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The Mössbauer and magnetic resonances investigations of structural phase transitions in K2ZnCl4crystals

Domenii publicaţii > Fizica + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: S. Constantinescu - M.N. Grecu

Editorial: Eur. Phys. J. B, 13, p.227-233, 2000.

Rezumat:

In limitele unui model simplu electrostatic care ia in considerare atat sacrcinile punctuale fractionare electrice, cat si reteaua rigida, care calculeaza contributia retelei cristaline la paotentialul V(r), intensitatea campului electric E(r) si componentele EFG, sunt discutate datele experimentale de spectroscopie Mössbauer si rezonanta magnetica in tranzitia structurala din cristalele de tip K2ZnCl4. The experimental data carried out by Mössbauer and magnetic resonances investigations of the structural phase transitions in K2ZnCl4 crystals are discussed by a simple electrostatic model, calculating, the lattice contributions to the local electric potential V(r), electric field intensity E(r) and electric field gradient tensor, (r) and taking into account both the fractional electric point charges and rigid lattice approximations. The validity of the model is proved by a good fit of the computing results and experimental data of quadrupole splitting parameters at K sites obtained by 39K-NMR methods in high temperature incommensurate phase ( Pnam symmetry). The experimental results obtained by Mössbauer and EPR methods in commensurate phase (Pna21 symmetry) of iron and copper doped K2ZnCl4 crystals are explained by relaxing the rigid lattice approximation. The insertion of probe ions appear to be done on not-exactly-Zn2+ site.

Cuvinte cheie: 76.80.+y efect Mössbauer ; spectroscopie nucleara gama, corp solid // PACS 76.80.+y Mössbauer effect; other -ray spectroscopy

URL: http://www.edpsciences.com/articles/epjb/abs/2000/02/b9090/b9090.html