Preparation and Luminescence of Selected Eu3+‐Activated Rare Earth‐Oxygen‐Sulfur Compounds

The hydrated sulfate, sulfate, oxysulfate, and oxysulfide compounds of yttrium, lanthanum, gadolinium, and lutetium were prepared using precipitation techniques and controlled atmosphere high temperature heat treatments. The temperature stability range in air for each compound was investigated by DTA and TGA methods. X‐ray diffraction powder data are presented for the fourteen compounds isolated. The only compounds that showed significant Eu3+‐activated luminescence were the oxy sulfates and oxysulfides. , the most efficient phosphor examined, is as bright as and distinctly more "red." Luminescence data are presented and discussed.