EPR of a VO²⁺‐Doped Fe(NH₄)₂ (SO₄)₂ · 6H₂O Single Crystal. VO²Fe²⁺ Exchange Interaction and Spin–Lattice Relaxation Time of Host Fe²⁺ Ions

Abstract

X-band (-9.5 GHz) electron paramagnetic resonance (EPR) studies of the VOz+ ion are carried out on a single crystal of the Tutton salt Fe(NH,),(SO,), . 6 H 2 0 (FASH) at 295, 80, and 4.2 K. The data indicate two physically-equivalent V 0 2 + sites in the unit cell, each consisting of three magneticallyinequivalent V 0 2 + ions. The principal values and direction cosines of the principal axes of the g2 and A' tensors are evaluated, using a least-squares-fitting program. An impurity [VO(H,O),]' + complex model of the vanadyl ion is found to explain the data well. The V 4 + -0 2 -bond directions for the V 0 2 + ions are deduced. The VOZ+-Fe2+ exchange-interaction constant in FASH is estimated. The host-ion (Fez +) spin-lattice relaxation time is estimated from V 0 2 + EPR linewidth. On a mesure le RPE a bande-X sur un monocristal du sel Tutton, Fe(NH,),(SO,), . 6 H 2 0 (FASH), a 295, a 80, et a 4,2 K. Les donnees indiquent deux sites physiquement equivalents de V 0 2 + dans l'unite de cellule, chacun contient trois ions de VOz +, non-equivalents magnetiquement. Les valeurs principaux et les cosinus des directions des axes principaux des tenseurs g2 et A' ont ete evalues, en utilisant un programme d'adaptation aux moindres carres a l'ordinateur. Un modele d'impurete, decrit par le complexe [VO(Hz0,]2+, explique bien les donntes. On a deduit les liens V4+-02-pour les ions de VOz+. Le constant d'interaction d'echange V02+-Fe2+ a 6tC estime. Le temps de relaxation spin-reseau des ions h8tes (Fez +) a Cte estimt, en utilisant les largeurs RPE de l'ion d'impurete V 0 2 +.

Synthesis and EPR studies of soluble vanadyl octakis(4-tert-butylbenzylthio) porphyrazine

“…The lowering of b 2 2 value arises from delocalization of electron onto the ligand with increase in covalent bonding. The values obtained in this study are in agreement with the literature values of VO 2+ [30,[42][43][44][45][46][47][48].…”

Synthesis and EPR studies of a near infrared absorbing tetrakis(2-naphthoxy)vanadylphthalocyanine

“…The lowering of b 2 2 value arises from delocalization of electron onto the ligand with the increase in covalent bonding. The values obtained in this study are in agreement with the literature values of VO 2+ [13][14][15][19][20][21][22][23][24][25].…”

Synthesis and EPR studies of vanadyl tetrakis(selenodiazole)porphyrazine

“…ion to different ligand field environments. More covalent bonding gives higher g values and lower hyperfine splittings [21][22][23][24][25][26].…”