About High Purity Materials
For many high-tech and scientific applications, the physical and chemical properties of materials must be both highly reliable and constrained within very narrow parameters. The exact properties of interest often vary by application, but what many such properties have in common is that they are exquisitely sensitive to minor variations in the precise chemical composition of a material. Impurities present even as fractions of a percentage of the makeup of an otherwise pure material can drastically alter how the material as a whole conducts electricity, interacts with light, reacts chemically with other compounds, or stands up to environmental damage. For these reasons, raw materials of exceptional purity are absolutely essential in many fields.
Unfortunately, the ways in which sellers describe chemical purity can often be confusing. Compounds may be sold with a declaration of purity based on percentages of elemental composition, or with a categorical label called a grade that indicates a relative level of purity or suitability for a given application. Additionally, various organizations and regulatory bodies publish standards for purity, and some grade labels are simply derived from these standards. For instance, the term “reagent grade” usually refers to materials that meet or exceed the purity and production standards published by the American Chemical Society (ACS).
Percentage purity measurements seem like they should be simple. If a product labeled as 99.999% pure, most buyers would conclude that 0.001% or less of the molecules in the product fail to match the chemical name on the label. In some cases, this assumption would be correct, but in many it would not.
Purity percentages may be absolute, or may be relative to only specific types of impurities. For instance, metals may be listed as 99.999% pure metals basis, meaning that the only impurities counted against the purity percentage are metallic elements. In some applications, metal contaminations are the primary concern, so this may be sufficient, but in other applications the unknown levels of non-metal contaminants present in products with metals-basis purity declarations can be a significant problem. Rare earth materials are often sold with a 99.99% purity designation, when in fact they are of lower unknown purity because many testing capabilities of production facilities in China calculate the purity of a specific rare earth element as a ratio based on other rare earths in the compound; the relative quantities of all other elements are assumed. Such producers will represent this type of purity as "RE/TREO". American Elements 99.999% purity designation always is calculated on an absolute basis, which ensures the product’s purity with respect to all elements on the periodic table.
Chemical grades often serve as a proxy for purity, but the information they provide most directly is on the suitability of a material for a given use. The three most common grades used by almost all chemical suppliers are reagent grade, laboratory grade, and technical grade. Of these, reagent grade is the most pure and technical grade is the least pure. Reagent grade materials are typically produced at or near the highest purity available for a given compound, and are considered to be suitable for almost all scientific purposes. Laboratory grade materials are usually still fairly pure, but are used in applications requiring larger volumes where absolute purity is not paramount. Laboratory grade materials are generally used for less-sensitive scientific applications and for educational labs. Industrial grade materials are usually used in industrial or commercial settings, and contain significant amounts of impurities.
Outside of reagent, lab, and technical grade labels, it is not necessarily useful to use grade labels to determine which of two products has higher absolute purity, as most grade labels exist to certify that a product is suitable for some specific application or that it meets specific industry standards, and therefore only provide information on the presence of impurities relevant to those specific uses. For instance, food grade chemicals may be more pure than laboratory grade chemicals, as lab grade chemicals may contain small quantities of impurities by absolute percentage, but nonetheless contain contaminants that endanger human health. On the other hand, food applications may tolerate relatively high percentages of impurities that are irrelevant to health, and as such it cannot necessarily be assumed that a product labeled food grade has exceptionally high absolute purity.
Applications for High Purity Materials
Analytical standards are used in laboratory environments to calibrate analytical equipment and to provide baseline measurements for comparison with experimental data. Because the analytical techniques requiring use of such standards are extremely sensitive, ultra-high purity compounds are essential for these applications.
Semiconductor devices including electronics and photovoltaics require high purity materials because minute structural defects caused by impurities within a semiconductor can significantly alter the electrical properties of the material, affecting the speed, reliability, or efficiency of the device.
Optical devices such as lenses and optical fibers are designed to manipulate light with extreme precision. As precise elemental composition and structural features at the micro- or nanoscale alter the interaction of light with a material, producing high-quality optical devices requires high-purity raw materials.
Pharmaceutical products are often complex molecules requiring elaborate organic synthesis processes for production. As even small variations in the final product can significantly impact the action of a drug in the body, selecting starting materials of appropriately high purity is essential.
Batteries, fuel cellsz, and supercapacitors for high-technology applications are becoming increasingly sophisticated in an effort to maximize efficiency and capacity. High purity compounds in powder form are often used to produce solid state electrolytes and electrodes with ideal electrical properties for these advanced devices.
American Element’s Production of High Purity Materials
American Elements is capable of producing materials to many standard grades including: Reagent grade, Laboratory grade, Technical grade, ACS grade, Mil Spec (military grade), Optical Grade, Food grade, Agricultural grade, Pharmaceutical grade, US Pharmacopeia (USP) grade, and European Pharmacopoeia/British Pharmacopoeia (EP/BP) grade.
In addition, American Elements can purify many materials to high percentages of absolute purity—up to 99.9999% in some cases—at our high purity production facility. Among its technical capabilities, this facility includes several large electric muffle furnaces, a tube furnace for hydrogen reduction, and 50 gallon glass-lined Pfaudler reactors. Production of high purity materials is overseen by Ph.D. chemists and supported by our extensive analytical laboratory, which uses atomic spectroscopy, x-ray diffraction analysis, scanning electron microscopy, and BET surface area analysis, among other technologies, to ensure that the elemental composition and structural properties of each product rigorously adhere to our standards.
American Elements can purify materials that are known to be difficult to refine but are essential to many high tech applications and research. These include most metals, oxides, fluorides, the entire rare earth (lanthanide) series, cobalt, europium, rhenium, rubidium, scandium, and others to 99.999% purity. We can reach high purities in forms such as fuel cells and solar energy applications.
American Elements can prepare aluminum chloride, erbium chloride and ytterbium chloride hydrates with iron and other transition metal impurities less than 100 ppb. Similar purity levels can be obtained with the other rare earth chlorides.
We have routinely prepared large batches of barium nitrate in a purity of 99.9999% with the largest impurity being strontium at less than .5 ppm. We synthesize cis-dichlorodiammineplatinum (II) in a purity of 99.999% with no other detectable heavy metals.
Crystal Synthesis and Substrates
American Elements' crystal growth production emphasizes ultra high purity elemental and compound materials produced in the form of single crystals, polycrystalline pieces, boules, and crackle, powders, ingots, discs, shaped charges and rods. We are recognized specialists in custom-grown single and polycrystalline materials of any of the III-V and II-VI compounds when special orientations, purities or dopants are required. Unlike many other producers, our facilities are also set up to cost-effectively produce small or pilot scale lots. All production materials are analyzed and certified prior to shipping.
American Elements produces custom combinations of layers and substrates for both commercial and research applications. For example, we can produce many custom variations of metallic nitride layers on various aluminum oxide-based substrates. We provide metallization for these materials and our other products.
American Element's crystal synthesis facility is equipped to synthesis crystalline structures using a variety of established technologies, including:
- Crystal "pulling" by the Czochralski method for production of semiconductor materials
- Flux growth and gradient freeze
- Directional solidification of fluorites using both the Bridgman-Stockbarger and float zoning techniques
Anhydrous/Ultra Dry Materials
American Elements specializes in the production of Ultra Dry and Anhydrous formulations for oxygen and moisture-sensitive applications. Ultra dry materials are produced to high purity (up to 99.9999%) and packaged in an argon atmosphere to minimize introduction of impurities.
Recent Research & Development for Ultra High Purity Metals
- Evangelos P. Favvas, Stephanos F. Nitodas, Andreas A. Stefopoulos, Sergios K. Papageorgiou, Konstantinos L. Stefanopoulos, Athanasios Ch. Mitropoulos, High purity multi-walled carbon nanotubes: Preparation, characterization and performance as filler materials in co-polyimide hollow fiber membranes, Separation and Purification Technology, Volume 122, 10 February 2014
- A. Evdou, V. Zaspalis, L. Nalbandian, La(1-x)SrxMnO3-d perovskites as redox materials for the production of high purity hydrogen, International Journal of Hydrogen Energy, Volume 33, Issue 20, October 2008
- M. Sudersanan, Role of analytical techniques for characterisation of advanced and high purity materials, Progress in Crystal Growth and Characterization of Materials, Volume 44, Issue 3, 2002
- , High purity tungsten powder from scheelite by self propagating high temperature synthesis: R.Curcic et al. (Inst. for Technology of Mineral Raw Materials, Yugoslavia.), Metal Powder Report, Volume 55, Issue 5, May 2000
- , High-purity materials: Research and PVD Materials Corp. Wayne, N.J., Metal Finishing, Volume 94, Issue 8, August 1996
- , From tungsten concentrates and scrap to ammonium paratungstate of high purity : E. Lassner (Sandgasse, Graz, Austria), Int. J. Refractory Metals and Hard Materials, vol 13, no 1/3, 1995, 35–44, Metal Powder Report, Volume 50, Issues 7–8, July–August 1995
- M.F. Churbanov, High-purity chalcogenide glasses as materials for fiber optics, Journal of Non-Crystalline Solids, Volume 184, 1 May 1995
- , High purity refractory metals and silicides for microelectronic application: R. Huenert et al (H.C. Starck GmbH, Goslar, Germany) Int J Refractory Metals & Hard Materials, Vol 11, No 6, 1992
- Masahiro Hosaka, Takeshi Miyata, Hydrothermal growth of a-quartz using high-purity a-cristobalite as feed material, Materials Research Bulletin, Volume 28, Issue 11, November 1993
- D. Murphy, G.J. Butterworth, Production of high-purity vanadium, chromium and titanium for use in low activation materials, Journal of Nuclear Materials, Volumes 191–194, Part B, September 1992