Crystal field analysis of different Er3+ sites in LiNbO3

The Er3+ defect in lithium niobate (LiNbO3), and the slightly different lattice environments ("sites") it experiences, have been investigated with combined excitation-emission spectroscopy under application of hydrostatic pressure and electric fields. The results give a solid basis for a crystal field analysis which yields site-specific crystal field parameters. We found that the Er3+ sites can be classified into two groups. Firstly, the sites are distinct due to different relative arrangements of the nearest-neighbor oxygens and secondly they encounter to different local electric fields which are caused by charge compensators and other defects in a more distant neighborhood.