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Abstract The oxidation-resistance of thin film sensors, particularly at high temperatures, is critical for the lifetime and performance of the sensor. The preparation and oxidation-resistance of an Al 2 O 3 /ZrBN-SiCN/Al 2 O 3 composite film with a sandwich-structure was performed using reactive magnetron sputtering. The microstructure evolution of the composite film is examined herein using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. Oxygen diffusion was significantly inhibited by the formation of crystalline Al 2 SiO 5 and Zr-B-C amorphous phase inside the composite film. The Pt-13%Rh/Pt thin film thermocouple (TFTC) with the Al 2 O 3 /ZrBN-SiCN/Al 2 O 3 composite film as a protective layer was fabricated and calibrated. Both the stability and lifetime of the TFTC was significantly enhanced for temperatures up to 1000 ℃. The test error of the TFTC was reduced by half, compared with that of the TFTC with the Al 2 O 3 protective layer, indicating an excellent oxidation-resistant performance of the composite film. [ABSTRACT FROM AUTHOR]

Electrical insulation of nickel-based superalloy substrate, especially at high temperature range, is one of the major challenges for the reliability and stability of the integrated thin-film sensors. Here, we report a solution-processed approach to fabricating high-temperature, electrically insulating coatings on Ni-based superalloy substrates. NiCrAlY coatings were fabricated by DC magnetron sputtering and heat-treated, and then Al 2 O 3 films were deposited by sol-gel method. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy were used to characterize the composition, phase, microstructure and morphology of these composite coatings. The electrical resistance of the composite coating was measured as a function of temperature up to 800 °C. Electrical resistance greater than 1 MΩ were consistently achieved from 600 °C to 800 °C. Moreover, this insulating coating survived thermal shock and thermal fatigue tests without cracking or delaminating. A type S thin-film thermocouple was prepared on the composite coating to verify its high-temperature electrical insulation performance. [ABSTRACT FROM AUTHOR]

Thin film thermocouples could provide precise temperature measurement of the hot components of gas turbine engines with fast response in harsh environments. ITO thin films were prepared by radio frequency magnetron sputtering in pure argon atmosphere and annealed in air at 1000 °C. The variation of the microstructure and electrical properties of indium tin oxide thin films with annealing was disclosed. ITO/Pt thin film thermocouple was fabricated on Ni-based superalloy substrate by sputtering with stencil mask. And the thermoelectric performance and stability of the thin film thermocouples were characterized with temperature up to 1100 °C. [ABSTRACT FROM AUTHOR]

Platinum (Pt) thin-film resistance temperature detector was fabricated on the flexible Hastelloy tapes using magnetron sputtering and MEMS processes. NiCrAlY buffer layer and AlON/Al 2 O 3 insulating layer were deposited on the tapes for stress release and electrical insulation. Post annealing was applied to improve the stability of the sensors. The performance of the sensor was calibrated with temperature up to 550 °C. Compared with the sensor on the alumina ceramic substrate, the sensor on Hastelloy tapes have much smaller thermal hysteresis, higher linearity and excellent stability. Moreover, this flexible sensor can be easily integrated with the metallic components by the welding and the maximum curvature of the sensor is 2 cm−1. This Pt thin-film temperature sensor has great potential in the surface temperature measurement of hot components in harsh environment. • This Hastelloy tape based RTD has small thermal hysteresis, higher linearity and excellent stability. • AlON/Al 2 O 3 structure ensures the electrical insulation between the Pt film and the metallic substrate. • This flexible sensor can be easily integrated with metallic components for surface temperature measurement. [ABSTRACT FROM AUTHOR]

In order to measure the surface temperature of aerospace hot-end components accurately, AlN thin film temperature measurement technology was explored. In this research, C-axis preferred orientation AlN thin film was deposited on Ni-based superalloy substrates by medium frequency (MF) reaction magnetron sputtering. Effect of temperature on the lattice structure of AlN thin film was studied. X-ray diffraction results show that the diffraction angles (2 θ) of AlN thin films shift to the left side monotonously with the increase of annealing temperature and annealing time. Based on this phenomenon, the maximum temperature experienced by the film can be deduced according to 2 θ values. A temperature interpretation algorithm equation was established with MATLAB. The algorithm is a binary linear equation, whose dependent variable is 2 θ and the independent variables are annealing temperature and annealing time. Then, temperature interpretation software was developed with Visual Studio 2019. The temperature interpretation range is 700–1200 °C and the relative interpretation error is less than 4.26%. [ABSTRACT FROM AUTHOR]

In this work, we propose a hydrogen sensor to realize ppb-level hydrogen detection at a lower temperature. To fabricate the sensor, foamed nickel was thermally oxidized in bismuth oxide vapor to form the Bi-doped oxidized nickel foam, and Pd nanoparticles were further deposited on its surface by magnetron sputtering. This sensor possesses a unique phenomenon, that is, the response of the sensor does not decline due to repeated hydrogen charging and discharging as same as most hydrogen sensors, but keeps increasing and reaches balance eventually. The Bi3+ doping leads to a reduction in the thickness of the NiO hole accumulation layer, which contributes to the high response. The Bi5+ self-doping occurring during the repeated cycle test further promotes oxygen adsorption, so that the sensor response is continuously improved. As a result, the response of the Pd-Bi-OFN sensor to 1% hydrogen is as high as 580% in the air, and the detection limit is as low as 20 ppb at a lower temperature of 75 °C. Meanwhile, the sensor possesses high selectivity, great humidity stability, and long durability. This work provides an outstanding guidance to fabricate reliable ppb-level hydrogen sensors. • A novel hydrogen sensor based on Pd-modified and Bi-doped NiO was fabricated. • The detected limit of the hydrogen sensor is as low as 20 ppb at 75 °C. • Long-term testing continuously improves the sensor response until reaching balance. • A Bi5+ self-doping phenomenon was first reported in the studies of gas sensors. [ABSTRACT FROM AUTHOR]

• Novel H 2 sensor based on Pd nanoparticles loaded on oxidized Ni foam is fabricated. • Ppb-level H 2 can be stably detected by the sensor activated by 4 % H 2 treatment. • The activated mechanism of the sensor is proposed firstly and analyzed innovatively. • H 2 with a large concentration range (7 ppb-2 %) can be detected by the sensor at 30 °C. • It has high cycling stability, humidity stability and selectivity, and is suitable for RT. A novel hydrogen sensor with ppb-level detection limit was fabricated in this work. The oxidized Ni foam was chosen as the substrate, whose 3D porous structure contributed to gas circulation, and insulating NiO nanowrinkles provided a large specific surface area. Pd nanoparticles as hydrogen sensing material were loaded on it by magnetron sputtering. Unprecedentedly, the incompletely reversible lattice distortion caused by the generation of Pd-H β-phase was applied to activate the hydrogen sensor, which significantly improved the response to low concentration H 2. The activation mechanism was proposed firstly and analyzed innovatively. Therefore, hydrogen with a large concentration range (7 ppb ∼ 2 %) can be detected by the prepared sensor, and the response changes regularly as H 2 concentration changes. The optimum temperature of the sensor is 30 °C, and it exhibits high cycling stability, humidity stability and gas selectivity. This work provides a brand new strategy for the development of low detection limit hydrogen sensors. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mid-frequency AC sputtering provides significant advantages. [•] Double-sided Y2O3 seed layers are prepared with high speed of 35m/h. [•] Sputtering voltage control was used to deposited epitaxial high quality films. [•] Coherent textures and surfaces of both sides of CeO2/YSZ/Y2O3 are achieved. [ABSTRACT FROM AUTHOR]

Epitaxial LaMnO (LMO) films, serving as the cap layer for high performance coated conductors, have been successfully fabricated on homo-epi MgO/Ion-Beam Assisted Deposition (IBAD)-MgO templates on polycrystalline hastelloy by radio-frequency magnetron sputtering. Crystalline structure and morphology analysis revealed good texture, and a smooth, dense, and crack-free surface. Highly epitaxial 500 nm thick YBaCuO (YBCO) films with the full width at half-maximum values around 3.8 and 1.2 for the ϕ-scan of (103) and rocking curve of (005) YBCO, respectively, exhibited the self-field critical current density ( J) of 1.2 MA/cm at 77 K. [ABSTRACT FROM AUTHOR]

Abstract: The CeO2 cap layer were deposited on yttria-stabilized zirconia (YSZ)/Y2O3 buffered Ni–5at.%W (Ni–W) substrate by direct-current magnetron reactive sputtering for YBa2Cu3O7−δ (YBCO) coated conductors. Morphology evolvements of CeO2 cap layers on the substrate temperature and deposition rate were investigated. Atomic force microscope exhibited the grain shape grown from granule to cluster with the temperature increasing, the grain size decreased as the sputter power increased, and their mechanisms were proposed. The root mean square surface roughness of the best sample was 1.8nm over a 3μm×3μm area. Moreover, YBCO films deposited on the CeO2/YSZ/Y2O3 buffered Ni–W substrates using pulsed laser deposition (PLD) achieved the critical current density J c of about 1.72MA/cm2 at 77K and self field. [Copyright &y& Elsevier]

• Al 2 O 3 /ZrB 2 thin films exhibit a favorable thermal stability at 600 °C for 30 h. • Al 2 O 3 /ZrB 2 thin films exhibit a high average infrared reflectance of 0.86 after annealing at 750 °C for 2 h. • Al 2 O 3 thin film can effectively prevent diffusion of oxygen atoms during the heat treatment process. In the present research, ZrB 2 thin films and Al 2 O 3 /ZrB 2 multilayer were deposited on silicon substrates using magnetron sputtering method. To investigate the thermal stability of the thin films, films were annealed at temperatures of 600 °C, 700 °C and 800 °C, respectively. Results from X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectrometer (FTIR) suggested that ZrB 2 thin films were severely oxidized at 700 °C for 2 h which caused the obvious increase of infrared emissivity. In contrast, double-layer-structure Al 2 O 3 /ZrB 2 thin films exhibited a low infrared emissivity of 0.16 after annealing at 750 °C for 2 h. Similarity, ZrB 2 thin films showed a rise of infrared emissivity after annealing at 600 °C for 10 h. However, double-layer-structure Al 2 O 3 /ZrB 2 thin films exhibited a favorable thermal stability at 600 °C for 30 h with a low average infrared emissivity of 0.13 in the waveband of 2–14 μm. Compared with ZrB 2 thin films, double-layer-structure Al 2 O 3 /ZrB 2 thin films could work as low infrared emissivity layers at higher temperature for longer time for the reason that the addition of Al 2 O 3 thin film can effectively prevent diffusion of oxygen in air during the heat treatment process. [ABSTRACT FROM AUTHOR]

A highly sensitive and flexible hydrogen sensor based on organic nanofibers decorated by Pd nanoparticles (NPs) was designed and fabricated for low-concentration hydrogen detection. Pd NPs were deposited on organic nanofiber materials by DC magnetron sputtering. The temperature dependence of the sensitivity at 25 ppm H2 was characterized and discussed, and the maximum response of the sensor increased linearly with increasing measurement temperature. Performances of the hydrogen sensor were investigated with hydrogen concentration ranging from 5 ppm to 50 ppm. This sensor exhibits high sensitivity, with the response up to 6.55% for H2 as low as 5 ppm, and the output response of the hydrogen sensor increased linearly with the square root of hydrogen concentration. A cycling test between pure nitrogen and 25 ppm hydrogen concentration was performed, and the hydrogen sensor exhibited excellent consistency. [ABSTRACT FROM AUTHOR]