title: Thermal expansion of diamond at low temperatures.
abstract: Temperature variation of a lattice parameter of a synthetic diamond crystal (type IIa) was measured using high-energy-resolution x-ray Bragg diffraction in backscattering. A 2 order of magnitude improvement in the measurement accuracy allowed us to directly probe the linear thermal expansion coefficient at temperatures below 100 K. The lowest value measured was 2x10{-9} K-1. It was found that the coefficient deviates from the expected Debye law (T3) while no negative thermal expansion was observed. The anomalous behavior might be attributed to tunneling states due to low concentration impurities.
authors.affiliation: Advanced Photon Source, Argonne National Laboratory, Illinois 60439, USA.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Stoupin
authors.forename: Yuri V
authors.initials: YV
authors.lastname: Shvyd'ko