Online Thesis Search Results

TITLE
DEDICATION
DECLARATION
CERTIFICATE
ACKNOWLEDGEMENT
PREFACE
CONTENTS
PART I
1. CRYSTAL GROWTH
1. Introduction
2. The thermodynamics of crystal growth
3. Nucleation
Fig. 1. 1 Free energy change for nucleation
4. Crystal growth theories
4.1 Earlier attempts
4.2 The surface nucleation models
FIg 1.2 Step, kink and ad-molecule on the growing face
4.3 Screw dislocation theory
Fig. 1.3 Change in surface free energy as a function of surface coverage for various values of α
5. Surface roughning and the α factor
6. Heat and matter transport
7. Crystal growth techniques
7.1 Crystallization from the solid phase
7.2 Growth from the melt
7.3 Crystallization from solution
7.4 Growth from vapour phase
8. The rare earth materials and the present problem of crystal growth
REFRENCES
2. CRYSTAL GROWTH BY GEL METHOD
1. Historical perspective
2. The structure and properties of the gel
2.1 Preparation of the hydrosilica gel
2.2 The gelling mechanism
3. Crystallization in gel medium
3.1 The chemical reaction method
Fig 2.1 Crystallization in single tubes by chemical reaction method
Fig.2.2 Crystallization by gel method employing U tubes
3.2 The chemical reduction method
3.3 Solubility reduction method
3.4 The complex dilution method
4. The growth mechanism in gel
5. Nucleation control methods in gel growth
6. Quality of the crystals
REFERENCES
3. EXPERIMENTAL TECHNIQUES IN CHARACTERIZATION
1. Introduction
2. Optical microscopy
3. Etching studies
Fig 3.1 Block diagram of Nanoscope
4. Atomic force microscopy
5. X-ray diffraction methods
6. Infra-red spectroscopy
7. Laser Raman spectroscopy
8. Thermogravimetric methods
9. Vibrating sample magnetometer
REFERENCES
4. THE GROWTH PROCESS
1. Introduction
2. The chemistry of the reactions
Fig 4.1 Sp.gravity of gel vs partial volume of water
3.Hydrosilica gel as the medium of growth
3.1 Preparation of the gel
4. Supernatent solutions
Fig.4.2 Gellation period vs pH ofthe medium
Fig.4.3 Thickness ofprecipitation band with concentration oflanthanum and oxalate ions
5. Growth kinetics and observations
5.1 The growth of lanthanum barium oxalate crystals
5.1 (i) Effect of the pH value
Fig 4.4 Effect of pH on the advancement of growthfront for lanthanum barium oxalat crystals
Fig.4.5 Population density of lanthanum barium oxalate crystals with pH of the medium
Table 4.1 Growth kinetics of lanthanum barium oxalate
Fig. 4.6 Advancement of the crystallization front with density of the gel medium for lanthanum barium oxalate crystals
Fig. 4.7 Population density of lanthanum barium oxalate crystals with concentration of the lanthanum ions.
5.1 (ii) Effect of the gel density
5. 1 (iii) Effect of the concentration of the reactants
Fig. 4.8 Advancement of the crystallization front with density of the gel medium for lanthanum potassium oxalate crystals
Fig. 4.9 Population density of lanthanum potassium oxalate crystals with pH of the gel medium
Table 4.2. Growth kinetics of lanthanum potassium oxalate crystals
5.2 Lanthanum potassium oxalate
5.2 (i) Effect of pH
5.2 (ii) Gel density and ageing of the gel
Fig. 4.10 Population density of lanthanum potassium oxalate crystals with concentration of the lanthanum ions
Fig. 4.1 1 Advancement of the crystallization front during the growth of lanthanum calcium oxalate crystals in gel
Table 4.3 Growth kinetics of lanthanum calcium oxalate crystals
5.2 (iii) Effect of concentration of feed solutions
5.3 Lanthanum calcium oxalate
5.3 (i) Effect of pH value
5.3 (ii) Effect of the concentration of the reactants
5.3 (iii) Gel ageing and density effects
Fig. 4.12 Population density of lanthanum calcium oxalate crystals with concentration ofthe lanthanum ions
Fig. 4.13 Advancement of the crystallization fiont with density of the gel medium for lanthanum calcium oxalate crystals
5.4 Lanthanum copper oxalate
6. Conclusions
REFRENCES
5. CHARACTERIZATION OF THE CRYSTALS
1. Surface studies
1.1 Morphology of the crystals
1.2 Microtopography by AFM
Fig. Captions 1
Fig S.1.2a AFM photograph of lanthanum barium oxalate
Fig 5.1.2b AFM photograph of lanthanum potassiurn.oxalate
Fig 5.1.2c AFM photograph of lanthanum calcium oxalate
Fig S.l.2d AFM photograph of lanthanum copper oxalate
Fig. Captions 2
2. Etching studies
2.1 Selection of the etchant and the morphology of etch pits
Fieure Captions
2.2 Dislocation studies
2.3 Kinetics of etching
3. Spectroscopic analyses
3.1 X-ray analysis
3.2 Infra red and Raman spectra
3.2 (i) Interpretation of the spectra
4. Thermal analysis
5. Magnetic properties
REFERENCES
PART II
6. LIESEGANG RING PHENOMENON-A REVIEW OF GENERAL THEORIES
1. Introduction
2. General features and empirical relations
3. The two models
4. The supersaturation theory
4.1 Limitations of Morce Pierce theory
5. The Wagner model
6. Other models
7. Computer simulation
REFERENCES
7. PERIODIC PRECIPITATION IN MULTICOMPONENT SYSTEMS
1. Introduction
2. Diffusion process in a two component system
2.1 Relation between diffusion depth and width of rings
3. Diffusion in multicomponent systems
Fig.7.l One dimensional periodic precipitation patterns
Fig.7.2 Liesegang ring formed in hydro silica gel impreganated with oxalic acid
4. Experimental set up
5. Observations and discussion
Fig.7.3 Needle like crystals growing inside the tubes
Fig.7.4 (a) A typical example of the double ring systems
5.1 Factors affecting the ring spacing
5.1 (i) Effect of the pH value of the medium
5.1 (ii) Effect of the concentration of the electrolytes
6. Effect of the electric field
7. Estimation of diffusion coefficients and verification of empirical relations in two species
8. Identification of the species
9. Conclusion
REFERENCES
8. CONCLUDING REMARKS AND INDICATIONS ON FUTURE RESEARCH
I. Introduction
2. On the process of growth of the crystals
3. Conclusions derived from the structural investigations
4. The dislocation studies
5. Periodic precipitation in multicomponent systems
6. Scope for future research
REFERENCES