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4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on KYF4 by Materials Project

KYF4 crystallizes in the trigonal P3_1 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.57–3.07 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.63–3.06 Å. In the third K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.63–3.06 Å. In the fourth K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.60–3.01 Å. In the fifth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YF7 pentagonal bipyramid, edges with two KF8 hexagonal bipyramids, and edges with six YF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.64–3.08 Å. In the sixth K1+ site, K1+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.62–2.93 Å. There are six inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.18–2.32 Å. In the second Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share corners with five YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.23–2.29 Å. In the third Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.18–2.31 Å. In the fourth Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share corners with five YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.23–2.30 Å. In the fifth Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.18–2.31 Å. In the sixth Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share corners with five YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.23–2.30 Å. There are twenty-four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the second F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Y3+ atoms. In the third F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Y3+ atoms. In the fourth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Y3+ atoms. In the fifth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the sixth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Y3+ atoms. In the seventh F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Y3+ atoms. In the eighth F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Y3+ atoms. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Y3+ atoms. In the tenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the eleventh F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Y3+ atoms. In the twelfth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Y3+ atoms. In the thirteenth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form a mixture of edge and corner-sharing FK3Y tetrahedra. In the fourteenth F1- site, F1- is bonded to two K1+ and two Y3+ atoms to form a mixture of distorted edge and corner-sharing FK2Y2 tetrahedra. In the fifteenth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form distorted FK3Y tetrahedra that share corners with seven FK3Y tetrahedra and edges with two FK2Y2 tetrahedra. In the sixteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the seventeenth F1- site, F1- is bonded to two K1+ and two Y3+ atoms to form a mixture of distorted edge and corner-sharing FK2Y2 tetrahedra. In the eighteenth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form distorted FK3Y tetrahedra that share corners with seven FK3Y tetrahedra and edges with two FK2Y2 tetrahedra. In the nineteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the twentieth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form distorted FK3Y tetrahedra that share corners with seven FK3Y tetrahedra and edges with two FK2Y2 tetrahedra. In the twenty-first F1- site, F1- is bonded to three K1+ and one Y3+ atom to form distorted FK3Y tetrahedra that share corners with eight FK2Y2 tetrahedra and an edgeedge with one FK3Y tetrahedra. In the twenty-second F1- site, F1- is bonded to two K1+ and two Y3+ atoms to form a mixture of distorted edge and corner-sharing FK2Y2 tetrahedra. In the twenty-third F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the twenty-fourth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form a mixture of distorted edge and corner-sharing FK3Y tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KYF4 by Materials Project

KYF4 crystallizes in the trigonal P3_2 space group. The structure is three-dimensional. there are six inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.63–3.05 Å. In the second K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YF7 pentagonal bipyramid, edges with three KF8 hexagonal bipyramids, and edges with six YF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.57–3.08 Å. In the third K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.60–3.15 Å. In the fourth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YF7 pentagonal bipyramid, edges with three KF8 hexagonal bipyramids, and edges with six YF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.62–3.05 Å. In the fifth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YF7 pentagonal bipyramid, edges with three KF8 hexagonal bipyramids, and edges with six YF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.62–2.93 Å. In the sixth K1+ site, K1+ is bonded to eight F1- atoms to form distorted KF8 hexagonal bipyramids that share a cornercorner with one YF7 pentagonal bipyramid, edges with three KF8 hexagonal bipyramids, and edges with six YF7 pentagonal bipyramids. There are a spread of K–F bond distances ranging from 2.64–3.11 Å. There are six inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YF7 pentagonal bipyramids, edges with four KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.18–2.32 Å. In the second Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share corners with five YF7 pentagonal bipyramids, edges with four KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.22–2.30 Å. In the third Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YF7 pentagonal bipyramids, edges with five KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.18–2.31 Å. In the fourth Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share corners with five YF7 pentagonal bipyramids, edges with three KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.23–2.30 Å. In the fifth Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with three equivalent YF7 pentagonal bipyramids, edges with four KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.18–2.32 Å. In the sixth Y3+ site, Y3+ is bonded to seven F1- atoms to form YF7 pentagonal bipyramids that share a cornercorner with one KF8 hexagonal bipyramid, corners with five YF7 pentagonal bipyramids, edges with four KF8 hexagonal bipyramids, and an edgeedge with one YF7 pentagonal bipyramid. There are a spread of Y–F bond distances ranging from 2.23–2.30 Å. There are twenty-four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the second F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Y3+ atoms. In the third F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Y3+ atoms. In the fourth F1- site, F1- is bonded in a distorted linear geometry to one K1+ and two Y3+ atoms. In the fifth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the sixth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Y3+ atoms. In the seventh F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Y3+ atoms. In the eighth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two equivalent Y3+ atoms. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two K1+ and two Y3+ atoms. In the tenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the eleventh F1- site, F1- is bonded in a 3-coordinate geometry to one K1+ and two equivalent Y3+ atoms. In the twelfth F1- site, F1- is bonded in a 2-coordinate geometry to one K1+ and two Y3+ atoms. In the thirteenth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form a mixture of edge and corner-sharing FK3Y tetrahedra. In the fourteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the fifteenth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form a mixture of distorted edge and corner-sharing FK3Y tetrahedra. In the sixteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the seventeenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the eighteenth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form a mixture of distorted edge and corner-sharing FK3Y tetrahedra. In the nineteenth F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the twentieth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form a mixture of distorted edge and corner-sharing FK3Y tetrahedra. In the twenty-first F1- site, F1- is bonded to three K1+ and one Y3+ atom to form a mixture of edge and corner-sharing FK3Y tetrahedra. In the twenty-second F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the twenty-third F1- site, F1- is bonded in a 4-coordinate geometry to two K1+ and two Y3+ atoms. In the twenty-fourth F1- site, F1- is bonded to three K1+ and one Y3+ atom to form a mixture of distorted edge and corner-sharing FK3Y tetrahedra.

36 MATERIALS SCIENCE↗
NASA NTRS1995

Spectroscopic Investigation of Ce(3+) Doped Fluoride Crystals

Doping of the trivalent rare-earth cerium ion into fluoride crystals is of interest in producing turnable ultra-violet solid state lasers. These lasers are desirable for many applications in medicine, industry, and scientific research, including remote sensing. High absorption and stimulated emission cross sections of the dipole allowed 4f-5d transitions show promise in cerium as a laser ion in crystals. Several research groups have already reported the observation of stimulated emission of cerium in LiYF4, LiSrAlF6, and LiCaAlF6. However, the color center formation in the crystals due to the excited state absorption of ultra-violet pump light adds difficulty to achieving laser action. We have investigated the spectroscopic properties of cerium such as absorption and emission spectra, and lifetimes in four different fluoride crystals, including LiCaAlF6, LiSrAlF6, KyF4 and LiYF4. We have derived the polarized absorption and stimulated emission cross sections from transmission and fluorescence emission measurements for each of the host crystals. we have measured the lifetime of the lowest 5d level; moreover, investigated the temperature dependence of this lifetime and color center formation. Our results on absorption and stimulated emission cross sections for LiCaAlF6 and LiSrAlF6 are similar to the results already published.

Reinhart, Donald H.↗
NASA NTRS2018

Mid-infrared Spectroscopy of Pr-Doped Materials

Solid state lanthanide doped lasers primarily operate in the ultraviolet, visible, near infrared and short-wavelength infrared out to around 2.1 μm. At longer wavelengths, the transitions in conventional oxide crystal and glass materials become susceptible to multiphonon quenching due to their relatively large phonon energy. The use of low phonon materials can minimize the nonradiative quenching, opening up possibilities for solid state lanthanide lasers operating in the mid-infrared (MIR). This provides motivation to study the spectroscopy of lanthanide ions in bromide, chloride and fluoride materials, which have relatively low phonon energies. In this article, the MIR spectroscopy or praseodymium ions in five different host materials is studied, specifically KPb2Br5 (KPB), LaF3, KYF4 (KYF), BaY2F8 (BYF) and YLiF4 (YLF) host crystals. The MIR emission cross sections have been measured from 3 to 6 μm and reciprocity of absorption and emission is utilized to validate the results. The lifetime dynamics in the MIR are covered for various pump and emission wavelengths. Results are also presented on MIR emission from 6.5 to 8.5 μm in a Pr: KPB crystal, which, to the best of the authors knowledge, is the first such measurement of luminescence in this wavelength range that has been published.

Brian M Walsh↗