A Schottky-Diode Model of the Nonlinear Insulation Resistance Effects in SPRTs—Part 1: Theory

White, D. R.; Arai, M.; Bittar, A.; Yamazawa, K.

doi:10.1007/s10765-007-0276-x

Cited by 13 publications

(15 citation statements)

References 13 publications

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“…We suspect that any 'non-identical set-up' that exists between the two measurement systems, which may come from the electrical configuration of the systems, is the source for this bias. As reported elsewhere by White et al [9], the difference in the electrical condition in a high-temperature furnace may lead to a difference in PRT readings, even for a stable silver plateau. We found that the difference in grounding conditions of two furnaces was at the level of 3 mK (on average), and this should be considered as an additional uncertainty.…”

Section: Cell Comparisonsmentioning

confidence: 52%

Confirming Impurity Effect in Silver-Point Realization from Cell-to-Cell Comparisons

et al. 2011

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As a continuation to earlier work on the silver-point realization, already reported at TEMPMEKO 2007, a new silver-point cell has been fabricated using 6N-nominal grade material that was analyzed by means of glow discharge mass spectrometry (GDMS) by the manufacturer. This new cell is evaluated by a direct cell comparison with one of the existing cells, which was also already reported at TEMP-MEKO 2007. One of those existing cells was drawn out from its crucible, and its ingot was analyzed by GDMS at four positions, namely, at around the center of the top, of the middle, of the bottom, and around the outer part of middle areas for the purpose of confirming whether or not there has been differences in the content of impurities before and after the cell fabrication, as well as differences in impurity homogeneity within the ingot. As results of the aforementioned measurements, it was found that the homogeneity of impurities in the silver ingot was on average within 50 %. It was also found that cell-to-cell temperature differences change along with the progressing solidification process. As a consequence, it was concluded that, for an accurate cellto-cell comparison, the location in the freezing plateau, where the comparison is done, should be determined. Also obtained here is that the slope analysis was consistent with both the cell-to-cell comparison and the impurity analysis.

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Section: Cell Comparisonsmentioning

confidence: 52%

Confirming Impurity Effect in Silver-Point Realization from Cell-to-Cell Comparisons

et al. 2011

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“…The complex insulation breakdown effect, which can contribute several millikelvin uncertainty even for 0.25 thermometers, is thought to be caused by the formation of metal-semiconductor diodes (Schottky or point-contact diodes) at the points of contact between the silica insulators and the platinum wire of the sensor and lead wires [41,42]. The recognition of the diodes may yet result in improvements to SPRT design, e.g., use of sapphire rather than fused silica insulation disks in the SPRTs.…”

Section: Insulation Breakdown Effectsmentioning

confidence: 99%

Uncertainties in the SPRT Subranges of ITS-90: Topics for Further Research

White¹,

Ballico

Campo

et al. 2010

Int J Thermophys

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The CCT has completed the guide summarizing the uncertainties in the realization of the SPRT subranges of ITS-90 between the triple point of neon (24.5561 K) and the freezing point of silver (961.78 • C). This article identifies aspects of standard platinum resistance thermometry where either data or models are lacking and further research is required. In the calibration of SPRTs, the two main concerns are the need for data on liquidus slopes for the different impurities in the fixed points and improved understanding of the impact of the thermal environment of the fixed point on the realized temperature. In the use of SPRTs, the two largest sources of uncertainty are Types 1 and 3 non-uniqueness and oxidation. The causes of Type 3 non-uniqueness are not yet understood, especially at low temperatures, and there is a paucity of data for the high-temperature subranges. In respect of oxidation, there is a need for validation of the models developed in the 1980s, especially in light of the reduced partial pressure of oxygen used in modern SPRTs. A range of other effects including vacancy effects in SPRTs, isotopic effects in fixed points, and improved statistical methods are discussed.

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“…was established. Very recently, White et al [4,5] explained the non-linear behavior of this insulation breakdown resistance by the Schottky-diode model.…”

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Measurement of AC and DC Insulation Leakage in Platinum Resistance Thermometers up to 960 °C

2011

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It is well known that insulation leakage at high temperatures can be one of the major contributions to uncertainties in measured temperatures above 600 • C. On the one hand, this insulation leakage shunts the sensor resistor leading to systematic errors in the measured temperatures, which are, in principle, characteristics of each thermometer. On the other hand, at high temperatures, degradation of the insulation materials used in the furnaces enhances the decrease of the insulation impedance between the thermometer and the furnace which also causes a systematic temperature measurement error. Two high-temperature standard platinum resistance thermometers have been used to measure these effects in different heat-pipe and three-zone furnaces. One of them was open-circuited by cutting the sensing element end allowing the measurement of the resistance between the two pairs of current-potential leads. Two different setups were used to measure the AC and DC insulation resistances leadto-lead and thermometer-to-furnace. The first one was a teraohmeter with a high value standard resistor in parallel with the leakage resistance to be measured and the other one an LCR meter to perform the AC measurements at different frequencies. In this article, results for both methods are presented.

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A Schottky-Diode Model of the Nonlinear Insulation Resistance Effects in SPRTs—Part 1: Theory

Cited by 13 publications

References 13 publications

Confirming Impurity Effect in Silver-Point Realization from Cell-to-Cell Comparisons

Confirming Impurity Effect in Silver-Point Realization from Cell-to-Cell Comparisons

Uncertainties in the SPRT Subranges of ITS-90: Topics for Further Research

Measurement of AC and DC Insulation Leakage in Platinum Resistance Thermometers up to 960 °C

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