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).

Purity Percentages

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 fewer of the total number of 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

Chemical grades often serve as a proxy for purity, but the information they provide is most directly related to 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.

American Elements can assist our customers with selecting the appropriate purity and grade of a material for a particular application.

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.

Biomedical and dental products such as ceramic or metal implants may require high-purity materials to ensure biocompatibility of the final product.

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 cells, 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 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 organometallic compounds, sputtering targets, foils, rods, pellets and wires; we also produce specialized high purity materials for 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 produce palladium metal, palladium nitrate, and tetraamminepalladium(II) nitrate of 99.999% purity with levels of the above analytes in the low ppb range.

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.

Innovation Case Study #1: American Elements Develops Additives to Produce Ultra White Coating for Satellite Applications

#1: American Elements Develops Additives to Produce Ultra White Coating for Satellite Applications

The Challenge

Space poses possibly the most difficult challenges to materials scientists. Solar radiation, intense UV light and wide temperature ranges test the limits of structural materials and coatings. Preventing UV light damage is in large part controlled by the “whiteness” of the coating system which deflects UV radiation.

The Innovation

When NASA contractors sought to develop a new generation of space-grade coatings for telecommunications satellites, they turned to American Elements to produce ultra-high purity forms of certain oxide compounds such as gallium, aluminum and zinc which share the property of extreme whiteness. We synthesized space-grade forms of each oxide in certified 99.999% purity and formulated custom blends to optimize the material.

The Result

A next generation coating system was developed in 2010 and is currently in use on several U.S. launched satellites to provide exceptional resistance to intense UV light exposure.