
Accession Number : AD0642519
Title : THE KNIGHT SHIFT IN LEAD TELLURIDE VIA RELATIVISTIC APW FUNCTIONS.
Descriptive Note : Technical rept.,
Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF ELECTRICAL ENGINEERING
Personal Author(s) : Bailey,Paul T.
Report Date : 22 AUG 1966
Pagination or Media Count : 138
Abstract : The 82Pb207 nucleus was used, via the measured Knight Shift, to test the accuracy of the relativistic APW calculations for the energy bands of PbTe. Possible Knight Shift contributions other than the contact type are considered and shown to be negligible; the confusion between the Knight Shift and the chemical shift is discussed. The standard formula for the contact Knight Shift in a semiconductor is examined, and is found to be based on the assumption, for a powder specimen, of an isotropic gfactor. It is shown that the large anisotropy of the gfactor in PbTe leads to a correction factor of 4. From the relativistic APW results a value is obtained for the scharacter, and also a value for the ionicity. This latter is used, together with relativistic and finite nucleus corrections important for hyperfine interactions involving heavy nuclei, to obtain a value for the hyperfine constant, using the GoudsmitFermiSegre formula. When the calculated scharacter, hyperfine constant and anisotropy correction factor are employed with the average experimental value of the gfactor, a Knight Shift value is obtained which is about half the experimental value. Taking into consideration the lack of selfconsistency of the relativistic APW calculations, and allowing for the possibility that the experimental values for the gfactor are too small, the APW results are felt to provide a good basis for the explanation of the Knight Shift. (Author)
Descriptors : (*SEMICONDUCTORS, HYPERFINE STRUCTURE), (*LEAD COMPOUNDS, *BAND THEORY OF SOLIDS), (*TELLURIDES, BAND THEORY OF SOLIDS), NUCLEAR MAGNETIC RESONANCE, LEAD(METAL), NUCLEI, ANISOTROPY, MAGNETIC PROPERTIES, ATOMIC ORBITALS, WAVE FUNCTIONS
Subject Categories : Solid State Physics
Distribution Statement : APPROVED FOR PUBLIC RELEASE