Research involving palladium’s thermal or evaporative properties are shown below. Original article abstracts with the url to complete article:
Title: Noise temperature measurements for the determination of the thermodynamic temperature of the melting point of palladium
Author(s): F Edler, M Kühne and E Tegeler
Publication date: February 2004 Volume: 41 Start page: 47
Publication: Metrologia
URL: http://stacks.iop.org/0026-1394/41/47
Abstract: The thermodynamic temperature of the melting point of palladium in air was measured by noise thermometric methods. The temperature measurement was based on noise comparison using a two-channel arrangement to eliminate parasitic noises of electronic components by cross correlation. Three miniature fixed points filled with pure palladium (purity: ∼99.99%, mass: ∼90 g) were used to realize the melts of the fixed point metal. The measured melting temperature of palladium in air amounted to 1552.95 °C ± 0.21 K ( k = 2). This temperature is 0.45 K lower than the temperature of the melting point of palladium measured by radiation thermometry.
Title: Correlation between abnormal deuterium flux and heat flow in a D/Pd system
Author(s): Xing Zhong Li, Bin Liu, Jian Tian, Qing Ming Wei, Rui Zhou and Zhi Wu Yu
Publication date: 7 December 2003 Volume: 36 Start page: 3095
Publication: Journal of Physics D: Applied Physics
URL: http://stacks.iop.org/0022-3727/36/3095
Abstract: Deuterium flux through the thin wall of a palladium tube has been studied by monitoring gas pressure and temperature. A high-precision calorimeter (Calvet) was used to detect heat flow when the heater was shut down and the palladium tube was cooling down slowly. At certain temperatures an abnormal deuterium flux appeared. This deuterium flux reached a peak when the temperature of the palladium was decreasing. This abnormal deuterium flux differs from the monotonic feature of a normal diffusive flux and is accompanied by a heat flow.
Title: An investigation of palladium oxidation in the platinum/palladium thermocouple system
Author(s): K D Hill
Publication date: February 2002 Volume: 39 Start page: 51
Publication: Metrologia
URL: http://stacks.iop.org/0026-1394/39/51
Abstract: The work reported explores the effect of Pd oxidation on the behaviour of Pt/Pd thermocouples within the temperature range 250 °C to 1000 °C. The results confirm that oxidation of Pd takes place primarily in the temperature range 600 °C to 800 °C. Uniform (isothermal) heat treatment in the critical temperature range can increase the thermoelectric emf by 1.5 µV (equivalent to 0.15 °C) at the zinc freezing point, with the peak change occurring for a heat-treatment temperature of 750 °C. When subjected to non-uniform heat treatment, an initially homogeneous thermocouple may develop a thermoelectric inhomogeneity of 1 µV (equivalent to 0.14 °C) at the tin freezing point when subjected to temperatures between 600 °C and 800 °C. The oxidation of palladium is more easily interpreted from our parallel investigation of a Pd resistor fashioned as a resistive temperature detector (RTD). For the Pd RTD, the peak of the palladium oxide formation occurs at 725 °C and oxide does not form at or above 800 °C. The changes in thermoelectric emf of the Pt/Pd thermocouple are less than would be expected for a Pt-Rh/Pt thermocouple such as a type S. However, the Pt/Pd thermocouple does not exhibit the stability of the gold/platinum thermocouple due to oxidation of the Pd component and is not recommended in its stead unless the maximum temperature of use exceeds 1000 °C.
Title: Thermocouple observations of melting and freezing plateaus for metal-carbon eutectics between the copper and palladium points
Author(s): Y Yamada, F Sakuma and A Ono
Publication date: February 2000 Volume: 37 Start page: 71
Publication: Metrologia
URL: http://stacks.iop.org/0026-1394/37/71
Abstract: Melting and freezing plateaus were observed with type-R thermocouples for the metal-carbon eutectics Pd-C, Ni-C, and Fe-C. For Pd-C, no apparent difference between the melting and freezing temperatures was observed at a heating/cooling rate of 3 °C/min. For Ni-C, the difference was 0.4 °C, and for Fe-C, 1.6 °C. The freezing temperature for Fe-C showed dependence on cooling rate, and the difference between the melt and the freeze decreased to 0.5 °C, though still significant, at a heating/cooling rate of 0.1 °C/min. The melting temperatures, measured with type-R thermocouples, were 1491 °C, 1329 °C, and 1153 °C, respectively, for Pd-C, Ni-C, and Fe-C eutectics, which agreed to within 1 °C with the values previously measured by radiation thermometers or the literature values. The crucibles, being made from graphite, were able to withstand heating cycles without breaking. The three metal-carbon eutectics, with melting temperatures between the copper point and the palladium point, are potentially useful practical reference points for calibration and evaluation of high-temperature thermocouples.
Title: Realization of the palladium freezing point for thermocouple calibrations
Author(s): Y-G Kim, K S Gam and K H Kang
Publication date: October 1999 Volume: 36 Start page: 465
Publication: Metrologia
URL: http://stacks.iop.org/0026-1394/36/465
Abstract: A vertical alumina palladium (Pd) freezing-point cell was made and used for the calibration of noble metal thermocouples. Various characteristics of the freezing process were investigated using type B thermocouples, and the best method of freezing is discussed. It was found that the freezing behaviour was influenced by the thermal history: it is preferable to freeze the Pd melt completely before carrying out the next test. The thermocouple emfs during freezing were determined by calculating the average emf during the first 10 minutes of the plateau just after the depression in the supercooling curve. This emf was reproducible within a standard deviation of 0.1 °C. The expanded uncertainty of calibrating a type B thermocouple in the Pd freezing-point cell was estimated to be 1.0 °C at the 95% confidence level ( k = 2).
Title: Platinum versus palladium thermocouples: an emf-temperature reference function for the range 0 °C to 1500 °C
Author(s): G W Burns, D C Ripple and M Battuello
Publication date: October 1998 Volume: 35 Start page: 761
Publication: Metrologia
URL: http://stacks.iop.org/0026-1394/35/761
Abstract: We present an emf-temperature reference function for platinum versus palladium (Pt/Pd) thermocouples in air for the range 0 °C to 1500 °C. The reference function is based on the International Temperature Scale of 1990 (ITS-90) and has an expanded uncertainty (coverage factor of two) of less than the equivalent of 11 mK for temperatures up to 1050 °C and rising smoothly to approximately 0.3 K at 1500 °C. The reference function is based on a set of Pt/Pd thermocouples of exceptional stability and homogeneity constructed from Pt and Pd wire of very high purity (99.999% mass fraction and 99.997% mass fraction, respectively). Experimental results are presented on the thermoelectric stability of Pt/Pd thermocouples at high temperatures and on the calibration of Pt/Pd thermocouples based on this reference function.
Title: Behaviour of Au/Pd thermocouple in various gases
Author(s): Yong-Gyoo Kim
Publication date: August 1998 Volume: 9 Start page: 1211
Publication: Measurement Science and Technology
URL: http://stacks.iop.org/0957-0233/9/1211
Abstract: Thermoelectric properties of Au/Pd thermocouple in various atmospheres are investigated at the Ag, Al and Zn fixed points in order to find the optimum conditions of use. Gas compositions are selected as pure argon, argon oxygen, pure nitrogen and nitrogen oxygen. In pure argon and nitrogen atmospheres, Au/Pd thermocouple shows smaller fixed point EMFs and poorer reproducibilities and immersion characteristics than in oxygen mixture. When thermocouples in pure argon and nitrogen are exposed to air, their properties become the same as those of oxygen-containing thermocouples. It is confirmed that any oxygen existing in oxide form on the palladium wire surface is sufficient to stabilize the Au/Pd thermocouple. It is believed that oxidized palladium has a more negative Seebeck coefficient than oxide-free palladium. Based on the experimental results, it is recommended to oxidize the palladium wire during the preparatory heat treatment stage before use in order to obtain a stable and reproducible thermal EMF. The use of the Au/Pd thermocouple in air can also be recommended.
Title: The thermoelectric inhomogeneity of palladium wire
Author(s): Yong-Gyoo Kim, Kee Sool Gam and Jeong Hoon Lee
Publication date: March 1997 Volume: 8 Start page: 317
Publication: Measurement Science and Technology
URL: http://stacks.iop.org/0957-0233/8/317
Abstract: Thermoelectric inhomogeneity tests were performed on pure palladium wire using a moving temperature gradient method and the results were analysed quantitatively. The Seebeck coefficient of palladium was found to differ with the heat-treatment conditions. The variation of extra EMF was explained well with the analytical approach. The calculation and experimental results closely coincided with each other. To keep the palladium homogeneous, high-temperature annealing for removal of plastic deformation and low-temperature heat-treatment for annealing out of quenched-in vacancies should be carried out.
Title: Power absorption and temperature control of multi-filament palladium - nickel thermoseeds for interstitial hyperthermia
Author(s): N van Wieringen, J D P van Dijk, G J Nieuwenhuys, C E Snel and T C Cetas
Publication date: November 1996 Volume: 41 Start page: 2367
Publication: Physics in Medicine and Biology
URL: http://stacks.iop.org/0031-9155/41/2367
Abstract: In interstitial hyperthermia using ferromagnetic seeds, multi-filament seeds have gained interest because of a more effective power absorption than solid seeds. Palladium - nickel (PdNi) seeds composed of filaments with diameters in the range from 0.1 to 1.0 mm (maximally 90 filaments) have been investigated to find the conditions for optimal power absorption and temperature control. Magnetic and calorimetric experiments have shown that a decreasing filament radius results in a more effective power absorption. The power absorption approaches a common asymptote for high field intensities at all filament diameters. This asymptotic behaviour can be understood as a consequence of the approach of saturation magnetization of PdNi. The sharpness of the transition at the Curie temperature, which is a measure for the quality of temperature control, improves as the magnetic field strength increases, but it is limited by the asymptote of the power absorption. When the asymptote has been reached the quality of temperature regulation of a seed can only be improved by increasing the amount of PdNi, e.g. by increasing the number of filaments. Calculations of the power absorption, using the generally applied theory based on a linear relation between the magnetization of PdNi and the magnetic field strength, do not correspond quantitatively with experimental results for seeds having an induction number smaller than the `optimal value' of 2.5. For these seeds the measured heat production is larger than the calculated one.
Title: Plasma assisted evaporation of palladium
Author(s): Claude Laure, Pascal Brault, Anne-Lise Thomman, Rod Boswell, Bernard Rousseau and Henriette Estrade-Szwarckopf
Publication date: August 1996 Volume: 5 Start page: 510
Publication: Plasma Sources Science and Technology
URL: http://stacks.iop.org/0963-0252/5/510
Abstract: We studied the deposition of palladium on silicon using a high-frequency argon plasma. It is shown that the argon ions are focused and sputtered a biased helicoidal palladium wire. An auxiliary continuous discharge enhancing palladium evaporation rate is obtained for a pressure and bias voltage above 50 m Torr and -200 V respectively, as revealed by optical emission spectroscopy. The growth rate is between 0.5 and 20 ≈ as deduced from x-ray photoelectron spectroscopy. Scanning tunnelling microscopy studies reveal that growth proceeds through nucleation.
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