We also maintain our ICDD database as well as other analysis software up-to-date.
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Pole figures of reflection from cubic phase of thin film specimen grown in different conditions. Synchrotron and neutron encompass a wide range of characterization techniques available at large-scale user facilities across the country. They are mostly used by academia for fundamental research, but increasingly they are used by industrial researchers for advanced characterization for challenging problems which cannot be solved by using conventional laboratory instrumentation. Synchrotron and neutron techniques can be used for structural, compositional and morphological characterization of materials by scattering and diffraction, imaging and spectroscopy.
Comparing with laboratory techniques, they are superior in many aspects including spatial, angular, energy, and temporal resolutions and high throughput capabilities enabled by current robotic and machine-learning technologies.
In recent years, synchrotron and neutron are more frequently used in in-situ measurements during materials testing and processing, e. We gain access to these user facilities in various modes, from proprietary measurements to collaborative research. Typical turnaround time is from a couple of weeks to several months, depending upon nature of the work. We have extensive expertise in many synchrotron and neutron based techniques, especially those listed below.
X-Ray Diffraction by Polycrystalline Materials
Back-reflection Laue is used for quantifying the crystallographic orientation of single crystals. The purpose of such a measurement ranges from:. Unlike typical X-ray diffraction, instead of a monochromatic beam, Laue diffraction uses Bremsstrahlung radiation. Her, J. Microscopy and Microanalysis, 22 S3 , pp. The team identifies complex unknown organic chemicals, elucidates molecular structure and chemical interactions.
Handbook of X-Ray Analysis of Polycrystalline Materials
Quadropole Time of Flight Mass Spectrometry Q-ToF MS is, in most cases, a liquid chromatography-based soft ionization mass spectrometry technique that can determine the accurate mass of nearly any molecule containing at least one heteroatom and having a mass between Daltons. The chemical requirement is that a stable or metastable ion can be produced by a molecule donating or accepting a proton to produce a charged species. Most traditional Time of Flight mass spectrometers can determine the accurate mass based on a charged species flight time between a pulsed start position and detection by a multi-channel plate detector.
The additional benefit of the Quadropole ToF MS system is that this instrument can isolate ionizable species in the Quadropole region that is upstream of the ToF Detector. Species that are isolated in the Quadropole then can be manipulated in several ways. This technique isolates parent compounds in the Quadropole where a collision gas is introduced, thus resulting in fragmentation of the parent molecule. The resulting fragmentation spectrum can then be searched in the database for possible identification matches or manually interpreted to obtain molecular formulae and structure of an unknown species.
Nuclear Magnetic Resonance NMR is a spectroscopic technique to observe local magnetic field around atomic nuclei. The NMR signal is generated by exciting the nuclei in a magnetic field with radio frequency pulses into nuclear magnetic resonances, which are detected with sensitive radio frequency receivers.
Handbook of X-Ray Analysis of Polycrystalline Materials | Lev. I. Mirkin | Springer
The local magnetic field around an atom changes the resonance frequency of its nucleus, thus giving access to details of the electronic structure of atoms, functional groups and molecules. Modern NMR techniques made it possible to detect neighboring nuclei either through covalent bonds or space using correlation spectroscopy techniques that allow fast and unambiguous structural elucidation. Molecular dynamics such as diffusion, relaxation or molecular binding can be probed using arrayed experiments. Composition of mixtures can be obtained using quantitative NMR analyses.
Over the past decades, the NMR lab obtained experience with remarkable depth and breadth in the areas of polymer analysis, small molecule structure elucidation and composite and ceramic materials characterization in solving a wide variety of problem for almost every GE business. DOSY NMR are routinely used for probing molecular dynamics, such as diffusion and binding of both small and large molecules. Infrared Spectroscopy IR is an analytical technique based on the absorption of IR light which probes the chemical bonds of materials at characteristic frequencies.
The IR spectrum of a material can often be used as a chemical fingerprint based on type and relative amounts of chemical bonds present. This chemical fingerprint can be used to identify an unknown species by comparison to large spectral databases of standard materials, map a phase across a heterogeneous sample, or track changes in chemical bonding due to reaction or degradation.
At GE Global Research, we commonly use IR as a rapid screening tool to identify an unknown contaminant and direct further analysis. Used in combination with XRF, we can rapidly identify both the organic, inorganic and metallic components of an unknown sample and attempt to trace its source. Our IR microscope can even obtain high quality spectra from a single fiber or particle when used in conjunction with a diamond transmission cell, therefore sample size is rarely an issue.
Raman Spectroscopy is an analytical technique which probes the movement of atoms or molecules at characteristic frequencies in response to excitation with a laser beam. Raman spectroscopy gives information about chemical bonding, phase and molecular orientation. At GE, this technique is widely used to map phase composition in ceramic coatings and composites. Our confocal Raman microscope can also be used for collecting fluorescence or photoluminescence PL spectra in the visible and near-IR nm. PL mapping can be used to track changes in composition or stress state across a semiconductor or other emissive material.
The high spatial resolution provided by the confocal microscope allows the properties grains and grain boundaries to be interrogated with sub-micrometer resolution. Raman is also commonly used to interrogate the structure of carbon graphite, graphene, amorphous carbon, carbon nanotubes, diamond and diamond-like carbon coatings due to its high sensitivity and specificity to differences in carbon-carbon bonding. Photoluminescence PL mapping of a polycrystalline semiconductor film shows defective dark colored material near grain boundaries.
A typical analysis uses EI to fragment species in the gas phase giving rise to a distinct fragmentation spectrum that is very often unique to, and diagnostic of, different chemical classes and individual compounds. Since the EI process produces fragmentation spectra that are usually very consistent from sample to sample regardless of what instrument is used, it has become an essential tool in chemical characterization of volatile and semi-volatile organic compounds.
The use of EI has a long history in the field of chemical analysis. Because of this, coupled with the robust reproducibility of EI spectra, there exists a vast resource of database information where fragmentation spectra can be searched against existing database entries to obtain positive identification of unknown compounds. The difference between typical GC and the 2-Dimensional system is traditional GC analyses separate gas phase species as a function of vapor pressure or boiling point in a 1-dimensional analysis.
The 2-dimensional system separates each species eluting on the first column 1st dimension , then separates based on polarity on the second column 2nd dimension. The increase chromatographic resolution allows for cleaner fragmentation spectra to be obtained thus resulting in less overlap of coeluting species.
When a sample is introduced into the instrument, the plasma causes the emission of light or the generation of ions that are characteristic to each element. The concentration of an element within a material can be quantitatively calculated by detecting the wavelengths of light OES or ions MS associated with the element and comparing the signal to that of known reference materials standards.
Most materials require some degree of preparation before they can be analyzed. Solids are converted into liquid form, usually by dissolution with mineral acids, and liquids are often treated with mineral acids to decompose organic components and to stabilize the elements in solution. GE Global Research has experience in many types of sample preparation procedures including hot block and microwave digestion, dry ashing, wet ashing sulfuric char , and fusion.
The laser is used to selectively remove a small quantity of material from a solid sample for direct introduction into the ICP. In this way, the solid test material does not need to be dissolved or digested into a liquid prior to analysis. The laser can be used to sample specific locations on a part, such as a defect, or it can be used to scan across the sample to create an elemental distribution map.
Ion chromatography IC is a specialized subset of liquid chromatography LC which is geared towards the quantification of anions and cations. The method separates the ions of interests in time through competitive interaction of the analyte ions and ions from the mobile phase with ion exchange sites on the stationary phase. Selectivity is based on many factors including the ion exchange site on the stationary phase and the charge, size and hydrophobicity of the ion.
Conductivity is most common because it is highly sensitivity to ions in solution and is easy to maintain and calibrate. However, conductivity is nonspecific, and to achieve the highest sensitivity, the ions from the mobile phase need to be removed to reduce background conductivity. This is typically accomplished by either chemical or electrolytic suppression devices. As with all LC techniques IC requires a sample to be in solution to be analyzed.
There are a variety of ways to accomplish this depending on the sample matrix and the analytes of interest. Once the analytes are in solution, sample matrix spikes are made and retention times for each analyte are determined for the specific separation method being employed. Once retention times are identified a series of known ion standards are run and used to create a calibration curve. Response of the analyte in the sample is compared to the calibration curve and concentrations are calculated. A chromatogram from ion chromatography used for the quantification of low levels of F, Cl, Br and SO4 in a detergent matrix.
X-ray Fluorescence Spectroscopy XRF is the holistic name for a host of different instruments or methods that can provide the identity of elements present in and elemental composition of materials. The information is generated when X-Rays hit the sample and core shell electrons are ejected.
These electrons leave holes, vacancies are filled with outer shell electrons, and the leftover energy is often emitted as X-rays. The energy of these emitted X-rays tells you what elements are present and the number of X-rays of a given energy are related to the concentrations of the element. Energy Dispersive instruments use a semiconductor detector to both discriminate the energy of and count the X-rays emitted by the sample.
The energy dispersive method generally provides fast analysis because it can analyze all the X-rays produced by the sample at once; however, this is at the expense of spectral resolution and the total count rates that can be achieved. Wavelength dispersive instruments scan through the relevant diffraction conditions so they are generally slower but provided the best spectral resolution and allow for higher count rates.
In addition, we routinely perform typical XRF sample preparation methods including pressed powder, fusion, liquid cell, loose powder and polished pieces. By combining these instruments and sample preparation methods we can analyze almost any material from much of the periodic table. It is a bulk technique that utilizes combustion, infrared absorption, and thermal conductivity detectors to determine the C, S, O, N, and H composition. C and S in a solid sample are measured by combustion analysis and detected by non-dispersive infrared NDIR detectors.
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When a pre-weighed sample is placed in ceramic crucibles it is oxidized to CO2 and SO2, respectively. The C and S concentrations of an unknown samples is determined relative to calibration standards.
Oxygen, nitrogen, and hydrogen are measured by inert gas fusion analysis, where a pre-weighed sample is placed in a graphite crucible, and is heated in an impulse furnace to release analyte gases. These analytes are then scrubbed out of the carrier gas stream. The final component in the flow stream is nitrogen and then detected by a thermal conductivity TC detector.
The O, N, and H concentrations of unknown samples are determined relative to calibration standards.
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How is IGA used? C, S, O, N and H determination in solids, powders or particulate inorganic materials, such as SiC, titanium, nickel, cobalt alloys, irons, steels, ceramics, ores, metals, etc.
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Crowder, J. Journal of Analytical Atomic Spectrometry, 31 6 , pp. A thermogravimetric analyzer equipped with a mass spectrometer TGA-MS continuously measures mass while a sample is heated over time. Mass, temperature and time in thermogravimetric analysis are considered base measurements while many additional measures may be derived from these three base measurements.