Magnetic Characterization of Electrodeposited Pt1−xNix Alloy Films: Influence of Deposition Potential and the Presence of Boric Acid

Abstract

Pt1-xNix (x = 0.25 to 0.92) thin films were examined for possible application as magnetic thermometers. The alloys were prepared by potentiostatic electrodeposition from aqueous chloride-based solutions in the presence and absence of 0.5 mol dm−3 B(OH)3. Alloy composition was controlled by the deposition potential with the Ni concentration increasing towards more reducing potentials. Films with x > 0.45 were ferromagnetic with the magnetization at 300 K increasing with nickel content. Magnetization vs temperature (M vs T) at 8 kA m−1 (100 Oe) showed an increase in the Curie temperature from less than 200 K to above 400 K for the alloys investigated. For films deposited at potentials >−0.6 V vs the saturated calomel electrode (SCE), boric acid had negligible effect on the magnetization at the maximum applied field in M vs H measurements. In contrast, for depositions at more reducing potentials <−0.6 V vs SCE the presence of boric acid resulted in diminished magnetization. This effect was attributed to elevated incorporation of oxygen (up to ∼4 atomic %), along with boron incorporation of about 400 μmol mol−1.