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With the rapid development of modern science and technology, the stability and reliability of electronic components become essential. Low-temperature drift resistors (LTDRs) are of importance owing to their excellent performance and stability in different temperature environments. LTDR technology is now widely used in the industrial field. This paper reviews the research status of LTDRs in order to provide reference for researchers and engineers in related fields. First, the basic principle of LTDRs is briefly discussed. A brief explanation of the mechanism behind low-temperature drift is illustrated. Second, the materials, types, and manufacturing processes of LTDRs are classified and discussed. The review ends with a brief conclusion concerning the challenges from mechanism to application and the future outlook. [ABSTRACT FROM AUTHOR]

Herein, in order to successfully create high-density La 0.67 Ca 0.33- x Sr x MnO 3 : Ag 0.15 (LCSMO: Ag) ceramics (0 ≤ x ≤ 0.05), this research combines sol-gel and solid-phase processes. LCSMO: Ag ceramics electrical transport and magnetic properties were thoroughly investigated. XRD verified that the high-purity orthorhombic perovskite structure (space group Pnma) was produced. As Sr doping rises, the grain size grows, the single electron bandwidth increases, the metal-insulator transition temperature (T MI) continues to climb, and temperature coefficient of resistance (TCR) and magnetoresistance (MR) steadily drop. When x = 0.04, the T MI reaches 302.2 K. At this time, the TCR peak (TCR peak) reaches 24.0 %·K−1 and the MR peak reaches 49.2 %. These results demonstrate that Sr may effectively raise the T MI of LCMO: Ag ceramics to room temperature while maintaining high TCR and MR Values, which benefits the material's potential applications in devices such as uncooled infrared detectors. [ABSTRACT FROM AUTHOR]

The influence of modernized three-electrode ion-plasma sputtering of a complex Fe–Si–B– (Cu, Nb)/(Ni, Mo) target on the structure and properties of sputtered films was studied. The formation of amorphous and nanocrystalline phases in Fe73Si15.8B7.2-(Cu, Nb)4 and Fe78.5Si6B14-(Ni, Mo)1.5 films with a coherent scattering region size of 1.6 nm and 12 nm, respectively, was established as a result of a modernized three-electrode ion - plasma sputtering. The thermal stability of metastable states of films as well as electrical and magnetic properties of freshly prepared and heat-treated films has been investigated. The conditions for obtaining films with low values of the temperature coefficient of electrical resistance (−0.9∙10−5 K−1) and coercive force (HC ∼11 A/m) have been determined. [ABSTRACT FROM AUTHOR]

Pt thin-film resistance temperature detectors (RTDs) have been fabricated by magnetron sputtering on various substrates, including silica, polyimide (PI) and LaAlO3 (LAO) (100) single crystal. The influences of different substrates on the performance of Pt thin-film RTDs have been studied. It is revealed that the substrates exhibit a significant dependence on the temperature coefficient of resistance (TCR). Silica, PI and LAO substrates yield TCRs of 3.2 × 10−3, 2.7 × 10−3 and 3.4 × 10−3 /K, respectively. The Pt thin-film RTDs on LAO substrate exhibit a significantly larger TCR, compared to most of the other reported values. These devices also demonstrate a fast response time of 680 μs, which is shorter than that of many other reported RTDs. Furthermore, Pt thin-film RTDs on PI substrates could serve as flexible detectors, maintaining a consistent linear relationship between resistance and temperature even when bent. [ABSTRACT FROM AUTHOR]

Graphene possesses weak electron-phonon interactions, small electron heat capacity, and broad-band absorption, which make it an excellent candidate as a fast and sensitive bolometer. This work studies the bolometric performance of fluorinated graphene (FG) films, which were synthesized using a vacuum filtration-assisted method with FG and chitosan. Thermal annealing (200-1000°C) under an Ar atmosphere was used to modulate the fluorine density. The electrical resistivity and thermal conductivity were measured from 320 to 10 K. As the ratio of F/C reduced from 4.06 to 0.003, the electrical resistivity decreased from 0.37 to 9.6 × 10-5 Ω·m at RT, and the thermal conductivity increased from 0.5 to 2.7 W·m-1·K-1 at RT. In addition, the higher fluorine density resulted in a higher temperature coefficient of resistance (TCR). A mildly reduced FG film with a F/C ratio of 4.06 exhibited the highest |TCR| of 1%·K-1 at 10 K and 0.48%·K-1 at 320 K. The temperature-dependent resistivity revealed that the electrical transport mechanisms are mainly due to a combination conduction processes of thermal activation and variable range hopping. The thermal activation energy reduced from 21 to 1 meV as the concentration of fluorine decreased, which confirms that the conductivity of FG is controlled by fluorinated structures and can be adjusted by thermal annealing treatment. Last, the bolometric performance of FG films was demonstrated across a wide range of wavelengths from ultraviolet to near-IR. The FG films can detect a human hand 25 cm away with good sensitivity and repeatability. For a sample with a suspended length of 1.2 mm, the response time was measured to be 436-449 ms. These results demonstrated that the FG films show great potential as flexible and sensitive bolometric IR sensors. [ABSTRACT FROM AUTHOR]

In this study, the characteristics of phosphorus-doped hydrogenated amorphous silicon carbide prepared by radio-frequency glow discharge decomposition of a mixture of silane (SiH4), methane (CH4) and hydrogen (H2) were investigated. Molecular vibration, surface morphology, dark electrical conductivity, and activation energy were analyzed. The gas phase composition of CH4 was varied in the range of 0.40–0.95 relative to SiH4, while the molar fraction of phosphine (PH3) in the gas phase was adjusted from 2.75% to 10%. It was observed that the molar fraction of carbon (C) in the film affects its homogeneity, resulting in the formation of regions rich in silicon (Si) and amorphous silicon carbide (a-SixC1−x), as well as the formation of nc-Si clusters, leading to lower surface roughness. The variation in electrical properties concerning doping and the molar fraction of carbon is consistently explained in this study. [ABSTRACT FROM AUTHOR]

This study analyzes the effect of the temperature coefficient of electric resistance on the thermal performance of a film heater for satellite applications. A heating element in the film heater was fabricated using silver paste and screen-printing technology. The temperature distributions of the film heater were numerically simulated on the basis of the heat transfer equation. The temperature coefficient of resistance was evaluated by measuring the film-heater temperature at various voltages using a forward-looking infrared (FLIR) camera. The results showed that the electric resistance linearly increased with a temperature variation. By considering the temperature coefficient of electric resistance, the error of numerical simulation decreased from 22.5% to 10%. The voltage required to reach the maximum allowable temperature at a given sink temperature was higher than the design voltage when the temperature coefficient was not considered. This indicated that greater power would be required to operate the film heater in real satellite applications. [ABSTRACT FROM AUTHOR]

La1-xCaxMnO3, as a candidate for thermal radiation detectors, has received more attention due to the quest for a higher temperature coefficient of resistance (TCR), however, the narrow high-TCR temperature range greatly limits its application in uncooled bolometer. In this paper, Mn3O4 - La1-xCaxMnO3 (x = 0–0.33) composite ceramics were prepared using the sol-gel method. A suitable TCR was achieved over a wide temperature range, including room temperature, by adjusting the Ca content. As the Ca content decreased, the resistivity (ρ) of the composite gradually increased at 300 K, and the positive TCR (PTC) peak shifted to a lower temperature. However, the negative TCR (NTC) was enhanced over a wider temperature range. When x = 0.05, the maximal NTC was −3.2%·K−1 within the range of 172 K–350 K and |TCR| > 2%·K−1, spanning a large temperature range around 180 K, including room temperature. These results strongly indicate that the composite, such as Mn3O4 - La1-xCaxMnO3, provides a new idea for uncooled bolometer/night vision. Highlights: Mn3O4 - La1-xCaxMnO3 composite ceramics with better density were prepared by sol-gel method. When x = 0.05, the sample Mn3O4 - La0.95Ca0.05MnO3 has a maximum |TCR| of −3.2%·K−1 in the range of 172 K–350 K, spanning the temperature range of about 180 K including room temperature. The wide temperature range and significant |TCR| values observed in the Mn3O4 - La1-xCaxMnO3 composite ceramics provide suitability for uncooled infrared bolometer applications under large temperature fluctuations. [ABSTRACT FROM AUTHOR]

This work studied a series of infrared detectors comprised of organic bulk heterojunctions to explain the origin of their broadband spectral response from the visible to the infrared spanning 1 to 8 μm and the transition from photonic to bolometric operation. Through comparisons of the detector current and the sub-bandgap density of states, the mid- and long-wave infrared response was attributed to charge trap-and-release processes that impact thermal charge generation and the activation energy of charge mobility. We further demonstrate how the sub-bandgap characteristics, mobility activation energy, and effective bandgap are key design parameters for controlling the device temperature coefficient of resistance, which reached up to -7%/K, better than other thin-film materials such as amorphous silicon and vanadium oxide.

High-performance Cu/Graphene composite wire synergistically strengthened by nano Cr 3 C 2 phase was directly synthesized via hot press sintering followed by severe cold plastic deformation, using liquid paraffin and CuCr alloy powder as the raw materials. Since graphene is in situ formed under the catalysis of copper powder during the sintering process, the problem that graphene is easy to agglomerate and difficult to disperse uniformly in the copper matrix has been solved. The nano Cr 3 C 2 -particles nailed at the interface favor to improve the interface bonding. The Cu/Graphene composite possesses high electrical conductivity, hardness, and plasticity. The composite wire exhibits high electrical conductivity of 96.93% IACS, great tensile strength of 488 MPa, and excellent resistance to softening. Even after annealing at 400°C for 1 h, the tensile strength can still reach 268 MPa with a conductivity of about 99.14% IACS. The wire's temperature coefficient of resistance (TCR) is largely reduced to 0.0035/°C due to the complex structure, which leads the wire to present low resistivity at higher temperatures. Such Cu/Graphene composite wire with excellent comprehensive performance has a good application prospect in high-power density motors.

The microstructural evolution of a single-phase Cu–12Mn–3Ni alloy during rolling and annealing has been investigated using electron backscatter diffraction and X-ray diffraction techniques. We have established the effects of microstructural characteristics on material strength and the temperature coefficient of resistance (TCR). The yield strength increased to 682 MPa after cold rolling with a strain of 0.87 due to an increase in the density of dislocation and low-angle grain boundary. A significant annealing softening is observed for the cold-rolled Cu–Mn–Ni alloy at temperatures above 400 °C, caused by recrystallization. The difference in yield strength for fully recrystallized alloys is mainly attributed to a difference in grain size, consistent with the Hall–Petch relationship. The addition of Ni and Mn enhanced the degree of difficulty in dislocation passing through the grain boundary, resulting in a higher Hall-Petch constant (274 MPa μm1/2) for Cu–12Mn–3Ni alloys when compared with pure copper. The TCR is related to grain size, dislocation and Cu–12Mn–3Ni alloy texture. Grain coarsening and reduced dislocation density can effectively enhance the resistance temperature stability. In addition, the strong copper texture formed during cold rolling results in a difference in TCR associated with the rolling direction (RD) and transverse direction (TD) of the cold-rolled sheet. The Cu–Mn–Ni alloy crystal exhibits a lower resistance sensitivity to temperature when the [110]Cu direction is parallel to the current direction compared with the [111]Cu direction parallel to the current direction. The absolute value of the TCR in the TD of the cold-rolled sheet is 10.2 × 10−6 °C−1, lower than that in the RD (19.3 × 10−6 °C−1).

Copper-graphene composites show remarkable electrical performance surpassing traditional copper conductors albeit at a micron scale; there are several challenges in demonstrating similar performance at the bulk scale. In this study, we used shear assisted processing and extrusion (ShAPE) to synthesize macro-scale copper-graphene composites with a simultaneously lower temperature coefficient of resistance (TCR) and improved electrical conductivity over copper-only samples. We showed that the addition of 18 ppm of graphene decreased the TCR of C11000 alloy by nearly 11 %. A suite of characterization tools involving scanning and transmission electron microscopy along with atom probe tomography were used to characterize the grain size, crystallographic orientation, structure, and composition of copper grains and graphene additives in the feedstock and processed samples. We posit that the shear extrusion process may have transformed some of the feedstock graphene additives into higher defect-density agglomerates while retaining the structure of others as mono-to-tri-layer flakes with lower defect density. The combination of these additives with heterogeneous structures may have been responsible for the simultaneous decrease in TCR and enhanced electrical conductivity of the copper-graphene ShAPE composites.

Knowledge of the emissivity and thermal conductivity of thin metal films used in conjunction with multilayer mirrors for the spectral selection of radiation in the extreme-ultraviolet- and "soft"-X-ray wavelength ranges is necessary in order to correctly calculate the heating of film elements at high heat loads. Heating is associated with absorption in the film of a significant fraction of the incident intensity, and the concept of a high heat load is somewhat arbitrary, since even at an absorbed intensity level on the order of 1 W/cm2 a freestanding film can be heated in vacuum by several hundred degrees. In the first approximation, to estimate the thermal-conductivity coefficient, one could use tabular values for bulk samples of the corresponding metals or use the well-known Wiedemann-Franz law which links the thermal conductivity and the electrical resistivity of the sample; the latter is easier to measure. However, an analysis of the published data indicates significant errors that are possible when using any of these approaches. Therefore, in this work, we measure the thermal conductivity directly by processing the temperature distribution obtained by infrared (IR) pyrometry over a film sample mounted on a heated frame or heated by a flowing electric current. The thermophysical characteristics (thermal conductivity and emissivity) are determined for samples of film absorption filters based on Mo, Al, and Be of submicron thickness (from 100 nm), as well as for films of copper: a metal whose bulk samples have high thermal and electrical conductivity. As expected, significant differences are found between the thermal and electrical properties of the film materials and the properties of the same metals in monolithic samples. [ABSTRACT FROM AUTHOR]

Recently, low‐temperature wearable strain sensors, referring to those working at sub‐zero temperatures, are attracting increasing attentions. However, the fabrication of low‐temperature strain sensors with large working ranges, high sensitivity, and good stability remains a major challenge. In this study, a novel low‐temperature wearable strain sensor is fabricated by depositing the silver nanoplates (Ag NPs)/carbon nanotubes (CNTs) composite onto a cured silicone (DS) substrate that is constructed by using a 3D printing technology. The synergistic effect of the Ag NPs with positive temperature coefficient of resistance (TCR) and the CNTs with negative TCR enable the Ag NPs/CNTs/DS strain sensor's TCR value (−1.16 × 10−5 K−1) to approach zero. The Ag NPs/CNTs/DS strain sensor demonstrates a high gauge factor over a large working range (0–100%) and fast response and recovery rates. Simultaneously, the Ag NPs/CNTs/DS strain sensor displays outstanding reproducibility and long‐term stability at −40 °C as well as excellent temperature cycling resistance under cyclic temperature of −40 to 60 °C. The Ag NPs/CNTs/DS strain sensor is further validated by incorporating into a wireless sensing system for remotely monitoring various human activities at −40 °C. This work provides wearable strain sensors for monitoring human‐machine interaction under low‐temperature condition. [ABSTRACT FROM AUTHOR]

Carbon nanostructures such as carbon nanotubes, graphene, and its multi‐layer derivatives exhiibit temperature‐dependent electrical conductivity. They can form percolated networks inside polymers, which render electrical conductivity to nanocomposites. Upon the formation of a percolated network, thermal energy applied to the material drives structural changes of the network, which manifest as changes in electrical conductivity. This principle is used to develop smart materials with self‐sensing temperature capabilities. This critical review covers past and present research on the electrical response to temperature (thermoresistivity) of carbon nanostructures and their polymeric nanocomposites. It covers few‐ and multi‐layer graphene, carbon nanotubes, carbon‐nanostructured arrays and fibers (yarns). The mechanisms driving the thermoresistive response of individual nanostructures, their arrays, and of their polymeric nanocomposites are addressed. The role of the nanostructured filler on the thermoresistivity of polymer nanocomposites depends on its morphology and concentration. For low filler concentrations, thermal expansion of the polymer may dominate over the inherent thermoresistivity of the filler. For high filler concentrations, or for densely packed arrays of carbon nanostructures, the inherent (quantum) thermoresistive response of the nanostructures becomes dominant. The review addresses recent progress in the field, highlights current issues, synthesizes published data, and provides outlooks and insights into future directions. [ABSTRACT FROM AUTHOR]

Data are presented on the effect of high-frequency three-electrode ion-plasma sputtering and modernized three-electrode ion-plasma sputtering of a Fe–Ag–Pt complex target on the structure and properties of deposited films. The formation of nanocrystalline films with a size of the coherent scattering region of 3.5 nm during high-frequency ion-plasma spraying has been established. With the modernized three-electrode ion-plasma sputtering, a nanocrystalline phase is formed with a coherent scattering region size of 3 nm and higher temperature stability, up to 660 K. There were investigated the thermal stability of the metastable states of the Fe–Ag–Pt films; the electro- and hysteresis magnetic properties of freshly prepared and heat-treated films. The conditions for obtaining films with low values of the temperature coefficient of electrical resistance (∼5 × 10−5 K−1) and coercive force (Hc ∼ 12 kA/m) are determined. [ABSTRACT FROM AUTHOR]

Purpose. Determination of the effect of temperature on the resistivity of composite coatings with different composition. Methodology. The surface electrical resistance was measured using the Kelvin method with a fourelectrode cell. The temperature of the heating surface was measured using a resistive temperature sensor. The thickness of the composite coating layer was determined using a micrometer. Findings. The change in the value of the electrical resistivity of composite coatings in the temperature range of 30-120 °C was determined. The composite coatings with polymer matrices of nitrocellulose and bakelite resin show a negative temperature coefficient of resistance. The composite coating based on polyvinyl butyral has a positive coefficient of resistance, which indicates the suitability of such a system for use in heating elements. The influence of residual moisture on the properties of composite coatings based on polyvinyl butyral and bakelite resin was revealed. A significant increase in resistance and the release of low molecular weight compounds is observed, which necessitates preliminary heat treatment of the coatings before its use. The influence of the polymer matrix on the resistivity value is significant. The lowest value of resistivity is observed in the composition based on nitrocellulose. The highest values were found in compositions based on bakelite resin and a mixture of bakelite resin and polyvinyl butyral. Originality. The influence of temperature on the electrical characteristics of conductive coatings and the value of temperature coefficients of resistance was determined. Practical value. The influence of cyclic heating and the need for preliminary heat treatment of samples before use have been determined. [ABSTRACT FROM AUTHOR]

The temperature coefficient of resistance (TCR) is the unique property of a material and plays a crucial role in defining the boundaries of electronic devices. Due to the semimetal behaviour of graphene, its TCR can be varied from near zero to very high and depends upon the doping, defects, and other structural properties. There is a significant impact of processing techniques and their parameters on the properties of graphene. Here, the effect of milling parameters on the crystallinity of graphene ink has been studied, and a 14% increase in crystallinity was found with the increase in milling time. The TCR of graphene ink-printed resistors has been analyzed from 123 to 423 K, and a 40% positive shift in TCR corresponding to variation in crystallinity has been observed. This methodology can be helpful to fabricate electronic components with variable TCR from single ink composition by just varying processing parameters. [ABSTRACT FROM AUTHOR]

This study analyzes the effect of the temperature coefficient of electric resistance on the thermal performance of a film heater for satellite applications. A heating element in the film heater was fabricated using silver paste and screen-printing technology. The temperature distributions of the film heater were numerically simulated on the basis of the heat transfer equation. The temperature coefficient of resistance was evaluated by measuring the film-heater temperature at various voltages using a forward-looking infrared (FLIR) camera. The results showed that the electric resistance linearly increased with a temperature variation. By considering the temperature coefficient of electric resistance, the error of numerical simulation decreased from 22.5% to 10%. The voltage required to reach the maximum allowable temperature at a given sink temperature was higher than the design voltage when the temperature coefficient was not considered. This indicated that greater power would be required to operate the film heater in real satellite applications.

Abstract Carbon nanostructures such as carbon nanotubes, graphene, and its multi‐layer derivatives exhiibit temperature‐dependent electrical conductivity. They can form percolated networks inside polymers, which render electrical conductivity to nanocomposites. Upon the formation of a percolated network, thermal energy applied to the material drives structural changes of the network, which manifest as changes in electrical conductivity. This principle is used to develop smart materials with self‐sensing temperature capabilities. This critical review covers past and present research on the electrical response to temperature (thermoresistivity) of carbon nanostructures and their polymeric nanocomposites. It covers few‐ and multi‐layer graphene, carbon nanotubes, carbon‐nanostructured arrays and fibers (yarns). The mechanisms driving the thermoresistive response of individual nanostructures, their arrays, and of their polymeric nanocomposites are addressed. The role of the nanostructured filler on the thermoresistivity of polymer nanocomposites depends on its morphology and concentration. For low filler concentrations, thermal expansion of the polymer may dominate over the inherent thermoresistivity of the filler. For high filler concentrations, or for densely packed arrays of carbon nanostructures, the inherent (quantum) thermoresistive response of the nanostructures becomes dominant. The review addresses recent progress in the field, highlights current issues, synthesizes published data, and provides outlooks and insights into future directions.

In this study, an experimental investigation was conducted to explore Ge1–xPbxOy as a candidate material for temperature-sensing layers in uncooled microbolometers. RF and DC sputtering techniques were used to deposit Ge1–xPbxOy thin films with various oxygen concentrations on silicon substrates at room temperature. The composition of the samples was experimentally analyzed using energy dispersive X-ray spectroscopy (EDX) that showed various oxygen concentrations. Atomic force microscopy (AFM) analysis showed excellent average surface roughness ranging from 0.6995 to 0.8660 nm. Increasing the concentration of oxygen up to 31% improved the thermoelectric and optical characteristics of the prepared Ge1–xPbxOy thin films. The highest temperature coefficient of resistance (TCR) of the fabricated samples was −3.85%/K for the Ge0.94Pb0.06O0.31 thin film. By using Essential McLeod software, optical simulation of the thin film samples was performed to assess the highest absorptance of the cavity microbolometer structure, which was 81.88% for the Ge0.94Pb0.06O0.31 thin film.

The physical properties of nanocrystalline systems of cadmium and zinc selenides have been studied experimentally and theoretically. The effect of temperature and various gaseous media on the specific conductivity of films of cadmium and zinc selenides has been experimentally studied. The values of the Fermi energy, the concentration of donor charge carriers in the conduction band, the activation energy of donors, and the temperature coefficient of resistance are theoretically calculated. It is shown that the calculated values correlate with the experimental ones, which will make it possible to predict the stability of the operation of semiconductor devices.

The Hot Disk method is a transient measurement method for the determination of thermal properties like the thermal conductivity, which is characterized by advantages such as a short measurement time or a low effort for the sample preparation. However, some difficulties related to measurements at elevated temperatures, which could be attributed to inaccuracies of the Temperature Coefficients of Resistance (TCRs), have been pointed out in the past. This paper presents a detailed investigation of the Hot Disk method for the determination of the thermal conductivity and contributes to a further improvement of its measurement accuracy. Subsequent to an extensive literature review of available reference materials for the thermal conductivity, measurements up to 750 °C were carried out with a Hot Disk TPS 2500 S with various Kapton and Mica sensors using three reference materials (Silcal 1100, Pyroceram 9606, Inconel 600). While room-temperature measurements confirmed the suitability of the reference samples as well as the independence of the measured thermal conductivity from the sensor, temperature-dependent measurements allowed the verification of the accuracy of the given TCRs. A set of optimized TCRs is proposed, with which the thermal conductivity of all three reference materials could be determined with an accuracy of 2 %. Furthermore, the measurement uncertainty of ± 5 % specified by the manufacturer could be confirmed. Hence, with the newly suggested TCRs, the Hot Disk method enables the determination of the thermal properties of a variety of materials even at high temperatures with high accuracy. [ABSTRACT FROM AUTHOR]

As a metal alloy, NiCr films have a relatively high resistivity and low temperature coefficient of resistance (TCR) and are widely used in electronic components and sensors. However, the resistivity of pure NiCr is insufficient for high-resistance and highly stable film resistors. In this study, a quaternary NiCrAlSi target (47:33:10:10, wt. %) was successfully used to prepare resistor films with resistivities ranging from 1000 to 10 000 μΩ cm and TCR within ±100 ppm/K. An oxygen flow was introduced during the sputtering process. The films exhibit high-temperature stability at 450 °C. The films were analyzed using Auger electron spectroscopy, x-ray diffraction, time-of-flight secondary-ion mass spectrometry, and x-ray photoelectron spectroscopy. The results show that the difference in the oxide proportion of the films caused the differences in resistivity. The near-zero TCR values were considered to be due to the competition between silicon and other metals. This study provides new insights into the electrical properties of NiCr-based films containing Si, which will drive the manufacturing of resistors with high resistivity and zero TCR. HIGHLIGHTS: • Resistor films with resistivities of over 10 000 μΩ cm were prepared using a quaternary NiCrAlSi target (47:33:10:10, wt. %) and reactive sputtering. • The resistances of the obtained resistors stayed nearly constant from 20 to 450 °C in vacuo. • The chemical compositions of the resistor films were determined using XPS, ToF-SIMS, and other methods. [ABSTRACT FROM AUTHOR]

In this work, we report the influence of annealing time on the electrical properties of Pt thin film resistance-temperature-detectors (RTD) with Ti adhesion layers. It is found that the temperature coefficient of resistance (TCR) of the Pt thin film RTD strongly depends on the air annealing time. Increasing the annealing durations from 1, 3, 10 to 60 min at 900 °C, the TCR tends to rise up firstly, and then drops down. A maximum TCR of 3.2 × 10−3/°C at 25 °C is achieved in the RTD annealed for 3 min, which is larger than most of other reported values. It is believed that the annealing time of 3 min may be sufficient to enlarge the grain size and to reduce the lattice defects, giving rise to the maximum TCR by decreasing the resistance at 25 °C. On the contrary, prolonging the annealing duration causes the interdiffusion and oxidation Ti significantly, which has been clearly evidenced by the depth analyses of X-ray photoelectron spectroscopy. Such interdiffusion and oxidation of Ti reduces the TCR by increasing the resistance. [ABSTRACT FROM AUTHOR]

The temperature dependence of the resistance of chromium films obtained by the thermal deposition on a substrate at room temperature was studied. It is shown that the most probable crystallite size in as-deposited films is 9 nm and increases by about 15% after the first annealing. According to the results of resistive studies, the structure formed after the first heating is stable and changes slightly during thermal cycling. It has been found that up to a temperature of approximately 200 °C, the temperature coefficient of resistance of the samples is negative and amounts to approximately −2 · 10−4 K−1. With a further increase in temperature, the temperature coefficient of resistance becomes positive, but remains significantly lower than the value corresponding to chromium in the bulk state. The observed effects are explained by the nanocrystalline structure of the samples. [ABSTRACT FROM AUTHOR]

The utilization of amorphous germanium-tin (Ge1-xSnx) semiconducting thin films as temperature-sensing layers in microbolometers was recently presented and patented. The work in this paper was performed as an extension of the latest study to acquire better Sn concentrations % for microbolometer applications. In this work, Ge1-xSnx thin films with various Sn concentrations %, x, where 0.31 ≤ x ≤ 0.48, were sputter-deposited. The elemental composition of each film was evaluated using energy-dispersive X-ray (EDX) spectroscopy, and the surface morphology was evaluated using atomic force microscopy (AFM), showing average roughness values between ~ 0.2 and 0.8 nm. Measurements of the sheet resistance versus temperature were performed and analyzed, revealing temperature coefficients of resistance, TCRs, ranging from –3.11%/K to –2.52%/K for x ranging from 0.31 to 0.40 above which the Ge1-xSnx thin film was found to exhibit metallic behavior at 0.40 < x ≤ 0.48. Empirical relationships relating the resistivity, TCR, and Sn concentration % of the amorphous Ge1-xSnx thin films were derived. One of the films with a 31% Sn concentration (Ge0.69Sn0.31) was used to fabricate 10×10 μm2 microbolometer prototypes using electron-beam lithography and lift-off techniques, and the microbolometer was fabricated on top of oxidized silicon substrates with no air gap between them. The noise behavior and the maximum detected signal of the fabricated microbolometer were measured. The signal-to-noise ratio, voltage responsivity, and noise equivalent power values of the prototypes were calculated. Finally, the expected performance of a proposed air-bridge microbolometer configuration was calculated. [ABSTRACT FROM AUTHOR]

In the phase diagram of iron pnictides, superconductivity arises at the border of antiferromagnetism, which raises the question of the role of symmetry of the gap and quantum criticality. Although more than 15-years of extensive research, the microscopic origin of the pairing symmetry inside the superconducting (SC) dome and its link to quantum criticality still remains elusive. Here, we report two new findings on BaFe2−xNixAs2: (1) A sharp peak in the x-dependence of the lower and upper critical fields, the SC critical current density Jc, the size of the jump in the specific heat ΔCel/T and the Sommerfeld coefficient (γ) at the optimum composition x = 0.10, where the SC transition temperature Tc reaches a maximum. Our obtained reliable values as a function of doping of the normal-state Sommerfeld coefficient increase with doping, illustrating the strong competition between magnetism and superconductivity and attributed to closing of spin density wave gap with Ni doping. (2) We show that doping induced a sudden change of the gap structure from nodeless to nodal. Our results imply that the superconductivity in BaFe2−xNixAs2 is closely linked to the quantum criticality and is characterized by a complex order parameter.

In this paper, the investigation of the crystal structure and electrophysical properties of Co/Ru/Co/Sub three-layer film systems with a Ru layer thickness dRu = 5-20 nm has been carried out. It is shown that for both as-deposited and annealed at 800 K thin-film samples the phase composition corresponds to hcp-Co + hcp-Ru. The dependence of resistivity and temperature coefficient of resistance as a function of dRu was received. It was demonstrated that the change in the resistivity value during the first cycle of heat treatment stays more significant than more Ru layer thickness. The value of temperature coefficient of resistance has an order of 10-4 and growth from 5.05×10-4 to 6.42×10-4 K-1 within the dRu range 0-20 nm.

In this work, oxygen vacancy-regulated La0.7Ca0.3MnO3-δ:Ag (LCMO:A) nanocomposite thin films on LaAlO3 (001) substrates were investigated to obtain films with large temperature coefficient of resistance (TCR) values. LCMO:A nanocomposite thin films were synthesized using pulsed laser deposition, and oxygen pressures during film deposition and annealing steps were optimized. As oxygen pressures increased, lattice parameter increased from 70 Pa to 100 Pa, Tp increased monotonically from 168 K to 282 K, and average Mn4+ concentration in the film increased as indicated by X-ray photoemission spectroscopy data. Record high TCR value of ∼37% K−1 was achieved in LCMO:A nanocomposite thin film prepared with optimal oxygen pressures, making this film promising candidate for applications in bolometers.

Background. The relevance of the research topic is due to the development of radio-electronic equipment, which requires an increase in the level of electrical parameters of the electronic component base. The aim of the work is to study and search for optimal modes of high-temperature annealing of multilayer thin-film resistive structures. Materials and methods. Multilayer thin-film resistors were obtained by thermal vacuum spraying of nichrome X20CrNi75Al and kermet K-20S at the UVN-71 installation. Results. The results of the study of processes occurring in the structure and at the interface of films in multilayer thin-film resistors as a result of exposure to high temperatures in vacuum and in air, their effect on the irreversible change in resistance and temperature coefficient of resistance are presented. Conclusions. Technological modes of high-temperature annealing have been obtained that extend the fitting life of multilayer thin-film resistors up to 20 %, with resistance instability not exceeding 0,4 %.

The structural stability of various structures (railroads, bridges, buildings, etc.) is lowered due to freezing because of the decreasing outside temperature in winter. To prevent damage from freezing, a technology for de-icing has been developed using an electric-heating composite. For this purpose, a highly electrically conductive composite film with multi-wall carbon nanotubes (MWCNTs) uniformly dispersed in a polydimethylsiloxane (PDMS) matrix through a three-roll process was fabricated by shearing the MWCNT/PDMS paste, through a two-roll process. The electrical conductivity and the activation energy of the composite were 326.5 S/m and 8.0 meV at 5.82 Vol% of MWCNTs, respectively. The dependence of the electric-heating performance (heating rate and temperature change) on the applied voltage and environmental temperature (from −20 °C to 20 °C) was evaluated. The heating rate and effective-heat-transfer characteristics were observed to decrease as the applied voltage increased, while they showed the opposite tendency when the environmental temperature was at sub-zero temperatures. Nevertheless, the overall heating performance (heating rate and temperature change) was maintained with little significant difference in the considered external-temperature range. The unique heating behaviors can result from the low activation energy and the negative-temperature (T) coefficient of resistance (R) (NTCR, dR/dT < 0) of the MWCNT/PDMS composite. [ABSTRACT FROM AUTHOR]

The ability of VO2 to undergo semiconductor-to-metal phase transition (SMT) upon heating makes it a very attractive material for uncooled bolometers. The SMT of VO2 represents a large temperature coefficient of resistance, which is an important parameter for the development of highly responsive microbolometers. However, other characteristics of the SMT of VO2 such as its high transition temperature (341.2 K), the sharpness of the transition, its hysteresis, and the high room temperature resistivity limit the performance of this material in microbolometers. In this work, we grow a high-quality epitaxial ultrathin film VO2 on c-plane Al2O3 by pulsed laser deposition. The low deposition temperature and tuning the oxygen partial pressure during the growth process enable control over the grain size and oxygen vacancy concentration. This allowed controlling the SMT parameters of the samples. In particular, we show that the high density of grain boundaries associated with nanosized grains suppresses the thermal hysteresis of the SMT. Simultaneous control over the density of oxygen vacancies and the size of grains enables the adjustment of the temperature coefficient of resistance, room temperature resistivity, SMT temperature, sharpness, and thermal hysteresis toward suitable values for the fabrication of efficient VO2-based uncooled bolometers. Compared with other VO2 fabrication methods, this approach can be viewed as a simpler alternative for VO2 fabrication with favorable properties for practical bolometer applications. [ABSTRACT FROM AUTHOR]

The influence of carbon nanotube (CNT) dispersions on the electrical properties and noise signal amplitude of V O x films is investigated. For a critical range of the CNT dispersion density on V O x films, the intrinsic properties of the V O x films are modified by the CNTs. The CNT concentrations reported in this work are about 0.3 μ g/cm 2 and 1.6 μ g/cm 2 , allowing for low density and high density dispersions on the V O x film surface to be investigated. These values are higher than the percolation threshold of about 0.12 μ g/cm 2 for these films. The composite film exhibits a significant reduction in the temperature coefficient of resistance (TCR) (from ≈3.8% K − 1 to ≈0.3% K − 1 ) for high density dispersions. In contrast, while V O x –CNT composites with low density single wall CNT dispersions exhibit no significant change in TCR values, an approximate two orders of magnitude reduction in the low frequency 1/f noise is measured. The noise signal amplitude measured at 0.1 V and at 1.0 Hz reduces from 6 × 10 − 5 V / (H z) for V O x films to 5 × 10 − 7 V / (H z) for the low density SWCNT dispersion on V O x film and to 3 × 10 − 6 V / (H z) for the low density MWCNT dispersion on V O x film. The CNT concentration is the critical factor for yielding the observed changes in conductivity and low frequency noise. The results presented in this work provide a better understanding of V O x -based composites, thereby enabling the development of new, versatile and functional materials for device applications. [ABSTRACT FROM AUTHOR]

Temperature dependence of electrical conductivity/resistivity of CNT networks (dry or impregnated), which is characterised by a temperature coefficient of resistance (TCR), is experimentally observed to be negative, especially for the case of aligned CNT (A-CNT). The paper investigates the role of three phenomena defining the TCR, temperature dependence of the intrinsic conductivity of CNTs, of the tunnelling resistance of their contacts, and thermal expansion of the network, in the temperature range 300–400 K. A-CNT films, created by rolling down A-CNT forests of different length and described in Lee et al., Appl Phys Lett, 2015, 106: 053110, are investigated as an example. The modelling of the electrical conductivity is performed by the nodal analysis of resistance networks, coupled with the finite-element thermomechanical modelling of network thermal expansion. The calculated TCR for the film is about −0.002 1/K and is close to the experimentally observed values. Comparative analysis of the influence of the TCR defining phenomena is performed on the case of dry and impregnated films. The analysis shows that in both cases, for an A-CNT film at the studied temperature interval, the main factor affecting a network's TCR is the TCR of the CNTs themselves. The TCR of the tunnelling contacts plays the secondary role; influence of the film thermal expansion is marginal. The prevailing impact of the intrinsic conductivity TCR on the TCR of the film is explained by long inter-contact segments of CNTs in an A-CNT network, which define the homogenised film conductivity. [ABSTRACT FROM AUTHOR]

The temperature coefficient of resistance (TCR) determines the electrical performance of materials in electronics. For a carbon nanotube (CNT) nanocomposite, change of resistivity with temperature depends on changes in CNT intrinsic conductivity, tunnelling thresholds and distances, matrix' coefficient of thermal expansion, and other factors. In our study, we add one more influencing factor–the degree of cure. Complexities of the curing process cause difficulties to predict, or even measure, the curing state of the polymer matrix while uncertainty in the degree of cure influences TCR measurements leading to biased values. Here we study the influence of the cure state on the TCR of a single-walled CNT/epoxy polymer nanocomposite. For the given degree of cure, TCR measurements are conducted in the temperature range 25–100 °C, followed by the next 24 h of post-curing and a new cycle of measurements, 8 cycles in total. We find that contrary to industry practice to expect a high degree of cure after 3 h at 130 °C, the curing process is far from reaching the steady state of the material and continues at least for the next 72 h at 120 °C, as we observe by changes in the material electrical resistivity. If TCR measurements are conducted in this period, we find them significantly influenced by the post-curing process continuing in parallel, leading in particular to non-monotonic temperature dependence and the appearance of negative values. The unbiased TCR values we observe only when the material reaches the steady state are no longer influenced by the heat input. The dependence becomes steady, monotonically increasing from near zero value at room temperature to 0.001 1/°C at 100 °C. [ABSTRACT FROM AUTHOR]

This work presents the results of the study of structural and electrical transport properties of the iron-insulator discontinuous multilayers (DMIMs). SiO 2 , HfO 2 , and MgO were chosen as the materials for the insulating layers. The discontinuous multilayers were prepared by the sequential magnetron sputtering on ceramic substrates. Obtained systems were annealed at different temperatures in an Ar + N 2 (2 %) environment using an annealing furnace with a continuous gas flow. Crystal structure analysis showed that the effect of annealing on the crystal structure of the samples varies and depends on the annealing temperature and the type of insulator. It has been demonstrated that the formation of iron oxide during annealing can be reduced by using HfO 2 as the insulating layer material. The resistivity and temperature coefficient of resistance variation with temperature and the effective thicknesses of the ferromagnetic layers were analyzed. • The dependence of electrical transport properties of the DMIMs [Fe/I] n on the type of insulator has been investigated. • The annealing effect on the sample's crystal structure depends on the annealing temperature and the type of insulator. • For all systems with d Fe = 2–3 nm, the insulator regime of conductance was observed regardless of the type of insulator. • In the case of [Fe/HfO 2 ] 10 /Sub systems, peculiarities in the temperature dependence of resistivity and TCR are observed. [ABSTRACT FROM AUTHOR]

With growing efforts of electrification, aluminum's role as a light-weight conductor material has become increasingly prominent. There is a critical need to improve the electrical performance of aluminum at room temperature and high operating temperatures. In this study, the effect of graphene nanoparticle additives on the electrical performance of a non-heat treatable alloy were (AA3003) explored. Graphene's unusual structure and electronic properties were used to improve AA3003 properties. Here, the effects of graphene on the evolution of electrical properties and microstructural features have been explored on lab scale hot extruded AA3003-graphene composites. Hot pressing schedules and extrusion temperatures were varied to investigate changes in intermetallic dispersion characteristics in the presence of dispersed graphene. We measured a reduction of 10.3 % in the temperature coefficient of resistance in the AA3003 sample with 0.05 wt% graphene extruded at 400 °C, along with a maximum increase of 1.1 % in electrical conductivity at 20 °C. Increasing the hot-pressing times up to 8 hours was also found to consistently increase the electrical conductivity, due to increased precipitation of intermetallic phases. Despite being a non-heat treatable alloy, AA3003 displays interesting precipitation dynamics and grain recrystallization trends that can be modulated with varying levels of heat treatment, graphene concentrations, and hot extrusion process parameters. [Display omitted] • AA3003 temperature coefficient of resistance decreased by >10 % by graphene addition. • Improved performance by optimized hot-pressing parameters, extrusion temperatures. • AA3003 precipitation dynamics modulated by processing conditions, graphene presence. [ABSTRACT FROM AUTHOR]

For the perovskite manganite La 1- x Ca x MnO 3 , achieving high temperature coefficient of resistance (TCR) and magnetoresistance (MR) is the key to realize its potential applications. In this study, high-quality La 0.67 Ca 0.33 Mn 0.97 Co 0.03 O 3 :Ag x polycrystalline ceramics were prepared by the sol-gel method. The results show that Ag doping has important impact on metal-insulator and ferromagnetic-paramagnetic transitions. A Ag doping amount increases, the grain size of the samples increases at x = 0.05 and then decreases. The doping of Ag can improve the crystalline quality of the samples and enhance the connectivity between grains, thereby improving the metallicity of the system. Additionally, with Ag doping amount increases, the resistivity of the samples gradually decreased, while the Curie temperature and the metal-insulator transition temperature gradually increased. Especially after Ag doping, both the TCR peak (TCR peak) and the MR peak (MR peak) values are significantly improved. The TCR peak reaches 65.2%·K−1 at x = 0.1, while the MR peak is as high as 82.6% at x = 0.05 under 1 T magnetic field. Doping perovskite manganite ceramics with Co and Ag can greatly optimize their TCR and MR, favoring the potential applications of these materials. [ABSTRACT FROM AUTHOR]

Graphene membranes act as temperature sensors in nanoelectromechanical devices due to their excellent thermal and high-temperature resistance properties. Experimentally, reports on the sensing performance of graphene mainly focus on the temperature interval under 400 K. To explore the sensing performance of graphene temperature sensors at higher temperature intervals, micro-fabricated single-layer graphene on a SiNX substrate is presented as temperature sensors by semiconductor technology and its electrical properties were measured. The results show that the temperature coefficient of the resistance value is 2.07 × 10−3 in the temperature range of 300–450 K and 2.39 × 10−3 in the temperature range of 450–575 K. From room temperature to high temperature, the "metal" characteristics are presented, and the higher TCR obtained at higher temperature interval is described and analyzed by combining Boltzmann transport equation and thermal expansion theory. These investigations provide further insight into the temperature characteristics of graphene. [ABSTRACT FROM AUTHOR]

This article presents modern structural and technological solutions for the manufacture of combined thin-film resistive structures with temperature self-compensation and strain-resistant sensors based on them, reaching values of the temperature coefficient of resistance of no more than ±1 × 10–6 K–1 and a permissible deviation and instability of resistance of no more than ±(0.01–0.02)%. Thin-film resistors are made in a chip design with a standard size of 0805. Thin-film strain gauges are obtained on a silicon substrate, where the sensitive elements of the pressure sensor are formed by plasma-chemical etching with vertical walls. The resistive structure is made of a metal-silicide alloy having a negative sign of the temperature coefficient of resistance, and a compensation layer of nickel sequentially sputtered in a single technological cycle, having a positive sign of the temperature coefficient of resistance much larger in modulus. By lithography methods, the resistive structure is divided into two series-connected resistance sections with opposite signs of the temperature coefficient of resistance. Changing the resistance by removing the material of the film element with a laser beam leads to a change in the ratio between the resistance sections of the thin-film resistive structure, thus leading to a change in the value of the temperature coefficient of resistance of the thin-film resistor as a whole. [ABSTRACT FROM AUTHOR]

In the context of intelligent components in industrial applications in the automotive, energy or construction sector, sensor monitoring is crucial for security issues and to avoid long and costly downtimes. This article discusses component-inherent thin-film sensors for this purpose, which, in contrast to conventional sensor technology, can be applied inseparably onto the component's surface via sputtering, so that a maximum of information about the component's condition can be generated, especially regarding deformation. This article examines whether the sensors can continue to generate reliable measurement data even after critical component loads have been applied. This extends their field of use concerning plastic deformation behavior. Therefore, any change in sensor properties is necessary for ongoing elastic strain measurements. These novel fundamentals are established for thin-film constantan strain gauges and platinum temperature sensors on steel substrates. In general, a k-factor decrease and an increase in the temperature coefficient of resistance with increasing plastic deformation could be observed until a sensor failure above 0.5% plastic deformation (constantan) occurred (1.3% for platinum). Knowing these values makes it possible to continue measuring elastic strains after critical load conditions on a machine component in terms of plastic deformation. Additionally, a method of sensor-data fusion for the clear determination of plastic deformation and temperature change is presented. [ABSTRACT FROM AUTHOR]

The regularities of changes in the concentration of an electrically active dopant in a nanostructured silicon film by changing the electrical resistivity depending on the doping conditions were investigated. The dependences of the changes in the obtained structures doped with rare-earth elements, such as La, Eu, Sm, Dy, Gd (lanthanides), on nanostructured silicon films are determined. The regularities of the obtained films changes and the temperature coefficient of resistance (TCR) change depending on the formation conditions are established. The regularities of the TCR are shown depending on the selected conditions for doping or non-doping of nanostructured silicon films with various impurities. It is shown that the main conditions under which the effect and change in the temperature coefficient of resistors resistance on thin films using rare-earth elements, such as oxygen, boron and phosphorus in the bulk of the film, is considered to be the temperature effect after deposition.

This paper reports the synthesis of indium tin oxide (ITO) nanoparticles and the effect of annealing temperature on the microstructural and electrical properties of ITO thin films. The synthesized ITO (90:10) nanoparticles are deposited at 29°C using E beam evaporation to form ITO thin films and annealed at 200, 400 and 500°C. The microstructural properties are investigated using XRD and AFM , and electrical properties such as temperature coefficient of resistance (TCR) and gauge factor are investigated using four-probe and four-point beam bending method, respectively. The investigations results reveal an increase in grain size, carrier concentration and gauge factor with an increase in the annealing temperature. The absolute value of TCR is constant at high temperatures for the film annealed at 500°C. The ITO thin film annealed at 500°C shows improved morphological and electrical properties and can be used for the development of sensors operating at high temperature. [ABSTRACT FROM AUTHOR]

Electrophysical properties of nanostructured (Ni80Fe20)xAu1-x thin films containing from 20 to 52 at.% of Au were investigated. All samples are characterized by metallic behavior upon annealing within the temperature range from 300 to 750 K. It was demonstrated that the resistivity is sensitive to the composition of the samples. Their value for the sample with 20 at.% of Au differs five times in comparison with the sample with 52 at.% of Au. The slope of the temperature dependence of resistivity depends on the composition of the samples too. This is caused by the effectiveness of electron–phonon interaction and peculiarities of the morphology of the samples. The temperature coefficient of resistance takes a positive value, has an order of 10−3 K−1, and grows with an increase of Au content. [ABSTRACT FROM AUTHOR]

At the phenomenological level, a theoretical analysis of the concentration dependence of the thermalresistance coefficient (βТ), strain sensitivity coefficient (SC) and Curie temperature (ΘС) for film high-entropysolid solutions based on Fe, Ni, Co, Cu, Cr was carried out. It was found that βТ of 4- and 5-component filmalloys varies within (1,00-1,75).10 – 3 К – 1, and SC – (4.00-5.75) units, which corresponds well to the data forsingle-component metal films. It was concluded that, from the point of view of βТ and SC, solid solutions ofHEA have no advantage over single-component films, but they can be more effective sensitive elements ofvarious sensors due to the thermal stability of the phase composition. The situation is different in the caseof ΘС, when ΘС can decrease or increase by 350-400 K. Since the information about the HEA domain structureis limited, we assume that the domain structure is realized in magnetic granules based on Cu atoms. But inthis case, the size effect can cause a ΘС decrease, which, unfortunately, we could not take into account withinour concept of additivity of the physical quantities of the solid solution of HEA [ABSTRACT FROM AUTHOR]

Thin film platinum resistive thermometers are conventionally applied for resistance thermometry techniques due to their stability and proven measurement accuracy. Depending upon the required thermometer thickness and temperature measurement, however, performance benefits can be realized through the application of alternative nanometallic thin films. Herein, a comparative experimental analysis is provided on the performance of nanometallic thin film thermometers most relevant to microelectronics and thermal sensing applications: Al, Au, Cu, and Pt. Sensitivity is assessed through the temperature coefficient of resistance, measured over a range of 10â€"300 K for thicknesses nominally spanning 25â€"200 nm. The interplay of electron scattering sources, which give rise to the temperature-dependent TCR properties for each metal, are analyzed in the framework of a Mayadasâ€"Shatzkes based model. Despite the prevalence of evaporated Pt thin film thermometers, Au and Cu films fabricated in a similar manner may provide enhanced sensitivity depending upon thickness. These results may serve as a guide as the movement toward smaller measurement platforms necessitates the use of smaller, thinner metallic resistance thermometers. [ABSTRACT FROM AUTHOR]