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Robert Jackson's Outputs (42)

Using Neural Network models to estimate stellar ages from lithium equivalent widths: An EAGLES expansion (2024)
Journal Article
Weaver, G., Jeffries, R. D., & Jackson, R. J. (in press). Using Neural Network models to estimate stellar ages from lithium equivalent widths: An EAGLES expansion. Monthly Notices of the Royal Astronomical Society, https://doi.org/10.1093/mnras/stae2133

We present an Artificial Neural Network (ANN) model of photospheric lithium depletion in cool stars (3000 < Teff/K < 6500), producing estimates and probability distributions of age from 7Li 6708Å equivalent width (LiEW) and effective temperatur... Read More about Using Neural Network models to estimate stellar ages from lithium equivalent widths: An EAGLES expansion.

The Gaia-ESO Survey: 3D dynamics of young groups and clusters from GES and Gaia EDR3 (2024)
Journal Article
Wright, N. J., Jeffries, R. D., Jackson, R. J., Sacco, G. G., Arnold, B., Franciosini, E., …Worley, C. C. (2024). The Gaia-ESO Survey: 3D dynamics of young groups and clusters from GES and Gaia EDR3. Monthly Notices of the Royal Astronomical Society, 533(1), 705–728. https://doi.org/10.1093/mnras/stae1806

We present the first large-scale 3D kinematic study of ∼2700 spectroscopically-confirmed young stars (< 20 Myr) in 18 star clusters and OB associations (hereafter groups) from the combination of Gaia astrometry and Gaia-ESO Survey spectroscopy... Read More about The Gaia-ESO Survey: 3D dynamics of young groups and clusters from GES and Gaia EDR3.

A comparison of oxygen Frenkel formation and rare earth doping in the Lu2SiO5 and Y2SiO5 orthosilicates using a computer modelling approach (2024)
Journal Article
de S. Santos, A. L., B. V. Freire, E., da C. Bispo, G. F., Jackson, R. A., Macedo, Z. S., & E. G. Valerio, M. (2024). A comparison of oxygen Frenkel formation and rare earth doping in the Lu2SiO5 and Y2SiO5 orthosilicates using a computer modelling approach. Computational Materials Science, 243, Article 113125. https://doi.org/10.1016/j.commatsci.2024.113125

The Lu2SiO5 (LSO) and Y2SiO5 (YSO) orthosilicates are well-known in the literature for their properties when doped with rare earth ions. Ce-doped LSO and YSO hosts have been considered as scintillators with high efficiency, but some questions about t... Read More about A comparison of oxygen Frenkel formation and rare earth doping in the Lu2SiO5 and Y2SiO5 orthosilicates using a computer modelling approach.

Defects and Spectroscopic Investigation of Eu3+ Doping in MgGa2O4 (2024)
Journal Article
Sousa, M. F., de Mesquita, B. R., Oliveira, J. L., Silva, C. H. P., Tavares, F. J. R., Santos, R. D. S., …Jackson, R. A. (in press). Defects and Spectroscopic Investigation of Eu3+ Doping in MgGa2O4. physica status solidi (b), Article 2300580. https://doi.org/10.1002/pssb.202300580

Atomistic simulation is performed to study the defect properties and spectroscopy in the MgGa2O4 structure. The calculations indicate that the most favorable type of intrinsic defect is generated by the cation antisite defect, in which there is an ex... Read More about Defects and Spectroscopic Investigation of Eu3+ Doping in MgGa2O4.

Local modification of the crystalline structure due to co-doping with RE3+ in cadmium metasilicate (2024)
Journal Article
Freire, E. B. V., Santos, A. L. D. S., Bispo, G. F. D. C., Macedo, Z. S., Jackson, R. A., & Valerio, M. E. G. (2024). Local modification of the crystalline structure due to co-doping with RE3+ in cadmium metasilicate. Ceramics International, 50(13), 22534-22543. https://doi.org/10.1016/j.ceramint.2024.03.355

Persistent emission is a well-known property of cadmium metasilicate (CdSiO3) doped and co-doped with rare earth ions due to the ease of choosing the desired luminescence colour, as well as the possibility of adjusting the emission colour and the lum... Read More about Local modification of the crystalline structure due to co-doping with RE3+ in cadmium metasilicate.

Effect of trivalent rare earth doping in cadmium silicates hosts: a theoretical study (2022)
Journal Article
Santos, A., Bispo, G., Freire, E., Macedo, Z., Jackson, R., & Valerio, M. (2022). Effect of trivalent rare earth doping in cadmium silicates hosts: a theoretical study. Physica Scripta, https://doi.org/10.1088/1402-4896/aca228

The objective of the present work is to investigate the possibilities for extrinsic defects in the three cadmium silicate matrices, CdSiO3, Cd2SiO4 and Cd3SiO5 and understand the final geometry of the most energetically favourable defects, which are... Read More about Effect of trivalent rare earth doping in cadmium silicates hosts: a theoretical study.

Defects in MgB4O7 (pure and doped with lanthanides): A case study using a computational modelling approach (2022)
Journal Article
Bispo, G., Nascimento, D., Santana, L., Ferreira, G., Macedo, Z., Lima, H., …Valerio, M. (2022). Defects in MgB4O7 (pure and doped with lanthanides): A case study using a computational modelling approach. Physica B: Condensed Matter, 1-9. https://doi.org/10.1016/j.physb.2022.414049

Lanthanide-doped MgB4O7 is a potential dosimetric material due to its thermoluminescence (TL) and optically stimulated luminescence (OSL) properties. These properties have been largely reported, but there are few theoretical studies dedicated to unde... Read More about Defects in MgB4O7 (pure and doped with lanthanides): A case study using a computational modelling approach.

Computer modelling of RbCdF3: Structural and mechanical properties under high pressure, defect disorder and spectroscopic study (2022)
Journal Article
Lucena, J. L. O., de Mesquita, B. R., Santos, R. D. S., Otsuka, A. M., dos Santos, M. A. C., Rezende, M. V. D. S., & Jackson, R. A. (2022). Computer modelling of RbCdF3: Structural and mechanical properties under high pressure, defect disorder and spectroscopic study. Journal of Solid State Chemistry, 312, Article ARTN 123173. https://doi.org/10.1016/j.jssc.2022.123173

In this work, a series of structural and physical properties of the RbCdF3 compound were investigated using atomistic simulation. The effect of hydrostatic pressure on structural and mechanical properties was investigated from 2 to 44 ​GPa and no pha... Read More about Computer modelling of RbCdF3: Structural and mechanical properties under high pressure, defect disorder and spectroscopic study.

Optical spectroscopy study of Eu-doped ions in BaAl2O4 phosphors (2021)
Journal Article
Rezende, M. D. S., Valerio, M., Araujo, R., Jackson, R., dos Santos Mattos, E., & dos Santos Junior, B. (2021). Optical spectroscopy study of Eu-doped ions in BaAl2O4 phosphors. Journal of Luminescence, 1-5. https://doi.org/10.1016/j.jlumin.2021.118011

Computational and experimental methodology is employed to study optical properties in Eu-doped BaAl2O4 phosphors. The symmetry and detailed geometry of the Eu-dopant site, predicted by atomistic simulation, are used to calculate the crystal field par... Read More about Optical spectroscopy study of Eu-doped ions in BaAl2O4 phosphors.

Intrinsic defects and non-stoichiometry in undoped cadmium silicate hosts (2021)
Journal Article
Vaz Freire, E., de Sales Santos, A., da Cunha Bispo, G., Macedo, Z., Gomes, M., Giroldo Valerio, M., & Jackson, R. (2021). Intrinsic defects and non-stoichiometry in undoped cadmium silicate hosts. Journal of Alloys and Compounds, https://doi.org/10.1016/j.jallcom.2020.157580

Cadmium silicates, mainly the CdSiO3 phase, are interesting materials due to their persistent and intrinsic luminescence, making them possible candidates for a number of applications. Although many of the luminescence properties of these materials ar... Read More about Intrinsic defects and non-stoichiometry in undoped cadmium silicate hosts.

Computer modelling of Bi12SiO20 and Bi4Si3O12: Intrinsic defects and rare earth ion incorporation (2020)
Journal Article
Jackson. (2020). Computer modelling of Bi12SiO20 and Bi4Si3O12: Intrinsic defects and rare earth ion incorporation. Journal of Solid State Chemistry, https://doi.org/10.1016/j.jssc.2020.121608

Defect properties of Bi12SiO12 and Bi4Si3O12 compounds were investigated using atomistic computer modelling techniques based on energy minimisation. Interatomic potentials obtained by empirical fitting reproduce the lattice parameters for both materi... Read More about Computer modelling of Bi12SiO20 and Bi4Si3O12: Intrinsic defects and rare earth ion incorporation.

Computer Simulation of the Incorporation of V2+, V3+, V4+, V(5+)and Mo3+, Mo4+, Mo5+, Mo(6+)Dopants in LiNbO3 (2020)
Journal Article
Jackson. (2020). Computer Simulation of the Incorporation of V2+, V3+, V4+, V(5+)and Mo3+, Mo4+, Mo5+, Mo(6+)Dopants in LiNbO3. Crystals, https://doi.org/10.3390/cryst10060457

The doping of LiNbO(3)with V2+, V3+, V(4+)and V(5+)as well as Mo3+, Mo4+, Mo(5+)and Mo(6+)ions is of interest in enhancing its photorefractive properties. In this paper, possible incorporation mechanisms for these ions in LiNbO(3)are modelled, using... Read More about Computer Simulation of the Incorporation of V2+, V3+, V4+, V(5+)and Mo3+, Mo4+, Mo5+, Mo(6+)Dopants in LiNbO3.

Site-selective laser spectroscopy and defect configurations of the Nd3+-Li+ centres in ZnO powders (2020)
Journal Article
Jackson. (2020). Site-selective laser spectroscopy and defect configurations of the Nd3+-Li+ centres in ZnO powders. Journal of Alloys and Compounds, 153306 - 153306. https://doi.org/10.1016/j.jallcom.2019.153306

Near-infrared emission in the 885–915?nm region was observed for two distinct Nd3+ centres that co-exist in hexagonal wurtzite ZnO:1?mol%Nd3+:10?mol%Li+ powders. The powder samples were prepared by sintering in air at 950?°C and the emission, attribu... Read More about Site-selective laser spectroscopy and defect configurations of the Nd3+-Li+ centres in ZnO powders.

Computer modeling of Zircon (ZrSiO4)—Coffinite (USiO4) solid solutions and lead incorporation: Geological implications (2019)
Journal Article
Jackson, & Montenari. (2019). Computer modeling of Zircon (ZrSiO4)—Coffinite (USiO4) solid solutions and lead incorporation: Geological implications. https://doi.org/10.1016/bs.sats.2019.08.005

The structure of zircon, ZrSiO4 is modeled using interatomic potentials. The uranium end-member, coffinite (USiO4) and intermediate solid solutions of zircon and coffinite (UxZr1–xSiO4) are then modeled, allowing the prediction of lattice parameters... Read More about Computer modeling of Zircon (ZrSiO4)—Coffinite (USiO4) solid solutions and lead incorporation: Geological implications.

Ln3+ doping in CaYAl3O7 and luminescence concentration quenching studied via a new computer modelling strategy (2019)
Journal Article
Jackson. (2019). Ln3+ doping in CaYAl3O7 and luminescence concentration quenching studied via a new computer modelling strategy. Optical Materials, 212-216. https://doi.org/10.1016/j.optmat.2019.04.036

Ln-doped CaYAl3O7 (CYAM) has several applications due to its optical properties. This crystal matrix belongs to the melilite family, where Ca2+/Y3+ ions are randomly distributed at the same crystallographic site keeping a composition ratio of 1:1. Th... Read More about Ln3+ doping in CaYAl3O7 and luminescence concentration quenching studied via a new computer modelling strategy.

A computational and spectroscopic study of Dy3+ doped BaAl2O4 phosphors (2018)
Journal Article
Jackson. (2018). A computational and spectroscopic study of Dy3+ doped BaAl2O4 phosphors. Optical Materials, 328 - 332. https://doi.org/10.1016/j.optmat.2018.06.039

Computational and experimental methods are employed to study the optical properties of Dy-doped BaAl2O4 matrix. Atomistic modelling is used to make predictions of Dy doping sites and charge compensation schemes. The symmetry predicts from atomistic m... Read More about A computational and spectroscopic study of Dy3+ doped BaAl2O4 phosphors.

The Gaia-ESO Survey: a kinematical and dynamical study of four young open clusters (2018)
Journal Article
Jeffries, R., Jackson, R., & Wright, N. (2018). The Gaia-ESO Survey: a kinematical and dynamical study of four young open clusters. Astronomy & Astrophysics, https://doi.org/10.1051/0004-6361/201832645

Context
The origin and dynamical evolution of star clusters is an important topic in stellar astrophysics. Several models have been proposed in order to understand the formation of bound and unbound clusters and their evolution, and they can be test... Read More about The Gaia-ESO Survey: a kinematical and dynamical study of four young open clusters.

Modelling of Intrinsic Defects in CaYAl3O7 (2018)
Journal Article
da C. Bispo, G., Jackson, R., & Valerio, M. (2018). Modelling of Intrinsic Defects in CaYAl3O7. Acta Physica Polonica A, 133(4), 781-784. https://doi.org/10.12693/aphyspola.133.781

CaYAl3O7 presents a challenge for computer modelling techniques because of its site-occupancy disorder related to the Ca/Y shared site. Supercells were built to reproduce experimental results which have the best agreement and lowest lattice energy. T... Read More about Modelling of Intrinsic Defects in CaYAl3O7.

Computer modelling of hafnium doping in lithium niobate (2018)
Journal Article
Jackson, R., Valerio, M., & Araujo, R. (2018). Computer modelling of hafnium doping in lithium niobate. Crystals, 123. https://doi.org/10.3390/cryst8030123

Lithium niobate, LiNbO3, is an important technological material with good electro-optic, acousto-optic, elasto-optic, piezoelectric and nonlinear properties. Doping LiNbO3 with hafnium, Hf has been shown to improve the resistance of the material to o... Read More about Computer modelling of hafnium doping in lithium niobate.

Computer modelling of double doped SrAl2O4 for phosphor applications (2017)
Journal Article
Jackson, R. A., Kavanagh, L. A., & Snelgrove, R. A. (2017). Computer modelling of double doped SrAl2O4 for phosphor applications. IOP Conference Series: Materials Science and Engineering, 169, Article 012004. https://doi.org/10.1088/1757-899x/169/1/012004

This paper describes a modelling study of SrAl2O4, which has applications as a phosphor material when doped with Eu2+ and Dy3+ ions. The procedure for modelling the pure and doped material is described and then results are presented for the single an... Read More about Computer modelling of double doped SrAl2O4 for phosphor applications.

On the compositional variability of dalyite, K2ZrSi6O15: a new occurrence from Terceira, Azores (2016)
Journal Article
Jeffery, A., Gertisser, R., Jackson, R., O'Driscoll, B., & Kronz, A. (2016). On the compositional variability of dalyite, K2ZrSi6O15: a new occurrence from Terceira, Azores. Mineralogical Magazine, 547-565. https://doi.org/10.1180/minmag.2016.080.018

The rare potassium zirconium silicate dalyite has been identified for the first time on Terceira, Azores, within syenitic ejecta of the Caldeira-Castelinho Ignimbrite Formation. New quantitative analyses of this dalyite were combined with the small n... Read More about On the compositional variability of dalyite, K2ZrSi6O15: a new occurrence from Terceira, Azores.

Atomistic simulation and XAS investigation of Mn induced defects in Bi12 TiO20 (2016)
Journal Article
Jackson. (2016). Atomistic simulation and XAS investigation of Mn induced defects in Bi12 TiO20. Journal of Solid State Chemistry, 210 -216. https://doi.org/10.1016/j.jssc.2016.03.029

This work reports an investigation of the valence and site occupancy of Mn dopants in Bi12TiO20 (BTO: Mn) host using X-ray Absorption (XAS) and atomistic simulation techniques based on energy minimisation. X-ray Absorption Near Edge Structure (XANES)... Read More about Atomistic simulation and XAS investigation of Mn induced defects in Bi12 TiO20.

Optical properties of Pr and Eu-doped SrAl12O19: A theoretical study (2015)
Journal Article
Jackson. (2015). Optical properties of Pr and Eu-doped SrAl12O19: A theoretical study. Optical Materials, 105 - 109. https://doi.org/10.1016/j.optmat.2015.07.032

This paper describes a computational study of extrinsic defect and optical properties of SrAl12O19 induced by trivalent rare earth dopants. Solution energies for a range of possible doping mechanisms are calculated, and predictions made of doping sit... Read More about Optical properties of Pr and Eu-doped SrAl12O19: A theoretical study.

Modelling the concentration dependence of doping in optical materials (2015)
Journal Article
Jackson. (2015). Modelling the concentration dependence of doping in optical materials. IOP Conference Series: Materials Science and Engineering, https://doi.org/10.1088/1757-899X/80/1/012010

As well as understanding the location of dopants in optical materials, it is also important to understand how much dopant can be added to a given material. A method for calculating the maximum concentration of dopants has been developed, and applied... Read More about Modelling the concentration dependence of doping in optical materials.

Study of Eu3+ -> Eu2+ reduction in BaAl2O4:Eu prepared in different gas atmospheres (2015)
Journal Article
Jackson. (2015). Study of Eu3+ -> Eu2+ reduction in BaAl2O4:Eu prepared in different gas atmospheres. Materials Research Bulletin, 348 -351. https://doi.org/10.1016/j.materresbull.2014.10.054

The effect of different gas atmospheres such as H2(g), synthetic air, carbon monoxide (CO) and nitrogen (N2) on the Eu3+ ? Eu2+ reduction process during the synthesis of Eu-doped BaAl2O4 was studied using synchrotron radiation. The Eu3+ ? Eu2+ reduct... Read More about Study of Eu3+ -> Eu2+ reduction in BaAl2O4:Eu prepared in different gas atmospheres.

Computer simulation of metal co-doping in lithium niobate (2014)
Journal Article
Araujo, R. M., Valerio, M. E. G., & Jackson, R. A. (2014). Computer simulation of metal co-doping in lithium niobate. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 470(2171), Article 20140406. https://doi.org/10.1098/rspa.2014.0406

Lithium niobate, LiNbO3, is an important technological material with good electro-optic, acousto-optic, elasto-optic, piezoelectric and nonlinear properties. Computer modelling provides a useful means of determining the properties of the material, in... Read More about Computer simulation of metal co-doping in lithium niobate.

Tantalum and niobium diffusion in single crystalline lithium niobate (2014)
Journal Article
Fielitz, P., Borchardt, G., Ganschow, S., Bertram, R., Jackson, R., Fritze, H., & Becker, K. (2014). Tantalum and niobium diffusion in single crystalline lithium niobate. Solid State Ionics, 259, 14-20. https://doi.org/10.1016/j.ssi.2014.02.005

LiNbO3 and LiTaO3 are isomorphous and Nb and Ta have the same valence electron configuration and the same ionic radii. This suggests the use of Ta as a tracer to probe the self-diffusion of Nb in LiNbO3. The diffusion system consisted of a 20 nm laye... Read More about Tantalum and niobium diffusion in single crystalline lithium niobate.

229Thorium-doped calcium fluoride for nuclear laser spectroscopy. (2014)
Journal Article
Jackson. (2014). 229Thorium-doped calcium fluoride for nuclear laser spectroscopy. Journal of Physics: Condensed Matter, 105402 -105402. https://doi.org/10.1088/0953-8984/26/10/105402

The (229)thorium isotope presents an extremely low-energy isomer state of the nucleus which is expected around 7.8 eV, in the vacuum ultraviolet (VUV) regime. This unique system may bridge between atomic and nuclear physics, enabling coherent manipul... Read More about 229Thorium-doped calcium fluoride for nuclear laser spectroscopy..

Preparation of high-purity LiF, YF3, and YbF3for laser refrigeration (2014)
Journal Article
Hehlen, M. P., Boncher, W. L., Melgaard, S. D., Blair, M. W., Jackson, R. A., Littleford, T. E., & Love, S. P. (2014). Preparation of high-purity LiF, YF3, and YbF3for laser refrigeration. Proceedings of SPIE, https://doi.org/10.1117/12.2039547

The role of transition-metal impurities in Yb3+-doped YLiF4 (YLF) laser-cooling crystals is studied. Divalent 3d transition-metal ions, in particular Fe2+, are found to have strong absorptions at the laser cooling pump wavelength and degrade the cool... Read More about Preparation of high-purity LiF, YF3, and YbF3for laser refrigeration.

Derivation of enhanced potentials for plutonium dioxide and the calculation of lattice and intrinsic defect properties (2014)
Journal Article
Read, M. S., Walker, S. R., & Jackson, R. A. (2014). Derivation of enhanced potentials for plutonium dioxide and the calculation of lattice and intrinsic defect properties. Journal of Nuclear Materials, 448(1-3), 20-25. https://doi.org/10.1016/j.jnucmat.2014.01.020

A new potential has been derived for plutonium dioxide and used to calculate its lattice and defect properties. The Pu4+ ⋯ O2− potential is obtained via a combination of empirical fitting to crystal structural data and parametric fitting to additiona... Read More about Derivation of enhanced potentials for plutonium dioxide and the calculation of lattice and intrinsic defect properties.

An atomistic simulation study of the effect of dopants on the morphology of YLiF 4 (2013)
Journal Article
Littleford, T. E., Jackson, R. A., & Read, M. S. D. (2013). An atomistic simulation study of the effect of dopants on the morphology of YLiF 4. physica status solidi (c), 10(2), 156-159. https://doi.org/10.1002/pssc.201200456

Solid-state optical materials are a continuing field of study that has many important applications including lasers. YLiF4 is one material has been studied in detail however, no studies into the surface properties or crystal morphology have been carr... Read More about An atomistic simulation study of the effect of dopants on the morphology of YLiF 4.

Modelling rare‐earth doped BaMgF 4 : a potential laser material (2013)
Journal Article
Littleford, T. E., Jackson, R. A., & Read, M. S. D. (2013). Modelling rare‐earth doped BaMgF 4 : a potential laser material. physica status solidi (c), 10(2), 153-155. https://doi.org/10.1002/pssc.201200455

Solid-state optical materials are a continuing field of study that has many important applications including lasers. BaMgF4 is one material has been studied in detail however, no studies into the surface properties or crystal morphology have been car... Read More about Modelling rare‐earth doped BaMgF 4 : a potential laser material.

Atomistic modelling of actinide oxides for nuclear fuel applications (2012)
Journal Article
Walker, S. R., Jackson, R. A., & Read, M. S. D. (2013). Atomistic modelling of actinide oxides for nuclear fuel applications. physica status solidi (c), 10(2), 197-201. https://doi.org/10.1002/pssc.201200513

Atomistic computer simulations were performed for the actinide oxides (UO2, PuO2 and MOX) in the temperature range 300 K-2000 K, in order to elucidate the physical and defect properties of these nuclear fuel materials. Parameterised cation-anion Buck... Read More about Atomistic modelling of actinide oxides for nuclear fuel applications.

Computer modelling of undoped and Eu 3+ ‐doped LiLa(WO 4 ) 2 (2012)
Journal Article
Amaral, J. B., de Moraes, J. R., Baldochi, S. L., Jackson, R. A., & Valerio, M. E. G. (2013). Computer modelling of undoped and Eu 3+ ‐doped LiLa(WO 4 ) 2. physica status solidi (c), 10(2), 165-167. https://doi.org/10.1002/pssc.201200510

In this work, computer modelling of the undoped and Eu3+-doped LiLa(WO4)2 structure was successfully achieved by energy minimization and mean field theory. The results were compared with experimental data previously published and are in good agreemen... Read More about Computer modelling of undoped and Eu 3+ ‐doped LiLa(WO 4 ) 2.

Optical spectroscopy of an atomic nucleus: Progress toward direct observation of the 229Th isomer transition (2011)
Journal Article
Hehlen, M. P., Greco, R. R., Rellergert, W. G., Sullivan, S. T., DeMille, D., Jackson, R. A., …Torgerson, J. R. (2013). Optical spectroscopy of an atomic nucleus: Progress toward direct observation of the 229Th isomer transition. Journal of Luminescence, 133, 91-95. https://doi.org/10.1016/j.jlumin.2011.09.037

The nucleus of the thorium-229 isotope possesses a first excited nuclear state (229mTh) at an exceptionally low energy of 7.8±0.5 eV above the nuclear ground state (229gTh), as determined by earlier indirect measurements. This is the only nuclear exc... Read More about Optical spectroscopy of an atomic nucleus: Progress toward direct observation of the 229Th isomer transition.