Synthesis of large optically clear AlPO4-5 single crystals

Jiang, Fuyi; Zhai, Jianpang; Ye, J.T.; Han, Jin; Tang, Zikang

doi:10.1016/j.jcrysgro.2005.05.069

Cited by 50 publications

(33 citation statements)

References 11 publications

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“…Both are of equal importance. Jiang et al [39][40][41] have reported their efforts to optimize the synthesis conditions for growing large and optically clear AFI crystals with good structural integrity. It was found that the incorporation of a bit of silicon into a zeolite framework can give rise to the formation of a negatively charged matrix and Brønsted acid sites, which can play a catalytic role in the formation of SWNTs.…”

Section: New Approach To Sample Synthesismentioning

confidence: 99%

Superconductivity in 4-Angstrom carbon nanotubes—a short review

et al. 2012

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We give an up-to-date review of the superconducting phenomena in 4-Angstrom carbon nanotubes embedded in aligned linear pores of the AlPO 4 -5 (AFI) zeolite, first discovered in 2001 as a fluctuation Meissner effect. With the introduction of a new approach to sample synthesis around 2007, new data confirming the superconductivity have been obtained. These comprise electrical, specific heat, and magnetic measurements which together yield a consistent yet complex physical picture of the superconducting state, largely owing to the one-dimensional (1D) nature of the 4-Angstrom carbon nanotubes. For the electrical transport characteristics, two types of superconducting resistive behaviors were reproducibly observed in different samples. The first type is the quasi 1D fluctuation superconductivity that exhibits a smooth resistance drop with decreasing temperature, initiating at 15 K. At low temperatures the differential resistance also shows a smooth increase with increasing bias current (voltage). Both are unaffected by an applied magnetic field up to 11 Tesla. These manifestations are shown to be consistent with those of a quasi 1D superconductor with thermally activated phase slips as predicted by the Langer-Ambegaokar-McCumber-Halperin (LAMH) theory. The second type is the quasi 1D to 3D superconducting crossover transition, which was observed to initiate at 15 K with a slow resistance decrease switching to a sharp order of magnitude drop at $7.5 K. The latter exhibits anisotropic magnetic field dependence and is attributed to a Berezinskii-Kosterlitz-Thouless (BKT)-like transition that establishes quasi-long-range order in the plane transverse to the c-axis of the aligned nanotubes, thereby mediating a 1D to 3D crossover. The electrical data are complemented by magnetic and thermal specific heat bulk measurements. By using both the SQUID VSM and the magnetic torque technique, the onset of diamagnetism was observed to occur at $15 K, with a rapid increase of the diamagnetic moment below $7 K. The zero-field-cooled and field-cooled branches deviated from each other below 7 K, indicating the establishment of a 3D Meissner state with macroscopic phase coherence. The superconductivity is further supported by the specific heat measurements, which show an anomaly with onset at 15 K and a peak at 11-12 K. In the 3D superconducting state, the nanotube arrays constitute a type-II anisotropic superconductor with H c1 z 60 to 150 Oe, coherence length x z 5 to 15 nm, London penetration length l z 1.5 mm, and Ginzburg-Landau k z 100. We give a physical interpretation to the observed phenomena and note the challenges and prospects ahead.

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Section: New Approach To Sample Synthesismentioning

confidence: 99%

Superconductivity in 4-Angstrom carbon nanotubes—a short review

et al. 2012

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“…reaction system. 39,40 And the acidity of reaction composition was mainly decided by the content of H 3 PO 4 , while keeping HF acid constant. As we knew, the concentration of H 3 PO 4 controlled the hydrolyzing rate of aluminium triisopropoxide and affected the formation of AlÀ ÀOÀ ÀP chains and the primary units of the molecular sieve.…”

Section: Effects Of Synthesis Conditions On Crystallinity Of the Alummentioning

confidence: 99%

Simple and safe synthesis of microporous aluminophosphate molecular sieves by ionothermal approach

Han

Wang

et al. 2007

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com).Pure and transition metal (Co, Fe) containing aluminophosphate molecular sieves were synthesized ionothermally by using a series of imidazolium-based ionic liquids as both solvent and structure-directing agent. Adopting this novel method, a large number of volatile organic solvents can be avoided, and the synthesis can be operated at near atmospheric pressure. Thus, the preparation becomes simple and safe compared with hydrothermal and solvothermal method. And, the recycling of ionic liquid can make the industrial synthesis process more efficient and environmental. The powder XRD patterns and FT-IR spectra displayed that all the synthesized samples were with sodalite structure. Crystal data for Co-substituted analogue: cubic, Pm-3n, a 5 9.0192 Å, and magnetic property analysis showed weak antiferromagnetic interactions between Co ions. The influences of synthesis conditions such as P 2 O 5 /Al 2 O 3 ratio, crystallization temperature, and the variety of ionic liquids on the character of the products were systematically investigated. In addition, the recycling of ionic liquid was studied based on the NMR and TGA.

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“…CoAPO-5 single crystals were synthesized using the same procedure as that of AlPO 4 -5, with the exception of adding cobalt acetate in the starting gel [6]. The as-grown CoAPO-5 crystals have a typical dimension of 500 µm × 60 µm × 60 µm, as shown by the SEM image in the left panel of Fig.…”

Section: Methodsmentioning

confidence: 99%

Catalytic growth of 0.4 nm single‐walled carbon nanotubes aligned inside porous zeolite crystals

Zhai

Tang²,

et al. 2006

Physica Status Solidi (b)

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We report our recent study on processes of decomposition of tripropylamine (TPA) molecules in the channels of AlPO 4 -5 (AFI) and Co-incorporated AlPO 4 -5 (CoAPO-5) zeolite crystals, by means of Fourier transform Infrared (FTIR) spectra and thermogravimetry (TG) techniques. In comparison with pure AlPO 4 -5 crystals, the carbonization temperature of TPA molecules inside the channels of Co-AFI crystals is notably decreased; indicating that Co atoms incorporated in the AFI framework plays an important catalyst role. These incorporated Co atoms are also favorable to the formation of the 0.4 nm single-walled carbon nanotubes (SWNTs) in the channels, characterized by a significant decrease in nanotubes formation energy. The resulting SWNTs have higher filling density in the channels than that fabricated without catalyst Co.

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Synthesis of large optically clear AlPO4-5 single crystals

Cited by 50 publications

References 11 publications

Superconductivity in 4-Angstrom carbon nanotubes—a short review

Superconductivity in 4-Angstrom carbon nanotubes—a short review

Simple and safe synthesis of microporous aluminophosphate molecular sieves by ionothermal approach

Catalytic growth of 0.4 nm single‐walled carbon nanotubes aligned inside porous zeolite crystals

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