are known as polymorphs. Polymorphs have different energies of activation, dissolution rates and degrees of reactivity.