Fixed-point Material Research Articles

Comparisons of some NIST fixed-point cells with similar cells of other standards laboratories

In this paper we present results of international comparisons of fixed-point cells of some of the defining fixed-point materials of the International Temperature Scale of 1990. These comparisons involved cells from seven national laboratories, although in some cases only one type of fixed-point material was compared. Except for silver cells, the agreement among cells of the same defining fixed-point material from the various laboratories was to within 1 mK. The expanded uncertainties (k = 2) of the comparison measurements were 12 µK for Ga, 18 µK for H2O, 27 µK for Sn, 35 µK for In, 37 µK for Zn, 42 µK for Al, and 55 µK for Ag.

The temperature calibration of scanning calorimeters: Part 2. Calibration substances

The recommendation for temperature calibration consists of two parts. Part 1 (see section 2.3) presented a correct method for the calibration of scanning calorimeters (DSC) and of instruments for differential thermal analysis (DTA), irrespective of the instrument type. The present paper recommends calibration substances for the range 120-1350 K. Sections 2 and 3 indicate the documents to be taken into account and define the most important terms used. Section 4 consists of general requirements to be met by the calibration substances, a list of the substances and explanations with respect to their use. Basically, such materials have been selected as calibration substances which define fixed points of the International Temperature Scale of 1990 (ITS-go). Added to these are fixed point materials from the previously valid International Practical Temperature Scale of 1968 (IPTS-68, see References in Table 1). Moreover, two substances are recommended for temperature ranges for which no suitable fixed point material exists, and the respective uncertainty of measurement is stated.

Determination of electrode/substrate surface temperatures through the solid–liquid transition of metals/eutectics in capacitively coupled radio frequency-plasma chemical vapor deposition reactors

In a capacitively coupled radio frequency-plasma chemical vapor deposition reactor, we took pure metals, In, Sn, Bi, and Pb with the melting points ranging from 157 to 327 °C, and the eutectic Al (45 wt. %)/Ge alloy with the eutectic point of 423 °C as the fixed point materials to determine surface temperatures of the electrode and a piece of stainless steel (SLS) plate placed on it. The surface temperatures thus obtained were compared with temperatures detected with a thermocouple mounted within the electrode. An analysis of the obtained results based on a simplified heat transfer model revealed the thermal contact resistance at the specimen-SLS plate interface to be as small as about one sixth that at an interface between two pieces of SLS plate. Criteria for the choice of eutectics as the thermometric fixed-point materials are discussed and some possible candidates usable for this purpose are listed.