Growth and microstructural analysis of nanosized Y2O3 doped with rare-earths

Nanosized cubic Y2O3 samples, undoped and doped with 10 mol% Nd2O3, Eu2O3, Gd2O3, Tb2O3, Ho2O3 and Er2O3 (Y(1.8)Ln(0.2)O(3), where Ln=Nd, Eu, Gd, Tb, Ho or Er), were prepared by means of a controlled hydrolysis method in an aqueous solution containing ammonia, Y(NO3)(3) and Ln(NO3)(3) as precursors, and a surface modifier. The microstrain and the average size of the diffraction domains have been calculated from the XRD patterns and the results have been compared with those obtained by a combustion synthesis. It is shown that the cell parameter of the C-M2O3 (bcc structure related to the CaF2 structure; the M atom is 6-coordinated) structure of doped Y2O3 is correlated to the ion size of the dopant. The shape of the crystallites appears to be needle-like in all cases, while the microstrains depend on the dopant and are probably due to surface effect. XRD and Raman analysis show that, despite the heavy doping, only one phase in the Y2O3 powders is present. (C) 2000 Elsevier Science S.A. All rights reserved

Application of the Quality by Design Principles for the Development of the Crystallization Process for a Piperazinyl-Quinoline and Definition of the Control Strategy for Form 1

The studies carried out to develop a robust crystallization method for the substituted piperazinyl-quinoline (<b>1</b>) a compound potentially active in the treatment of depression, are described in this contribution. These studies include the control of a solvate that could have potentially formed in the crystallization process. The principles of quality by design (QbD) were applied to generate the process understanding and to define the control strategy for the control of the formation of the solvate during the crystallization. The application of process analytical technology (PAT) tools was key in achieving the desired process control