Melting Point Of Gallium Research Articles

A new interpolation equation in the ITS-90 subrange from the triple point of water to the freezing point of indium

For all the subranges above 0.01 °C, other than the interpolation between the triple point of water (TPW) to the melting point of gallium, temperatures on the international temperature scale of 1990 (ITS-90) are specified without the melting point of gallium. This study suggests a new interpolation equation in the subrange from the TPW to the freezing point of indium which is a polynomial of fractional third order with two coefficients to be determined by the measuring values of standard platinum resistance thermometers (SPRTs)’ resistance ratios at the melting point of gallium (W Ga) and at the freezing point of indium (W In). A sample set of 30 SPRTs from various countries and laboratories is used to quantify the comparisons between this new interpolation and the ITS-90. Analyses show that the reproducibility is significantly improved compared with the ITS-90 in the same subrange. The peak value of overlapping subrange inconsistencies (SRI) from TPW to the melting point of gallium is reduced from 0.91 mK to 0.21 mK. Both the mean and standard deviation of the SRI peak values for the new equation decrease by approximately a factor of four compared to those of the ITS-90 (mean decreasing form 0.20 mK to 0.05 mK and standard deviation decreasing form 0.32 mK to 0.07 mK). Type 3 non-uniqueness (NU3) determinations of the same subrange have also been looked into with a data set of four SPRTs compared in thermostatic baths using a copper block and the results show that NU3 scales down from a range −0.15 mK–0.25 mK of the ITS-90 to −0.10 mK–0.15 mK of the new interpolation equation. Propagation of Uncertainties investigation shows that the new equation inflates merely 7% the measurement uncertainties of fixed points in a relatively short interval from 30 °C to 60 °C.

SIM.T-K9.3: Standard platinum resistance thermometer ITS-90 realizations from the Hg triple point to the Zn freezing point

Main textThis report shows the results of a bilateral comparison of temperature standards between Instituto Nacional de Metrologia, Qualidade e Tecnologia (Inmetro, Brazil), and Trinidad and Tobago Bureau of Standards (TTBS, Trinidad and Tobago), carried out between January and July of 2020. The measurands of this comparison were the W(t90) ratios of two Standard Platinum Resistance Thermometers (SPRTs), used as transfer standards, measured at the zinc freezing point (Zn FP, 419.527 °C), tin freezing point (Sn FP, 231.928 °C), gallium melting point (Ga MP, 29.7646 °C), triple point of water (TPW, 0.01 °C) and mercury triple point (Hg TP, -38.8344 °C).To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

TWO TYPES OF GALLIUM EXPOSURE TO ALUMINUM

The effect of gallium on aluminum during their fusion is investigated. The corrosion rate of aluminum alloys with 1, 2 and 5 at % gallium content was experimentally determined, which was 0.001, 0.00101 and 0.00062 g/m2 · h, respectively, which is less than that of pure grade A99 aluminum – 0.0016 g/m2 · h. The rate of dissolution of these alloys in acidic and alkaline media is determined. X-ray phase analysis showed the homogeneity of the alloys under consideration. The morphology of aluminum alloys with gallium was studied, after exposure to an aggressive environment – a solution of hydrochloric acid. The possibility of obtaining hydrogen and nanoscale alumina by decomposition of water by activated gallium aluminum alloy is shown. Activation of the aluminum surface by gallium alloy occurs according to the Rebinder effect and the article presents a micrograph of the surface of aluminum treated with Ga-Sn alloy, clearly demonstrating this effect. When using metallic gallium in contact with aluminum, the interaction requires heating to a temperature above 30°C (the melting point of gallium is 29.7°C), the melting point of the eutectic composition 92Ga–8Sn is 20.0°C, which allows the interaction to begin at room temperature. At temperatures of about 4°C, activated aluminum can be stored for a long time. The quality of hydrogen obtained by decomposition of water should be higher than that obtained by cracking, and the cost is close to a well-developed technology of electrolysis of water and no more than 2 times the cost of its synthesis via cracking of hydrocarbons. Gallium and its liquid alloys are non-toxic, almost do not interact with water, activate aluminum, preventing the formation of a protective oxide film, penetrate into the intergranular space and aluminum easily interacts with water, forming hydrogen and aluminum hydroxide.

Novel tribological test rig prototype and primary results of experiments for additively manufactured test samples

This paper presents a new design of tribological test rig - (TTR), reciprocating type, with a ramp characteristic typical of computer numerical control drives. The guide temperature is measured by a series of sensors, calibrated using the triple point of water and gallium melting point methods. The uncertainty of wear measurements is provided. Experiments showed that TTR gives repeatable results of measurements with respect to wear and temperature. Each experiment was performed under different conditions: dry sliding, dry sliding with intermissions, dry sliding with a temporarily increased payload, and sliding with lubrication and with silicon oil residue. Wear rate was determined to predict the wear and compare it with established methods. Normal force and payload were predicted for a set distance and assumed wear. A set of micro-photographs helped to determine the contact surface position.

Investigations of Type 3 non-uniqueness in standard platinum resistance thermometers between 83 K and 353 K

A key feature of the International Temperature Scale of 1990 (ITS-90) is Type 3 non-uniqueness which arises from differences between individual Standard Platinum Resistance Thermometers (SPRTs) over a given subrange. This can be significant in the context of the best reported uncertainties of SPRT calibrations, but it is extremely difficult to determine because it is easily obscured by the measurement uncertainties. Hence, there is little good information available, particularly over much of the temperature range commonly encountered by long-stem SPRTs, and the estimates of its magnitude are potentially overstated. This paper presents high precision comparisons at NPL and CEM of two cohorts of 8 and 6 long-stem SPRTs, by measuring the ratio of each SPRT against a common SPRT in stirred liquid baths at temperatures from 178 K to 303 K, and 274 K to 353 K, respectively. Measurements of a third cohort of 8 SPRTs were made at INTiBS in a stirred liquid bath from 198 K to 303 K and in a temperature-controlled cryostat from 84 K to 185 K. The measurements were augmented by calibrations of each SPRT at the triple points of argon and mercury, the melting point of gallium and the freezing point of indium, so extending the overall temperature range down to 84 K and up to 429 K. The three cohorts were linked by two SPRTs which were common to all of them. The comparison differences, which ideally should represent the Type3 non-uniqueness, are presented for the specified ITS-90 interpolations, and for some alternative interpolation schemes. Specifically, it is assessed for interpolations in which the mercury triple point is replaced with the triple point of Xe, CO2 or SF6, which are widely considered to be potential candidates for replacing mercury in a future amendment of the ITS-90. The further alternative of using the melting point of gallium is also investigated.

Self-Cooling Gallium-Based Transformative Electronics with a Radiative Cooler for Reliable Stiffness Tuning in Outdoor Use.

Reconfigurability of a device that allows tuning of its shape and stiffness is utilized for personal electronics to provide an optimal mechanical interface for an intended purpose. Recent approaches in developing such transformative electronic systems (TES) involved the use of gallium liquid metal, which can change its liquid–solid phase by temperature to facilitate stiffness control of the device. However, the current design cannot withstand excessive heat during outdoor applications, leading to undesired softening of the device when the rigid mode of operation is favored. Here, a gallium‐based TES integrated with a flexible and stretchable radiative cooler is presented, which offers zero‐power thermal management for reliable rigid mode operation in the hot outdoors. The radiative cooler can both effectively reflect the heat transfer from the sun and emit thermal energy. It, therefore, allows a TES‐in‐the‐air to maintain its temperature below the melting point of gallium (29.8 ℃) under hot weather with strong sun exposure, thus preventing unwanted softening of the device. Comprehensive studies on optical, thermal, and mechanical characteristics of radiative‐cooler‐integrated TES, along with a proof‐of‐concept demonstration in the hot outdoors verify the reliability of this design approach, suggesting the possibility of expanding the use of TES in various environments.

2D and 3D Structuring of Freestanding Metallic Wires Enabled by Room-Temperature Welding for Soft and Stretchable Electronics.

In this work, a facile and cost-effective approach to assemble metallic wires into two-dimensional (2D) and three-dimensional (3D) freestanding geometries by room-temperature welding is demonstrated. The low melting point of gallium (29.8 °C) enables the welding at room temperature without the aid of high-energy sources required for high-melting-point metals and alloys. The welding enables assembly of solid gallium wires into 2D and 3D geometries that could create freestanding architectures with multiple junctions along any inclined direction. These 2D and 3D freestanding metallic structures are freeze-cast in soft elastomers to obtain stretchable and soft devices: a 2D stretchable resistive and capacitive sensor patterned with parallel metal lines, a 2D stretchable capacitive sensor patterned with an interdigitated metal structure with capacitive changes on stretching in both x- and y-axes, and a 3D compressive sensor by assembly of liquid metal helices, which could sense foot pressure compression. We also developed a facile method to interconnect between soft circuits and external electronics, suppressing stress during mechanical deformation.

Metrological Evaluation of Deep-Ocean Thermometers

An accurate metrological investigation was performed on several units of the two de facto standards for deep-ocean temperature measurements—the SBE35 (the reference thermometer) and the SBE3 (the working thermometer) from SeaBird Scientific. Four SBE35 units were repeatedly calibrated against state-of-the-art fixed-point cells (triple point of water at 0.01 °C and melting point of gallium at 29.7646 °C), with calibration uncertainties of approximately 0.2 mK and 0.5 mK, respectively. Three SBE35 units and one SBE3 unit were calibrated in the temperature range 0 °C to 30 °C, again with sub-millikelvin calibration uncertainties, in a recently-developed water–bath calibration facility. All these calibrations evidenced (1) the deviation of each unit from its original manufacturer’s calibration (up to 1.7 mK), which were found to be inconsistent with the manufacturer’s uncertainty claims and (2) unexplained irreproducibilities, which could not be attributed to the calibration system of up to 1.5 mK. The effect of high pressures (up to 60 MPa) on the response of two SBE35 units was investigated by pressurizing the SBE35 units inside a purpose-built compact pressure enclosure. The results of the pressure investigation confirmed the existence of a small device-dependent pressure effect (approximately 0.3 mK at 60 MPa) and the need for individual temperature–pressure calibration of each SBE35 unit.

Non‐polymeric thin wires by drawing materials near room temperature

AbstractHerein, non‐polymeric thin cross‐sectional wires were fabricated by injecting materials into elastomeric hollow fibers with subsequent drawing. Once materials were injected into hollow elastic fibers, cores were drawn as fibers elongated. Solidifying the core and removing polymeric shell could form free‐standing wires with thin cross‐sections. In this work, two different thin wires, metallic wires (gallium), and SiCN ceramic wires, were fabricated. Although mechanical and physical properties of these wires completely differed, fabrication approaches were identical by drawing materials near room temperature. Solidified wires enhanced mechanical properties of fibers. Thus, fibers could store elastic energy and preserve deformed complex shapes with the assist of solidified cores. Although the wires with thin cross sections are inherently brittle, the relatively low melting point of gallium (29.8°C) allows it to heal easily upon body heating.

Liquid–Solid Mixtures of Ga Metal Infused with Cu Microparticles and Nanoparticles for Microscale and Nanoscale Patterning of Solid Metals at Room Temperature

This paper demonstrates and characterizes a simple ink for nanopatterning of solid metallic structures under ambient conditions by taking advantage of the low melting point of gallium and its affin...

Thermodynamic Temperature Measurements from the Triple Point of Water up to the Melting Point of Gallium

A new acoustic gas thermometry (AGT) system, which introduces a 1-L quasi-spherical resonator (QSR) made of oxygen-free copper, was built at the National Metrology Institute of Japan (NMIJ/AIST). The inner surface of the new QSR was machined using a diamond-turn tool. Improvement in the pressure measurement was introduced to allow direct measurement of the gas pressure in the resonator. The new AGT system was evaluated based on the measurement of the speed of sound in argon at the triple point of water and the melting point of gallium under the pressure range from 700 kPa down to 50 kPa. Based on these speed of sound measurements, the thermodynamic temperatures at the melting point of gallium were determined. The speed of sound measurements at isotherms of 283.15 K and 293.15 K were also conducted, and the related thermodynamic temperatures were determined. Based on the measured thermodynamic temperature T, the values of difference between T and the temperature T90 based on the International Temperature Scale of 1990 (ITS-90), (T − T90), along with the associated uncertainties, were calculated. The (T − T90) obtained in the present work were 1.3 ± 0.7 mK, 2.7 ± 0.8 mK, and 4.1 ± 0.8 mK for T90 of 283.15 K, 293.15 K, and 302.9146 K, respectively. These values were found to be in agreement within the estimated uncertainty with the currently reported values that exist in temperature range overlapping with the present work.

Evaluation of High-Temperature Platinum Resistance Thermometers Based on ITS-90

High-temperature standard platinum resistance thermometers (HTSPRTs) are used to establish the International Temperature Scale of 1990 (ITS-90) for temperatures up to 960 °C. Currently available thermometers, which may differ in the design of the platinum winding of the sensor, the shape and finish of the sensor frame, the frame material, the protective sheaths, and sealing materials, need some treatments to exhibit the stabilities expected of them and some of the causes of the instability are not well understood. This paper demonstrates a novel model of commercial HTSPRT that reportedly employs a novel sensor winding construction designed to eliminate instability arising from strain on the sensor winding due to differential thermal expansion between the sensor and the sensor frame. The stability of eight different HTSPRTs, including the novel model, are compared at the triple point of water (TPW), the melting point of gallium, and the freezing points of tin, zinc, aluminum and silver. Heat treatments included annealing at 500 °C, a preheating temperature for use at the freezing points of aluminum and silver, and at 800 °C, which was selected for checking the stability of the HTSPRTs in the middle of the temperature range between the freezing points of aluminum and silver. The consistency of the resistance values at the different fixed points was also confirmed by calculating the S parameter. We found three HTSPRTs stable during the described thermal conditions within ± 0.5 mK at the TPW. The novel model of commercial HTSPRT was the best one with a stability in the resistance at the TPW of within ± 0.3 mK over the entire temperature range. These indicate that the stable three HTSPRTs are promising instruments to provide accurate temperature scale at temperatures from the freezing point of aluminum up to the freezing point of silver based on the ITS-90.

Realization of the ITS-90 from 273.16 K to 692.677 K

The bilateral comparison of the ITS-90 realizations at the National Metrological Institutes of Germany (PTB) and the Russian Federation (VNIIM) in the temperature range from 273,16 K to 692,677 K was initiated by the Technical Committee on "Thermometry and thermal physics" TC1.10 of COOMET.The purpose of the comparison was to evaluate the differences between the realizations of the national standards in the most essential temperature range with the highest requirements to the measurement uncertainty. This temperature range includes five ITS-90 fixed points: the triple point of water, the melting point of gallium, the freezing points of indium, tin and zinc.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

How a conductive baffle improves melting characteristic and heat transfer in a rectangular cavity filled with gallium

The configuration of a latent heat thermal energy storage (LHTES) is an important factor considered by manufacturers of heat storage systems. In this study, an applicable and low-cost way of improving melting behavior in a rectangular cavity was remarked. There was a preconceived idea that with a single conductive baffle, embedded on the upper wall of the cavity, the melting rate and the amount of heat storage could improve. Therefore, for different locations as well as lengths of a baffle, the heat transfer and melting characteristic of gallium as a phase change material (PCM) in a rectangular cavity were investigated numerically. The cavity has the insulated upper and bottom walls. The sidewalls are regarded to have constant temperatures one higher and another lower than the melting point of gallium. The phase change process is modeled with the fixed grid-based enthalpy-porosity method coupled with the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. The isotherm lines and streamlines, as well as the liquid fraction and Nusselt number on the hot wall, are considered to present the results at a constant Rayleigh number equal to 106. The results show the baffle imposes noticeable improvement on the melting process of gallium in a rectangular cavity by influencing the feature of convective heat transfer. Investigating the different baffle’s locations (LX/L = 0.2 to 0.9) revealed that when the baffle located at the right half of the cavity, melting initiates from the left side, the more amount of PCM melts in comparison with the other cases. Ultimately, the dimensionless location of LX/L = 0.8 demonstrates the best melting characteristic and the most final liquid fraction. The more liquid-fraction, the more energy storing concluded. It also observed a dimensionless height of LY/L = 0.4 represents the most liquid-fraction compared to the heights of LY/L = 0.2, 0.3, and 0.4.

Miniature gallium phase-change cells for in situ thermometry calibrations in space

The melting point of gallium, 29.7646 °C, makes it a very convenient fixed point for in situ calibration of thermometry in space applications such as Earth observation. NPL and RAL Space have collaborated to develop a miniature ‘phase-change cell’ using gallium. This report describes the modelling, construction and thermal metrological performance of miniature phase change gallium cells. These cells are intended to be embedded in the calibration blackbody structure, near the temperature sensors, for the purpose of in situ recalibration of those sensors. In this study, the blackbody structure was simulated by a monolithic aluminium block, and the phase-change cell and thermometers were embedded within the block. A thermal model of the system was also developed using Comsol Multiphysics® and validated against the experimental results, which provides useful information on further optimisation of the system. Under the (realistic) test conditions in this study, the phase-change cell, containing 2.1 g of gallium, was able to produce clearly defined melting curves with a duration of several hours and melting range of less than 5 mK, which represents sufficient performance for the envisaged application. Overall it has been shown that the current design methodology is fit for purpose and represents a solid foundation for raising the technology readiness level sufficiently for in-flight use.

Measurement of the Melting Point of Gallium Using a Johnson Noise Thermometer

We measured the thermodynamic temperature of the melting point of gallium $T_{\mathrm {Ga}}$ using a Johnson noise thermometer (JNT) with an integrated quantum voltage noise source (IQVNS) as a reference. $T_{\mathrm {Ga}}$ was calculated using the fundamental constants recommended by the Committee on Data for Science and Technology (CODATA) for the revision of the International System of Units (SI). The measured $T_{\mathrm {Ga}}$ is consistent with the value defined in the International Temperature Scale of 1990.

The free electron gas primary thermometer using an ordinary bipolar junction transistor approaches ppm accuracy.

In this paper, it is demonstrated that the free electron gas primary thermometer based on a bipolar junction transistor is able to provide the temperature with an accuracy of a few parts per million. Its simple functioning principle exploits the behavior of the collector current when properly biased to extract the temperature. Using general purpose silicon transistors at the water triple point (273.16 K) and gallium melting point (302.9146), an accuracy of a few parts per million has been reached, constituting the simplest and the easiest to operate primary thermometer, that might be considered even for the redefinition of Kelvin.

Construction of Gallium Point at NMIJ

Two open-type gallium point cells were fabricated using ingots whose nominal purities are 7N. Measurement systems for the realization of the melting point of gallium using these cells were built. The melting point of gallium is repeatedly realized by means of the measurement systems for evaluating the repeatability. Measurements for evaluating the effect of hydrostatic pressure coming from the molten gallium existing during the melting process and the effect of gas pressure that fills the cell were also performed. Direct cell comparisons between those cells were conducted. This comparison was aimed to evaluate the consistency of each cell, especially related to the nominal purity. Direct cell comparison between the open-type and the sealed-type gallium point cell was also conducted. Chemical analysis was conducted using samples extracted from ingots used in both the newly built open-type gallium point cells, from which the effect of impurities in the ingot was evaluated.

Structural, mechanical, and magnetic properties of GaFe3N thin films

Using the density-functional theory, the structural, mechanical, and magnetic properties were investigated for different GaFe3N configurations: ferromagnetic, ferrimagnetic, paramagnetic, and nonmagnetic. Ferrimagnetic and high-spin ferromagnetic states exhibit the lowest energy and are the competing ground states as the total energy difference is 0.3 meV/atom only. All theoretically predicted values could be fully confirmed by experiments. For this, the authors synthesized phase pure, homogeneous, and continuous GaFe3N films by combinatorial reactive direct current magnetron sputtering. Despite the low melting point of gallium, the authors succeeded in the growth of GaFe3N films at a temperature of 500 °C. Those thin films exhibit a lattice parameter of 3.794 Å and an elastic modulus of 226 ± 20 GPa. Magnetic susceptibility measurements evidence a magnetic phase transitions at 8.0 ± 0.1 K. The nearly saturated magnetic moment at ±5 T is about 1.6 μB/Fe and is close to the theoretically determined magnetic moment for a ferrimagnetic ordering (1.72 μB/Fe).

Report on NIM-NMC bilateral comparison: SPRT calibration comparison from −190°C to 420°C

A bilateral comparison of local realization of the International temperature scale of 1990 (ITS-90) between National Institute of Metrology (NIM) and National Metrology Centre (NMC) was carried out over the temperature range from -190°C to 420°C. It involved six fixed points including the argon triple point, the mercury triple point, the triple point of water, the melting point of gallium, the freezing point of tin and the freezing point of zinc. In 2009, NMC asked NIM to participate in a bilateral comparison to link the NMC results to the Consultative Committee for Thermometry Key comparison 3 (CCT-K3) and facilitate the NMC's Calibration and measurement capabilities (CMCs) submission. This comparison was agreed by NIM and Asia Pacific Metrology Programme (APMP) in 2009, and registered in the Key Comparison Database (KCDB) in 2010 as CCT-K3.2. NMC supplied two 25 Ω fused silica sheath standard platinum resistance thermometers (SPRTs) as traveling standards. One of them was used at the Ga, Sn and Zn fixed points, while the other one was used at the Ar and Hg fixed point. NMC measured them before and after NIM measurement. During the comparison, a criterion for the SPRT was set as the stability at the triple point of water to be less than 0.3 mK. The results for both laboratories are summarized. A proposal for linking the NMC's comparison results to CCT-K3 is presented. The difference between NMC and NIM and the difference between NMC and the CCT-K3 Average Reference Value (ARV) using NIM as a link are reported with expanded uncertainties at each measured fixed point.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).