Feroz Ahmed Dar

119 Pages·2013·1.15 MB·English

Crystallization of Some Pure and Substituted
Rare-Earth Oxalates

Dissertation
submitted for the award of the degree of

Master of Philosophy

In

Physics

by

Feroz Ahmad Dar

Under the Supervision of

Dr. Basharat Want

Department of Physics, University of Kashmir,
Hazratbal, Srinagar, 190006

January, 2013

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Post Graduate Department of Physics,
University of Kashmir, Srinagar.

Certificate

This is to certify that the dissertation entitled “Crystallization of Some Pure and
Substituted Rare-earth Oxalates" submitted by Feroz Ahmad Dar, in partial fulfillment for the
award of the degree of Master of Philosophy in Physics, is the original research work carried out
by him under my supervision and guidance. It is further certifieded that the dissertation has not
been submitted for the award of M. Phil or any other degree to this University or any other
University. The scholar has attended the department for statutory period as required under rules.

Dr. Basharat Want Prof. Sheikh Javid Ahmad
(Supervisor ) (Head of the Department )

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Acknowledgments

It gives me great pleasure and satisfaction to acknowledge the endowment of the creator
and sustainer of this universe, Allah Almighty, the most gracious, compassionate and beneficent
to His creature, Who blessed me with knowledge and potential to plan my research work. I offer
my humblest words of thanks to His most noble messenger Muhammad (P.B.U.H), who is
forever, a torch of guidance and Knowledge for all humanity.
I owe my indescribable special indebtedness to my Research Supervisor, Dr. Basharat
Want who was very affectionate and cooperative during this research work and guided me at
every step very politely, without his kind and sincere efforts it might not be possible for me to
end this task in time. May he live long and prosper.
I am thankful to Prof. Sheikh Javid Ahmad, Head of Physics Department, University of
Kashmir for the provision of all possible facilities and full cooperation. I also extend my thanks
to the whole teaching faculty of the department for their generous help whenever needed.
My sincere thanks to my labmates Mr Zahoor Ahmad Bhat, Mr. Mehraj-U-din Shah,
Mr. Bilal Hamid Bhat, Mr Ab. Qayoom and Syed Nisar for their timely suggestions. My special
thanks to other research scholars of the department for their help during the completion of my
course work. I sincerely thank all the members of technical and non-technical/non-teaching staff
of the department for their affection and kind co-operation.

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I extend cordial thanks from the core of my heart to my parents and other family
members who encouraged me for higher studies and always wished to see me glittering high at
the skies of success. I shall always remain indebted to them for their unstinted support, be it
financially, morally or inspirationally.
May the Almighty Allah give them a happy life and bless them with good health (Amin!).

Feroz Ahmad Dar

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Dedicated

To

My Beloved
Parents

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Preface

The work presented in this thesis was carried out at the Solid-State Research Laboratory,
Department of Physics, University of Kashmir, Srinagar. Due to the large applicability of rare
earth oxalate crystal, it was thought with an aim of this thesis to investigate how to grow and also
to characterize some of the rare earth oxalate crystals for scientific investigations by a very
simple and inexpensive technique, gel diffusion technique.
The thesis is divided into five chapters. First chapter gives an introduction to crystals and
a brief overview of crystallization processes and different techniques of growing crystals, the
main emphasis has been put on gel diffusion method.
Chapter second consists of experimental techniques used for the characterization of
samples, such as powder X-ray diffraction (XRD), Energy-Dispersive Analysis of X-rays
(EDAX), Thermal methods (TGA, DTA) etc. Chapters third and fourth discuss the growth and
characterization of the holmium oxalate heptahydrate crystals and Holmium barium oxalate
crystals respectively. Chapter five gives summary and future scope of the present work.
References to the literature are mentioned at the end of each chapter.

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Contents

CHAPTER 1
Crystal growth: Theory and techniques: A brief introduction Pages

1.1 Introduction ……………………………………………………………………………………………………………………. 1
1.2 Various crystal growth techniques ………………………………………………………………………………… 3
1.2.1 Growth from solution ………………………………………………………………………………………….. 4
1.2.2 Growth from melt ……………………………………………………………………………………………….. 5
1.2.3 Growth from vapour ……………… …………………………………………………………………………… 5
1.2.4 Growth from solids ……………………………………………………………………………………………… 6
1.3 Classical theory of nucleation ………………………………………………………………………………………….. 6
1.3.1 Homogenous nucleation……………………………………………………………………………………….. 7
1.3.2 Heterogeneous nucleation …………………………………………………………………………………… 11
1.4 Crystal growth by gel diffusion method…………………………………………………………………………… 13
1.4.1 Introduction ………………………………………………………………………………………………………… 13
1.4.2 Properties of the gel………………………………………………………………………………………………. 15
1.4.3 Advantages and disadvantages of gel diffusion method ……………………………………….. 15
1.4.4 Preparation and structure of silica gel…………………………………………………………………….. 17

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1.4.5 Properties and structure of agar gel ……………………………………………………………………. 18
1.4.6 Properties of agar gel……………………………………………………………………………………………. 19
1.5 Crystallization in gel medium……………………………………………………………………………………………… 20
1.5.1 Chemical reaction method………………………………………………………………………………………. 21
1.5.2 Chemical reduction method……………………………………………………………………………………. .23
1.5.3 Solubility reduction method……………………………………………………………………………………… 23
1.5.4 Complex dilution method……………………………………………………………………………………………23
1.6 Nucleation control in gel method…………………………………………………………………………………………….23
1.7 Theories of crystal growth……………………………………………………………………………………………………… 24
1.7.1 Surface energy theory……………………………………………………………………………………………….. 25
1.7.2 Diffusion theory………………………………………………………………………………………………………… 26
1.7.3 Adsorption layer theory……………………………………………………………………………………………… 26
1.7.4 Screw dislocation theory…………………………………………………………………………………………… 28
References ………………………………………………………………………………………………………………………………………… 30
CHAPTER 2
Characterization techniques
2.1 Introduction …………………………………………………………………………………………………………….. 36

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2.2 X-ray diffraction ………………………………………………………………………………………………………… 37
2.3 Energy dispersive analysis of X-rays ………………………………………………………………………… 38
2.4 CHN - Analysis………………………………………………………………………………………………………. 39
2.5 Thermo analytical techniques………………………………………………………………………………… 40
2.5.1 Thermo-gravimetric analysis……………………………………………………………………… 40
2.5.2 Differential thermal analysis……………………………………………………………………. 41
2.6 Fourier transformation infra-red spectroscopy……………………………………………………. 42
References……………………………………………………………………………………………………………………… 44
CHAPTER 3
Growth and characterization of holmium-oxalate heptahydrate crystals
3.1 Literature Review…………………………………………………………………………………………….. 46
3.2 Experimental procedure ………………………………………………………………………………… 52
3.2.1 Preparation of agar gel……………………………………………………………………….. 53
3.2.2 Preparation of upper reactant solution ………………………………………………. 53
3.3 Characterization of holmium- oxalate crystals………………………………………………… 57
3.3.1 Powder X-ray diffraction studies…………………………………………………………. 57

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3.3.2 Energy dispersive X-ray analysis………………………………………………………………. 63
3.3.3 CHN analysis……………………………………………………………………………………………… 64
3.3.4 Thermal analysis………………………………………………………………………………………. 64
3.3.5 Fourier transformation infra-red spectroscopy…………………………………………… 67
3.3.6 Morphology of holmium-oxalate heptahydrate crystals …………………………… 70
References …………………………………………………………………………………………………………………… 76
CHAPTER 4
Growth and characterization of holmium-barium oxalate crystals
4.1 Introduction ……………………………………………………………………………………………………. 86
4.2 Experimental procedure …………………………………………………………………………………. 87
4.2.1 Preparation of agar gel …………………………………………………………………………. 87
4.2.2 Preparation of upper reactant solution …………………………………………………. 87
4.3 Morphology of holmium-barium oxalate crystals ……………………………………………… 91
4.4 Characterization of holmium-barium oxalate……………………………………………………... 93
4.4.1 Powder X-ray diffraction studies ……………………………………………………………. 93
4.4.2 Energy dispersive X-ray analysis …………………………………………………………… 99

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