Structural, thermal, and spectral characterization of the different crystalline forms of Alq3, tris(quinolin-8-olato)aluminum(III), an electroluminescent material in OLED technology

The interest in organic materials for use in organic light-emitting diodes (OLEDs) began with the pioneering report of efficient green electroluminescence from Alq3, tris(quinolin-8-olato)aluminum(III), by Tang and Van Slyke [C.W. Tang, S.A. Van Slyke, Appl. Phys. Lett. 51 (1987) 913]. After more than 20 years of intense research and development in OLEDs, Alq3 continues to be a widely used electroluminescent material in OLED technology. Alq3 is used in the electron-transport and/or electron-injecting layer in multilayer device structures and also as an effective host material for various dyes. Much is known about the properties of this metal chelate complex, yet much remains unknown despite numerous studies. In recent years, five crystalline phases (α, β, γ, δ, and ε) of Alq3 have been identified. In the present report, a combined structural, thermal, and spectroscopic (Raman, fluorescence, and nuclear magnetic resonance) analysis of different crystalline phases of Alq3 is presented. © 2008 Elsevier Ltd. All rights reserved

Changes in the body, glaze and enamel compositions of early Meissen porcelain, 1723– c.1740

The evolution of early Meissen body, glaze and colorant compositions is examined using X-ray fluorescence spectroscopy (XRF) measurements on three artefacts that can be accurately dated to the period 1723-c.1740. The results are interpreted based on recipes recorded in the earliest documents of the Meissen archives. The pure Aue kaolinite contains low levels of Ti and can be distinguished from secondary clays, for example, clay from Colditz. The excess Ti in the glaze versus the body reported earlier and confirmed by the present authors is explained by the exclusive use of Colditz clay for the glaze, as described in the recipes before 1730, providing a terminus ante quem for Meissen porcelain exhibiting this particular asymmetry. After 1730, the presence of elevated Ti in the body could serve as a marker for the experimental admixture of clays to Aue kaolinite to alter its properties. Based on the detection of As, Ba and Bi, it is suggested that smalt from Erzgebirge was the colorant for blue enamels until at least 1725