Cellular Paracrystal Formation from Co-Doped CaO Polycrystals

Shen, Pouyan; Wang, Junyi

doi:10.1006/jssc.2001.9332

Cited by 5 publications

(4 citation statements)

References 31 publications

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“…), the moving {110} grt growth fronts would ‘drag’ the rutile tubes from the core of garnet outwards continuously, resulting in the interesting linear features as reported here. In this regard, cellular precipitation occurs in metal alloys (Porter et al ., ) and ceramics (Shen & Wang, ) when intergranular precipitates or particles grow in a coupled manner with the epitaxial host grain along a certain growth direction.…”

Section: Discussionmentioning

confidence: 97%

Origin of rutile needles in star garnet and implications for interpretation of inclusion textures in ultrahigh‐pressure metamorphic rocks

Hwang

Shen

Chu

et al. 2015

Journal Metamorphic Geology

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The asterism effect of star garnet has been attributed to the oriented distribution of needle-like rutile inclusions. Rutile needles occur in garnet from a wide range of metamorphic settings and rock bulk compositions, and their origin has been ascribed to different mechanisms, such as exsolution, and used to interpret petrological and tectonic processes. Results from an optical and transmission electron microscopy of Idaho star garnet indicate a co-precipitation origin. It was found that rutile needles are predominantly oriented along the <103> rt //<111> grt and <001> rt //<001> grt directions following multiple crystallographic orientation relationships (CORs); i.e. COR-1, 2, 2 0 , 3, 4 and 5 in 6-ray star garnet, and are oriented solely along the <103> rt //<111> grt directions following exclusively COR-2 in 4-ray star garnet. The sole presence of COR-2 <111> grt needles in the common 4-ray star garnet, in contrast to the presence of both <111> grt and <001> grt needles with multiple CORs in the rare 6-ray star garnet, suggests that the COR-2 <111> grt needle probably is the energetically most favoured variant, as is also supported by the coincidence site lattice considerations. The unique crystallography-controlled microstructures of 4-ray star garnet, including the cloudy domains behind the {111} grt or {100} grt fronts with abundant inclusions of rutile needle, rutile compound needle and multiple-phase-inclusion, as well as the clear domains behind the {110} grt fronts with only a few above inclusions concentrated exclusively within the linear, <110> grt -oriented, continuous tube-like domains, further suggest that the COR-2 <111> grt needles in 4-ray star garnet most likely have a growth-in origin, co-precipitating with garnet at its growth fronts close to thermodynamic equilibrium conditions. The 6-ray star garnet, on the other hand, most likely formed under far-from equilibrium conditions, thereby yielding a maximum of 99 crystallographic variants of rutile needles with multiple CORs in a single crystal. In the light of these findings, along with the common occurrences of the sole COR in many inclusion-host systems owing to the requirement to minimize the energy barrier in an exsolution process, the presence of both <103> rt //<111> grt and <001> rt //<001> grt needles with multiple CORs in garnet of Sulu eclogite and Erzegebirge quartzofeldspathic rock would therefore cast doubt on the assertion of an exsolution origin of rutile needles in garnet from these ultrahigh-pressure rocks.

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Section: Discussionmentioning

confidence: 97%

Origin of rutile needles in star garnet and implications for interpretation of inclusion textures in ultrahigh‐pressure metamorphic rocks

Hwang

Shen

Chu

et al. 2015

Journal Metamorphic Geology

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“…52 The side band spots around the main diffractions in FFT in Figures 2−5 are also accountable by a paracrystalline distribution of such defect clusters in P-doped α-Ca 2 SiO 4 and (Si, P)-codoped CaO in view of Ni 2+ or Co 2+ -doped CaO. 53,54 Therefore, the 1-D commensurate superstructure could be derived from such paracrystals in the α-Ca 2 SiO 4 /R-CaO nanocondensates. It is beyond the scope of this study to provide experimental evidence for the exact positions of the cation vacancies (V Ca ″ ) and cation interstitials (Si i…”

Section: Discussionmentioning

confidence: 99%

“…The cation vacancies (V Ca ″ ) associated with Si 4+ and P 5+ in R-CaO and P 5+ in α-Ca 2 SiO 4 would help stabilize the superstructures analogous to cation vacancy stabilization of the surfaces of Fe 3 O 4 and Pt 1 /Ni(OH) x . The side band spots around the main diffractions in FFT in Figures – are also accountable by a paracrystalline distribution of such defect clusters in P-doped α-Ca 2 SiO 4 and (Si, P)-codoped CaO in view of Ni 2+ or Co 2+ -doped CaO. , Therefore, the 1-D commensurate superstructure could be derived from such paracrystals in the α-Ca 2 SiO 4 /R-CaO nanocondensates. It is beyond the scope of this study to provide experimental evidence for the exact positions of the cation vacancies (V Ca ″ ) and cation interstitials (Si i •••• and P i ••••• ) and the above defect schemes of the (Si, P)-doped R-CaO and P-doped α-Ca 2 SiO 4 nanocondensates.…”

Section: Discussionmentioning

confidence: 99%

P-Doped α-Ca₂SiO₄ and (Si, P)-Codoped CaO with Special Defect Microstructures and Luminescence due to an Enhanced Solid Solution by a Pulsed Laser Ablation Condensation Route

Huang

2021

Crystal Growth & Design

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The α-Ca2SiO4 and rocksalt-type (R) CaO condensates/particulates with an enhanced solid solution of P and Si + P ions, respectively, were produced via pulsed laser ablation of a silicocarnotite (Ca5(PO4)2SiO4) target under a relatively high peak power density of 1.8 × 109 Watt/cm2 in high vacuum (8 × 10–5 torr). The condensates were dispersed in an amorphous phase of Ca–Si–P–O linkage as spheres up to submicrons in size or coalesced in particulates by the {100}R, {111}R, and {1̅21̅0}α facets to follow a preferred crystallographic relationship of (1̅1̅1)R//(1̅21̅0)α; [101]R//[101̅1]α, with a fair three-dimensional match of the lattice planes. The 1-D commensurate superstructures n × (200)R and n × (1̅21̅0)a, where n = 1.5 and 3, were commonly noted for the condensates in the particulates. The P-doped α-Ca2SiO4 and (Si, P)-codoped CaO showed characteristic luminescence at 407 and 537 nm, respectively, under the combined influences of internal compressive stress as well as substitutional and/or interstitial defects with charge/volume-compensating cation vacancies for potential optoelectronic and photocatalytic applications.

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“…13:4, 16:5 and form a paracrystal [1,2]), which order further into Fe 3 O 4 spinel or other ordered phases: p 00 and p 000 [5,6]. The experimental results of Ni 1Àx O dissolved with Zr 4+ [7] or Ca 2+ [8], Co 1Àx O dissolved with Zr 4+ [9] or Mg 2+ [10] and CaO dissolved with Ni 2+ [11] or Co 2+ [12], further showed that paracrystalline interspacing of defect clusters of rock salt-type oxides could be tailored by doping specific cations.…”

Section: Introductionmentioning

confidence: 95%

Spinel precipitation in Sn4+-doped Co1−xO polycrystals with dispersed Co2+xSn1−xO4 particles

Pan

Shen

2010

Ceramics International

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Cellular Paracrystal Formation from Co-Doped CaO Polycrystals

Cited by 5 publications

References 31 publications

Origin of rutile needles in star garnet and implications for interpretation of inclusion textures in ultrahigh‐pressure metamorphic rocks

Origin of rutile needles in star garnet and implications for interpretation of inclusion textures in ultrahigh‐pressure metamorphic rocks

P-Doped α-Ca₂SiO₄ and (Si, P)-Codoped CaO with Special Defect Microstructures and Luminescence due to an Enhanced Solid Solution by a Pulsed Laser Ablation Condensation Route

Spinel precipitation in Sn4+-doped Co1−xO polycrystals with dispersed Co2+xSn1−xO4 particles

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Cellular Paracrystal Formation from Co-Doped CaO Polycrystals

Cited by 5 publications

References 31 publications

Origin of rutile needles in star garnet and implications for interpretation of inclusion textures in ultrahigh‐pressure metamorphic rocks

Origin of rutile needles in star garnet and implications for interpretation of inclusion textures in ultrahigh‐pressure metamorphic rocks

P-Doped α-Ca2SiO4 and (Si, P)-Codoped CaO with Special Defect Microstructures and Luminescence due to an Enhanced Solid Solution by a Pulsed Laser Ablation Condensation Route

Spinel precipitation in Sn4+-doped Co1−xO polycrystals with dispersed Co2+xSn1−xO4 particles

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P-Doped α-Ca₂SiO₄ and (Si, P)-Codoped CaO with Special Defect Microstructures and Luminescence due to an Enhanced Solid Solution by a Pulsed Laser Ablation Condensation Route