Gomez Rojas, O., Song, G., & Hall
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Gomez Rojas, O., Song, G., & Hall, S. (2017). Fast and scalable synthesis of strontium niobates with controlled stoichiometry. CrystEngComm, 36, 5351-5355. https://doi.org/10.1039/C7CE01298E Peer reviewed version License (if available): Unspecified Link to published version (if available): 10.1039/C7CE01298E Link to publication record in Explore Bristol Research PDF-document This is the author accepted manuscript (AAM). The final published version (version of record) is available online via RSC at http://pubs.rsc.org/en/Content/ArticleLanding/2017/CE/C7CE01298E#!divAbstract. Please refer to any applicable terms of use of the publisher. University of Bristol - Explore Bristol Research General rights This document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/red/research-policy/pure/user-guides/ebr-terms/ View Article Online View Journal CrystEngComm Accepted Manuscript This article can be cited before page numbers have been issued, to do this please use: O. Gomez, G. Song and S. Hall, CrystEngComm, 2017, DOI: 10.1039/C7CE01298E. Volume 18 Number 1 7 January 2016 Pages 1–184 This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. CrystEngComm Accepted Manuscripts are published online shortly after www.rsc.org/crystengcomm acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available. You can find more information about Accepted Manuscripts in the author guidelines. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the ethical guidelines, outlined in our author and reviewer resource centre, still apply. In no HIGHLIGHT Tiddo J. Mooibroek, Antonio Frontera et al. Towards design strategies for anion–π interactions in crystal engineering event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. rsc.li/crystengcomm Page 1 of 5 PleaseCrystEngComm do not adjust margins View Article Online DOI: 10.1039/C7CE01298E Journal Name COMMUNICATION Fast and Scalable Synthesis of Strontium Niobates with Controlled Stoichiometry Received 00th January 20xx, a,b a,b a,b Accepted 00th January 20xx Omar Gomez , Ge Song Simon R. Hall* DOI: 10.1039/x0xx00000x www.rsc.org/ Recently a new method for the synthesis of metal oxides has been from a high degree of crystallinity, good control over the reported, using ionic liquids as an effective metal cation solvent morphology, high purity and a more even particle size and chelating agent. Here we discuss the mechanism of action of distribution, coupled with a reduction of time and this technique and demonstrate its efficacy as a means to temperature needed to obtain such materials 8,9 . synthesise phase-pure strontium niobates of controlled Disadvantages come however from the complexity of the Manuscript stoichiometry. synthesis and a poor understanding of the mechanism of action as it is hard to monitor the reaction process in an Complex functional materials can be synthesized by a wide enclosed environment. range of techniques. Some of these syntheses tend to be Another interesting alternative method to synthesize complex highly time and energy consuming however, raising the overall functional materials is the molten salt synthesis (MSS). expense of the process. In addition, having control over the Compared to solid state reactions, MSS lowers significantly the homogeneity of the sample can be a hard task to attain. The reaction temperature as it allows faster mass transport in the rapid progress of technological developments in ferroelectric 1, liquid phase. Furthermore, MSS is good at solvating metals and ferromagnetic 2, superconducting 3, and piezoelectric 4 materials oxides at high temperature owing to a destabilization of demand the discovery of new synthetic routes to create bonding by the strong polarizing forces provided by the salt Accepted materials with high efficiency. As a result of this, different melts. MSS has the additional advantage of low cost and low synthetic approaches have been developed, among which toxicity as well as abundant availability 10 . solid-state reactions are without doubt the most commonly Perhaps the most actively researched method in recent years used, with well-established conditions and a fairly simple is sol-gel chemistry. Broadly, this the preparation of inorganic Published on 05 September 2017. Downloaded by Gazi Universitesi 06/09/2017 01:28:11. methodology. A feature of these reactions is that mass phases from a transformation of liquid precursors to a sol and transport tends to be poor however and therefore formation finally to a network structure called a gel 11 . Sol-gel chemistry of the desired target phase may require long synthesis times has been widely used due to its ability to generate chemically or simply may not occur. homogeneous precursors allowing atomic level mixing of An alternative route is the hydrothermal method. Some key reagents. It is worth noting however that this does not ensure features of this process are the ability to synthesize ultrafine homogeneity throughout a reaction; having randomly well- particles; morphology can be relatively controlled to some distributed precursors does not necessarily guarantee an extent through tuning pressure or temperature and control optimal reaction process. One way to improve upon a solution- over stoichiometry is possible through reducing or oxidizing based synthetic approach is to use ionic liquids. An Ionic liquid atmospheres, provided via adding extra components or gases 5. (IL) is composed of an intimate mixture of long-chain cations Recently, work has been done on the combination of sol-gel and coordinating anions 12 . These compounds have been and hydrothermal methods. Combining features of both described as “green” and “super-dissociating” solvents, CrystEngComm techniques, the sol-gel-hydrothermal method has achieved providing an environmentally friendly way to completely very interesting results in synthesis of metal oxides 6,7. This solvate inorganic salts 13 . Moreover, ILs can work as templates technique has become an attractive tool as advantages range and precursors, as they have good thermal stability, tuneable solubility, fairly low vapour pressure 14, as well as enabling fast mass transport. ILs have already proven to be a great tool in the synthesis of nanoparticles 15, metal salts 16, metal oxides and metal chalcogenides 17–20 , silicas and organosilicas 21,22 . ILs have been used to synthesize multi-element complex This journal is © The Royal Society of Chemistry 20xx J. Name ., 2013, 00 , 1-3 | 1 Please do not adjust margins PleaseCrystEngComm do not adjust margins Page 2 of 5 View Article Online DOI: 10.1039/C7CE01298E COMMUNICATION Journal Name functional oxides, creating phase pure superconductors, In this work, samples of strontium niobates of controlled stoichiometries were prepared using strontium nitrate (99 %), niobium ethoxide (99.95 %), 1-Ethyl-3-methylimidazolium acetate (emim)OAc (95 %) and dextran from Leuconostoc sp . (molecular weight 70,000 Da). All materials were purchased from Sigma-Aldrich UK. Deionized water was obtained using a MilliQ PureLab Ultra (18.2 M Ω cm-1). None of the materials required further purification and were used as received. A typical synthesis can be described as follows: Strontium nitrate (99 %) (1 mL, 0.1 M) was added to 1 mL (emim)OAc under stirring until evenly dispersed. The whole was then heated to 80 °C in an alumina crucible under stirring to remove water from the mixture for 1 to 2 hr. Niobium ethoxide (99.95 %) was then added. The mixture remained under heating and constant stirring for one further hour, ensuring full dehydration of the system. Finally, dextran was added as a weakly coordinating, Figure 1.: Powder X-ray diffraction pattern of the synthesis of nonspecific chelating agent, (1 g) and mechanically mixed until Sr 5Nb 4O15 with (A) dextran and C) (emim)OAc as chelating agents. B) a dense paste-like gel was formed. This was done to avoid represents a control synthesis using no chelating agents. metal specific or preferential chelation and enhance piezoresponsive, multiferroic, ferromagnetic and homogeneity in the system. Adding a carbon source into the phosphorescent materials 23 . Another advantage to using ILs is reaction also serves a second purpose, as carbonization occurs over the calcination process, thereby providing a cocooning that it is possible to solubilise other non-specific chelating Manuscript agents such as biopolymers within them, thereby increasing environment which prevents the sintering of crystallites the chelating ability of the system. restricting them to the nanoscale, thereby enhancing Strontium Niobates have been widely studied for several reactivity. Moreover, dextran provides a reducing atmosphere, reasons and find application in a wide range of areas. One of generating CO 2 as the carbon is oxidised over the course of the the most interesting yet to be exploited is