Bell, AJ

Brown, AP

Collins, S

Foster, RJ

White Rose Research Online

Production of Lead Titanate Nanoparticles for Inkjet Printing: A Comparison of Solid State and Molten Salts Processing Techniques and Conditions π

This is a repository copy of Production of Lead Titanate Nanoparticles for Inkjet Printing: A Comparison of Solid State and Molten Salts Processing Techniques and Conditions π.White Rose Research Online URL for this paper:http://eprints.whiterose.ac.uk/148922/Version: Accepted VersionConference or Workshop Item:Foster, RJ orcid.org/0000-0002-5337-3615, Collins, S, Brown, AP et al. (1 more author) (2019) Production of Lead Titanate Nanoparticles for Inkjet Printing: A Comparison of SolidState and Molten Salts Processing Techniques and Conditions π. In: F²Cπ² Lausanne 2019. eprints@whiterose.ac.ukhttps://eprints.whiterose.ac.uk/Reuse Items deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. IntroductionThe incorporation of piezoelectric materials to the inkjet printing process has the potential to allow full device integration, for example, of pressure sensors, energy harvesting and energy storage capacitors. Theproblem with approaches to date in this area are that the functional properties of in-device materials are under-developed due to incomplete thermal processing into ceramics and hence are ill-defined in terms ofmorphology, crystallographic orientation and electrical properties. The challenge is therefore to produce high quality ferroelectric crystals, where the upper size is set by current ink-jet printing technology.Here we compare lead titanate (PT) nanocrystals produced by two different processing routes: low temperature calcination (LTC) and molten salt processing (MSP). Variation in processing conditions (e.g.temperature, salt ratio) and size of titanium dioxide starting materials have been investigated.ConclusionsProduction of PbTiO3 nanoparticles for inkjet printing: a comparison of solid state and molten salt processing conditionsR.J. Foster, S.Collins, A.P. Brown & A.J. BellSchool of Chemical and Process Engineering, University of Leeds, LS2 9JT UKCorresponding Author: r.j.foster@leeds.ac.ukMolten Salts Processing (MSP)PT samples were produced by a mixed oxide synthesis route consisting of drying lead oxide and titaniumdioxide powders in an oven, weighing a stoichiometric ratio then adding 2-propanol and zirconium beadsand ball-milling for 24 hours, then evaporating the 2-propanol (and extracting the Zr beads) with stirringfollowed by oven drying. The mix was then sieved through a 300 m nylon mesh. Two different titaniumdioxides were used: one with micrometre sized particles and one with nanoscale sized.The samples were then mixed in a potassium chloride/sodium chloride eutectic salt mix and calcined at arange of temperatures from 600 to 850C. For some samples, lithium chloride or lithium fluoride wereadded to the salt mix. After calcining, the PT was recovered by dissolving the salt flux in water, withregular water changes until no chloride ions were detected by silver nitrate solution and then left to dry.Particle size analysis was achieved by observing the PT samples with scanning electron microscopy(SEM) followed by image analysis. The size of the discrete X-ray scattering volume (grain size) wasdetermined by Williamson-Hall analysis of wide angle X-ray diffraction (XRD) patterns of the PT powders.Micrometre sized TiO2650 660 670 680 690 7000.420.440.460.480.500.520.540.560.58  1:0.25 PT:Salt Ratio 1:0.5 PT:Salt Ratio 1:1 PT:Salt RatioParticle size ( m)Temperature0.25 0.50 0.75 1.000.420.440.460.480.500.520.540.560.58 650C 675C 700CParticle size (m)Salt RatioLow Temperature Calcination (LTC)PT samples were produced by following the same mixed oxide synthesis route as MSP until thecalcination step. LTC samples were prepared without salt flux and calcined in atmosphere at temperaturesfrom 450 to 650C. As with the MSP, both a nanoscale TiO2 and a micrometre TiO2 were used.Samples were observed under SEM, transmission electron microscopy (TEM) and XRD.Hot Stage XRD comparison of MSP and LTCHot stage XRD was used to calcine a series of samples whilst simultaneously performing XRDacquisitions. Both MSP and LTC samples were prepared in this fashion. The powders were prepared bythe same route as those prepared for standard LTC and MSP.SEM: Nano TiO2 derived PT calcined at 600C10 20 30 40 50 60 70 80024681012141618202224Intensity (arb units/103)2 (o) 200oC 250oC 300oC 350oC 400oC 450oC 500oC 600#2oC 600#1oC 25oC0->600C @ 3C/s, hold 1hr @ 600C, cool @ 3C/s with profiles at diff TPbTiO3/nano TiO2 MSP: NaCl/KCl salt flux 1:1 ratio10 20 30 40 50 60 70 800102030405060708090100110PbTiO3/standard TiO2 : Standard Calcination0->600C @ 3C/s, hold 1hr @ 600C, cool @ 3C/s with profiles at diff TIntensity (arb units/103)2 (o) 200oC 250oC 300oC 350oC 400oC 450oC 500oC 600#2oC 600#1oC 25oC10 20 30 40 50 60 70 800102030405060708090100110PbTiO3/nano TiO2: standard calcination0->600C @ 3C/s, hold 1hr @ 600C, cool @ 3C/s with profiles at diff TIntensity (arb units/103)2 (o) 200oC 250oC 300oC 350oC 400oC 450oC 500oC 600#2oC 600#1oC 25oC0.5 1.0 1.5 2.0304050607080901:1 NaCl/KCl w/LiF. 200oC/hr.750oC LiF 1hr Dwell LiF 4hr DwellGrain Size (nm)Additive Level (%)0.5 1.0 1.5 2.00.180.200.220.240.260.28 1hr Dwell 4hr DwellParticle size ( m)% LiF1 3 5180200220240260280 850oC 60mins 850oC 30mins 800oC 60mins 750oC 60minsParticle size (nm)Salt RatioNo Additive750 775 800 825 850170180190200210220230240250260270 No Additive 1:1 1:3 1:5Particle size (nm)Temperature (oC)MSP and LTC were compared using hot stageXRD.This work is still ongoing, but data to dateconfirms the results from samples produced in thefurnace.The nano TiO2 samples show that a good qualityPT is formed at 600C, but with the micrometreTiO2, the PT is not formed until highertemperatures.Nano sized TiO2PT particle size was seen to decrease with increasing calcination temperature (L) and with increasing salt ratio (R), although changes were relatively small.When a lithium fluoride additive was added, the PT particle size decreased to 260 nm (no additive 440nm), and was seen to decrease further to 190 nm as the amount of additive increased. A similar trendwas seen for the lithium chloride additive.All PT particles sizes were an order of magnitude greater than XRD grain size (~50-60 nm) for all MSPsamples produced. There was a small decrease in grain size with additive level.PT particle sizes produced with the nano TiO2 precursor were smaller than those produced with themicrometre TiO2 and also showed a decrease with increasing salt ratio at all calcination temperatures. Adifferent trend was seen with temperature, where PT particle size increased with calcination temperature.Grain size was similar (~50-60 nm) to that with the micrometre TiO2, showing similar processing trends.SEM: Micrometre TiO2 derived PT calcined at 600CTEM: Nano TiO2 derived PT calcined at 600C. Calcination at ‘low’ temperatures produced larger PT particlesthan the MSP process, that were, in general, less agglomerated.These particles could be broken up by a mechanical attritionprocess.The PT particles produced by the MSP process show clear‘necking’ between each other, whereas the particles from LTCare more isolated, particularly with the nano TiO2TEM showed that the PT particles formed by LTC using thenano TiO2 were close to being single crystals, with few grainboundaries.XRD of samples produced at different calcination temperaturesshowed that the lowest temperature at which PT could beformed was 600C using the nano TiO2 and 700C for themicrometre sized TiO2.• PT particle size in MSP was seen to decrease with increasing flux ratio.• PT grain size in MSP was observed to be an order of magnitude less than particle size.• The addition of Lithium salt additive to the salt flux resulted in a decrease in particle size.• The use of a nano TiO2 precursor resulted  in smaller particles from MSP.• LTC produced larger, less agglomerated particles.• PT was produced at a lowest calcination temperature of 600C• Hot stage XRD is being used to investigate the differences between LTC and MSP.10 20 30 40 50 60 70 800102030405060708090Intensity x1032 (o)Nanoscale TiO210 20 30 40 50 60 70 800102030405060708090Intensity x1032 (o) 800oC 700oC 600oC 600oC 550oC 500oC 450oCMicrometre TiO2XRD patterns at different calcination temperatures.L: たm TiO2 R: nm TiO2

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Production of Lead Titanate Nanoparticles for Inkjet Printing: A Comparison of Solid State and Molten Salts Processing Techniques and Conditions π

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