Reversible Tuning of Ca Nanoparticles Embedded in a Superionic CaF2 Matrix

ABSTRACT: Controlling the size and shape of metallic colloids is crucial for a number of nanotechnological applications ranging from medical diagnosis to electronics. Yet, achieving tunability of morphological changes at the nanoscale is technically difficult and the structural modifications made on nanoparticles generally are irreversible. Here, we present a simple non-chemical method for controlling the size of metallic colloids in a reversible manner. Our strategy consists on applying hydrostatic pressure on a Ca cationic sublattice embedded in the irradiated matrix of CaF2 containing a large concentration of defects. Application of our method to CaF2 along with in situ optical absorption of the Ca plasmon shows that the radii of the Ca nanoparticles can be reduced with an almost constant rate of −1.2 nm/GPa up to a threshold pressure of ∼ 9.4 GPa. We demonstrate recovery of the original nanoparticles upon decompression of the irradiated matrix. The mechanisms for reversible nanocolloid-size variation are analyzed with first-principles simulations. We show that a pressure-driven increase in the binding energy between fluorine centers is responsible for the observed nanoparticle shrinkage. We argue that the same method can be used to generate other metallic colloids (Li, K, Sr, and Cs) with tailored dimensions by simply selecting an appropriate matrix

Crystal-field mediated electronic transitions of EuS up to 35 GPa

An advanced experimental and theoretical model to explain the correlation between the electronic and local structure of Eu2+ in two different environments within a same compound, EuS, is presented. EuX monochalcogenides (X: O, S, Se, Te) exhibit anomalies in all their properties around 14 GPa with a semiconductor to metal transition. Although it is known that these changes are related to the 4f75d0 → 4f65d1 electronic transition, no consistent model of the pressure-induced modifications of the electronic structure currently exists. We show, by optical and x-ray absorption spectroscopy, and by ab initio calculations up to 35 GPa, that the pressure evolution of the crystal field plays a major role in triggering the observed electronic transitions from semiconductor to the half-metal and finally to the metallic state

Interplay between local structure and electronic properties on CuO under pressure

The electronic and local structural properties of CuO under pressure have been investigated by means of X-ray absorption spectroscopy (XAS) at Cu K edge and ab-initio calculations, up to 17 GPa. The crystal structure of CuO consists of Cu motifs within CuO$_4$ square planar units and two elongated apical Cu-O bonds. The CuO$_4$ square planar units are stable in the studied pressure range, with Cu-O distances that are approximately constant up to 5 GPa, and then decrease slightly up to 17 GPa. In contrast, the elongated Cu-O apical distances decrease continuously with pressure in the studied range. An anomalous increase of the mean square relative displacement (EXAFS Debye Waller, \sigma$^2$) of the elongated Cu-O path is observed from 5 GPa up to 13 GPa, when a drastic reduction takes place in \sigma$^2$. This is interpreted in terms of local dynamic disorder along the apical Cu-O path. At higher pressures (P>13 GPa), the local structure of Cu$^{2+}$ changes from a 4-fold square planar to a 4+2 Jahn-Teller distorted octahedral ion. We interpret these results in terms of the tendency of the Cu$^{2+}$ ion to form favorable interactions with the apical O atoms. Also, the decrease in Cu-O apical distance caused by compression softens the normal mode associated with the out-of-plane Cu movement. CuO is predicted to have an anomalous rise in permittivity with pressure as well as modest piezoelectricity in the 5-13 GPa pressure range. In addition, the near edge features in our XAS experiment show a discontinuity and a change of tendency at 5 GPa. For P < 5 GPa the evolution of the edge shoulder is ascribed to purely electronic effects which also affect the charge transfer integral. This is linked to a charge migration from the Cu to O, but also to an increase of the energy band gap, which show a change of tendency occurring also at 5 GPa

Structural, Vibrational, and Elastic Properties of Yttrium Orthoaluminate Nanoperovskite at High Pressures

"This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/page/policy/articlesonrequest/index.html."[EN] The structural and vibrational properties of nanocrystalline yttrium orthoaluminate perovskite (YAlO3) under compression have been experimentally studied. Experimental results have been compared to ab initio simulations of. bulk YAlO3, in the framework of the density functional theory. Furthermore, they have been complemented with an ab initio study of its elastic properties at different pressures. Calculated total and partial phonon density of states have allowed us to understand the contribution of the different atoms and structural units, YO12 dodecahedra and AlO6 octahedra, to the vibrational modes. The calculated infrared-active modes and their pressure dependence are also reported. Finally, the pressure dependences of the, elastic constants and the mechanical stability of the perovskite structure have been analyzed in detail, showing that this phase is mechanically stable until 92 GPa. In fact, experimental results up to 30 GPa show no evidence of any phase transition. A previously proposed possible phase transition in YAlO3 above 80 GPa is also discussed.This research was partially supported by MINECO (MAT2013-46649-C4-2/3/4-P, MAT2015-71070-REDC, and MAT2016-75586-C4-2/3/4-P) and by EU-FEDER funds. M.A.H.-R. thanks MINECO for an FPI grant (BES-2014-068666).Hernández-Rodríguez, M.; Monteseguro, V.; Lozano-Gorrín, A.; Manjón, F.; González-Platas, J.; Rodríguez-Hernández, P.; Muñoz, A.... (2017). Structural, Vibrational, and Elastic Properties of Yttrium Orthoaluminate Nanoperovskite at High Pressures. The Journal of Physical Chemistry C. 121(28):15353-15367. https://doi.org/10.1021/acs.jpcc.7b04245S15353153671212

Phase stability and electronic structure of iridium metal at the megabar range

[EN] The 5d transition metals have attracted specific interest for high-pressure studies due to their extraordinary stability and intriguing electronic properties. In particular, iridium metal has been proposed to exhibit a recently discovered pressure-induced electronic transition, the so-called core-level crossing transition at the lowest pressure among all the 5d transition metals. Here, we report an experimental structural characterization of iridium by x-ray probes sensitive to both long- and short-range order in matter. Synchrotron-based powder x-ray diffraction results highlight a large stability range (up to 1.4 Mbar) of the low-pressure phase. The compressibility behaviour was characterized by an accurate determination of the pressure-volume equation of state, with a bulk modulus of 339(3) GPa and its derivative of 5.3(1). X-ray absorption spectroscopy, which probes the local structure and the empty density of electronic states above the Fermi level, was also utilized. The remarkable agreement observed between experimental and calculated spectra validates the reliability of theoretical predictions of the pressure dependence of the electronic structure of iridium in the studied interval of compressions.The authors thank the financial support of the Spanish Ministry of Science, Innovation and Universities, the Spanish Research Agency (AEI), the European Fund for Regional Development (FEDER) under Grant No. MAT2016-75586-C4-1/2-P and the Generalitat Valenciana under Grant Prometeo/2018/123 (EFIMAT). V. M. acknowledges the Juan de la Cierva fellowship (FJCI-2016-27921) and J.A.S. acknowledges the Ramón y Cajal fellowship program (RYC-2015-17482) and Spanish Mineco Project FIS2017-83295-P. We acknowledge the European Synchrotron Radiation Facility for provision of official research beamtimes, the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU No 2009 00971), Knut and Alice Wallenbergs Foundation Project Strong Field Physics and New States of Matter CoTXS (2014 2019). The interpretation of theoretical results was supported by the Ministry of Science and High Education of the Russian Federation in the framework of Increase Competitiveness Program of NUST MISIS (No. K2-2019-001) implemented by a governmental decree dated 16 March 2013, No 211.Monteseguro, V.; Sans-Tresserras, JÁ.; Cuartero, V.; Cova, F.; Abrikosov, I.; Olovsson, W.; Popescu, C.... (2019). Phase stability and electronic structure of iridium metal at the megabar range. Scientific Reports. 9:1-9. https://doi.org/10.1038/s41598-019-45401-xS199Cynn, H., Klepeis, J. E., Yoo, C.-S. & Young, D. A. Osmium has the Lowest Experimentally Determined Compressibility. Phys. Rev. Lett. 88, 135701–135704 (2002).Döhring, T. et al. Prototyping iridium coated mirrors for x-ray astronomy. Proc. SPIE 10235, 1023504–1023511 (2017).Bednorz, J. G. & Müller, K. A. Possible high Tc superconductivity in the Ba−La−Cu−O system. Z. Phys. B: Condens. Matter 64, 189–193 (1986).Tokura, Y. & Nagaosa, N. Orbital Physics in Transition-Metal Oxides. Science 288, 462–468 (2000).Kobayashi, K.-I., Kimura, T., Sawada, H., Terakura, K. & Tokura, Y. Room-temperature magnetoresistance in an oxide material with an ordered double-perovskite structure. Nature (London) 395, 677–680 (1998).Hrubiak, R., Meng, Y. & Shen, G. Microstructures define melting of molybdenum at high pressures. Nature Commun. 8, 14562–14571 (2017).Cerenius, Y. & Dubrovinsky, L. Compressibility measurements on iridium. J. Alloys Compd. 306, 26–29 (2000).Grussendorff, S., Chetty, N. & Dreysse, H. Theoretical studies of iridium under pressure. J. Phys. Condens. Matter 15, 4127–4134 (2003).Burakovsky, L. et al. Ab initio phase diagram of iridium. Phys. Rev. B 94, 094112–094120 (2016).Dubrovinsky, L. et al. The most incompressible metal osmium at static pressures above 750 gigapascals. Nature 525, 226–229 (2015).Tal, A. A. et al. Pressure-induced crossing of the core levels in 5d metals. Phys. Rev. B 93, 205150–205156 (2016).Merkel, S. et al. Deformation of polycrystalline MgO at pressures of the lower mantle. J Geophys Res. 107, 2271–2287 (2002).Greenberg, E. et al. Pressure-Induced Site-Selective Mott Insulator-Metal Transition in Fe2O3. Phys. Rev. X 8, 031059–031071 (2018).Nemoshkalenko, V. V., Mil’man, V. Y., Zhalko-Titarenko, A. V., Antonov, V. N. & Shitikov, Y. L. Pis’ma Zh. Eksp Teor. Fiz 47, 295–297 (1988).Rehr, J. J. & Albers, R. C. Theoretical approaches to x-ray absorption fine structure. Rev. Mod. Phys. 72, 621–654 (2000).Poiarkova, A. V. & Rehr, J. J. Multiple-scattering x-ray-absorption fine-structure Debye-Waller factor calculations. Phys. Rev. B 59, 948–957 (1998).Glazyrin, K. et al. Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition. Phys. Rev. Lett. 110, 117206–117210 (2013).Sham, T. K. L-edge x-ray-absorption systematics of the noble metals Rh, Pd, and Ag and the main-group metals In and Sn: A study of the unoccupied density of states in 4d elements. Phys. Rev. B 31, 1888–1902 (1985).Leapman, R. D., Grunes, L. A. & Fejes, P. L. Study of the L23 edges in the 3d transition metals and their oxides by electron-energy-loss spectroscopy with comparisons to theory. Phys. Rev. B 26, 614–635 (1982).Choy, J.-H., Kim, D.-K., Hwang, S.-H., Demazeau, G. & Jung, D.-Y. the Ir-O Bond Covalency in Ionic Iridium Perovskites. J. Am. Chem. Soc. 117, 8557–8566 (1995).Clancy, J. P. et al. Spin-orbit coupling in iridium-based 5d compounds probed by x-ray absorption spectroscopy. Phys. Rev. B 86, 195131- (2012).Snigirev, A., Kohn, V., Snigireva, I. & Lengeler, B. A compound refractive lens for focusing high-energy X-rays. Nature 384, 49–51 (1996).Dewaele, A., Loubeyre, P. & Mezouar, M. Equations of state of six metals above 94 GPa. Phys. Rev. B 70, 094112–094119 (2004).Prescher, C. & Prakapenka, V. B. DIOPTAS: a program for reduction of twodimensional X-ray diffraction data and data exploration. High Pressure Res. 35, 223–230 (2015).Toby, B. H. & Von Dreele, R. B. GSAS-II: the genesis of a modern open-source all-purpose crystallography software package. J. Appl. Cryst. 46(2), 544–549 (2013).Birch, F. Finite strain isotherm and velocities for single‐crystal and polycrystalline NaCl at high pressures and 300 K. J. Geophys. Res. 83, 1257–1268 (1978).Angel, R. J., González-Platas, J. & Alvaro, M. EosFit7c and a Fortran module (library) for equation of state calculations. Z. Kristallogr. 229, 405–419 (2014).Mathon, O. et al. The time-resolved and extreme conditions XAS (TEXAS) facility at the European Synchrotron Radiation Facility: the general-purpose EXAFS bending-magnet beamline BM23. J. Synchrotron Radiat. 22, 1548–1554 (2015).Ohfuji, H. et al. "Natural occurrence of pure nano-polycrystalline diamond from impact crater". Scientific Reports. 5: 14702.s, L. D., 2000. J. Alloys Compd. 306, 26–29 (2015).Ravel, B. & Newville, M. ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT. J. Synchrotron Radiat. 12, 537–577 (2005).Blaha, P., Schwarz, K., Madsen, G. K. H., Kvasnicka, D. & Luitz, J. WIEN2K, An Augmented Plane Wave + Local Orbitals Program for Calculating Crystal Properties. Karlheinz Schwarz, Techn. Universität, Wien, Austria. (2001).Perdew, J. P., Burke, S. & Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 77, 3865–3868 (1996)

Optical nanothermometer based on the calibration of the Stokes and upconverted green emissions of Er3+ ions in Y3Ga5O12 nano-garnets

The temperature-dependent green luminescence of Y3Ga5O12 nano-garnets doped with different concentrations of Er3+ ions has been measured from 300 to 850 K and, in more detail, in the biological range from 292 to 335 K. The green emissions were obtained by excitation under 488 nm blue or 800 nm near-infrared laser radiations. Both excitations give rise to bright green luminescence that can be seen by the naked eye, and which can be associated either with Stokes processes, i.e. multiphonon relaxations followed by green spontaneous emission, in the former case or with infrared-to-visible upconversion processes in the latter. The temperature-induced changes in the Er3+ green emissions have been calibrated for both excitations and results point to a strong dependence on the concentration of optically active Er3+ ions. The maximum value of the thermal sensitivity, 64 × 10−4 K−1 at 547 K, has been obtained for the nano-garnets doped with the lowest concentration of Er3+ ions, which is one of the highest values found in the literature. These results allow to conclude that a relatively low concentration of optically active ions is advisable and the changes induced by temperature on the green emissions are independent of the laser excitation radiation used, which is necessary to calibrate the temperature of the immediate environment of the Er3+-doped Y3Ga5O12 nano-garnets.This work have been partially supported by Ministerio de Economía y Competitividad de España (MINECO) under The National Program of Materials (MAT2010-21270-C04-02/-03, and MAT2013-46649-C4-3-P/-4-P), The Consolider-Ingenio 2010 Program (MALTA CSD2007-00045), and the Indo- Spanish Joint Programme of Cooperation in Science and Technology (PRI-PIBIN-2011-1153/DST-INT-Spain-P-38-11), and by the EU-FEDER funds. V. Venkatramu is also grateful to Council of Scientific and Industrial Research (CSIR), New Delhi for the sanction of major research project (No. 03(1229)/12/EMR-II, dated: 16th April, 2012). V. Monteseguro wishes to thank MICINN for the FPI grant (BES-2011- 044596)

High pressure theoretical and experimental analysis of the bandgap of BaMoO4, PbMoO4, and CdMoO4

We have investigated the origin of the bandgap of the BaMoO4, PbMoO4, and CdMoO4 crystals on the basis of optical absorption spectroscopy experiments and ab initio electronic band structure, density of states, and electronic localization function calculations under high pressure. Our study provides an accurate determination of the bandgaps Eg and their pressure derivatives dEg/dP for BaMoO4 (4.43 eV, -4.4 meV/GPa), PbMoO4 (3.45 eV, -53.8 meV/GPa), and CdMoO4 (3.71 eV, -3.3 meV/GPa). The absorption edges were fitted with the Urbach exponential model which we demonstrate to be the most appropriate on thick crystals with direct bandgaps. So far, the narrowing of the bandgap of distinct PbMoO4 had been qualitatively explained considering only the presence of the Pb 6s levels at the top of its valence band. Its fast pressure dependent redshift and the occurrence of its direct bandgap away from Γ in contrast to the other scheelites had remained unsolved. Here we show that contrary to what had been proposed and differently to the other scheelites, in PbMoO4 the band gap takes place between the Pb 6s levels at the top of the valence band and the antibonding O 2p levels at the bottom of the conduction band. For this reason the direct bandgap is pushed away from zone center in order to allow s − p mixing. Its pressure dependence is one order of magnitude faster than in the other shceelites due to two effects: its delocalized character and the higher compressibility of dodecahedral units, PbO8, compared to tetrahedral units, MoO4

Electronic and elastic properties of yttrium gallium garnet under pressure from ab initio studies

In this paper, we present an ab initio study within the framework of density functional theory employing the generalized gradient approximation applied to the study of the structural, elastic, and electronic properties of yttrium gallium garnet, Y3Ga5O12, under hydrostatic pressure. The calculated structural ground state properties are in good agreement with the available experimental data. Pressure dependence of the elastic constants and the mechanical stability are analysed up to 90 GPa, showing that the garnet is mechanically unstable above 84 GPa. We also present the electronic band structure calculations which show that upon compression the fundamental direct gap first increases up to 63 GPa and later monotonically decreases under pressure. (C) 2013 AIP Publishing LLC.This work has been supported by Ministerio de Ciencia e Innovacion of Spain (MICINN) under the National Program of Materials (MAT2010-21270-C04-02/03/04) and the Consolider-Ingenio 2010 Program (MALTA CSD2007-0045), by the Vicerrectorado de Investigacion y Desarrollo of the Universitat Politecnica de Valencia (UPV2011-0914 PAID-05-11 and UPV2011-0966 PAID-06-11) and by the EU-FEDER funds. V. Monteseguro wishes to thank MICINN for the FPI Grant (BES-2011-044596). We thank the computer time provided by the Red Espanola de Supercomputacion (RES).Monteseguro, V.; Rodríguez-Hernández, P.; Lavín, V.; Manjón Herrera, FJ.; Muñoz, A. (2013). Electronic and elastic properties of yttrium gallium garnet under pressure from ab initio studies. Journal of Applied Physics. 113(18):183505-1-183505-8. https://doi.org/10.1063/1.4804133S183505-1183505-81131

Chemical pressure effects on the spectroscopic properties of Nd3+-doped gallium nano-garnets

[EN] Nd3+-doped RE3Ga5O12 (RE = Gd, Y, and Lu) nano-crystalline garnets of 40-45 nm in size have been synthesized by a sol-gel method. With the decrease of the RE atom size, the chemical pressure related to the decreasing volumes of the GaO4 tetrahedral, GaO6 octahedral and REO8 dodecahedral units drive the nano-garnets toward a more compacted structure, which is evidenced by the change of the vibrational phonon mode frequencies. The chemical pressure also increases the crystal-field strength felt by the RE3+ ions while decreases the orthorhombic distortion of the REO8 local environment. These effects alter the absorption and emission properties of the Nd3+ ion measured in the near-infrared luminescence range from 0.87 to 1.43 ¿m associated with the 4 F3/2¿4 IJ (J = 9/2, 11/2, 13/2) transitions. The 4 F3/2 luminescence decay curves show non-exponential behavior due to dipole-dipole energy transfer interactions among Nd3+ ions that increases with pressure.Authors are grateful to The Governments of Spain and India for the Indo-Spanish Joint Programme of Bilateral Cooperation in Science and Technology (PRI-PIBIN-2011-1153/DST-INT-Spain-P-38-11). Dr. Venkatramu is grateful to DAE-BRNS, Government of India for the award of DAE Research Award for Young Scientist (No. 2010/20/34/5/BRNS/2223). This work have been partially supported by MINECO under The National Program of Materials (MAT2013-46649-C4-2-P/-3-P/-4-P), The Consolider-Ingenio 2010 Program (MALTA CSD2007-00045), by Fundacion CajaCanarias (ENER-01), and by the EU-FEDER funds. V. Monteseguro wishes to thank MICINN for the FPI grant (BES-2011-044596). Authors also thank Agencia Canaria de Investigacion, Innovacion y Sociedad de la Informacion for the funds given to Universidad de La Laguna, co-financed by The European Social Fund by a percentage of 85%.Monteseguro, V.; Rathaiah, M.; Linganna, K.; Lozano-Gorrin, AD.; Hernandez-Rodriguez, MA.; Martin, IR.; Babu, P.... (2015). Chemical pressure effects on the spectroscopic properties of Nd3+-doped gallium nano-garnets. Optical Materials Express. 5(8):1661-1673. https://doi.org/10.1364/OME.5.001661S1661167358Pollnau, M., Hardman, P. ., Clarkson, W. ., & Hanna, D. . (1998). Upconversion, lifetime quenching, and ground-state bleaching in Nd3+:LiYF4. Optics Communications, 147(1-3), 203-211. doi:10.1016/s0030-4018(97)00524-5Brandle, C. D., & Barns, R. L. (1974). Crystal stoichiometry of Czochralski grown rare-earth gallium garnets. Journal of Crystal Growth, 26(1), 169-170. doi:10.1016/0022-0248(74)90223-1Venkatramu, V., Giarola, M., Mariotto, G., Enzo, S., Polizzi, S., Jayasankar, C. K., … Speghini, A. (2010). Nanocrystalline lanthanide-doped Lu3Ga5O12garnets: interesting materials for light-emitting devices. Nanotechnology, 21(17), 175703. doi:10.1088/0957-4484/21/17/175703Speghini, A., Piccinelli, F., & Bettinelli, M. (2011). Synthesis, characterization and luminescence spectroscopy of oxide nanopowders activated with trivalent lanthanide ions: The garnet family. Optical Materials, 33(3), 247-257. doi:10.1016/j.optmat.2010.10.039Krsmanović, R., Morozov, V. A., Lebedev, O. I., Polizzi, S., Speghini, A., Bettinelli, M., & Tendeloo, G. V. (2007). Structural and luminescence investigation on gadolinium gallium garnet nanocrystalline powders prepared by solution combustion synthesis. Nanotechnology, 18(32), 325604. doi:10.1088/0957-4484/18/32/325604Naccache, R., Vetrone, F., Speghini, A., Bettinelli, M., & Capobianco, J. A. (2008). Cross-Relaxation and Upconversion Processes in Pr3+ Singly Doped and Pr3+/Yb3+ Codoped Nanocrystalline Gd3Ga5O12: The Sensitizer/Activator Relationship. The Journal of Physical Chemistry C, 112(20), 7750-7756. doi:10.1021/jp711494dAntic-Fidancev, E., Hölsä, J., Lastusaari, M., & Lupei, A. (2001). Dopant-host relationships in rare-earth oxides and garnets doped with trivalent rare-earth ions. Physical Review B, 64(19). doi:10.1103/physrevb.64.195108Rodríguez-Carvajal, J. (1993). Recent advances in magnetic structure determination by neutron powder diffraction. Physica B: Condensed Matter, 192(1-2), 55-69. doi:10.1016/0921-4526(93)90108-iMonteseguro, V., Rodríguez-Hernández, P., Ortiz, H. M., Venkatramu, V., Manjón, F. J., Jayasankar, C. K., … Muñoz, A. (2015). Structural, elastic and vibrational properties of nanocrystalline lutetium gallium garnet under high pressure. Physical Chemistry Chemical Physics, 17(14), 9454-9464. doi:10.1039/c4cp05903dRay, S., León-Luis, S. F., Manjón, F. J., Mollar, M. A., Gomis, Ó., Rodríguez-Mendoza, U. R., … Lavín, V. (2014). Broadband, site selective and time resolved photoluminescence spectroscopic studies of finely size-modulated Y2O3:Eu3+ phosphors synthesized by a complex based precursor solution method. Current Applied Physics, 14(1), 72-81. doi:10.1016/j.cap.2013.07.027Nekvasil, V. (1978). The Crystal Field for Nd3+ in Garnets. Physica Status Solidi (b), 87(1), 317-323. doi:10.1002/pssb.2220870137Rodríguez-Mendoza, U. R., León-Luis, S. F., Muñoz-Santiuste, J. E., Jaque, D., & Lavín, V. (2013). Nd3+-doped Ca3Ga2Ge3O12garnet: A new optical pressure sensor. Journal of Applied Physics, 113(21), 213517. doi:10.1063/1.4809217Kaminska, A., Buczko, R., Paszkowicz, W., Przybylińska, H., Werner-Malento, E., Suchocki, A., … Saxena, S. (2011). Merging of the4F3/2level states of Nd3+ions in the photoluminescence spectra of gadolinium-gallium garnets under high pressure. Physical Review B, 84(7). doi:10.1103/physrevb.84.075483Allik, T. H., Stewart, S. A., Sardar, D. K., Quarles, G. J., Powell, R. C., Morrison, C. A., … Pinto, A. A. (1988). Preparation, structure, and spectroscopic properties ofNd3+:{La1−xLux}3[Lu1−yGay]2Ga3O12crystals. Physical Review B, 37(16), 9129-9139. doi:10.1103/physrevb.37.9129Wu, K., Yao, B., Zhang, H., Yu, H., Wang, Z., Wang, J., & Jiang, M. (2010). Growth and properties of Nd:Lu3Ga5O12 laser crystal by floating-zone method. Journal of Crystal Growth, 312(24), 3631-3636. doi:10.1016/j.jcrysgro.2010.09.029Jia, Z., Arcangeli, A., Tao, X., Zhang, J., Dong, C., Jiang, M., … Tonelli, M. (2009). Efficient Nd3+→Yb3+ energy transfer in Nd3+,Yb3+:Gd3Ga5O12 multicenter garnet crystal. Journal of Applied Physics, 105(8), 083113. doi:10.1063/1.3115442Guillot-Noel, O., Bellamy, B., Viana, B., & Gourier, D. (1999). Correlation between rare-earth oscillator strengths and rare-earth–valence-band interactions in neodymium-dopedYMO4(M=V,P, As),Y3Al5O12,andLiYF4matrices. Physical Review B, 60(3), 1668-1677. doi:10.1103/physrevb.60.1668Demidovich, A. A., Shkadarevich, A. P., Danailov, M. B., Apai, P., Gasmi, T., Gribkovskii, V. P., … Batay, L. E. (1998). Comparison of cw laser performance of Nd:KGW, Nd:YAG, Nd:BEL, and Nd:YVO 4 under laser diode pumping. Applied Physics B: Lasers and Optics, 67(1), 11-15. doi:10.1007/s003400050467Inokuti, M., & Hirayama, F. (1965). Influence of Energy Transfer by the Exchange Mechanism on Donor Luminescence. The Journal of Chemical Physics, 43(6), 1978-1989. doi:10.1063/1.1697063Lupei, V., & Lupei, A. (2000). Emission dynamics of the4F3/2level ofNd3+in YAG at low pump intensities. Physical Review B, 61(12), 8087-8098. doi:10.1103/physrevb.61.8087Maeda, K., Wada, N., Umino, M., Abe, M., Takada, Y., Nakano, N., & Kuroda, H. (1984). Concentration Dependence of Fluorescence Lifetime of Nd3+-Doped Gd3Ga5O12Lasers. Japanese Journal of Applied Physics, 23(Part 2, No. 10), L759-L760. doi:10.1143/jjap.23.l759Geusic, J. E., Marcos, H. M., & Van Uitert, L. G. (1964). LASER OSCILLATIONS IN Nd‐DOPED YTTRIUM ALUMINUM, YTTRIUM GALLIUM AND GADOLINIUM GARNETS. Applied Physics Letters, 4(10), 182-184. doi:10.1063/1.1753928Löhring, J., Nicklaus, K., Kujath, N., & Hoffmann, D. (2007). Diode pumped Nd:YGG laser for direct generation of pulsed 935 nm radiation for water vapour measurements. Solid State Lasers XVI: Technology and Devices. doi:10.1117/12.708220Maunier, C., Doualan, J. L., Moncorgé, R., Speghini, A., Bettinelli, M., & Cavalli, E. (2002). Growth, spectroscopic characterization, and laser performance of Nd:LuVO_4, a new infrared laser material that is suitable for diode pumping. Journal of the Optical Society of America B, 19(8), 1794. doi:10.1364/josab.19.00179