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Effect of Impurities on the High‐Temperature Creep of LiF
Author(s) -
RUOFF ARTHUR L.,
NARAYAN RAO C. V. S.
Publication year - 1975
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1975.tb18769.x
Subject(s) - dopant , creep , materials science , doping , vacancy defect , atmospheric temperature range , impurity , analytical chemistry (journal) , diffusion , mineralogy , crystallography , composite material , chemistry , thermodynamics , optoelectronics , physics , organic chemistry , chromatography
Creep of undoped and Mg‐doped single‐crystal LiF was investigated in the range 650° to 750°C. The behavior observed is similar to that of pure metals. The strain rate was proportional to (stress)″, with n = 5.0±0.4 at T = 650° and 700°C and n = 3.60±0.2 at T = 750°C; n was independent of dopant level. The activation energies for creep were 2.09±0.08 eV for undoped specimens in the intrinsic range and 2.60±0.08 eV for doped specimens in the extrinsic range. A lower creep rate was found in doped samples than in undoped samples. However, the creep strain rates observed in heavily doped samples were not inversely proportional to the dopant level. The observations for pure LiF are explained on the basis of vacancy diffusion through the lattice. A model based on dopant cation vacancy complexes and binding of dopant to charged dislocations is presented to explain the behavior of the doped specimens.