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 BaCl 2 or Ba(OH) 2 and TiO 2 precursors Alkaline solution (NaOH) Ar Purge  Reduce xCO 3 Oven heating for 40+ hrs Water wash & centrifuge Dry powder Analyze

DACS Titania BaTiO 3 Synthesis Forms TiO 2 nanoclusters TiO 2 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 X 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 Diffraction High Magnification ImagingHigh Magnification Imaging –Determine size & morphology Drawbacks:Drawbacks: –Requires delicate sample preparation –Very sensitive to contamination Electron diffraction patternElectron diffraction pattern –Identifies crystalline or amorphous –Used 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 ,-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 –XRD –TEM –Particle Size Analyzer –Acid Test (control)

XRD

Particle Size Analysis

TEM Wide Particle Size Distribution Follows laser diffraction distribution Crystalline Smallest range ~70nm 12,000X

150,000X

100,000X Note the large difference in particle size

Group : Ba Concentration Adjusted barium concentration – = 0.16M – = 0.08M – = 0.04M High Purity Samples Examined under XRD, Laser Dispersion, TEM

XRD Low Carbonate Sharp Peaks

Particle Size Analysis

TEM Still have wide particle size distribution 12,000X

TEM ,000X

TEM ,000X 30,000X Very Wide Size Distribution Smallest Particles Larger Comparable to

TEM

General Patterns from 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 BaCl 2 & NaOH [Ba]~0.1M –Phosphine Surfactant II DACS Titania with BaOH 2 [Ba]~0.1M –Phosphine Surfactant III DACS Titania with BaOH 2 [Ba]~0.1M –Sodium Citrate Surfactant IV DACS Titania mixed with BaCl 2 & 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 BaCl 2 & 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 & 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 TEM take 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 (H 4 Ba 6 (O)-(OCH 2 Ch 2 OCH 3 ) & Ti(OC 4 H 9 -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(OCH 2 CH(CH 3 )OCH 3 ) 6 on alkoxide-Kraton thin film

Future Work Standard Hydrothermal: –Determine affect of increasing Ba concentration not changing BaCl 2 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