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DOE OSTI2020

Materials Data on Ho(IO3)3 by Materials Project

Ho(O3I)3 crystallizes in the orthorhombic Pmmn space group. The structure is three-dimensional. Ho3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ho–O bond distances ranging from 2.19–2.74 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+ and two I5+ atoms. There are one shorter (1.93 Å) and one longer (2.45 Å) O–I bond lengths. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Ho3+ and two equivalent I5+ atoms. Both O–I bond lengths are 2.80 Å. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ho3+ and two equivalent I5+ atoms. Both O–I bond lengths are 2.12 Å. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+ and one I5+ atom. The O–I bond length is 1.90 Å. There are two inequivalent I5+ sites. In the first I5+ site, I5+ is bonded in a 6-coordinate geometry to six O2- atoms. In the second I5+ site, I5+ is bonded in a 4-coordinate geometry to four equivalent O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(PO3)3 by Materials Project

Ho(PO3)3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to six O2- atoms to form HoO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Ho–O bond distances ranging from 2.24–2.29 Å. In the second Ho3+ site, Ho3+ is bonded to six O2- atoms to form HoO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Ho–O bond distances ranging from 2.22–2.27 Å. In the third Ho3+ site, Ho3+ is bonded to six O2- atoms to form HoO6 octahedra that share corners with six PO4 tetrahedra. There are four shorter (2.25 Å) and two longer (2.27 Å) Ho–O bond lengths. In the fourth Ho3+ site, Ho3+ is bonded to six O2- atoms to form HoO6 octahedra that share corners with six PO4 tetrahedra. There are a spread of Ho–O bond distances ranging from 2.24–2.26 Å. There are nine inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two HoO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 9–29°. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two HoO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 17–27°. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two HoO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 24–48°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two HoO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 30–37°. There is two shorter (1.50 Å) and two longer (1.61 Å) P–O bond length. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two HoO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedral tilt angles are 31°. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two HoO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 25–35°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent HoO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 10–26°. There is two shorter (1.50 Å) and two longer (1.60 Å) P–O bond length. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two equivalent HoO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 29–38°. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the ninth P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with two HoO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 26–30°. There is two shorter (1.50 Å) and two longer (1.61 Å) P–O bond length. There are twenty-seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the ninth O2- site, O2- is bonded in a linear geometry to one Ho3+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted linear geometry to one Ho3+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+ and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom. In the twentieth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the twenty-first O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms. In the twenty-third O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the twenty-sixth O2- site, O2- is bonded in a linear geometry to one Ho3+ and one P5+ atom. In the twenty-seventh O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(ZnP)3 by Materials Project

Ho(ZnP)3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ho3+ is bonded to six equivalent P3- atoms to form HoP6 octahedra that share corners with six equivalent ZnP4 tetrahedra, edges with six equivalent HoP6 octahedra, and edges with six equivalent ZnP4 tetrahedra. All Ho–P bond lengths are 2.83 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded in a trigonal planar geometry to three equivalent P3- atoms. All Zn–P bond lengths are 2.30 Å. In the second Zn2+ site, Zn2+ is bonded to four P3- atoms to form ZnP4 tetrahedra that share corners with three equivalent HoP6 octahedra, corners with seven equivalent ZnP4 tetrahedra, and edges with three equivalent HoP6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are one shorter (2.40 Å) and three longer (2.47 Å) Zn–P bond lengths. There are two inequivalent P3- sites. In the first P3- site, P3- is bonded to three equivalent Ho3+ and three equivalent Zn2+ atoms to form PHo3Zn3 octahedra that share corners with three equivalent PHo3Zn3 octahedra, corners with three equivalent PZn5 trigonal bipyramids, and edges with nine equivalent PHo3Zn3 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second P3- site, P3- is bonded to five Zn2+ atoms to form PZn5 trigonal bipyramids that share corners with six equivalent PHo3Zn3 octahedra and corners with six equivalent PZn5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 69°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(ClO4)3 by Materials Project

Ho(O4Cl)3 crystallizes in the trigonal R3c space group. The structure is three-dimensional. Ho is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Ho–O bond distances ranging from 2.35–2.47 Å. There are four inequivalent O sites. In the first O site, O is bonded in a water-like geometry to one Ho and one Cl atom. The O–Cl bond length is 1.48 Å. In the second O site, O is bonded in a bent 150 degrees geometry to one Ho and one Cl atom. The O–Cl bond length is 1.47 Å. In the third O site, O is bonded in a single-bond geometry to one Cl atom. The O–Cl bond length is 1.42 Å. In the fourth O site, O is bonded in a water-like geometry to one Ho and one Cl atom. The O–Cl bond length is 1.48 Å. Cl is bonded in a tetrahedral geometry to four O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(IO3)3 by Materials Project

Ho(O3I)3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.29–2.77 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two I5+ atoms. There are one shorter (1.84 Å) and one longer (2.67 Å) O–I bond lengths. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+ and one I5+ atom. The O–I bond length is 1.86 Å. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+ and one I5+ atom. The O–I bond length is 1.84 Å. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ho3+ and one I5+ atom. The O–I bond length is 1.83 Å. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ho3+ and one I5+ atom. The O–I bond length is 1.86 Å. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+ and two I5+ atoms. There are one shorter (1.85 Å) and one longer (2.85 Å) O–I bond lengths. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Ho3+ and one I5+ atom. The O–I bond length is 1.85 Å. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to three I5+ atoms. There are a spread of O–I bond distances ranging from 1.87–2.67 Å. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ho3+ and one I5+ atom. The O–I bond length is 1.85 Å. There are three inequivalent I5+ sites. In the first I5+ site, I5+ is bonded in a 6-coordinate geometry to six O2- atoms. In the second I5+ site, I5+ is bonded in a 3-coordinate geometry to four O2- atoms. In the third I5+ site, I5+ is bonded in a 3-coordinate geometry to three O2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(ClO4)3 by Materials Project

Ho(O4Cl)3 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. Ho is bonded in a 9-coordinate geometry to nine O atoms. There are six shorter (2.40 Å) and three longer (2.44 Å) Ho–O bond lengths. There are three inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to one Cl atom. The O–Cl bond length is 1.42 Å. In the second O site, O is bonded in a bent 150 degrees geometry to one Ho and one Cl atom. The O–Cl bond length is 1.47 Å. In the third O site, O is bonded in a bent 150 degrees geometry to one Ho and one Cl atom. The O–Cl bond length is 1.47 Å. Cl is bonded in a tetrahedral geometry to four O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(AlC)3 by Materials Project

Ho(AlC)3 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ho3+ is bonded to six equivalent C4- atoms to form HoC6 octahedra that share corners with six equivalent AlC4 tetrahedra, edges with six equivalent HoC6 octahedra, and edges with six equivalent AlC4 tetrahedra. All Ho–C bond lengths are 2.54 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four C4- atoms to form AlC4 tetrahedra that share corners with three equivalent HoC6 octahedra, corners with seven equivalent AlC4 tetrahedra, and edges with three equivalent HoC6 octahedra. The corner-sharing octahedral tilt angles are 19°. There are one shorter (2.02 Å) and three longer (2.10 Å) Al–C bond lengths. In the second Al3+ site, Al3+ is bonded in a trigonal planar geometry to three equivalent C4- atoms. All Al–C bond lengths are 1.98 Å. There are two inequivalent C4- sites. In the first C4- site, C4- is bonded in a 6-coordinate geometry to three equivalent Ho3+ and three equivalent Al3+ atoms. In the second C4- site, C4- is bonded to five Al3+ atoms to form corner-sharing CAl5 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(CuS)3 by Materials Project

Ho(CuS)3 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Ho3+ is bonded to six equivalent S2- atoms to form HoS6 octahedra that share corners with twelve equivalent CuS4 tetrahedra, edges with three equivalent HoS6 octahedra, and edges with six equivalent CuS4 tetrahedra. All Ho–S bond lengths are 2.74 Å. Cu1+ is bonded to four equivalent S2- atoms to form CuS4 tetrahedra that share corners with four equivalent HoS6 octahedra, corners with six equivalent CuS4 tetrahedra, edges with two equivalent HoS6 octahedra, and edges with three equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 17–55°. There are a spread of Cu–S bond distances ranging from 2.35–2.43 Å. S2- is bonded in a 6-coordinate geometry to two equivalent Ho3+ and four equivalent Cu1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(CuTe)3 by Materials Project

Ho(CuTe)3 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Ho3+ is bonded to six equivalent Te2- atoms to form HoTe6 octahedra that share corners with twelve equivalent CuTe4 tetrahedra, edges with three equivalent HoTe6 octahedra, and edges with six equivalent CuTe4 tetrahedra. There are three shorter (3.04 Å) and three longer (3.05 Å) Ho–Te bond lengths. Cu1+ is bonded to four equivalent Te2- atoms to form CuTe4 tetrahedra that share corners with four equivalent HoTe6 octahedra, corners with six equivalent CuTe4 tetrahedra, edges with two equivalent HoTe6 octahedra, and edges with three equivalent CuTe4 tetrahedra. The corner-sharing octahedra tilt angles range from 15–57°. There are a spread of Cu–Te bond distances ranging from 2.61–2.65 Å. Te2- is bonded to two equivalent Ho3+ and four equivalent Cu1+ atoms to form a mixture of distorted edge and corner-sharing TeHo2Cu4 octahedra. The corner-sharing octahedra tilt angles range from 1–91°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ho(BO2)3 by Materials Project

Ho(BO2)3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are four inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.27–2.59 Å. In the second Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.28–2.54 Å. In the third Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.27–2.84 Å. In the fourth Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.32–2.64 Å. There are six inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.53 Å. In the second B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There is one shorter (1.47 Å) and three longer (1.48 Å) B–O bond length. In the third B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.54 Å. In the fourth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.54 Å. In the fifth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.45–1.53 Å. In the sixth B3+ site, B3+ is bonded to four O2- atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.52 Å. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+ and two B3+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+ and two B3+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Ho3+ and two equivalent B3+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ho3+ and two B3+ atoms. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to three B3+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ho3+ and two B3+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Ho3+ and two B3+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+ and two B3+ atoms. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two Ho3+ and two B3+ atoms. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ho3+ and two equivalent B3+ atoms. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ho3+ and two equivalent B3+ atoms. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to three Ho3+ and one B3+ atom. In the thirteenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Ho3+ and two equivalent B3+ atoms. In the fourteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Ho3+ and two equivalent B3+ atoms. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+ and two equivalent B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Tailoring Ion Transport in Li 3‐3y Ho 1+y Cl 6‐x Br x via Transition‐Metal Free Structural Planes and Charge Carrier Distribution

Abstract Localized atomistic disorder in halide‐based solid electrolytes (SEs) can be leveraged to boost Li + mobility. In this study, Li + transport in structurally modified Li 3 HoCl 6 , via Br − introduction and Li + deficiency, is explored. The optimized Li 3‐3 y Ho 1+ y Cl 6‐ x Br x achieves an ionic conductivity of 3.8 mS cm −1 at 25 °C, the highest reported for holmium halide materials. 6,7 Li nuclear magnetic resonance and relaxometry investigations unveil enhanced ion dynamics with bromination, attaining a Li + motional rate neighboring 116 MHz. X‐ray diffraction analyses reveal mixed‐anion‐induced phase transitions with disproportionate octahedral expansions and distortions, creating Ho‐free planes with favorable energetics for Li + migration. Bond valence site energy analysis highlights preferred Li + transport pathways, particularly in structural planes devoid of Ho 3+ blocking effects. Molecular dynamics simulations corroborate enhanced Li + diffusion with Br − introduction into Li 3 HoCl 6 . Li‐Ho electrostatic repulsions in the (001) plane presumably drive Li + diffusion into the Ho‐free (002) layer, enabling rapid intraplanar Li + motion and exchange between the 2d and 4h sites. Li 3‐3 y Ho 1+ y Cl 6‐ x Br x also demonstrates good battery cycling stability. These findings offer valuable insights into the intricate correlations between structure and ion transport and will help guide the design of high‐performance fast ion conductors for all‐solid‐state batteries.

Chemistry↗
NASA NTRS1989

Development of flashlamp-pumped Q-switched Ho:Tm:Cr:YAG lasers for mid-infrared LIDAR application

A flashlamp-pumped 2.1 micron Ho:Tm:Cr:YAG laser was studied for both normal mode and Q-switched operations under a wide variety of experimental conditions in order to optimize performance. Laser output energy, slope efficiency, threshold and pulselength were determined as a function of operating temperature, output mirror reflectivity, input electrical energy and Q-switch opening time. The measured normal-mode laser thresholds of a Ho(3+) (0.45 atomic percent):Tm(3+) (2.5 atomic percent):Cr(3+) (0.8 atomic percent):YAG crystal ranged form 26 to 50 J between 120 and 200 K with slope efficiencies up to 0.36 percent with a 60 percent reflective output mirror. Under Q-switched operation the slope efficiency was 90 percent of the normal-mode result. Development of solid state lasers with Ho(3+), Tm(3+) and/or Er(3+) doped crystals has been pursued by NASA for eye-dafe mid-infrared LIDAR (light detection and ranging) application. As a part of the project, the authors have been working on evaluating Ho(3+):Tm(3+):Cr(3+):YAG crystals for normal-mode and Q-switched 2.1 micron laser operations in order to determine an optimum Tm(3+) concentration under flashlamp pumping conditions. Lasing properties of the Ho(3+) in the mid-infrared region have been studied by many research groups since the early 1960's. However, the technology of those lasers is still premature for lidar application. In order to overcome the inefficiency related to narrow absorption bands of the Ho(3+), Tm(3+) and Er(3+), the erbium has been replaced by chromium. The improvement in flashlamp-pumped Ho(3+) laser efficiency has been demonstrated recently by several research groups by utilizing the broad absorption spectrum of Cr(3+) which covers the flashlamp's emission spectrum. Efficient energy transfer to the Tm(3+) and then the Ho(3+) occurs subsequently. It is known that high Tm(3+) concentration and low Ho(3+) concentration are preferred to achieve a quantum efficiency approaching two and to avoid large reabsorption losses. However, determination of the optimum Tm(3+) concentration required to ensure efficient energy transfer from Cr(3+) to Tm(3+) and from Tm(3+) to Ho(3+) has not been made in the Ho:Tm:CR:YAG crystal. The results obtained so far are given.

Choi, Young S.↗
NASA NTRS1994

Development of infrared sensors using energy transfer/energy upconversion processes: Study of laser excited fluorescence in rare Earth ion doped crystals

A summary is presented of the spectroscopic study of three systems: LaF3:Ho(3+), LaF3:Er(3+) and CaF2:Nd(3+). When the D levels of Ho(3+) in LaF3 were resonantly excited with a laser beam of 640 nm, upconverted emissions were detected from J (416 nm), F (485 nm), and E (546 nm) levels. Energy upconverted emissions were also observed from F and E levels of Ho(3+) when the material was excited with an 800 nm near infrared laser. When the D levels of Er(3+) in LaF3 were resonantly excited with a laser beam of 637 nm, upconverted emissions were detected from the E (540 nm) and P (320, 400, and 468 nm) levels. Energy upconverted emissions were also observed from F, E, and D levels of Er(3+) when the material was resonantly excited with an 804 nm near infrared laser. When the D levels of Nd(3+) in CaF2 were resonantly excited with a laser beam of 577 nm, upconverted emissions were detected from the L (360 and 382 nm), K (418 nm), and I (432 nm) levels. Very weak upconverted emissions were detected when this system was irradiated with a near infrared laser. The numbers in parentheses are the wavelengths of the emissions.

Nash-Stevenson, S. K.↗
NASA NTRS1989

Development of mid-infrared solid state lasers for spaceborne lidar

Laser performance of Ho(3+):Tm(3+):Cr(3+):YAG crystals was investigated under both Cr:GSAG laser and flashlamp pumping. A flashlamp pumped Cr:GSAG laser was built to simulate high power quasi-CW laser diode pumping of a 2.1 micrometer holmium laser. The 2.1 micrometer output laser energy exceeded more than 14 mJ, the highest value reported to date under laser pumping near 785 nm. This was obtained in a pulse length of nearly 650 microsec from a 3 x 3 mm Ho:Tm:Cr:YAG rod by using the flashlamp-pumped Cr:CSAG laser as a pumping source at the diode laser wavelength, 785 micrometers. In addition, Ho:Tm:Cr:YAG crystals with various Tm(3+) concentrations were evaluated for flashlamp-pumped normal mode and Q-switched 2.1 micrometer laser operations under a wide variety of experimental conditions in order to understand internal dynamic processes among the ions and to determine an optimum lasing condition. An increase of the laser slope efficiency was observed with the increase of the Tm(3+) concentration from 2.5 to 4.5 atomic percent. The thermal dependence of the laser performance was also investigated. Q-switched laser output energies corresponding to nearly 100 percent of the normal-mode laser energies were obtained in a strong single spike of 200 ns pulse length by optimizing the opening time of a lithium niobate Q-switch.

Whitney, Donald A.↗
NASA NTRS1990

Development of mid-infrared solid state lasers for spaceborne lidar

Researchers investigated laser performance of Ho(3+):Tm(3+):Cr(3+):YAG crystals under both Cr:GSAG laser and flashlamp pumping. A flashlamp pumped Cr:GSAG laser was built to simulate high power quasi-CW laser diode pumping of a 2.1 micron holmium laser. The 2.1 micron output laser energy exceeded more than 14 mJ, the highest value reported to date under laser pumping near 785 nm. This was obtained in a pulse length of nearly 650 microns from a 3 x 3 mm Ho:Tm:Cr:YAG rod by using the flashlamp-pumped Cr:GSAG laser as a pumping source at the diode laser wavelength, 785 microns. In addition, Ho:Tm:Cr:YAG crystals with various Tm(3+) concentrations have been evaluated for flashlamp-pumped normal mode and Q-switched 2.1 micron laser operations under a wide variety of experimental conditions in order to understand internal dynamic processes among the ions and to determine an optimum lasing condition. An increase of the laser slope efficiency was observed with the increase of the Tm(3+) concentration from 2.5 atomic percent to 4.5 atomic percent. The thermal dependence of the laser performance was also investigated. Q-switched laser output energies corresponding to nearly 100 percent of the normal-mode laser energies were obtained in a strong single spike of 200 ns pulse length by optimizing the opening time of a lithium niobate Q-switch.

Whitney, Donald A.↗
NASA NTRS1989

Development of mid-infrared solid state lasers for spaceborne lidar

The laser performance of a Ho(3+):Tm(3+):Cr(3+):YAG crystal was measured under flashlamp pumping at various operating temperatures. The normal mode laser thresholds of a Ho(3+)(0.45 at. percent):Tm(3+)(2.5 at. percent):Cr(3+)(1.5 at. percent ):YAG crystal were found to range from 26 to 50 J between 120 and 200 K with slope efficiencies up to 0.36 percent with a 60 percent reflective output mirror. From the Q-switched operations a slope efficiency corresponding to 90 percent of the normal mode operation was observed. Laser wavelengths were measured for various operating conditions and fluorescence spectra were obtained at various temperatures in order to help understand the dynamic energy processes among the Ho(3+), Tm(3+), and Cr(3+) ions. A pulse forming network for a flashlamp pumped Cr:GSAG laser, which is to be used as a high power laser diode simulator in rare earth laser pumping, was completed and tested. The network provided critically damped, 1 ms FWHM, square pulses with a rise time of about 160 micrometers at an input electrical energy of 300 J.

Whitney, Donald A.↗
DOE OSTI2020

Quantum dynamics in strongly driven random dipolar magnets

The random dipolar magnet LiHo x Y 1– x F 4 enters a strongly frustrated regime for small Ho 3+ concentrations with x < 0.05. In this regime, the magnetic moments of the Ho 3+ ions experience small quantum corrections to the common Ising approximation of LiHo x Y 1– x F 4 , which lead to a $\mathbb{Z}_2$-symmetry breaking and small, degeneracy breaking energy shifts between different eigenstates. Here we show that destructive interference between two almost degenerate excitation pathways burns spectral holes in the magnetic susceptibility of strongly driven magnetic moments in LiHo x Y 1– x F 4 . Such spectral holes in the susceptibility, microscopically described in terms of Fano resonances, can already occur in setups of only two or three frustrated moments, for which the driven level scheme has the paradigmatic Λ shape. For larger clusters of magnetic moments, the corresponding level schemes separate into almost isolated many-body Λ schemes, in the sense that either the transition matrix elements between them are negligibly small or the energy difference of the transitions is strongly off-resonant to the drive. This enables the observation of Fano resonances, caused by many-body quantum corrections to the common Ising approximation also in the thermodynamic limit. Finally, we discuss its dependence on the driving strength and frequency as well as the crucial role that is played by lattice dissipation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗