Optimization of Sol–Gel-Formed ZnO:Al Processing Parameters by Observation of Dopant Ion Location Using Solid-State <sup>27</sup>Al NMR Spectrometry
Tim Kemmitt
Bridget Ingham
Rachael Linklater
10.1021/jp204283k.s001
https://acs.figshare.com/articles/journal_contribution/Optimization_of_Sol_Gel_Formed_ZnO_Al_Processing_Parameters_by_Observation_of_Dopant_Ion_Location_Using_Solid_State_sup_27_sup_Al_NMR_Spectrometry/2626466
We report the discrimination of Al doping sites in sol–gel-formed ZnO powders by solid-state <sup>27</sup>Al nuclear magnetic resonance (NMR) spectrometry. A degree of control of dopant placement is demonstrated by modifying sol precursors and processing parameters. ZnO powders containing 1–8 at. % aluminum ions were prepared from aqueous citrate-amino-alcohol-based gels calcined at 500 °C. The powders were characterized using <sup>27</sup>Al NMR spectrometry, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Solid-state <sup>27</sup>Al NMR spectrometry clearly distinguished between different Al environments and was effective in determining the relative amounts of incorporation of Al dopant ions into the Zn lattice sites in the zincite structure. This allowed a synthesis protocol to be developed to optimize the doping effectiveness. Relatively minor variations in processing conditions could influence the degree and mode of Al incorporation. Optimal conditions were found to include a 90 °C drying step, followed by placement in a preheated (500 °C) furnace for 1 h. An ethanolamine-containing precursor was shown to perform much better than precursors containing alternative amino alcohols.
2011-08-04 00:00:00
Al dopant ions
synthesis protocol
Al environments
Al doping sites
sol precursors
zincite structure
27 Al
XRD
Dopant Ion Location
Zn lattice sites
processing conditions
dopant placement
SEM
ZnO powders
scanning electron microscopy
1 h
Al incorporation
27 Al NMR spectrometry
Optimal conditions
doping effectiveness
processing parameters