In:
Journal of Physics C: Solid State Physics, IOP Publishing, Vol. 15, No. 16 ( 1982-06-10), p. 3441-3453
Abstract:
The results of a package of FORTRAN computer programs for modelling defects in ionic crystals and for fitting experimental data are described. The fundamental concept of the defect simulation is similar to HADES except that the minimisation procedure is different since the package is designed to run on small computers. As an example of the use of this package, the relative stabilities of NN and NNN complexes for various rare earths, Ianthanum and yttrium are considered. First, the data-fitting routine was used to analyse relaxation data for NN and NNN complexes in rare-earth-doped strontium fluoride. The experimental results for strontium fluoride were then used in conjunction with the defect-simulation program to determine potentials for all of the rare earths, yttrium and lanthanum. Those rare-earth potentials were then used in the simulation of calcium fluoride and show that the NNN complex should not be observable except for possibly the smallest rare earths. This implies that the B site of Wright and co-workers or the RII relaxation requires another explanation. Also, the potentials were used in the simulation of barium fluoride, showing that the NN complex should be observable only for the largest rare earths or lanthanum. Next, the enthalpy for NN to NN reorientation via the interstitialcy mechanism was calculated for rare earths in calcium and strontium fluoride. In general, the calculated reorientation enthalpies are larger than the experimental values. However, the variation of the enthalpy with the size of the rare earth is in reasonable agreement with experiment. Finally, the variation of the calculated enthalpy with pressure is found to be in excellent agreement with experiment.
Type of Medium:
Online Resource
ISSN:
0022-3719
DOI:
10.1088/0022-3719/15/16/006
Language:
Unknown
Publisher:
IOP Publishing
Publication Date:
1982
detail.hit.zdb_id:
209219-0
detail.hit.zdb_id:
2104406-5
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