Development And Application Of Physical Properties Comprehensive Measurement System For Micro/Nanoscale Filamentary Materials

The properties of micro/nanoscale filamentary materials are significantly different from the corresponding bulk materials,they have wide applications in MEMS/NEMS sensors and micro/nano electrical devices.As the measurement methods for bulk materials are difficult to be applied for nanoscale filamentary materials,development of the precise measurement method and technology for micro/nanoscale filamentary materials has been attracting intense interest.In this dissertation,a highly integrated measurement system for comprehensively measuring the thermophysical,electrical and thermoelectric properties of micro/nanoscale filamentary materials has been developed,three rules for optimal dimensions of sample and sensor have been proposed,electrical conductivity,thermal conductivity,Seebeck coefficient and the figure of merit of Pd-based metallic glass fibers and KD-II SiC fibers have been measured,and the effects of components and fabrication processes on material properties have been revealed.Based on ac-heating-dc-detecting T-type method,a novel ac T-type method has been further proposed to measure Seebeck coefficient and thermal conductivity simultaneously.The accuracy of the ac T-type method has been verified by measuring a constantan fiber.The effects of radiation,geometry dimensions and variable electrical conductivity on uncertainty and sensitivity of the system have been calculated.Three rules for optimal dimensions of sample and sensor have been proposed to guide users to select appropriate length of hot wire and test fiber in preparation processes,in order to achieve the best sensitivity.In this dissertation,a highly integrated measurement system has been developed for comprehensively measuring the thermophysical,electrical and thermoelectric properties of micro/nanoscale filamentary materials from 40 K to 500 K,including electrical conductivity,temperature coefficient of resistance,thermal conductivity,thermal diffusivity,thermal effusivity,specific heat,Seebeck coefficient and the figure of merit.Platinum wire and constantan wire have been measured and compared with reference values to verify the measurement accuracy of the measurement system.The electrical conductivity,thermal conductivity,Seebeck coefficient and figure of merit of Pd-based metallic glass have been measured at different environment temperature,and the effects of components and fabrication processes to amorphous degree and material properties have been revealed.Amorphous degree of Pd-Ni-Cu-P metallic glass rises with the higher components of Pd and lower components of Cu;Amorphous degree of metallic glass produced by plastic deformation method is lower than that produced by undercooled melt method,because of better aligning;with the amorphous degree rising,the ability of transport becomes lower and the dependence between transport properties and environment temperature is also lower.The electrical conductivity,thermal conductivity,Seebeck coefficient and figure of merit of KD-II SiC fiber have been measured at different environment temperature,empirical correlations between the thermal conductivity of SiC fiber and the grain size of ?-SiC,the tensile strength of fiber have been proposed.A linear relationship between the thermal conductivity of SiC fiber and the grain size of ?-SiC,and an exponential relationship between the thermal conductivity of SiC fiber and the tensile strength of the fiber have been found.