Photochromism of three photosensitive Fe centers in SrTiO3

Abstract

Three paramagnetic Fe defect complexes have been observed by electron-spin resonance in chemically reduced crystals of SrTi03. These are identified as (1) in Fe + ion substituted on a Ti site with a nearby charge-compensating interstitial impurity, and (2) and (3) two charge states of substitutional Fe with a near-neighbor oxygen v icancy, Fe +-Vp and Fe'+-&p. These three defects are related in the sense that photoexcitation can reversibly switch electrons between the vacancy-associated and interstitial-associatedsites. An analysis of the response to pol prized light, and of the kinetics of charge transfer, shows that in both the forward and reverse directions of optical pumping the mobile charge carrier is a valence-band hole. Four distinct charge states of the Fe-&p system have now been identified, ind the rel itive instability of SrTi03 toward formation of multiple-impurity charge states is briefly discussed.

Oxygen sensitivity of perovskite-type dielectric thin films

“…The electronic configurations of acceptor-doped (particularly in Fe 3+ -doped or Cr 3+ -doped) SrTiO 3 are shown in Refs. [7][8][9][10][11][12][13]. Donor (Nb 5+ ) doping could lower the resistance; however, the sensitivity could decrease, as shown in Fig.…”

Synthesis, characterization, and electrical studies on Cu-doped K2Ti6O13 lead-free ceramics: Role of defect associate dipoles

“…The other centre at 1846 G (g ∼ 3.82) is also characteristic of a defect that is in an octahedral field with a very strong tetragonal distortion, except that S = 3/2 [33][34][35]. Following our earlier arguments, the fact that g ⊥ ∼ 3.82 strongly suggests that D h .…”

Iron-related defect levels in SrTiO3 measured by photoelectron paramagnetic resonance spectroscopy

“…1͑c͒ and 2͑c͒. 20,24,30,31 Measurements made over a wide magnetic field range showed no evidence of Fe 2+ V O in either annealed or unannealed samples, however, low temperature studies without illumination revealed the presence of Fe 4+ V O . However, the Fe 5+ spectrum increases in intensity by 1.5 compared with that observed in the dark.…”