Dopant control over the crystal morphology of ceramic materials

Alfredsson, Maria; Corà, Furio; Dobson, David P.; Davy, James M.; Brodholt, John P.; Parker, S. C.; Price, G. D.

doi:10.1016/j.susc.2007.07.025

Cited by 26 publications

(27 citation statements)

References 37 publications

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“…For the Ni only doped (no Er) sample, broad emission band ranging from 1300 nm to 1600 nm originated from the 3 T 2 ( 3 F) / 3 A 2 ( 3 F) transition of Ni 2+ was observed. [26][27][28][29][30][31][32][33] However, by introducing Er 3+ (Li + ) co-dopants, the Ni 2+ emission almost disappeared and Er 3+ emissions at around 1550 nm ( 4 I 13/2 / 4 I 15/2 ) and 980 nm ( 4 I 11/2 / 4 I 15/2 ) appeared (see Fig. S5 † for 1180 nm excited UC at 980 nm).…”

Section: Resultsmentioning

confidence: 99%

“…[24][25][26][27][28][29][30][31] It has been demonstrated that six coordinated Ni 2+ ions located at the centers of octahedrons have substantial absorption around 1100-1400 nm that can further be tuned in a wide range by manipulating the crystal eld strength around the Ni 2+ ions. 26,30,32 Accordingly, its NIR emission band is also wide ranging from 1200 nm to longer than 1700 nm with extremely high quantum yield reaching unity in some crystals such as LiGa 5 O 8 .…”

Section: Materials Designmentioning

confidence: 99%

“…26,30,32 Accordingly, its NIR emission band is also wide ranging from 1200 nm to longer than 1700 nm with extremely high quantum yield reaching unity in some crystals such as LiGa 5 O 8 . 33 There are other reports of the Ni 2+ emission bands in the NIR ranges [25][26][27][34][35][36][37] that sufficiently overlap with the Er 3+ absorption bands making possibility of Ni 2+ / Er 3+ resonance energy transfer (sensitization). 32,38,39 Zhang et al has reported that Ni 2+ to Er 3+ energy transfer or vice versa in glass ceramics depending on the host matrix and Ni 2+ to Er 3+ physical separation to achieve NIR broadband Stokes emission for amplier and lasers.…”

Section: Materials Designmentioning

confidence: 99%

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Broadband-sensitive Ni²⁺–Er³⁺ based upconverters for crystalline silicon solar cells

et al. 2016

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We have developed Ni 2+ , Er 3+ codoped CaZrO 3 broadband-sensitive upconverters that significantly broaden the sensitive range, and hence overcome the shortcomings of conventional Er 3+ doped upconverters used for crystalline silicon (c-Si) solar cells that utilize only a small fraction of the solar spectrum around 1550 nm. We have designed the combination of sensitizers and host material to utilize photons that are not absorbed by c-Si itself or Er 3+ ions. Six coordinated Ni 2+ ions substituted at the Zr 4+ sites absorb (1060-1450) nm photons and transfer the energies to the Er 3+ ions, and the Er 3+ upconverts at 980 nm. Co-doping with monovalent charge compensators such as Li + for high Er 3+ solubilisation at the Ca 2+ sites and multivalent ions (Nb 5+ ) for stabilization of Ni 2+ at the Zr 4+ sites is essential. In addition to 1450-1600 nm (z2 Â 10 20 m À2 s À1 ) photons directly absorbed by the Er 3+ ions, we have demonstrated upconversion of 1060-1450 nm (z6 Â 10 20 m À2 s À1 ) photons in the Ni 2+ absorption band to 980 nm photons using the CaZrO 3 :Ni 2+ ,Er 3+ upconverters. Compared with the current density gain of present c-Si solar cells ($40 mA cm À2 ), the upconverted photons could increase this by $7.3 mA cm À2 , which is about 18% improvement. This architecture for broadband-sensitive upconversion may pave a new direction for the improvement in efficiency of the present c-Si solar cells to surpass the limiting conversion efficiency of single-junction solar cells.

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Section: Resultsmentioning

confidence: 99%

Section: Materials Designmentioning

confidence: 99%

Section: Materials Designmentioning

confidence: 99%

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Broadband-sensitive Ni²⁺–Er³⁺ based upconverters for crystalline silicon solar cells

et al. 2016

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“…The surface energies of the doped surfaces were calculated from the surface energies of the undoped surfaces and the surface segregation energy of the dopant as follows (per Ref. [33]):…”

Section: Methodsmentioning

confidence: 99%

Stabilization of MgAl2O4 spinel surfaces via doping

et al. 2016

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Surface structure of complex oxides plays a vital role in processes such as sintering, thin film growth, and catalysis, as well as being a critical factor determining the stability of nanoparticles. Here, we report atomistic calculations of the low-index stoichiometric magnesium aluminate spinel (MgAl2O4) surfaces, each with two different chemical terminations. High temperature annealing was used to explore the potential energy landscape and provide more stable surface structures. We find that the lowest energy surface is {100} while the highest energy surface is {111}. The surfaces were subsequently doped with three trivalent dopants (Y 3+ , Gd 3+ , La 3+) and one tetravalent dopant (Zr 4+) and both the surface segregation energies of the dopants and surface energies of the doped surface were determined. All of the dopants reduce the surface energy of spinel, though this reduction in energy depends on both the size and valence of the dopant. Dopants with larger ionic radius tend to segregate to the surface more strongly and reduce the surface energy to a greater extent. Furthermore, the ionic valence of the dopants seems to have a stronger influence on the segregation than does ionic size. For both undoped and doped spinel, the predicted crystal shape is dominated by {100} surfaces, but the relative fraction of the various surfaces changes with doping due to the unequal changes in energy, which has implications on equilibrium nanoparticle shapes and therefore on applications sensitive to surface properties.

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“…This process between particles tends to form threedimensional architectures, resulting in energy loss. Thus, the process reduces accumulated energies associated with incomplete surfaces at random distances and, by converging, eliminates the mineral-air or mineral-fluid interfaces [32]. The interaction between components of self-organized systems are controlled by hydrogen bonds, Van der Waals forces, and electrostatic or hydrophobic interactions.…”

Section: Fe-sem Analysismentioning

confidence: 99%

Crystal growth and photoluminescence of europium-doped strontium titanate prepared by a microwave hydrothermal method

Gonçalves¹,

Moura²,

Godinho³

et al. 2015

Ceramics International

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Dopant control over the crystal morphology of ceramic materials

Cited by 26 publications

References 37 publications

Broadband-sensitive Ni²⁺–Er³⁺ based upconverters for crystalline silicon solar cells

Broadband-sensitive Ni²⁺–Er³⁺ based upconverters for crystalline silicon solar cells

Stabilization of MgAl2O4 spinel surfaces via doping

Crystal growth and photoluminescence of europium-doped strontium titanate prepared by a microwave hydrothermal method

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Dopant control over the crystal morphology of ceramic materials

Cited by 26 publications

References 37 publications

Broadband-sensitive Ni2+–Er3+ based upconverters for crystalline silicon solar cells

Broadband-sensitive Ni2+–Er3+ based upconverters for crystalline silicon solar cells

Stabilization of MgAl2O4 spinel surfaces via doping

Crystal growth and photoluminescence of europium-doped strontium titanate prepared by a microwave hydrothermal method

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Broadband-sensitive Ni²⁺–Er³⁺ based upconverters for crystalline silicon solar cells

Broadband-sensitive Ni²⁺–Er³⁺ based upconverters for crystalline silicon solar cells