Structure property relationship in rare earth based intermetallics

Abstract

Background and Motivation Solid state chemistry is integral part of past and modern-day research. This field came into existence in ~1950s and ever since this field is growing. In earlier days solid state chemistry was dominated by mainly ionic compounds such as transition metal-based oxides, sulphides, nitrides, borides, phosphides and chalcogenides. These material gives the opportunity for physicists and chemist to come across the table as they show very interesting physical properties specially in case of oxides1-3. One of the most important phenomenon high temperature superconductivity in cuprates and still research is going on4. Later the less ionic intermetallic compounds were also reported for their interesting phenomenon. Specially, rare-earth (RE) based intermetallics gives the battleground of theoreticians and experimentalist to understand some basic concept of spin-orbit coupling, highly correlated localized f- electrons and their interaction with conduction electrons and competition between all sorts of interaction results in various interesting phenomenon like superconductivity5-7, heavy fermion8,9, Kondo behaviour10,11, spin-liquid behaviour12,13, etc. These interactions between can be modulated by doping5, substitution of any foreign element14 or by some external pressure14 and magnetic field15. Intermetallics are not only fascinated for physical properties but they are also rich in structural chemistry. There are wide variety of crystal system exist like AlB216, BaAl417 and their derivative crystal structure which are related through group-subgroup relationships. Ternary derivative of this structure type of comprising RE, transition metal (T), main block element X crystallises in there several superstructures. It depends on the number of atoM.S. in unit call, ratio of number RE, T and X atoM.S., electron count, chemical nature, solubility limit of elements. Sometimes it leads to the formation of solid solution and disordered phase also. Major problem in this system is unavailability of good quality single crystal to study their anisotropic properties and their phase purity.