Growth, structure and upconversion mechanisms of Ba₂ErCl₇ crystal

The methods to grow a novel upconversion crystal Ba2ErCI7 are reported in this note. Ba2ErCI7 material was synthesized with Er2Oa, BaCI2'2H20 and NH4CI by using a so,called "direct synthesis method". High quality Ba2ErCI7 single crystals with size up to 4 ramx8 ramx 15 mm were grown by using the Czochralski and the Bridgman methods. Intense yellow-green luminescence was detected when the crystal was pumped by an 803 laser diode (LD). Transmittance Spectrum was measured by using HITACH U-3500 spectrophotometer at room temperature for the first time, in which one can see that the transmittance is high in the range from 350 to 1 600 nm and the cut-off wavelength of the crystal was 230 rim. The upcnversion mechanisms were discussed.