Editing Thermocouple (section)

===Others===

====Chromel–gold/iron-alloy thermocouples====
[[File:Low temperature thermocouples reference functions.svg|thumb|Thermocouple characteristics at low temperatures. The AuFe-based thermocouple shows a steady sensitivity down to low temperatures, whereas conventional types soon flatten out and lose sensitivity at low temperature.]]
In these thermocouples ([[chromel]]–[[gold]]/[[iron]] alloy), the negative wire is gold with a small fraction (0.03–0.15 atom percent) of iron. The impure gold wire gives the thermocouple a high sensitivity at low temperatures (compared to other thermocouples at that temperature), whereas the chromel wire maintains the sensitivity near room temperature. It can be used for [[cryogenics|cryogenic]] applications (1.2–300 K and even up to 600 K). Both the sensitivity and the temperature range depend on the iron concentration. The sensitivity is typically around 15 μV/K at low temperatures, and the lowest usable temperature varies between 1.2 and 4.2 K.

====Type P (noble-metal alloy) or "Platinel II"====
Type P (55%[[palladium|Pd]]/31%Pt/14%Au–65%Au/35%Pd, by weight) thermocouples give a thermoelectric voltage that mimics the type K over the range 500&nbsp;°C to 1400&nbsp;°C, however they are constructed purely of noble metals and so shows enhanced corrosion resistance. This combination is also known as Platinel II.<ref>[https://maniadsanat.com/thermocouple/ Other Types of Thermocouples]. maniadsanat.com.[https://adsn.io/thermocouple-inch-wide-mile-deep/]</ref>

====Platinum/molybdenum-alloy thermocouples====
Thermocouples of platinum/molybdenum-alloy (95%Pt/5%Mo–99.9%Pt/0.1%Mo, by weight) are sometimes used in nuclear reactors, since they show a low drift from [[nuclear transmutation]] induced by neutron irradiation, compared to the platinum/rhodium-alloy types.<ref name="Pollock">Thermoelectricity: Theory, Thermometry, Tool, Issue 852 by Daniel D. Pollock.</ref>

====Iridium/rhodium alloy thermocouples====
The use of two wires of [[iridium]]/[[rhodium]] alloys can provide a thermocouple that can be used up to about 2000&nbsp;°C in inert atmospheres.<ref name="Pollock"/>

====Pure noble-metal thermocouples Au–Pt, Pt–Pd====
Thermocouples made from two different, high-purity noble metals can show high accuracy even when uncalibrated, as well as low levels of drift. Two combinations in use are gold–platinum and platinum–palladium.<ref>[http://content.fluke.com/comx/pages/hrt_5629_en.htm  5629 Gold Platinum Thermocouple] {{Webarchive|url=https://web.archive.org/web/20140105050650/http://content.fluke.com/comx/pages/hrt_5629_en.htm |date=2014-01-05 }}. fluke.com.</ref> Their main limitations are the low melting points of the metals involved (1064&nbsp;°C for gold and 1555&nbsp;°C for palladium). These thermocouples tend to be more accurate than type S, and due to their economy and simplicity are even regarded as competitive alternatives to the [[platinum resistance thermometer]]s that are normally used as standard thermometers.<ref>[http://www.bipm.org/en/publications/mep_kelvin/its-90_techniques.html BIPM – "Techniques for Approximating the ITS-90"] {{Webarchive|url=https://web.archive.org/web/20140201232752/http://www.bipm.org/en/publications/mep_kelvin/its-90_techniques.html |date=2014-02-01 }} Chapter 9: Platinum Thermocouples.</ref>

====HTIR-TC (High Temperature Irradiation Resistant) thermocouples====
HTIR-TC offers a breakthrough in measuring high-temperature processes. Its characteristics are: durable and reliable at high temperatures, up to at least 1700&nbsp;°C; resistant to irradiation; moderately priced; available in a variety of configurations - adaptable to each application; easily installed. Originally developed for use in nuclear test reactors, HTIR-TC may enhance the safety of operations in future reactors. This thermocouple was developed by researchers at the Idaho National Laboratory (INL).<ref>{{Cite web |url=http://core.materials.ac.uk/search/detail.php?id=3629 |title=CORE-Materials • High Temperature Irradiation Resistant Thermocouple (HTIR-TC) |access-date=2019-05-29 |archive-date=2017-06-27 |archive-url=https://web.archive.org/web/20170627184309/http://core.materials.ac.uk/search/detail.php?id=3629 |url-status=dead }}</ref><ref>{{Cite web|title=high-temperature irradiation-resistant thermocouples: Topics by Science.gov|url=https://www.science.gov/topicpages/h/high-temperature+irradiation-resistant+thermocouples.html|access-date=2020-12-02|website=www.science.gov}}</ref>