EPR and TEM Characterization of Electroluminescent Alq₃

Abstract

EPR and TEM investigations on sublimated solid Alq3, [tris(8- hydroxyquinoline)aluminum(III)] are reported. Different paramagnetic centers in microcrystalline Alq3 fractions as synthesized and annealed are observed. Their nature, thermal treatment dependence, as well as correlation with the crystal structure are analyzed. The existence of randomly oriented triplets and quartets in annealed Alq3 fractions is evidenced from the temperature dependence of X- and Q-band EPR spectra. The spin Hamiltonian parameters are given and proposals for the model structures are made.

Growth and characterization of undoped, Sr2+-, and Mn2+-doped ammonium tetrachlorozincate

“…This, in its turn, would enhance conduction with a faster rate. Super ionic conduction was also observed for KZC in the normal phase and it was attributed to a fast chemical exchange of K + ions between different, equivalent at high temperatures, sites [18,19]. + ion a process which would result in one free electron.…”

Paramagnetic defect centres in crystalline Alq3

“…Examples of room temperature EPR spectra are plotted in figure 7. A hyperfine structure due to the interactions with N and H nuclei was observed, partially resolved at low temperatures [25].…”

Dielectric constant, loss factor and ac conductivity of Ni2+-doped K2ZnCl4 crystals in the ferroelectric-commensurate, incommensurate and normal phases

“…ε increased by ~10% of its value at the end of the heating run. This increase may be associated with a 'quick' annealing process that is due to the increase in the potassium ions mobility [2] and the fast chemical exchange between various equivalent K + sites found in the Nphase of KZC [6]. It can be also considered as a thermal lagging process due to which the sample needs time to reach its thermal stability.…”

“…In a comprativite EPR study of Mn +2 doped Rb 2 ZnCl 4 (RZC) and K 2 ZnCl 4 in the normal phase Grecu et al [2] found that K + ions became more mobile by raising temperature. During…”

“…In recent years, a number of compounds of the family A 2 BX 4 , have been subjected to great interest because of variety of physical properties found in their sequence of transitions including normal, incommensurate, commensurate, superionic, ferroelectric and ferroelastic phases [2]. paraelectric phase with orthorhombic symmetry and a space group (SG) Pmcn having four molecules per unit cell.…”