Strain-Resistive Properties of (Bi0.23Sb0.75)2Te3 Films at One-Sided Cyclic Alternating Strains
Аннотация
The results of a study of the deformation characteristics of polycrystalline films from the (Bi0.25Sb0.75)2Te3 solid solution at one-sided cyclic alternating mechanical stresses is presented. The films were obtained on a polyamide substrate by the method of thermal vacuum condensation of molecular beams and had a columnar porous structure with the dimensions of individual crystalline grains of 2.0-2.5 µm. The effect of static and cyclic deformations on the electrical resistance and volt-ampere characteristics of strain gauge films was studied in order to manufacture strain gauges for fatigue damage accumulation on their basis. It was shown that at room temperature such films have an abnormally high static strain sensitivity G ≈ 103 arb. units and a significant hysteresis of their resistance change was detected at small numbers of alternating deformation cycles. As a result of N = 5∙105 deformation cycles, the linear section of the volt-ampere characteristic expands from (0-5) V at N = 0 to (0‑12) V. And the temperature coefficient of resistance in the range of 293 K-Tmin changes from α = -5.6∙10-3 K-1 to α = -2.5∙10-4 K-1. The characteristic value of Tmin, at which α = 0, increases with the growth of N. The studied strain gauge films can be successfully used as a sensor of fatigue stress accumulation in the temperature range of T = 273-413 K and the value of N = 0 – 5∙105.