The parameters of most devices in ordinary temperatures have approached their technical limit. This means that the possibilities determined by the properties of materials have been largely exhausted. Cooling is one of the obvious ways in which some materials change their properties significantly. The use of superconducting materials is effective, with a minimal risk of system failure, only in a narrow range of cryogenic temperatures, which entails significant costs and is sometimes extremely difficult. The use of superconducting materials has other enormous difficulties and limitations, including limitations in some tasks and conditions in terms of other physical characteristics and properties.

Materials are often of interest for a combination of several physical characteristics and properties. Electrical conductivity, thermal conductivity, thermal diffusivity, reflectance, yield strength, etc. - not the only thing that may be of interest. A serious impact on the use of some materials is also affected by such parameters as toxicity, complexity in processing, brittleness under external influence, etc. Therefore, the possibilities of manufacturing systems, device elements from non-superconducting metals, including those operating at non-helium temperatures, are considered.

Copper is of particular interest in many respects. Copper has high characteristics of electrical conductivity and thermal conductivity and is used in various fields and devices. It is known that electrical conductivity (and not only) depends significantly on the presence and distribution of impurities in copper. The influence of impurities is most noticeable in cryogenics. Hundredths and thousandths (or less) of a percent of an impurity can sharply reduce its thermal and electrical conductivity. Electrical conductivity is not the only parameter that may be of interest. Differences in characteristics determined by the purity of copper may be of interest not only at cryogenic temperatures 

Used in various fields and tasks, classical copper and its grades are described by well-known generally accepted standards and have a purity in the range of 99.0-99.99%. The standards describe a specific list of chemical elements, according to which purity and specific restrictions for each chemical element or groups of them are determined for each grade of copper. Accordingly, different brands differ somewhat in characteristics and are used for their tasks. The most famous standards are ASTM B170 (USA) and GOST 859-2001 (Russia). There are other similar standards in other countries: Japan, UK, Germany, etc.

Oxygen-free copper has the highest characteristics among classical copper, which is explained by higher requirements for copper in a number of applications, respectively, to the composition of impurities, both in terms of overall purity and the specific content of impurities. The used classical oxygen-free copper is “conditionally” subdivided into pure and high-purity copper with a purity of mim 99.95% and min 99.99%, respectively.

There is a special grade of copper CG-OFC manufactured by Hitachi Cable Ltd (Japan) for use in cryogenics. Copper grade CG-OFC provides RRR ~500 and λ 4.2K / λ 293K ~7.

The RRR characteristic is a measure of how pure and perfect the copper is. RRR for very high-quality copper can reach values of 2000-3000: in one of the research papers, copper was obtained in the form of a single crystal with RRR ~ 2000; in another of the works, copper with the characteristics RRR ~3000 and λ 4.2K / λ 293K ~40 was investigated.

Стоит отметить, что при низких температурах данные характеристики ведут себя нелинейно. Некоторые данные будут приведены в разделе "Продукция/Характеристики".

In classical production, individual results of the purity of copper grades may be higher than those declared in the GOST 859-2001 and ASTM B170 standards, but only what is indicated there is guaranteed, and for the best grades of copper it is only "not less than 99.99%". Guaranteed compliance with 99.99% purity according to these standards is also not so simple: in addition to the overall purity of the declared impurities, it is necessary to comply with the restrictions for each of them. There are other, non-mass technologies, but they have a number of limitations and difficulties, and by these standards it is extremely difficult to achieve a guaranteed result above 99.995-8%

Therefore, manufacturers often set their own specifications for copper 99.995-99.999% and higher: they set their own list of elements for determining purity, and sometimes rules for how to "calculate purity". In some tasks and technological processes, it is permissible not to take into account some elements from generally accepted standards, to take into account impurities that are not included in these standards, but these points must be distinguished and associated with the task. For example, in cryogenics, any impurity has an effect, to a greater or lesser extent....

We have carried out R&D and created pilot production. We have consistently guaranteed results and produced the highest quality experimental product: Ultra-Pure and Super-Pure Copper Ingots. Chemical purity is determined according to the impurities of the generally accepted standards GOST 859-2001 (Russia) and ASTM B170 (USA), and according to the generally accepted simple mathematical rules for calculating purity, which are defined in these standards

The predictive expectations of RRR and λ are justified, the values may be underestimated... There are studies that do not contradict the predictions, as well as considerations arising from our Technology. Forecast expectations are quite justified and the question is rather in the statistical interval distribution of this forecast for the current product. In any case, such results can be obtained. A multiple increase in the RRR characteristic also entails a significant improvement in many other characteristics, such as Thermal conductivity.

Ultra-Pure copper was obtained in the process of researching technological parameters and is not planned for release

The use of the resulting ultrapure copper is due to its characteristics, which differ from classical or other ultrapure copper in the most balanced chemical purity, and, accordingly, physicochemical and mechanical and technological characteristics. In different applications, these differences can have different benefits.

The use of the resulting ultrapure copper may be of interest in the manufacture of ultrathin wires and ribbons, copper laser mirrors or substrates for them, thermal bridges and other products (especially those operating at low temperatures), in electronics (micro/nano, radiation-resistant), nanophotonics, chemistry, etc..

The greatest differences in the obtained copper will be at low temperatures: Electrical conductivity and Thermal conductivity, the largest differences in the range of 5-20K, reflectivity in the range of 5-50K. Other different characteristics and properties are also of interest.

In each specific application area, in a specific task and conditions, in accordance with the dominant characteristic or a set of necessary characteristics and properties, the effect of the replacement may vary, and also have a multiplicative effect. In some cases, the economic effect may not be decisive - the question is the existence of a material with the appropriate characteristics.