This work aimed at assessing relationships between composition and performance of thick film resistors (TFRs) for cryogenic thermonmeters. The temperature dependence of resistance in RuO_2-based TFRs was studied in the range 1.2K to 300K. The resistance fits the exponential relationship R = R_oexp (T_o/T)~x with x = 1/4 at higher temperatures with a transition to the x = 1/2 regime on the same sample at lower temperatures (<20 K). The transition temperature T_c between these regimes has a well defined dependence on the sample sheet resistance R_s. Both the R_o values scale down as the RuO_2 fraction and show similar dependencies on the Mn content. The magnetoresistive responses were measured in the same temperature range in magnetic field H up to 20 Testa. The measured relative change of resistance DELTA R/R never exceeds 10~(-2) for H values up to 8 Tesla. In summary the developed resistors exhibit superior performances in comparison with the presently used thermometers. In addition, they show predictable properties at changing temperature and magnetic field strength, making easier their calibration.
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