Characterization of Flux-Grown SmxNd1–xVO4 Compounds and High-Pressure Behavior for x = 0.5

The crystal structure and the vibrational and optical characteristics of flux-grown mixed lanthanide vanadate compounds SmxNd1–xVO4 (x = 0, 0.1, 0.25, 0.5, 0.75 and 1) are reported. A linear, monot...

Precise Characterization of the Rich Structural Landscape Induced by Pressure in Multifunctional FeVO4

We have studied the high-pressure behavior of FeVO4 by means of single-crystal X-ray diffraction (XRD) and density functional theory (DFT) calculations. We have found that the structural sequence o...

High pressure phase transitions in NdVO4

Raman-scattering measurements on NdVO4 suggest a pressure-induced zircon to monazite phase transition beyond 5.9 GPa. The monazite phase undergoes a second phase transition to a yet unknown phase at 18.1 GPa. Lattice-dynamics calculations well support the experimental findings and predict a possible orthorhombic structure for the post-monazite structure of NdVO4.

Monazite-type SrCrO4 under compression

We report a high-pressure study of monoclinic monazite-type SrCrO4 up to 26 GPa. Therein we combined x-ray diffraction, Raman and optical-absorption measurements with ab initio calculations, to find a pressure-induced structural phase transition of SrCrO4 near 8-9 GPa. Evidence of a second phase transition was observed at 10-13 GPa. The crystal structures of the high-pressure phases were assigned to the tetragonal scheelite-type and monoclinic AgMnO4-type structures. Both transitions produce drastic changes in the electronic band gap and phonon spectrum of SrCrO4. We determined the pressure evolution of the band gap for the low-pressure and high-pressure phases as well as the frequencies an…

In situ high-pressure synchrotron X-ray diffraction study of the structural stability in NdVO4 and LaVO4

Abstract Room-temperature angle-dispersive X-ray diffraction measurements on zircon-type NdVO 4 and monazite-type LaVO 4 were performed in a diamond-anvil cell up to 12 GPa. In NdVO 4 , we found evidence for a non-reversible pressure-induced structural phase transition from zircon to a monazite-type structure at 6.5 GPa. Monazite-type LaVO 4 also exhibits a phase transition but at 8.6 GPa. In this case the transition is reversible and isomorphic. In both compounds the pressure induced transitions involve a large volume collapse. Finally, the equations of state and axial compressibilities for the low-pressure phases are also determined.

High-pressure structural and vibrational properties of monazite-type BiPO4, LaPO4, CePO4, and PrPO4

[EN] Monazite-type BiPO4, LaPO4, CePO4, and PrPO4 have been studied under high pressure by ab initio simulations and Raman spectroscopy measurements in the pressure range of stability of the monazite structure. A good agreement between experimental and theoretical Raman-active mode frequencies and pressure coefficients has been found which has allowed us to discuss the nature of the Raman-active modes. Besides, calculations have provided us with information on how the crystal structure is modified by pressure. This information has allowed us to determine the equation of state and the isothermal compressibility tensor of the four studied compounds. In addition, the information obtained on th…

Bandgap behavior and singularity of the domain-induced light scattering through the pressure-induced ferroelectric transition in relaxor ferroelectric A(x)Ba(1-x)Nb(2)O(6) (A: Sr,Ca)

[EN] In this letter, we have investigated the electronic structure of A(x)Ba(1-x)Nb(2)O(6) relaxor ferroelectrics on the basis of optical absorption spectroscopy in unpoled single crystals with A = Sr and Ca under high pressure. The direct character of the fundamental transition could be established by fitting Urbach's rule to the photon energy dependence of the absorption edge yielding bandgaps of 3.44(1) eV and 3.57(1) eV for A = Sr and Ca, respectively. The light scattering by ferroelectric domains in the pre-edge spectral range has been studied as a function of composition and pressure. After confirming with x-ray diffraction the occurrence of the previously observed ferroelectric to pa…

Experimental and theoretical study on the optical properties of LaVO4 crystals under pressure

We report optical absorption and luminescence measurements in pure and trivalent neodymium (Nd3+) doped LaVO4 crystals up to 25 GPa. Nd3+ luminescence has been employed as a tool to follow the structural changes in the crystal. We also present band-structure and crystal-field calculations that provide the theoretical framework to accurately explain the observed experimental results. In particular, both optical absorption and luminescence measurements evidence that a phase transition takes place close to 12 GPa. They also provide information on the pressure dependence of the band-gap as well as the emission lines under compression. We found drastic changes in the optical properties of LaVO4 …

PrVO$_4$ under High Pressure: Effects on Structural, Optical and Electrical Properties

In pursue of a systematic characterization of rare-earth vanadates under compression, in this work we present a multifaceted study of the phase behavior of zircon-type orthovanadate PrVO$_4$ under high pressure conditions, up until 24 GPa. We have found that PrVO$_4$ undergoes a zircon to monazite transition at around 6 GPa, confirming previous results found by Raman experiments. A second transition takes place above 14 GPa, to a BaWO$_4$-I--type structure. The zircon to monazite structural sequence is an irreversible first-order transition, accompanied by a volume collapse of about 9.6%. Monazite phase is thus a metastable polymorph of PrVO$_4$. The monazite-BaWO$_4$-II transition is found…

Theoretical and Experimental Study of the Crystal Structures, Lattice Vibrations, and Band Structures of Monazite-Type PbCrO4, PbSeO4, SrCrO4, and SrSeO4

The crystal structures, lattice vibrations, and electronic band structures of PbCrO4, PbSeO4, SrCrO4, and SrSeO4 were studied by ab initio calculations, Raman spectroscopy, X-ray diffraction, and optical-absorption measurements. Calculations properly describe the crystal structures of the four compounds, which are isomorphic to the monazite structure and were confirmed by X-ray diffraction. Information is also obtained on the Raman- and IR-active phonons, with all of the vibrational modes assigned. In addition, the band structures and electronic densities of states of the four compounds were determined. All are indirect-gap semiconductors. In particular, chromates are found to have band gap…

Phase Stability of Lanthanum Orthovanadate at High Pressure

The journal of physical chemistry / C 120(25), 13749 - 13762(2016). doi:10.1021/acs.jpcc.6b04782

Experimental and theoretical study of dense YBO3 and the influence of non-hydrostaticity.

[EN] YBO3 is used in photonics applications as a host for red phosphors due to its desirable chemical stability, high quantum efficiency and luminescence intensity. Despite its fundamental thermodynamic nature, the isothermal bulk modulus of YBO3 has remained a contentious issue due to a lack of comprehensive experimental and theoretical data and its vibrational modes are far from being understood. Here, we present an experimental-theoretical structural and vibrational study of YBO3. From structural data obtained from synchrotron X-ray diffraction data and ab initio calculations, we have determined the YBO3 bulk modulus, isothermal compressibility tensor and pressure-volume (P-V) equation o…

The electronic structure of zircon-type orthovanadates: Effects of high-pressure and cation substitution

The electronic structure of four ternary-metal oxides containing isolated vanadate ions is studied. Zircon-type YVO4, YbVO4, LuVO4, and NdVO4 are investigated by high-pressure optical-absorption measurements up to 20 GPa. First-principles calculations based on density-functional theory were also performed to analyze the electronic band structure as a function of pressure. The electronic structure near the Fermi level originates largely from molecular orbitals of the vanadate ion, but cation substitution influence these electronic states. The studied ortovanadates, with the exception of NdVO4, undergo a zircon-scheelite structural phase transition that causes a collapse of the band-gap energ…

High-pressure stability and compressibility ofAPO4(A=La, Nd, Eu, Gd, Er, and Y) orthophosphates: An x-ray diffraction study using synchrotron radiation

Room-temperature angle-dispersive x-ray diffraction measurements on zircon-type ${\text{YPO}}_{4}$ and ${\text{ErPO}}_{4}$, and monazite-type ${\text{GdPO}}_{4}$, ${\text{EuPO}}_{4}$, ${\text{NdPO}}_{4}$, and ${\text{LaPO}}_{4}$ were performed in a diamond-anvil cell up to 30 GPa using neon as pressure-transmitting medium. In the zircon-structured oxides we found evidence of a reversible pressure-induced structural phase transformation from zircon to a monazite-type structure. The onset of the transition is at 19.7 GPa in ${\text{YPO}}_{4}$ and 17.3 GPa in ${\text{ErPO}}_{4}$. In ${\text{LaPO}}_{4}$ a nonreversible transition is found at 26.1 GPa and a barite-type structure is proposed for …

Magnetic Properties of a New Hexahalorhenate(IV) Compound and Structural Comparison with Its Hexahaloplatinate(IV) Analog

High-pressure structural, elastic, and thermodynamic properties of zircon-type HoPO4 and TmPO4

[EN] Zircon-type holmium phosphate (HoPO4) and thulium phosphate (TmPO4) have been studied by single-crystal x-ray diffraction and ab initio calculations. We report on the influence of pressure on the crystal structure, and on the elastic and thermodynamic properties. The equation of state for both compounds is accurately determined. We have also obtained information on the polyhedral compressibility which is used to explain the anisotropic axial compressibility and the bulk compressibility. Both compounds are ductile and more resistive to volume compression than to shear deformation at all pressures. Furthermore, the elastic anisotropy is enhanced upon compression. Finally, the calculation…

High Pressure Raman, Optical Absorption, and Resistivity Study of SrCrO4

We studied the electronic and vibrational properties of monazite-type SrCrO4 under compression. The study extended the pressure range of previous studies from 26 to 58 GPa. The existence of two previously reported phase transitions was confirmed at 9 and 14 GPa, and two new phase transitions were found at 35 and 48 GPa. These transitions involve several changes in the vibrational and transport properties with the new high-pressure phases having a conductivity lower than that of the previously known phases. No evidence of chemical decomposition or metallization of SrCrO4 was detected. A tentative explanation for the reported observations is discussed.

Compressibility Systematics of Calcite-Type Borates: An Experimental and Theoretical Structural Study on ABO(3) (A = Al, Sc, Fe, and In)

The structural properties of calcite-type orthoborates ABO(3) (A = Al, Fe, Sc, and In) have been investigated at high pressures up to 32 GPa. They were studied experimentally using synchrotron powder X-ray diffraction and theoretically by means of ab initio total-energy calculations. We found that the calcite-type structure remains stable up to the highest pressure explored in the four studied compounds. Experimental and calculated static geometries (unit-cell parameters and internal coordinates), bulk moduli, and their pressure derivatives are in good agreement. The compressibility along the c axis is roughly three times that along the a axis. Our data clearly indicate that the compressibi…

Luminescence properties of neodymium-doped yttrium aluminium garnet obtained by the co-precipitation method combined with the mechanical process

Nanopowders of yttrium aluminium garnet Y3Al5O12 (YAG) doped with neodymium ions were obtained by the co-precipitation method from the reaction of aluminium and yttrium nitrate and neodymium oxide with ammonia. After washing and drying the hydroxide precursors were calcined at 500, 700, 800 and 900 °C for 1 hour and at 1000 °C for 3 hours. This product was treated by ball milling in a zirconia vial for 0.5, 1.5 and 10 h in order to achieve smaller nanoparticles. The structure, microstructure, morphology and optical properties were investigated by means of diffractometric, microscopic and spectroscopic techniques. The course of the amorphous-to-crystalline transformation was complete after c…

High-Pressure High-Temperature Stability and Thermal Equation of State of Zircon-Type Erbium Vanadate.

Inorganic chemistry 57(21), 14005 - 14012 (2018). doi:10.1021/acs.inorgchem.8b01808

High-pressure phase transformations in NdVO4 under hydrostatic, conditions: a structural powder x-ray diffraction study

Room temperature angle dispersive powder x-ray diffraction experiments on zircon-type NdVO4 were performed for the first time under quasi-hydrostatic conditions up to 24.5 GPa. The sample undergoes two phase transitions at 6.4 and 19.9 GPa. Our results show that the first transition is a zircon-to-scheelite-type phase transition, which has not been reported before, and contradicts previous non-hydrostatic experiments. In the second transition, NdVO4 transforms into a fergusonite-type structure, which is a monoclinic distortion of scheelite-type. The compressibility and axial anisotropy of the different polymorphs of NdVO4 are reported. A direct comparison of our results with former experime…

Phase Behavior of TmVO4 under Hydrostatic Compression: An Experimental and Theoretical Study

We present a structural and optical characterization of magnetoelastic zircon-type TmVO4 at ambient pressure and under high pressure. The properties under high pressure have been determined experimentally under hydrostatic conditions and theoretically using density functional theory. By powder X-ray diffraction we show that TmVO4 undergoes a first-order irreversible phase transition to a scheelite structure above 6 GPa. We have also determined (from powder and single-crystal X-ray diffraction) the bulk moduli of both phases and found that their compressibilities are anisotropic. The band gap of TmVO4 is found to be Eg = 3.7(2) eV. Under compression the band gap opens linearly, until it unde…

High-pressure polymorphs of gadolinium orthovanadate: X-ray diffraction, Raman spectroscopy, and ab initio calculations

We present a study of the different high-pressure polymorphs of $\mathrm{GdV}{\mathrm{O}}_{4}$ and its stability. Powder x-ray diffraction and Raman experiments show a phase transition from a zircon- to a scheelite-type structure taking place at 6.8(4) GPa. Ab initio density functional theory calculations support this conclusion. The equations of state of these two phases are reported. In addition, we studied the pressure evolution of the Raman modes for the zircon and scheelite phases, showing good agreement between calculations and experiments. For the sake of completeness, we performed optical-absorption measurements up to 16 GPa, showing a band-gap collapse at the transition point. Beyo…

LiCrO2 Under Pressure: In-Situ Structural and Vibrational Studies

The high-pressure behaviour of LiCrO2, a compound isostructural to the battery compound LiCoO2, has been investigated by synchrotron-based angle-dispersive X-ray powder diffraction, Raman spectroscopy, and resistance measurements up to 41, 30, and 10 Gpa, respectively. The stability of the layered structured compound on a triangular lattice with R-3m space group is confirmed in all three measurements up to the highest pressure reached. The dependence of lattice parameters and unit-cell volume with pressure has been determined from the structural refinements of X-ray diffraction patterns that are used to extract the axial compressibilities and bulk modulus by means of Birch&ndash

Lattice dynamics of zircon-type NdVO4 and scheelite-type PrVO4 under high-pressure

Abstract Zircon-type NdVO4 and scheelite-type PrVO4 have been studied by means of Raman spectroscopy up to approximately 20 GPa. In the first compound, zircon-scheelite and scheelite-fergusonite phase transitions are reported at 6.4(3) and 19.6(4) GPa, respectively. In the case of scheelite-type PrVO4, a reversible phase transition to a PbWO4-III structure is observed at 16.8(5) GPa. In both cases, a scheelite-type structure is recovered in a metastable state at low pressures. The pressure evolution of the Raman modes is also reported. Our experimental findings are supported by ab initio calculations, which allowed us to discuss the role of mechanic and dynamical instabilities in the phase …

CSD 1987965: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 2002439: Experimental Crystal Structure Determination

Related Article: Enrico Bandiello, Catalin Popescu, Estelina Lora da Silva, Juan Ángel Sans, Daniel Errandonea, Marco Bettinelli|2020|Inorg.Chem.|59|18325|doi:10.1021/acs.inorgchem.0c02933

CSD 1852498: Experimental Crystal Structure Determination

Related Article: Javier Ruiz-Fuertes, Domingo Martínez-García, Tomás Marqueño, Daniel Errandonea, Simon G. MacLeod, Thomas Bernert, Eiken Haussühl, David Santamaría-Pérez, Jordi Ibáñez, Anitha Mallavarapu, S. Nagabhusan Achary, Catalin Popescu, and Marco Bettinelli|2018|Inorg.Chem.|57|14005|doi:10.1021/acs.inorgchem.8b01808

CSD 2004534: Experimental Crystal Structure Determination

Related Article: Enrico Bandiello, Catalin Popescu, Estelina Lora da Silva, Juan Ángel Sans, Daniel Errandonea, Marco Bettinelli|2020|Inorg.Chem.|59|18325|doi:10.1021/acs.inorgchem.0c02933

CSD 1987954: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 1987963: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CCDC 1983533: Experimental Crystal Structure Determination

Related Article: Fabio Piccinelli, Marco Bettinelli, Joan Cano, Francesc Lloret, Miguel Julve, Alessandro Dolmella|2020|Eur.J.Inorg.Chem.|2020|2246|doi:10.1002/ejic.202000199

CSD 1987960: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 1987956: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 1987958: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 1979580: Experimental Crystal Structure Determination

Related Article: Enrico Bandiello, Daniel Errandonea, Javier Gonz��lez-Platas, Pl��cida Rodr��guez-Hern��ndez, Alfonso Mu��oz, Marco Bettinelli, Catalin Popescu|2020|Inorg.Chem.|59|4882|doi:10.1021/acs.inorgchem.0c00147

CSD 1852499: Experimental Crystal Structure Determination

Related Article: Javier Ruiz-Fuertes, Domingo Martínez-García, Tomás Marqueño, Daniel Errandonea, Simon G. MacLeod, Thomas Bernert, Eiken Haussühl, David Santamaría-Pérez, Jordi Ibáñez, Anitha Mallavarapu, S. Nagabhusan Achary, Catalin Popescu, and Marco Bettinelli|2018|Inorg.Chem.|57|14005|doi:10.1021/acs.inorgchem.8b01808

CSD 1987964: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 1987962: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 1852497: Experimental Crystal Structure Determination

Related Article: Javier Ruiz-Fuertes, Domingo Martínez-García, Tomás Marqueño, Daniel Errandonea, Simon G. MacLeod, Thomas Bernert, Eiken Haussühl, David Santamaría-Pérez, Jordi Ibáñez, Anitha Mallavarapu, S. Nagabhusan Achary, Catalin Popescu, and Marco Bettinelli|2018|Inorg.Chem.|57|14005|doi:10.1021/acs.inorgchem.8b01808

CSD 1987955: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 1852496: Experimental Crystal Structure Determination

Related Article: Javier Ruiz-Fuertes, Domingo Martínez-García, Tomás Marqueño, Daniel Errandonea, Simon G. MacLeod, Thomas Bernert, Eiken Haussühl, David Santamaría-Pérez, Jordi Ibáñez, Anitha Mallavarapu, S. Nagabhusan Achary, Catalin Popescu, and Marco Bettinelli|2018|Inorg.Chem.|57|14005|doi:10.1021/acs.inorgchem.8b01808

CSD 1987959: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 1852501: Experimental Crystal Structure Determination

Related Article: Javier Ruiz-Fuertes, Domingo Martínez-García, Tomás Marqueño, Daniel Errandonea, Simon G. MacLeod, Thomas Bernert, Eiken Haussühl, David Santamaría-Pérez, Jordi Ibáñez, Anitha Mallavarapu, S. Nagabhusan Achary, Catalin Popescu, and Marco Bettinelli|2018|Inorg.Chem.|57|14005|doi:10.1021/acs.inorgchem.8b01808

CSD 2002441: Experimental Crystal Structure Determination

Related Article: Enrico Bandiello, Catalin Popescu, Estelina Lora da Silva, Juan Ángel Sans, Daniel Errandonea, Marco Bettinelli|2020|Inorg.Chem.|59|18325|doi:10.1021/acs.inorgchem.0c02933

CSD 1987961: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CCDC 1983534: Experimental Crystal Structure Determination

Related Article: Fabio Piccinelli, Marco Bettinelli, Joan Cano, Francesc Lloret, Miguel Julve, Alessandro Dolmella|2020|Eur.J.Inorg.Chem.|2020|2246|doi:10.1002/ejic.202000199

CSD 1852500: Experimental Crystal Structure Determination

Related Article: Javier Ruiz-Fuertes, Domingo Martínez-García, Tomás Marqueño, Daniel Errandonea, Simon G. MacLeod, Thomas Bernert, Eiken Haussühl, David Santamaría-Pérez, Jordi Ibáñez, Anitha Mallavarapu, S. Nagabhusan Achary, Catalin Popescu, and Marco Bettinelli|2018|Inorg.Chem.|57|14005|doi:10.1021/acs.inorgchem.8b01808

CSD 1987957: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 1987953: Experimental Crystal Structure Determination

Related Article: Javier Gonzalez-Platas, Sinhue Lopez-Moreno, Enrico Bandiello, Marco Bettinelli, Daniel Errandonea|2020|Inorg.Chem.|59|6623|doi:10.1021/acs.inorgchem.0c00772

CSD 1979664: Experimental Crystal Structure Determination

Related Article: Enrico Bandiello, Daniel Errandonea, Javier Gonz��lez-Platas, Pl��cida Rodr��guez-Hern��ndez, Alfonso Mu��oz, Marco Bettinelli, Catalin Popescu|2020|Inorg.Chem.|59|4882|doi:10.1021/acs.inorgchem.0c00147