Measurement of the thermal-expansion coefficient of nickel from 300 to 1000 K and determination of the power-law constants near the Curie temperature

A fused-quartz dilatometer was used to measure the thermal-expansion coefficient α of nickel between 300 and 1000 K. Measurements on National Bureau of Standards certified copper and tungsten standards with the dilatometer established the uncertainty in the α measurements on nickel as ±{} 0.8% (±{}0.10 ×{} 10^-6 K^-1), except within ±{} 2 K of the Curie temperature TC where the uncertainty was about ±{} 1.6%. Results of 38 investigations of the expansion of nickel reported in the literature were analyzed critically, resulting in a compilation of α of nickel from 0 to 1500 K. Theories of thermal expansion were employed to separate α into its paramagnetic αₚ and magnetic αₘ components. The calculated values of αₘ near TC were fitted to the power-law equation, αₘ=A(t^-a-1)a^-1+B, that describes critical phenomena near the critical temperature [t=(T-TC)TC^-1]. It was demonstrated that the critical exponents above and below TC, a and a^', respectively, are the same as those derived from specific-heat measurements and that a=a^'=-0.093(±0.010) in agreement with scaling laws of critical phenomena.