Growth and luminescence mechanisms of Ba₂ErCl₇: a new laser up-conversion crystal

A modified synthesis method for the preparation of Ba₂ErCl₇, a new laser up-conversion material using Er₂O₃, BaCl₂·2H₂O and NH₄Cl, is reported for the first time. Single crystals 5-8 mm in diameter and 10-20 mm in length were grown by both the Czochralski and Bridgman methods. The transmittance spectra for a Ba₂ErCl₇ single crystal was first measured using a HITACHI U-3500 spectrophotometer. There were three intense absorption peaks ⁴I_9/2, ⁴I_11/2 and ⁴I_13/2 in the infrared range which can be excited by 803 and 980 nm and 1.5 μm laser diode (LD), respectively. The cut-off wavelength of the crystal was 230 nm. Intense green luminescence was observed when the crystals were pumped by an 803 nm LD. Up-conversion mechanisms are discussed.