The growth of crystals from the vapour

Brinkman, A.W.; Carles, J.

doi:10.1016/s0960-8974(99)00004-2

Cited by 20 publications

(21 citation statements)

References 34 publications

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“…The constant diffusion of the gas at the same pressure and for 24 h provided the constant diffusion velocity. The process is comparable to a chemical vapour transport for which the crystals growth is governed by a mass transfer as explained by Brinknan et al [17]. However, even if we consider here that N 2 gas flow helps for crystallization by acting in the flowability of SA and the temperature difference, it is not sure at this time that it is involved in any chemical reaction.…”

Section: Resultsmentioning

confidence: 82%

“…The vapour crystallization and the nucleation process were explained by the mass transfer trough the vapour. The dependence of the mass flux on the source materials pre-treatment, on the source temperature, and on the temperature difference between the source and transfer product has been clearly explained and reviewed by Brinknan et al [17].…”

Section: ____________________mentioning

confidence: 99%

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Characterization and solventless growth of salicylic acid macro‐crystals involving a nitrogen gas flow

Menaa

Takahashi

Tokuda

et al. 2010

Cryst. Res. Technol.

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We report an original solventless thermal crystallisation method to grow large needle-like salicylic acid (SA) crystals of 10-12 mm in length. The method is based on the utilization of nitrogen gaz flow on salicylic acid powder during heating just below melting point temperature for 24 h. Salicylic acid provides one of the best examples of a pharmaceutical substance used for cosmetics whose physical and chemical properties indicate hydrogen-bond formation between the hydroxyl group and an adjacent oxygen atom of the same molecule. The structure of the crystals is confirmed by single crystal X-ray diffraction; it is monoclinic, a=4.93(2) Å, b =11.23(5) Å, c=11.56(6) Å, β = 90.77(4)° with the space group P2 1 /c. The macrocrystals formation using this method is new and represents an interesting finding for a wide range of applications to be developed in the fields of biotechnology and photonics.

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Section: Resultsmentioning

confidence: 82%

Section: ____________________mentioning

confidence: 99%

Characterization and solventless growth of salicylic acid macro‐crystals involving a nitrogen gas flow

Menaa

Takahashi

Tokuda

et al. 2010

Cryst. Res. Technol.

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“…there is no change in the composition), no foreign gases are involved and the vapour stoichiometry is preserved across the growth facility. Thus there is no relative motion of the vapour components -the diffusion plays no role, the transport is provided by the "Stefan wind" ("drift transport" (Karpov et al, 1999)) and the growth rate is maximal (Brinkman & Carles, 1998). An experimental path to the "Dryburgh" regime is the decreasing the pressure in the reactor (Wolfson & Mokhov, 2010).…”

Section: Sublimation Growth Of Aln Crystalsmentioning

confidence: 99%

Development of 2" AlN Substrates Using SiC Seeds

Avdeev¹,

Chemekova²,

Мохов³

et al. 2012

Modern Aspects of Bulk Crystal and Thin Film Preparation

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“…In general, the mass flux can be expressed as a sum of these two contributions [26] by means of eq. (4).…”

Section: Mass Transport In a Vapour Transport Processmentioning

confidence: 99%

A new approach to the growth of ZnO by vapour transport

Muñoz‐Sanjosé

Tena‐Zaera

Martı́nez-Tomás

et al. 2005

phys. stat. sol. (c)

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The crystal growth of ZnO by vapour transport is classically made in presence of additional species which enhance the growth process. Usually, additional species have been considered as chemical transport agents that promote a typical CVT (Chemical Vapour Transport) process. Recently, we have proposed a new interpretation of the chemical role of some of these species. This new interpretation considers that, in some cases, the additional species promote a partial consumption of the O 2 provided by the ZnO decomposition and, consequently, a Zn excess is generated. This excess of Zn pressure activates the ZnO decomposition and the growth rate is enhanced. Among those species, carbon shows an additional beneficial role in the ZnO growth process. The deposition of a graphite layer on the inner walls of the generally used growth silica ampoules avoids the reaction between the ZnO crystals and the silica. In order to gain a further insight into the growth process, the time dependence of the transported mass in presence of graphite has been studied using an in-situ dynamic technique. A systematic study of the mass transport rate dependence on the thermal difference between the source material and the crystallisation zone (∆T) has been made. On the other hand the influence of a residual gas on the transport rate has been also systematically analysed. Two different gases have been used, argon (Ar) and carbon dioxide (CO 2 ). The experiments with Ar have allowed the analysis of the effects of an inert gas on the transport processes. Meanwhile, the experiments with CO 2 have shown its chemical role on the generation of a non-reacted Zn which is necessary to activate the ZnO decomposition. This role paves the way to control the Zn excess during the growth experiments. Thus, CO 2 can be used to act on the off-stoichiometry degree of the ZnO crystals and consequently to control, at least partially, some of the physical properties of this material.

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The growth of crystals from the vapour

Cited by 20 publications

References 34 publications

Characterization and solventless growth of salicylic acid macro‐crystals involving a nitrogen gas flow

Characterization and solventless growth of salicylic acid macro‐crystals involving a nitrogen gas flow

Development of 2" AlN Substrates Using SiC Seeds

A new approach to the growth of ZnO by vapour transport

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