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Nuclear Quadrupole Interaction of 69 Ga in AgGaS 2 and AgGaSe 2
Author(s) -
Breuer A.,
Siebert D.
Publication year - 1997
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(199709)203:1<207::aid-pssb207>3.0.co;2-2
Subject(s) - quadrupole , coupling constant , electric field gradient , orbital overlap , coupling (piping) , chemistry , tetrahedron , materials science , condensed matter physics , atomic physics , physics , crystallography , molecular orbital , quantum mechanics , organic chemistry , composite material , molecule
By FT‐NMR we measured the first‐order shifts for the resonances of 69 Ga in a single crystal of AgGaS 2 and in a AgGaSe 2 powder specimen. We determined the nuclear quadrupole coupling constant of (0.40 ± 0.01) MHz for AgGaS 2 and (0.55 ± 0.03) MHz for AgGaSe 2 . The theory of Lines is applied to explain the corresponding electric field gradients. After that the rather small values are due to a strong compensation of two contributions, the lattice contribution and the orbital contribution. This compensation cannot take place in CuGaS 2 with its much higher coupling constant of 1.8 MHz, because of its small orbital contribution due to a very small local deviation from perfect tetrahedral symmetry.