Spectroscopy and CW first laser operation of Yb-doped Gd_3(Al_05Ga_05)_5O_12 crystal

We present the spectroscopic characterization and laser operation of a 2%at. Yb doped Gd3(Al0.5Ga0.5)5O12 (Yb:GAGG) crystal, grown with the Czochralski method. We determined the absorption and the emission spectrum, the upper level lifetime, and the thermal conductivity. The internal disordered structure determines a significant broadening of the emission band (12.1 nm FWHM) with respect to the parent composition Yb:GGG (8 nm FWHM). The laser performances were evaluated on an end pumped cavity, using a CW semiconductor laser as the pump source. We obtained a maximum slope efficiency of 60.8% and an optical to optical efficiency of 46.0%, with a maximum output power of 4 W, limited only by the available pump power. The tuning range extends from 995 nm to 1050 nm. To our knowledge this is the first spectroscopic investigation and the first assessment of the laser performance of an Yb:GAGG crystal with this composition (i.e. Al/Ga balance = 0.5/0.5)

Thermally induced fading of Mn-doped YAP nanoceramic

We study pomax games, a family of combinatorial games which are always integer-valued. Specifically, we study games played on Young diagrams and Boolean lattices. We find a linear algorithm for computing the values of pomax games played on Young diagrams with only two rows. Some of the statements involved in this proof hold also for games on general Young diagrams. For pomax games on Boolean lattices, we introduce the concept of upper and lower games and use that as a tool to study the distribution of possible game values. We prove that games that equal any sufficiently small even integer can always be found, and that the density of distinct game values converges when the game size tends to infinity. Based on computational evidence, we conjecture that if the upper and lower games of some game are identical, then the value of that game is the sum of the upper and lower game.Vi studerar pomaxspel, en familj av heltalsvärda kombinatoriska spel. Mer specifikt studerar vi dessa spel då de spelas på Youngdiagram och Boolska lattis. Vi hittar en linjär algoritm för att beräkna värdet av pomaxspel på Youngdiagram med som mest två rader. Vissa av de ingående resultaten håller även for spel på allmänna Youngdiagram. Gällande pomaxspel pa Boolska lattis introducerar vi koncepten övre och undre spel, och använder detta for att analysera fördelningen av möjliga spelvärden. Vi visar att det alltid finns spel av varje tillräckligt litet jämnt värde, och att densiteten av distinkta spelvärden konvergerar då spelstorleken går mot oändligheten. Baserat på beräkningar förmodar vi att om det övre och undre spelet hörande till något spel ar identiska, så är detta spel lika med summan av det övre och undre spelet

Band Gap Engineering and Trap Depths of Intrinsic Point Defects in RAlO3 (R = Y, La, Gd, Yb, Lu) Perovskites

The work was supported by the Polish National Science Centre (Project No. 2018/31/B/ST8/00774), by the NATO SPS Project G5647, and by the Ministry of Education and Science of Ukraine (Project DB/Kinetyka no. 0119U002249). L.V. acknowledges support of the National Research Foundation of Ukraine under Grant No. 2020.02/0373 “Crystalline phosphors’ engineering for biomedical applications, energy saving lighting and contactless thermometry”. Researchers from Tartu were supported by the ERDF fundings in Estonia granted to the Centre of Excellence TK141 “Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelectronics (HiTechDevices)” (Grant No. 2014-2020.4.01.15-0011) and Estonian Research Council Grant PRG-629. The Institute of Solid State Physics, University of Latvia as the Center of Excellence acknowledges funding from the H2020-WIDESPREAD-01-2016-2017-Teaming Phase2 under Grant Agreement No. 739508, Project CAMART2. N.K. was supported by the National long-term project No. WQ20142200205 (Recruitment Program of Global Experts, PRC). Authors are thankful to George Loutts from Norfolk State University, United States, and Dorota Pawlak from Institute of Electronic Materials Technology, Poland for providing some single crystals studied in the work, as well as to Kirill Chernenko from FinEstBeAMS of MAX IV for his assistance with synchrotron experiments.The possibility of band gap engineering (BGE) in RAlO3(R = Y, La, Gd, Yb, Lu) perovskites in the context of trap depths of intrinsic point defects was investigated comprehensively using experimental and theoretical approaches. The optical band gap of the materials,Eg, was determined via both the absorption measurements in the VUV spectral range and the spectra of recombination luminescence excitation by synchrotron radiation. The experimentally observed effect ofEgreduction from ∼8.5 to ∼5.5 eV in RAlO3perovskites with increasing R3+ionic radius was confirmed by the DFT electronic structure calculations performed for RMIIIO3crystals (R = Lu, Y, La; MIII= Al, Ga, In). The possibility of BGE was also proved by the analysis of thermally stimulated luminescence (TSL) measured above room temperature for the far-red emitting (Y/Gd/La)AlO3:Mn4+phosphors, which confirmed decreasing of the trap depths in the cation sequence Y → Gd → La. Calculations of the trap depths performed within the super cell approach for a number of intrinsic point defects and their complexes allowed recognizing specific trapping centers that can be responsible for the observed TSL. In particular, the electron traps of 1.33 and 1.43 eV (in YAlO3) were considered to be formed by the energy level of oxygen vacancy (VO) with different arrangement of neighboring YAland VY, while shallower electron traps of 0.9-1.0 eV were related to the energy level of YAlantisite complexes with neighboring VOor (VO+ VY). The effect of the lowering of electron trap depths in RAlO3was demonstrated for the VO-related level of the (YAl+ VO+ VY) complex defect for the particular case of La substituting Y. © 2021 The Authors. Published by American Chemical SocietyNATO SPS G5647; National Research Foundation of Ukraine 2020.02/0373; Polish National Science Centre 2018/31/B/ST8/00774; Eesti Teadusagentuur PRG-629; Latvijas Universitate 739508, WQ20142200205; Institute of Solid State Physics, Chinese Academy of Sciences; Ministry of Education and Science of Ukraine 0119U002249; European Regional Development Fund 2014-2020.4.01.15-0011, TK14

The pressure and temperature evolution of the Ca3V2O8 crystal structure using powder X-ray diffraction

We present a comprehensive experimental study of the crystal structure of calcium vanadate (Ca3V2O8) under systematic temperature and pressure conditions. The temperature evolution (4-1173 K) of the Ca3V2O8 structural properties is investigated at ambient pressure. The pressure evolution (0-13.8 GPa) of the Ca3V2O8 structural properties is investigated at ambient temperature. Across all pressures and temperatures used in the present work, the Ca3V2O8 crystal structure was determined by Rietveld refinement of powder X-ray diffraction data. The experimental high-pressure data are also supported by density-functional theory calculations. According to the high-pressure results, Ca3V2O8 undergoes a pressure-induced structural phase transition at a pressure of 9.8(1) GPa from the ambient pressure trigonal structure (space group R3c) to a monoclinic structure (space group Cc). The experimentally determined bulk moduli of the trigonal and monoclinic phases are, respectively, B0 = 69(2) GPa and 105(12) GPa. The trigonal to monoclinic phase transition appears to be prompted by non-hydrostatic conditions. Whilst the trigonal and monoclincic space groups show a group/subgroup relationship, the discontinuity in the volume per formula unit observed at the transition indicates a first order phase transition. According to the high-temperature results, the trigonal Ca3V2O8 structure persists over the entire range of studied temperatures. The pressurevolume equation of state, axial compressibilities, Debye temperature (264(2) K), and thermal expansion coefficients are all determined for the trigonal Ca3V2O8 structure

Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≥ II, EF ≤35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure < 100 mmHg (n = 1127), estimated glomerular filtration rate < 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

Pressure-induced amorphization of the Y3Ga5O12 garnet studied to 1 Mbar

We use micro-beam synchrotron x-ray diffraction to study the pressure-induced amorphization of nano-sized and single crystals of Y3Ga5O12 up to pressures exceeding 1 Mbar in static compression. The abrupt pressure-induced amorphization found for both 56 nm and bulk micrometric crystals at around 76 GPa independently of the pressure transmitting medium employed demonstrates its intrinsic nature, previously predicted at 79 GPa by ab initio calculations. The single crystal structural solution at 50 GPa shows that the contraction of the unit-cell, mostly accommodated by the compressible YO8 dodecahedra, gives rise to a regularization and tilting increase of the GaO6 polyhedra with the Y?O-Ga angle changing from 104.84° to 102.34° in 50 GPa. We obtain a bulk modulus of 178(3) GPa for the single crystal and 172(3) GPa for the nanocrystals in excellent agreement with previous calculations.V. M. and J.R–F. thank the Spanish Ministry of Science, Innovation and Universities for the Juan de la Cierva program (FJCI-2016-27921) and for project PGC-2018-097520-A-100, respectively

Magnetic and Electrical Characteristics of Nd³⁺-Doped Lead Molybdato-Tungstate Single Crystals

Single crystals of Pb1−3x▯xNd2x(MoO4)1−3x(WO4)3x (PNMWO) with scheelite-type structure, where ▯ denotes cationic vacancies, have been successfully grown by the Czochralski method in air and under 1 MPa. This paper presents the results of structural, optical, magnetic and electrical, as well as the broadband dielectric spectroscopy measurements of PNMWO single crystals. Research has shown that replacing diamagnetic Pb2+ ions with paramagnetic Nd3+ ones, with a content not exceeding 0.01 and possessing a screened 4f-shell, revealed a significant effect of orbital diamagnetism and Van Vleck’s paramagnetism, n-type electrical conductivity with an activation energy of 0.7 eV in the intrinsic area, a strong increase of the power factor above room temperature for a crystal with x = 0.005, constant dielectric value (~30) and loss tangent (~0.01) up to room temperature. The Fermi energy (~0.04 eV) and the Fermi temperature (~500 K) determined from the diffusion component of thermopower showed shallow donor levels

Growth and EPR properties of ErVO4 single crystals

Single crystals of ErVO4 were grown by the Czochralski method under ambient pressure in a nitrogen atmosphere. Obtained crystals were transparent with strong pink coloring. Electron paramagnetic resonance (EPR) spectra were recorded as a function of the applied magnetic field. Temperature and angular dependences of the EPR spectra of the samples in the 3–300 K temperature range were analyzed applying both Lorentzian––Gauss approximation for diluted medium and Dyson for dense magnetic medium. EPR-NMR program was done to find local symmetry and spin Hamiltonian parameters of erbium ions