Exploratory synthesis in the quaternary system including rare-earth, transition metal, gallium and a tetrelide using liquid gallium as a solvent

We initiated investigations of new pathways for preparation of multinary intermetallic compounds and employed a synthetic technique that utilizes molten metals as solvents (fluxes). Form these reactions we have reported a number of quaternary and ternary compounds obtained from molten Al solutions. Our continued investigation was further extended to probe the applicability of molten Ga to perform similar reaction chemistry. Consequently, we find molten Ga flux to be an excellent tool for exploration in the quaternary system that includes rare-earth element (RE), transition metal (M), gallium and a tetrelide (Tt = silicon or germanium). In Chapter II, the examples of non-reactive behavior of Ga as a solvent are presented. The synthesis, structure and magnetic properties of new intermetallics RE2Ni3+xSi 5-x and Tb4FeGe8 are discussed in Parts A and B, respectively. Further, the systems obtained via reactive behavior of molten Ga are considered. In Chapter III the ternary compounds of the general formulae RE/Ga/Ge (where the transition metal is not included in the structure) are reported. The Part A gives the synthesis, structure, electronic and magnetic properties of new Zintl compounds Yb 2Ga4Ge6 and Yb3Ga4Ge 6. The Part B reports on the structure and magnetic properties of new family of pol1ygallides RE3Ga9Ge. A number of quaternary compounds of the RE/M/Ga/Tt type have been also obtained in the reactions in molten Ga. In particular, Chapter IV is devoted to the systems with M = Fe, where novel cubic phases of the formula RE4FeGa12- xGex were produced and characterized from the point of view of their structural and magnetic properties.The systems with M = Ni and Co, as presented in Chapters V and VI, are especially interesting, owing to their rich chemistry, magnetism and, most of all, unusual structural arrangements. Chapter V deals with the systems with RE : M < 1. Here, two new families of compounds RE0.67M 2Ga5+n-xGe x of homologous series with n = 0 and 1 were discovered. A thorough investigation of structural and magnetic properties of these compounds has been carried out and the results are reported. In Chapter VI the reactions with the ratios RE : M &ge 1 are considered. The synthesis, structure and magnetic properties of three families of novel quaternary compounds REMGa 3Ge, RE3Ni3Ga8Ge3 and RE 4Ni3Ga6Ge4 are presented. Lastly, the preparation of the new compounds RE2MGa9Ge2 (M = Ni, Co), RE2Ga2Ge5 and La3Ga 2Ge using RE: M >> 1 (M = Fe, Ni, Co) is given in Chapter VII together with characterization of their structural and magnetic properties.