Temperature coefficient

Summary

A temperature coefficient describes the relative change of a physical property that is associated with a given change in temperature. For a property R that changes when the temperature changes by dT, the temperature coefficient α is defined by the following equation: :\frac{dR}{R} = \alpha,dT Here α has the dimension of an inverse temperature and can be expressed e.g. in 1/K or K−1. If the temperature coefficient itself does not vary too much with temperature and \alpha\Delta T \ll 1, a linear approximation will be useful in estimating the value R of a property at a temperature T, given its value R0 at a reference temperature T0: :R(T) = R(T_0)(1 + \alpha\Delta T), where ΔT is the difference between T and T0. For strongly temperature-dependent α, this approximation is only useful for small temperature differences ΔT. Temperature coefficients are specified for various applications, including electric and magnetic properties of materials as we

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2003

In this study, we fabricated thin-film resistors using CuMn and yttrium targets by DC/RF magnetron cosputtering. CuMnY-resistive thin films were deposited onto glass and Al2O3 substrates. The electrical properties and microstructures of CuMn alloy films with different yttrium content were investigated. The CuMnY films were annealed at temperature ranging from 250 degrees C to 350 degrees C in N-2 atmosphere. The phase variation, microstructure, film thickness, and constitutional analysis of CuMnY films were characterized using X-ray diffraction, field emission scanning, and high-resolution transmission electron microscopy and related energy dispersive X-ray analyses (XRD, FESEM, and HRTEM/EDX). It was found that CuMnY alloy films separated into two parts after annealing. The first part is the MnO phase on the bottom side of the film. The second part is an amorphous structure on the upper side of the film. The MnO phase is a microcrystalline that exists in CuMn films, which is dependent on the Y content and annealing temperature. CuMn alloy films with 15.7% yttrium addition annealed at 300 degrees C exhibited higher resistivity similar to 4000 mu omega-cm with -41 ppm/degrees C of temperature coefficient of resistance (TCR).

Hindawi Limited2019

A Study on the Characteristics of Cu-Mn-Dy Alloy Resistive Thin Films

Ho-Yun Lee

Cu-Mn-Dy resistive thin films were prepared on glass and Al2O3 substrates, which was achieved by co-sputtering the Cu-Mn alloy and dysprosium targets. The effects of the addition of dysprosium on the electrical properties and microstructures of annealed Cu-Mn alloy films were investigated. The composition, microstructural and phase evolution of Cu-Mn-Dy films were characterized using field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction. All Cu-Mn-Dy films showed an amorphous structure when the annealing temperature was set at 300 degrees C. After the annealing temperature was increased to 350 degrees C, the MnO and Cu phases had a significant presence in the Cu-Mn films. However, no MnO phases were observed in Cu-Mn-Dy films at 350 degrees C. Even Cu-Mn-Dy films annealed at 450 degrees C showed no MnO phases. This is because Dy addition can suppress MnO formation. Cu-Mn alloy films with 40% dysprosium addition that were annealed at 300 degrees C exhibited a higher resistivity of 2100 cm with a temperature coefficient of resistance of -85 ppm/degrees C.

2019