Ge-73 NMR spectra in germanium single crystals with different isotopic composition

We have studied the influence of isotopic disorder on the local deformation s in Ge single crystals from both experimental and calculation points of vi ew. The nuclear magnetic resonance (NMR) spectra of Ge-73 nuclei (the nucle ar spin equals 912) in perfect single crystals of germanium with different isotopic content were measured at temperatures 80, 300 and 450 K. Abnormal broadening of the spectrum was found to occur when the magnetic field was a ligned along the [111] axis of a crystal. The observed specific angular dep endence of the quadrupole broadening was attributed to isotopic disorder am ong atoms of germanium sited around the Ge-73 NMR probe. Local lattice defo rmations in germanium crystal lattice due to isotopic impurity atoms were c alculated in the: framework of the adiabatic bond charge model. The results obtained were applied to study random noncubic crystal field interactions with the nuclear quadrupole moments and corresponding effects in NMR spectr a. Simulated second and fourth moments of resonance frequency distributions caused by the magnetic dipole-dipole and electric quadrupole interactions are used to analyze the lineshapes, theoretical predictions agree qualitati vely with the experimental data.