Accelerating the screening of high-entropy Co-Mn-Fe-Ni-Zn-O gradient films for highly stable NTC materials through co-sputtering combinatorial synthesis

High-entropy negative temperature coefficient (NTC) thermistor thin films, renowned for their exceptional stability, represent a significant advancement in the field of temperature measurement, facilitating the miniaturization of next-generation information and electronic devices. However, "trial and error" approach to developing multi-component NTC oxides significantly constrains the efficiency of the design process. To accelerate development process, we prepared Co-Mn-Fe-Ni-Zn-O gradient films by co-sputtering combinatorial synthesis. The effects of stoichiometric ratios on the resistance (R-25), material constant (B-25/50) and stability (Delta R/R-0) of gradient films were visually represented through color-coded maps for straightforward and intuitive analysis. Samples close to the MnCoFe target in gradient films showed a trend of decreasing resistance and increasing material constant, both reaching 1.71 M Omega and 4083 K, respectively. The high-entropy Co21Mn17Fe19Ni21Zn22O4 +/-delta film exhibited the lowest resistance drift rate only 2.68 % after 500 h ageing at 125 degree celsius. Another delightful result was that the corresponding homogeneous films, achieved through sputtering with a composite target, had a relative deviation in resistance drift rate of merely 0.18 %. This showcased the successful translation from the screening outcome to the homogeneous film, significantly accelerating the development of NTC materials via the utilization of gradient films screening.