Ytterbium and erbium derivatives of 2-methoxyethanol and their use in the thin film deposition of Er-doped Yb₃Al₅O₁₂

We have proved different methods for yttrium and erbium 2-methoxyethoxides preparation. Our aim was to prepare a solution applicable at the subsequent sol–gel preparation of Yb₃Al₅O₁₂ garnet thin films. We tested the direct reaction of a metal with 2-methoxyethanol in the presence of HgCl₂, the electrolytic dissolution of metals, an alcohol interchange using isopropoxides and, finally, the exchange reaction of acetates with 2-methoxyethanol. Because our demand was to prepare a solution without the necessity of purification, we omitted chlorides as a source of cations. The formation of the metal alkoxides was examined by IR spectroscopy in each case. Both exchange reactions were fully successful; only in the case of acetate use, the arising acetic acid forms ester immediately. The direct reaction of metals with the alcohol did not achieve a full yield; on the other hand, after electrolysis application, the metals dissolved readily. However, in both cases, the filtration of either unreacted metal (direct reaction) or eroded metal pieces (electrolysis) was necessary. Because the filtration has to be processed under inert atmosphere these methods are less convenient for the subsequent use in the sol–gel deposition. Er:Yb₃Al₅O₁₂ thin films deposited on silicon substrates were also prepared using the two appropriate intermediates—the solutions prepared either from acetates or isopropoxides. Both layers were monophase; however, the microstructure and luminescent properties were influenced by the solution used. The Er:YbAG layers exhibited the sharp and discreet luminescence peaks of the Er³⁺ transition ⁴I_13/2 → ⁴I_15/2.