Tetrahedral ferric complexes in silver halides

An Electron Spin Resonance Study of Cubic Fe3+ in Alkali Chloride Crystals

“…4), a model which was verified by ENDOR studies [12, 131. The very small variation in the spin-Hamiltonian parameters, going from one lattice host t o another one, supports the earlier expressed opinion [5] that the formation and stability of this centre is a reflection of the great stability of the (FeC14)-ion, in which there is a high degree of covalent bonding between iron and the chlorine ligands.…”

“…This SHF structure is very similar in intensities and splittings to that observed in NaCl or SgC1 [4, 51. It can be where the z-direction is parallel to the axis joining the i-th ligand t o the Pe3+ ion, I r = f the spin of the i-th halogen nucleus, gt the nuclear gyromagnetic ratio, and /IN the nuclear magneton [ 5 ] . The corresponding spin-Hamiltonian parameters A , B, and P (Table 1) (Fig.…”

“…Indeed the Fe3+ is found in the tetrahedrally symmetric interstitial position with all four nearest-neighboor cation sites being vacant, as earlier observed in AgCl 151. This center, referred to as Fe:i has been previously observed only in AgCl and AgBr, either after heating iron-doped crystals in halogen gas 161, or by X-irradiation [5,7 I. Compared with silver halides, the interstitialization of cation impurities in alkali halides represents a rather unusual property.…”

Thermally-Induced Depolarization Current Spectra of NaCl:Ni2+Crystals

“…Namely, one has to consider the interstitial and off-centre positions for the impurity as well as the next-nearest-neighbour-site for the vacancy. Some considerations of these problems can be found for AgCl with Fe 2 + [5], NaCl and KCl with Be2+ [6], and -more generally -for the AH crystals doped with Me 2 + cations of different size [7][8][9].…”

Mössbauer Effect Study of Iron Impurity States in AgCl and NaCl

“…Model e2) of a trivalent iron ion (Fe, 2 a;) in NaCl and KC1 is given in [I, 261. I n papers [20] and [22] the results of the paramagnetic resonance of Fe+++ in AgCl are interpreted by model f in which a trivalent iron ion is located a t the interstitial site and associated with four vacancies Fe; 4 0;. In + -+ -+ -Many possible iron impurity states give a natural explanation of the variety of MBssbauer spectra observed, the type of which depends on the purity of starting material, preparation conditions, thermal history of the sample and measurement conditions.…”