Growth, structure and upconversion mechanisms of Ba2ErCl7 crystal

The methods to grow a novel upconversion crystal Ba2ErCl7 are reported in this note. Ba2ErCl7 material was synthesized with Er2O3, BaCl2·2H2O and NH4Cl by using a so-called “direct synthesis method”. High quality Ba2ErCl7 single crystals with size up to 4 mm×8 mm×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 nm. The upconversion mechanisms were discussed.