Stoichiometry deviations in aluminium and gallium garnet crystals are investigated by measuring the spectra of rare‐earth impurities ions as indicator. All garnet crystals prepared from the melt are found to have a nonstoichometric composition due to incorporation of some part of the rare‐earth ions into Al3± or Ga3± octahedral sites. The stoichiometry deviations in the homologous series of aluminium and gallium garnet crystals are estimated quantitatively. The spectra of Er3± ions occupying a‐sites with octahedral oxygen environment in garnet lattice are registered and studied. An effect is found of difference in the sizes of the rare‐earth ions on their co‐occupation of octahedral sites in the gallium garnet lattice.
The luminescence and absorption spectra of gadolinium—gallium (Gd3Ga5O12), yttrium—gallium (Y3Ga5O12), gadolinium—scandium—aluminum (Gd3Sc2Al3O12), and yttrium—aluminium (Y3Al5O12) garnet single crystals, doped with Er3+ ions (the Er2+ concentration varies from 0.1 to 40 wt%) are investigated at 4.2 and 77 K. The Stark component level schemes for the above‐mentioned single crystals are constructed. Two types (N and A) of Er3+ activator centres with greatly differing structures of the crystalline environment are revealed in the spectra of 4I15/2 ⇄ 4I13/2 transitions in Gd3Ga5O12 and Y3Ga5O12 crystals. The interaction of these centres at low temperatures are observed. The reason of these effects is discussed.
Formation of A-centres and divacancies in silicon p + -n-n + structures was investigated for 4 MeV electron irradiation in the low-intensity range of 10 11 -5 × 10 12 cm −2 s −1 . It is shown that the introduction rates of both A-centres and divacancies increase with intensity in this range and then saturate at intensities above 10 12 cm −2 s −1 . Using the data from the literature the introduction rates of these defects are discussed in a wide range of intensities of electron irradiation of 10 11 -10 15 cm −2 s −1 , indicating a consistent role of carbon interstitial atoms and electron-enhanced migration of Si self-interstitials in the observed behaviour of introduction rates.
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