PHASE EQUILIBRIA IN THE SYSTEM LiF—YF₃

Abstract

The phase equilibrium diagram of the condensed system LiF-YFg is presented. Data were obtained from thermal analysis of heating and cooling curves and by identifying the phases present in small samples which were quenched after equilibration at high temperatures. Within the system two invariant points occur, the eutectic at 19 mole % YF3 and 695°, and the peritectic at 49 mole % YF3 and 819°. The single intermediate compound, LiF-YF», is formed. It melts incongruently to YF3 and liquid at 819°, and is tetragonal, o» = 5.26 ± 0.03 A., and c0 = 10.94 ± 0.03 Á., space group I4i/a. The compound LiF-YF3 is colorless, uniaxial (+), with refractive indices = 1.454, N< = 1.472. No solid solutions are formed among the equilibrium solids in the system LiF-YFa. The melting point of YF3, 1148°, determined by other workers, was corroborated in the present study. A solid state transition in YFS was shown to occur at 1052°.

Magneto-optical properties of neodymium-doped LiYF4

“…CaWO lattice, the Li ion replaces W and the F ion 4 22 In this paper we combine spectroscopic and magnetic takes the O position. The scheelites are tetragonal and 6 properties and evaluate the optimisation of the correbelong to the I4 / a (C ) (no 88 of the International and is used for the optimisation of the free ion and crystal the Y ion [13]. The cell parameters of the 1.5% neodymium doped LiYF unit cell are determined using an Enraf Nonius pure LiYF parameter values [13] and this is due to the The unit cell of LiYF :Nd (1.5%) is given in Fig.…”

Upconversion Nanocrystal‐Doped Glass: A New Paradigm for Photonic Materials

“…The decomposition temperature of LiYF 4 NCs was measured using differential thermal analysis (DTA): two eutectic melting peaks at 647 °C (minor) and 821 °C (sharp and major) correspond to the decomposition of tetragonal LiYF 4 NCs. [ 26 ] Hence, the onset of the decomposition temperature (≈625 °C, symbol # in The lower limit of the doping temperature is determined by the glass melt viscosity. As the glass melt viscosity increases with decreasing temperature, a temperature point exists where the glass melt is too viscous to disperse doped NCs in the melt.…”

A Short Review on Fluoride Laser Crystals Grown by Czochralski Method at IPEN

“…Thermal gradients in the system will change when using a platinum or a graphite (or vitreous carbon) crucible and/or after-heaters, as well as with their sizes, which are related to the desired crystal dimensions. In the pioneering work, published in 1961 by Thoma et al [11], it was proposed a reevaluation of the phase relationships in the LiFYF 3 system of a previously published work [12]. It was established the existence of the Good results can also be obtained with the direct use of pure uoride commercial powders (99.99% or better), if a reactive atmosphere, such as CF 4 , is used during crystal growth process [27,28] to prevent the reaction of rare earth uorides with oxygen and moisture.…”