Crystal chemistry of the garnets*

Geller, S.

doi:10.1524/zkri.1967.125.125.1

Cited by 579 publications

(185 citation statements)

References 0 publications

Supporting

Mentioning

168

Contrasting

Unclassified

Order By: Relevance

“…43 On the other hand, in the range 0.08 ≤ x ≤ 0.84 for Li 7−3x Ga x La 3 Zr 2 O 12 , Rettenwander et al suggested, based on the relatively large NMR asymmetry parameter that they derived, η Q = 0.46 (3), that Ga 3+ mainly occupies a distorted 4-fold coordinated environment corresponding to the general 96h octahedral site. 44 Allen et al 18 also proposed the 96h octahedral site occupancy, following the work of Geller et al 46 who reported that Ga 3+ preferred 6-fold coordination in garnet.…”

Section: ■ Introductionmentioning

confidence: 99%

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

et al. 2015

View full text Add to dashboard Cite

Garnet-type Li 7 La 3 Zr 2 O 12 (LLZrO) is a candidate solid electrolyte material that is now being intensively optimized for application in commercially competitive solid state Li + ion batteries. In this study we investigate, by forcefield-based simulations, the effects of Ga 3+ doping in LLZrO. We confirm the stabilizing effect of Ga 3+ on the cubic phase. We also determine that Ga 3+ addition does not lead to any appreciable structural distortion. Li site connectivity is not significantly deteriorated by the Ga 3+ addition (>90% connectivity retained up to x = 0.30 in Li 7−3x Ga x La 3 Zr 2 O 12 ). Interestingly, two compositional regions are predicted for bulk Li + ion conductivity in the cubic phase: (i) a decreasing trend for 0 ≤ x ≤ 0.10 and (ii) a relatively flat trend for 0.10 < x ≤ 0.30. This conductivity behavior is explained by combining analyses using percolation theory, van Hove space time correlation, the radial distribution function, and trajectory density. ■ INTRODUCTIONSolid electrolytes with high lithium ionic conductivity are now being actively investigated for application in commercially competitive all-solid-state rechargeable lithium-ion batteries. Among them, Li-based garnet oxides have shown promise for meeting the much needed safety and reliability requirements of today's commercial lithium ion batteries.1−7 One of the garnet compositions being considered is the cubic Li 7 La 3 Zr 2 O 12 (LLZrO), this is due to its stability with elemental lithium and a total conductivity on the order of 10 −4 S/cm. 2 Its structure is usually defined in the Ia3̅ d space group with Li cations partiallly occupying 24d tetrahedral (Td) and 48g/96h octahedral (Oh) sites, La cations fully occupying 24c dodecahedral sites, Zr cations fully occupying 16a octahedral sites, and O anions fully occupying the 96h sites (see Figure 1). However, a more stable tetragonal symmetry (I4 1 /acd) has also been reported to exist at room temperature, with Li ordering in three crystallographic sites: one at the 8a site, which forms a subset of the cubic garnet 24d site, and the other two highly distorted 16f and 32g sites which, when combined, are equivalent to the cubic garnet 48g/96h sites. 8,9 This ordering is responsible for the low bulk Li + ion conductivity measured for tetragonal LLZrO, a value on the order of 1 × 10 −6 S/cm at room tempertaure.

show abstract

Section: ■ Introductionmentioning

confidence: 99%

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Una de las estructuras candidatas para ser moduladas en su composición por su amplia variedad cristaloquímica y su estabilidad térmica, es la estructura del granate (6). Los granates se describen estructuralmente bajo la fórmula A 3 B 2 C 3 O 12 , donde A suele representar a un catión divalente en coordinación octaédrica, B representa a un catión trivalente en coordinación octaédrica y C a un catión tetravalente en coordinación tetraédrica.…”

Section: Introductionunclassified

Síntesis de nuevos pigmentos cerámicos de color rojo mediante el método de Pechini

Pavlov¹,

Blasco²,

Cordoncillo³

et al. 2000

Bol. Soc. Esp. Ceram. Vidr.

View full text Add to dashboard Cite

A través del presente trabajo, se han estudiado la obtención de diferentes disoluciones sólidas en la estructura granate de itrio y aluminio, Y 3 Al 5 O 12 (YAG) sintetizadas vía Pechini y la posibilidad de modificar la intensidad del campo cristalino, D o , que actúa sobre el ion Cr(III), como agente cromóforo, mediante la introducción de cationes divalentes (Mn(II) y Mg(II)) y tetravalentes (Ce(IV), Zr(IV) y Sn(IV)). Los resultados alcanzados han posibilitado comprender que con la introducción de los iones divalentes, éstos no han sido suficientes para intensificar dicho campo del Cr(III), ya que estabilizan al ion Cr(IV) y esto provoca distorsiones estructurales. Con la introducción de los iones tetravalentes, sí que se consigue intensificar el campo que actúa sobre el ion cromóforo, observándose la transición de la tonalidad verde, típica del Cr(III) en un campo débil, a una tonalidad roja, típica para el mismo ion en un campo fuerte. Sin embargo y a través de los estudios estructurales mediante difracción de rayos X, se ha observado que junto con el desarrollo de la estructura granate, disolución sólida, aparecen fases laterales de Y 0,15 Zr 0,85 O 1,93 y Y 2 Sn 2 O 7 , esta última como fase pirocloro. Se ha comprobado la obtención de una tonalidad roja-violácea con la introducción de Cr(III) en dicha estructura pirocloro. Por último, se han probado las fases sintetizadas como pigmentos mediante la utilización de un vidriado (frita) transparente de naturaleza borácica, industrial. Los materiales que contienen estaño en su estructura han mostrado un buen poder pigmentante y estabilidad a 1080ºC. Palabras clave: granates, pigmentos cerámicos, Pechini, síntesis, cristaloquímica. Synthesis of new red coloured ceramic pigments by Pechini methodVarious garnet solid solutions within the structure of the yttrium aluminium garnet, Y 3 Al 5 O 12 (YAG) were sinthesized via Pechini and the possibility for the modification of the crystal field intensity acting on the chromophore Cr(III) ion by means of substitution with divalent (Mn(II) and Mg(II)) and tetravalent (Ce(IV), Zr(IV) and Sn(IV)) cations was studied. The results obtained indicate that the crystal field can not be intensifyed through the introduction of divalent ions since they stabilize the Cr(IV) ion which probably expands the structure by inducing distortions in it. The introduction of tetravalent ions makes possible the intensification of the crystal field acting on the chromium and the change of the typical green colour of Cr(III) in a week field to red which is typical for the same in strong field. However, the structural studies carried out by X-ray diffraction show that together with the garnet fase Y 0,15 Zr 0,85 O 1,93 and Y 2 Sn 2 O 7 are formed, the latter having pyrochlore structure. It was demonstarted that the introduction of Cr(III) in the mantioned pyrochlore structure results in the formation of a redviolet pigment. Finally, the sinthesized fases were checked as pigments using an industrial transparent boron containing frit. The tin containi...

show abstract

“…The garnet structure was firstly reported by Menzer [67]-according to Geller [68]. It has been found that the garnet structure exists in a number of minerals, particularly in oxide minerals.…”

Section: Garnet Type Host Lattices and Yag:ce 31mentioning

confidence: 96%

Inorganic Phosphor Materials for Lighting

2016

View full text Add to dashboard Cite

This chapter addresses the development of inorganic phosphor materials capable of converting the near UV or blue radiation emitted by a light emitting diode to visible radiation that can be suitably combined to yield white light. These materials are at the core of the new generation of solid-state lighting devices that are emerging as a crucial clean and energy saving technology. The chapter introduces the problem of white light generation using inorganic phosphors and the structureproperty relationships in the broad class of phosphor materials, normally containing lanthanide or transition metal ions as dopants. Radiative and non-radiative relaxation mechanisms are briefly described. Phosphors emitting light of different colors (yellow, blue, green, and red) are described and reviewed, classifying them in different chemical families of the host (silicates, phosphates, aluminates, borates, and non-oxide hosts). This research field has grown rapidly and is still growing, but the discovery of new phosphor materials with optimized properties (in terms of emission efficiency, chemical and thermal stability, color, purity, and cost of fabrication) would still be of the utmost importance.

show abstract

Crystal chemistry of the garnets*

Cited by 579 publications

References 0 publications

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

Síntesis de nuevos pigmentos cerámicos de color rojo mediante el método de Pechini

Inorganic Phosphor Materials for Lighting

Contact Info

Product

Resources

About

Crystal chemistry of the garnets*

Cited by 579 publications

References 0 publications

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li5La3Ta2O12 by ab-Initio Calculations

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li5La3Ta2O12 by ab-Initio Calculations

Síntesis de nuevos pigmentos cerámicos de color rojo mediante el método de Pechini

Inorganic Phosphor Materials for Lighting

Contact Info

Product

Resources

About

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations