Synthesis of Barium Titanate Nanoclusters

Presented by Marc Landeweer

Advisor: Prof. Slamovich

Objectives

• Examine mechanism of barium titanate synthesis

• Create barium titanate nanoclusters– Hydrothermal– Distributed Arc Cluster Source (DACS)

Hydrothermal Synthesis

• BaCl2 or Ba(OH)2 and TiO2 precursors

• Alkaline solution (NaOH)

• Ar Purge Reduce xCO3

• Oven heating for 40+ hrs

• Water wash & centrifuge

• Dry powder

• Analyze

DACS Titania BaTiO3 Synthesis

• Forms TiO2 nanoclusters

• TiO2 nanoclusters added to barium solution, then heated

• Titania added directly to alkaline barium solution

Analysis Methods

• X-Ray Diffraction• Re-sample particle size analyzer (Coulter 250)• Carbonate Examination

– Acid Test (HCl 10%wt)

– Optical Microscopy 200X-500X

• Transmission Electron Microscopy (TEM) 10,000X-350000X

• Electron Diffraction Pattern (using TEM)

• Identifies – Crystal structure– Compound (if crystalline)

• Detects impurities (~5% limit)

• Can be used to estimate particle size

• Requires minimally 0.5 grams of sample

X-Ray Diffraction

TEM/Electron DiffractionTEM/Electron Diffraction

• High Magnification ImagingHigh Magnification Imaging– Determine size & morphologyDetermine size & morphology

• Drawbacks:Drawbacks:– Requires delicate sample preparationRequires delicate sample preparation– Very sensitive to contaminationVery sensitive to contamination

• Electron diffraction pattern Electron diffraction pattern – Identifies crystalline or amorphous Identifies crystalline or amorphous – Used to identify sample and crystal informationUsed to identify sample and crystal information

Particle Size Analyzer

• Uses laser diffraction of suspension

• Limited to about 40nm

• Does not give much information alone– No indication of sample composition– Little morphological data– Requires properly dispersed sample

Control Group

• 060502-01,-02,-03 & 2H– 0.4M Ba; 1.0M NaOH; 1.1:1 Ba:Ti; 40+ hours – Relatively high purity– XRD appears normal for all samples

• 2H shows shift in lattice parameter

• Concentrate analysis of 060502-02– XRD– TEM– Particle Size Analyzer– Acid Test (control)

060502-02 XRD

Particle Size Analysis

0

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60502-02

TEM• Wide Particle Size Distribution• Follows laser diffraction

distribution

• Crystalline• Smallest range ~70nm

12,000X

150,000X

100,000X

Note the large differencein particle size

Group 062502: Ba Concentration

• Adjusted barium concentration– 062502-01 = 0.16M– 062502-02 = 0.08M– 062502-03 = 0.04M

• High Purity Samples

• Examined under XRD, Laser Dispersion, TEM

XRD

• Low Carbonate

• Sharp Peaks

Particle Size Analysis062502

0

1

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0.0400.0530.0700.0930.1230.1620.2140.2840.3750.4960.6570.8691.1491.5202.0102.6603.5194.6566.1588.147

Microns

% b

y v

olu

me

062502-01

062502-02

062502-03

TEM 062502-01

• Still have wide particle size distribution

12,000X

TEM 062502-01

40,000X

TEM 062502-02

100,000X

30,000X

• Very Wide Size Distribution

Smallest Particles Larger Comparable to 062502-01

TEM 062502-03

General Patterns from 062502

• Decreased [Ba] yields larger particles– Higher concentration provides more nuclei for

barium titanate formation

• Results are consistant with proposed dissolution-precipitation mechanism

• Future Approaches:– Adjust Ba Molarity without changing mass

DACS Titania Under TEM

• Amorphous Component

• 300,000X

DACS Synthesis

• I: DACS Titania added to BaCl2 & NaOH [Ba]~0.1M– Phosphine Surfactant

• II DACS Titania with BaOH2 [Ba]~0.1M– Phosphine Surfactant

• III DACS Titania with BaOH2 [Ba]~0.1M– Sodium Citrate Surfactant

• IV DACS Titania mixed with BaCl2 & NaOH [Ba]~0.4M– No Surfactant

• All Samples yielded too little product for proper XRD or particle size evaluation

DACS Syn I

• Grey precipitate formed soon after addition to BaCl2 & NaOH solution

• Grey powder suspected to be barium carbonate

• Washed with DI water and dried to form powder

• Prepared sample for Coulter Machine– Sample data insufficient to produce result

• Performed acid test on DACS Syn I & 060502-02 to compare reaction with dilute hydrochloric acid– Inspected results under optical microscope

• Examined DACS Syn I under TEM

DACS Syn II & III

• Processed with Barium Hydroxide– Formed barium carbonate precipitate too quickly

– Used filter to remove precipitate

• DACS Syn II – Used 06/21 Titania– Bis(p-sulfonatophenyl) phenyl phosphine dihydrate dipotassim

salt

• DACS Syn III – Used 0718 Titania– Using Sodium Citrate Dihyrate Na3C6H5O7 * 2 H2O

• Washed with HCl & Water

• Samples not examined under TEM

DACS Syn IV

• Processed directly using DACS• Formation of white precipitate very soon after

DACS reaction• No Surfactant• Ba Concentration ~0.4M (compared to NaOH)

DACS Syn IV TEM

• Quite abnormal

• High Cabonate

DACS Syn IV TEMtake two

Final Conclusions

• Final? Far from….• Precipitation-Dissolution Dominates Present

Literature– Project results can be interrupted to fit either model

• Nanoparticle synthesis in only water proves to be very difficult to process– Brownies in motion? Brownian motion?

– Present processing method does not account for Brownian motion (e.g. water or acid wash)

Nanoparticle Synthesis

• Solvothermal: Chen & Jiao– Barium alkoxide (H4Ba6(O)-(OCH2Ch2OCH3) &

Ti(OC4H9-n)4

• Using organic precursors or organic films: Lee, Yao, Imai, & Aksay– Titanyl acylate and barium acetate, fine but not nano

– Yielded Nanoparticles with barium titanium methoxypropanoxide (BaTi(OCH2CH(CH3)OCH3)6 on alkoxide-Kraton thin film

Future Work

• Standard Hydrothermal:– Determine affect of increasing Ba concentration not

changing BaCl2 mass

– Develop method of powder collection accounting for Brownian motion

• For DACS:– Retry direct reaction of DACS, post washing with alcohol – Adjust Ba:Ti to as close to 1:1 as possible– Perform entire reaction and post-reaction in nitrogen

atmosphere