A gold thermocouple measuring extreme heat

Gold Standard Thermocouples: Are They Ready to Redefine High-Temperature Measurement?

Soraya Malik in Science & Nature August 2025 • 3 min read.

"Exploring the potential of gold/platinum thermocouples to replace traditional thermometers in critical temperature ranges."

For decades, the International Temperature Scale of 1990 (ITS-90) has relied on platinum resistance thermometers to define temperatures with high precision. However, at extreme temperatures—specifically between the melting points of aluminum (660.323°C) and silver (961.78°C)—these thermometers face significant challenges. They become vulnerable to contamination, lack stability, and often show poor repeatability, pushing scientists to seek alternatives.

Enter the gold/platinum (Au/Pt) thermocouple, a promising candidate to replace the traditional high-temperature platinum resistance thermometers (HTSPRTs). Made from pure gold and platinum wires, these thermocouples offer the potential for exceptional thermoelectric stability and homogeneity, which are critical for precise temperature measurements. The idea isn’t new, but recent research is exploring how to make Au/Pt thermocouples a reliable standard.

This article dives into the latest research on Au/Pt thermocouples, examining their thermoelectric properties, the challenges in their development, and their potential to redefine high-temperature measurement. We will explore how scientists are working to overcome historical limitations to make Au/Pt thermocouples a viable alternative to HTSPRTs.

Why Are Gold/Platinum Thermocouples Gaining Attention?

A gold thermocouple measuring extreme heat

The core appeal of Au/Pt thermocouples lies in their potential for superior stability and uniformity compared to HTSPRTs. Traditional platinum resistance thermometers become less reliable at high temperatures due to several factors:

These issues have driven a quest for a more dependable standard. Au/Pt thermocouples, known for their inherent material properties, present a compelling solution. However, realizing this potential requires overcoming significant hurdles related to material purity, structural consistency, and calibration accuracy.

Susceptibility to Contamination: High temperatures increase the risk of impurities affecting the platinum's electrical resistance.
Lack of Stability: The resistance of platinum can change over time, leading to inconsistent readings.
Poor Repeatability: Measurements may vary significantly, making it difficult to obtain reliable results.

To address these problems, recent research focuses on refining the manufacturing and handling processes of Au/Pt thermocouples. This includes sourcing high-purity materials, optimizing annealing procedures (heat treatments to relieve stress and improve homogeneity), and developing precise calibration techniques. The goal is to create thermocouples that not only offer stability but also minimize measurement uncertainties, making them suitable for high-precision applications.

Are Gold/Platinum Thermocouples the Future of High-Temperature Measurement?

While challenges remain, the progress in refining Au/Pt thermocouples is promising. Ongoing research aims to improve thermoelectric homogeneity and reduce measurement uncertainties, bringing these thermocouples closer to practical application. Though HTSPRTs have long been the standard, Au/Pt thermocouples may redefine high-temperature metrology in the years to come.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1051/ijmqe/2015016, Alternate LINK

Title: Thermoelectric Properties Of Currently Available Au/Pt Thermocouples Related To The Valid Reference Function

Subject: Safety, Risk, Reliability and Quality

Journal: International Journal of Metrology and Quality Engineering

Publisher: EDP Sciences

Authors: F. Edler, N. Arifovic, G. Atance, C. Dinu, C.J. Elliott, C. Garcia Izquierdo, N. Hodzic, S. Kalisz, J.V. Pearce, S. Simic, R. Strnad, D. Taubert

Published: 2015-01-01

Everything You Need To Know

What are the primary limitations of using platinum resistance thermometers for high-temperature measurements?

Platinum resistance thermometers face several challenges at extreme temperatures. They are vulnerable to contamination, which can alter their electrical resistance and affect readings. They also exhibit a lack of stability, meaning their resistance can change over time, leading to inconsistent results. Finally, they often show poor repeatability, where measurements vary significantly, making reliable data acquisition difficult. These limitations are particularly pronounced between the melting points of aluminum (660.323°C) and silver (961.78°C), the specific range where alternatives are actively sought.

How do gold/platinum thermocouples aim to improve upon the current standards for high-temperature measurement?

Gold/platinum thermocouples aim to overcome the limitations of platinum resistance thermometers by leveraging the inherent properties of gold and platinum. They are designed to offer superior thermoelectric stability and homogeneity. Thermoelectric stability means they are less prone to changes in their electrical output over time and temperature. Homogeneity refers to the consistency of the materials, ensuring uniform response to temperature changes. Researchers are focusing on enhancing the reliability of Au/Pt thermocouples through refined manufacturing processes. This involves using high-purity materials, optimizing annealing procedures to improve homogeneity, and developing precise calibration methods to minimize measurement uncertainties.

What specific research areas are crucial for the development of reliable gold/platinum thermocouples?

The current research focuses on several key areas. Firstly, ensuring the highest purity of gold and platinum wires is essential to minimize contamination and maintain accurate readings. Secondly, optimizing annealing procedures, which involve heat treatments, is important. Annealing helps to relieve stress and improve the homogeneity of the thermocouple materials. Finally, the development of precise calibration techniques is crucial. Accurate calibration minimizes measurement uncertainties, allowing these thermocouples to be used in high-precision applications. These steps collectively enhance the reliability of Au/Pt thermocouples, making them viable for replacing platinum resistance thermometers.

Why is thermoelectric stability and homogeneity important for precise temperature measurement using Au/Pt thermocouples?

Thermoelectric stability and homogeneity are critical because they directly impact the accuracy and reliability of temperature measurements. Thermoelectric stability means that the thermocouple's output voltage remains consistent over time and at different temperatures. This is essential to avoid measurement drift. Homogeneity ensures that the temperature change is consistently reflected throughout the thermocouple's structure. If the materials lack homogeneity, different parts of the thermocouple will respond differently to the same temperature, leading to inaccurate results. The combination of these two characteristics makes Au/Pt thermocouples a promising alternative to the current standards by providing more precise and dependable temperature readings.

What are the main challenges scientists are working to overcome to make gold/platinum thermocouples a viable alternative to platinum resistance thermometers?

Scientists are working to overcome several significant challenges to make Au/Pt thermocouples a reliable alternative. These challenges include ensuring the purity of the materials, as contamination can compromise accuracy. Moreover, the thermocouples need to maintain thermoelectric stability to ensure consistent readings over time. Researchers must also address the issue of homogeneity, which involves creating a uniform response across the thermocouple. Furthermore, developing precise calibration techniques is essential to minimize measurement uncertainties, ensuring that the thermocouples provide reliable data in high-precision applications. The goal is to refine the manufacturing and handling processes to meet and exceed the performance of the existing standards, platinum resistance thermometers, especially within the critical temperature range between the melting points of aluminum and silver.