Anomalous behavior induced by water insertion in Molybdenum disulfide nanoflowers

2021 ◽  
Author(s):  
Anu Roshini ◽  
Chandrasekhar Malavika ◽  
Manoj Kumar ◽  
Ethirajalu Senthamarai Kannan
Keyword(s):  
Molybdenum Disulfide ◽  
Anomalous Behavior ◽  
Positive Temperature Coefficient ◽  
Optical Switches ◽  
Positive Temperature ◽  
Transport Channel ◽  
Pinched Hysteresis ◽  
Hysteresis Characteristics ◽  
Interesting Behavior ◽  
Red Radiation

Abstract The coexistence of negative photoconductivity and metallic-like behavior in conventional semiconductors is very uncommon. In this work, we report the existence of such unconventional physical properties in Molybdenum disulfide nanoflowers (MoS2-NF). This is achieved by making the surface of MoS2 hygroscopic by alcohol treatment and creating a transport channel that favors protonic over electronic conduction. On cooling the MoS2-NF in a heat sink, the excess water that condenses on the surface forms a proton (H3O+) wire which exhibits pinched hysteresis characteristics. The conductivity of MoS2 increased by two orders of magnitude in the proton-dominated conduction regime with an exceptionally high positive temperature coefficient of 1.3×104 Ω/K. Interestingly, MoS2-NF also exhibits strong negative photoresponse (NPC) at room temperature when illuminated with UV and infra-red radiation. This interesting behavior observed in MoS2 NF can be useful for energy harvesting applications and the realization of fast thermal memories and optical switches.

KANTHAL 70

Alloy Digest ◽  
1981 ◽  
Vol 30 (9) ◽  
Keyword(s):  
Operating Temperature ◽  
Heat Treating ◽  
Positive Temperature Coefficient ◽  
Pure Nickel ◽  
Voltage Source ◽  
Voltage Regulator ◽  
Positive Temperature ◽  
Automotive Applications ◽  
Resistance Thermometers ◽  
In Series

Abstract KANTHAL 70 alloy was designed to provide a high positive temperature coefficient to electrical resistance comparable with that of pure nickel; however, it has much higher electrical resistivity than pure nickel. This makes it useful as a voltage regulator when placed in series with another electrical device across a fluctuating voltage source. Kanthal 70 has a maximum recommended operating temperature of 600 C and is used widely in resistance thermometers and in various appliance and automotive applications. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: Ni-270. Producer or source: The Kanthal Corporation.

scholarly journals Thermal Noise Decoupling of Micro-Newton Thrust Measured in a Torsion Balance

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1357
Author(s):  
Linxiao Cong ◽  
Jianchao Mu ◽  
Qian Liu ◽  
Hao Wang ◽  
Linlin Wang ◽  
...  
Keyword(s):  
Thermal Noise ◽  
Rotation Axis ◽  
Electrostatic Force ◽  
Thermal Control ◽  
Positive Temperature Coefficient ◽  
Torsion Balance ◽  
Positive Temperature ◽  
Thermal Drift ◽  
Low Thrust ◽  
Z Domain

The space gravitational wave detection and drag free control requires the micro-thruster to have ultra-low thrust noise within 0.1 mHz–0.1 Hz, which brings a great challenge to calibration on the ground because it is impossible to shield any spurious couplings due to the asymmetry of torsion balance. Most thrusters dissipate heat during the test, making the rotation axis tilt and components undergo thermal drift, which is hysteretic and asymmetric for micro-Newton thrust measurement. With reference to LISA’s research and coming up with ideas inspired from proportional-integral-derivative (PID) control and multi-timescale (MTS), this paper proposes to expand the state space of temperature to be applied on the thrust prediction based on fine tree regression (FTR) and to subtract the thermal noise filtered by transfer function fitted with z-domain vector fitting (ZDVF). The results show that thrust variation of diurnal asymmetry in temperature is decoupled from 24 μN/Hz1/2 to 4.9 μN/Hz1/2 at 0.11 mHz. Additionally, 1 μN square wave modulation of electrostatic force is extracted from the ambiguous thermal drift background of positive temperature coefficient (PTC) heater. The PID-FTR validation is performed with experimental data in thermal noise decoupling, which can guide the design of thermal control and be extended to other physical quantities for noise decoupling.

Temperature Dependence of Hole Impact Ionization Coefficient in 4H-SiC Photodiodes

2009 ◽  
Vol 615-617 ◽  
pp. 311-314 ◽  
Author(s):  
W.S. Loh ◽  
J.P.R. David ◽  
B.K. Ng ◽  
Stanislav I. Soloviev ◽  
Peter M. Sandvik ◽  
...  
Keyword(s):  
Phonon Scattering ◽  
Impact Ionization ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Different Temperatures ◽  
Ionization Coefficients ◽  
Increasing Temperature ◽  
The Impact ◽  
Good Agreement ◽  
Ionization Rates

Hole initiated multiplication characteristics of 4H-SiC Separate Absorption and Multiplication Avalanche Photodiodes (SAM-APDs) with a n- multiplication layer of 2.7 µm were obtained using 325nm excitation at temperatures ranging from 300 to 450K. The breakdown voltages increased by 200mV/K over the investigated temperature range, which indicates a positive temperature coefficient. Local ionization coefficients, including the extracted temperature dependencies, were derived in the form of the Chynoweth expression and were used to predict the hole multiplication characteristics at different temperatures. Good agreement was obtained between the measured and the modeled multiplication using these ionization coefficients. The impact ionization coefficients decreased with increasing temperature, corresponding to an increase in breakdown voltage. This result agrees well with the multiplication characteristics and can be attributed to phonon scattering enhanced carrier cooling which has suppressed the ionization process at high temperatures. Hence, a much higher electric field is required to achieve the same ionization rates.

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