Specific Heat of Terbium Metal between 0.37 and 4.2°K

The specific heat

C_{p}

of terbium metal, measured between 0.37 and 4.2°K in a

{He}^{3}

cryostat, could be separated by a least squares analysis into three contributions; the lattice specific heat

C_{L} = 0.58 T^{3}

(corresponding to a Debye

θ = 150 °

K), the electronic specific heat

C_{E} = 9.05 T

, and the nuclear specific heat

C_{N} = 238 T^{- 2} - 11.9 T^{- 3} - 4.5 T^{- 4} + 0.38 T^{- 5} + 0.06 T^{- 6}

(

C_{p}

in mJ/mole °K).

C_{N}

is due to the splitting of the nuclear spin states by the magnetic field

H_{eff}

of the

4 f

electrons and by the nuclear electric quadrupole coupling. In the series expansion for

C_{N}

there are only two independent constants, the magnetic hyperfine constant

a^{'}

and the quadrupole coupling constant

P

. Our experimental values of

a^{'} = 0.150 °

K and

P = 0.021 °

K are in good agreement with results obtained by electron paramagnetic resonance and nuclear magnetic resonance techniques which gave

a^{'} = 0.152 °

K and

P = 0.029 °

K. By assuming

μ = 1.52

nuclear Bohr magnetons for

{Tb}^{159}

one obtains

H_{eff} = 4.1

MG. In sharp contrast with earlier results, our measurements revealed no anomalies in

C_{p}

between 1 and 4°K. Such anomalies thus were probably caused by impurities in the samples of the other investigators.

This publication has 18 references indexed in Scilit: