Growth of Tartrate Crystals of Lanthanide Series Elements in Silica Gel

Crystals have ever fascinated mankind. The growth of crystals occurs either in nature or artificially in a laboratory. The Mother Nature has grown a variety of crystals in the crust of earth, which are mainly diamond and other precious stones. Systematic study of the growth and properties of crystals is covered under the subject “Crystal Growth.” Today, the growth of crystals does not remain the phenomena only occurring in nature, but it has become a well advanced as well as widely used laboratory technique. There always has been a requirement of good quality crystals for various applications. In this regard the crystals having specific properties can be treated as the backbone of today's technological development. This led the investigators and scientists to concentrate on the developments of new variety of defect-free crystals of high degree of purity. Earlier crystal growth techniques were considered an art rather than science. Theories are now available on the growth of crystals so that crystal growth is no more an art. A variety of experimental techniques are developed and modified to such a level as to grow tailor made crystals for specific applications.

To explore the inherent properties in a crystal single crystal are always required. The search for high quality crystals -for better analytical results brought in different techniques for crystal growth. Growth of crystals from all the three phases of matter is tested by various methods. A particular method has been selected only after considering the constraints such as the specific requirement; the quality of the sample, economy etc. Among the various methods used for the growing single crystals, the gel technique is believed to be simple, sordid and elegant in many respects. The gel is a neutral medium. It allows the free passage of ions and sustains nucleation, which are essential for the growth of a crystal. It is believed that many natural crystals have been formed in gelatinous mediums. The versatility of the method and its close resemblance with biological systems has attracted the attention of many workers.

This book reports the detailed studies on the growth of lanthanides tartrate crystals in gel medium. Materials in the form of tartrate compounds deserves special attention because of their many interesting physical properties such as dielectric, piezoelectric, ferroelectric and optical second harmonic generation. The rare earth compounds have attracted considerable attention on account of their luminescent and magnetic properties. Among the rare earth compounds lanthanum, cerium and neodymium tartrate crystals were selected because of their promising technical applications in optics and magnetism. Beside this the lack of work on the growth of these materials prompted the initiation of this work. This book is a comprehensive account of the experimental and theoretical aspects of various stages of crystal growth and growth controlling parameters in gel medium. The scope of the book is straight forward and designed in six chapters. It contains the observations and results of the growth of lanthanum tartrate, cerium tartrate and neodymium tratrate crystals.

Chapter 1 contains various aspects of the growth of crystals and begins with an outline of the developments of the subject. A discussion on the classification of the methods of crystal growth and the essential fragments of the theories which seems to be logical and consistent with the elementary nature of the thesis are included in this chapter. An outline on the importance of lanthanide series elements (rare earths) materials and the topic of the present problem is also seated in this chapter.

Chapter 2 introduces the subject of gel growth. The advantages of gel method over the conventional methods in growing certain type of materials especially the tartrate crystals are described. Exhaustive surveys of the literature concerning the subject, the various modifications of the methods are discussed.

Chapter 3 deals with growth of lanthanum tartrate crystals. The experimental setup, chemical reactions involved, growth kinetics, effect of the change in different parameters on growth mode are described in full length in this chapter. By changing the concentration of reactants, age, density and pH of the medium the nature of the growth has been investigated. Appreciable changes in the habit of the crystals, nucleation density, advancement of the crystallization front into the medium etc are
attributed to the changes in the environmental conditions of the growth. All observations and findings are correlated to the theories.

Chapter 4 gives a detailed account of the growth of cerium tartrate crystals.

Chapter 5 covers the growth of neodymium tartrate crystals in detail.

Chapter 6 devoted to the summary and comparative study on the growth of these gel grown crystals.