Ba4YZr3F23 and Ba4LnZr3F23: a new noncentrosymmetric potential host structure type for optical devices

The first ternary BaF2–Ln(Y)F3–ZrF4 phases crystallizing near the composition range of fluoride glasses, namely Ba4YZr3F23 (barium yttrium fluoridozirconate) and isotypic Ba4LnZr3F23 (Ln = Yb, Er and Nd), have been synthesized. The crystal structure of Ba4YZr3F23 cannot be correctly determined in the centrosymmetric space group Pnma (R1 = 0.09); it is preferably described in the noncentrosymmetric space group Pn21 a (R1 = 0.028). All cations are located at y = 0.25–0.29 and 0.75–0.79. This new structure type is formed by infinite {[YZr3F23]8−} n columns associating, along [001], YF9 tricapped trigonal prisms, ZrF8 dodecahedra and ZrF7 polyhedra. These columns are interconnected via BaF10+1 and BaF12 irregular polyhedra.

Near-Infrared-to-Green Upconversion in Yb3+/Er3+ Co-Doped BaYF5 by Chemical Co-Precipitation Method

Barium yttrium fluorides ( BaYF5 ) co-doped with Er3+ and Yb3+ were synthesized by the chemical co-precipitation method and the structural and optical properties of solution-processed Er3+/Yb3+ co-doped BaYF5 were characterized. Intense visible emissions centered at around 523, 546 and 658 nm, originated from the transitions of 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, and 4F9/2 → 4I15/2 of Er3+, respectively, have been observed in samples upon excitation with a 980nm laser diode, and the involved mechanisms have been explained.