Diffuse X-ray scattering measurements of dissolved H were carried out room temperature. It was found that the application of uniaxial stresses below the elastic limit led to a transformation of all of the H atoms from 1T to 4T states. Each H tom was delocalized over 4 neighbouring T sites by tunnelling. Diffusion of 4T H under an external stress, applied in a [111]-type direction, was measured at 200 to 340K. The results could be described by:

D (cm2/s) = 1.6 x 10-3 exp[-0.006(eV)/kT]

T.Suzuki, H.Namazue, S.Koike, H.Hayakawa: Physical Review Letters, 1983, 51[9], 798-803