▎ 摘　　要

NOVELTY - A linear negative temperature coefficient thermistor material comprises graphene oxide and transition metal oxide, doped with urea, melamine, dicyandiamide, thiourea, boric acid or sodium borohydride, synthesized by hydrothermal method The specific steps are as follows: pre-treatment of graphene oxide and transition metal oxide powder: a. preparing graphene oxide by an improved Hummer method (c) placing doping agent urea, melamine, dicyandiamide, thiourea, boric acid, or sodium borohydride in a beaker, introducing deionized water and stirring magnetically, transfering suspension to a hydrothermal synthesis reactor, place the product in a vacuum drying oven and drying. USE - The linear negative temperature coefficient thermistor material is useful in temperature sensing field, industrial field, and temperature accurate measurement and control. It is also used in temperature sensitive applications. ADVANTAGE - The material has obvious NTC performance, and the resistance value of the temperature exhibits an obvious linear relationship. The preparation step is simple, the process is safe, the cost is low, the performance is stable, and it is easy to popularize in the industrial field. The material overcomes the process that the current nonlinear thermistor device needs to complex design of the circuit part in the application process to realize the process of the electrical parameter is linear compensation by non-linear compensation, and compared with only the linear negative temperature coefficient thermistor material obtained by doping modification has larger TCR value, in the temperature sensing field, it has good application prospect. DETAILED DESCRIPTION - A linear negative temperature coefficient thermistor material comprises graphene oxide and transition metal oxide, doped with urea, melamine, dicyandiamide, thiourea, boric acid or sodium borohydride, synthesized by hydrothermal method. The specific steps are as follows: pre-treatment of graphene oxide and transition metal oxide powder: a. preparing graphene oxide by an improved Hummer method. The obtained graphene oxide is a brown viscous liquid, which is freeze-dried for 10-30 hours and grounding in a mortar for 10-30 minutes to obtain a uniform graphene oxide powder, (b) passing transition metal oxide powder of manganese nickel oxide, cobalt manganese oxide, nickel manganese oxide, or manganese cobalt oxide through a 200-400 mesh sieve, hydrothermal synthezing composite material, (c) placing doping agent urea, melamine, dicyandiamide, thiourea, boric acid, or sodium borohydride in a beaker, introducing deionized water and stirring magnetically at room temperature for 15-30 minutes to obtain a colorless transparent solution, introducing graphene oxide powder and stirring magnetically for 20-60 minutes, introducing transition metal oxide powder and stirring magnetically at room temperature for 15-30 minutes to obtain a suspension, where mass ratio of graphene oxide, doping agent, and transition metal oxide powder is 1:1-50:1-70, (d) transfering suspension to a hydrothermal synthesis reactor, placing it in an oven, setting hydrothermal temperature to 100-300℃, and set the reaction time to 5-30 hours (e) after the hydrothermal reaction is completed, cooling the reactor to room temperature, removing reaction mixture, and filtering with deionized water 3-9 times, each time using 5-10 ml water for washing, washing it 2-6 times with anhydrous ethanol, using 1-5 ml anhydrous ethanol each time, completing filtration, place the product in a vacuum drying oven and drying at 60-120℃. An INDEPENDENT CLAIM is also included for a preparation method of linear negative temperature coefficient thermistor material.