David Brown

Horst Wedemeyer

The present volume, Thorium C5, deals with the compounds of thorium and sulfur, selenium, tellurium, and boron, as well as with oxoacid compounds of the three chalcogen elements. Thorium borates have already been treated in Thorium C2. In contrast to the corresponding compounds of uranium the thorium sulfides, etc. , do not show any nuclear or other technological application; they are only of academic interest, despite some very interest ing electronic properties, especially of the 1 : 1 compounds. The thorium-sulfur and the thorium boron systems in particular were studied in detail, so that we have a clear picture of them, whereas there are still a lot of open questions in the systems Th-Se and Th-Te - not very different from other metal chalcogenide systems. Thorium sulfates are of some technological importance because they are formed in solution during recovery of thorium from monazite by sulfuric acid leaching. The very detailed and critical treatment of the chemical and physical properties of the compounds discussed also enables us to find gaps still remaining in our knowledge and thus to initiate new research in this field. I want to thank the two authors, Dr. Horst Wedemeyer (Karlsruhe) and Dr. David Brown (Harwell), for their excellent contributions, the "Literaturabteilung" of the Karlsruhe Nuclear Research Center for its help in providing reports and other documents difficult to procure, as well as the staff of the Gmelin-Institute, especially to Dr. K. -C.

Compounds with S, Se, Te and B

Th Thorium

Hans Ulrich Borgstedt

The volume covers alloys and intermetallic compounds of thorium with metals of main groups I to IV as well as related ternary and quaternary alloys. It is the first comprehensive and critical treatise on this topic. The physical properties of ThBe13 have been studied in some detail in order to compare them with those of the heavy fermion compound UBe13. The Th-MG system is of interest for the metallurgy of Mg, since small amounts of Th improve the mechanical strength of Mg and some of its alloys. Detailed information is available on the Th-AI system which is complicated by several intermediate binary phases. Several years ago, this system had attained some technological interest when Th-AI alloys were considered as a potential fuel in thorium breeder reactors. Other Th-main group intermetallic systems are more of scientific than of technological interest. The phase relations in these systems were not elucidated until the 1980s. Numerous ternary alloys consisting of thorium, a metal of main groups I to IV, and a third metal are described. Recent interest has focused on some ternary compounds related to the Th-AI and Th-Sn systems, e.g., THAI8Fe4 and ThSnM (M = Ni, Co, Pt).

Alloys of Thorium with Metals of Main Groups I to IV

Hans U. Borgstedt

Alloys of Uranium with Alkali Metals, Alkaline Earths, and Elements of Main Groups III and IV. The description of uranium and its compounds, for which the Gmelin Institute has started a series of volumes supplementing the main volume of 1936, follows in its arrangement closely the order chosen for the transuranium volumes. Part A treats "The Element", Part B "The Metal and its Alloys", Part C "The Compounds", Part D "The Chemistry in Solution", and finally Part E "The Coordination Compounds". Part E, "The Coordination Compounds" comprises two volumes which already have been finished and are available - completely written in English. Series A comprises 7 volumes which are all available. Series C will comprise 14 volumes of which only volume 6 is missing. Series D consists of 4 volumes dealing with the chemistry in solution, which already have been finished and are available. The present volume describes the alloys and the intermetallic compounds with the metals of main groups I to IV - those systems with semimetals such as boron and germanium are to be found in corresponding volumes in Uranium C series. In the volume B 2 main emphasis is given to the binary systems. The most frequently investigated systems are uranium-beryllium and uranium-aluminium because of their special scientific (U-Be) and technological (U-Al) importance.

Supplement Volume B2 Alloys of Uranium with Alkali Metals, Alkaline Earths, and Elements of Main Groups III and IV

U Uranium

Michael Bickel

This volume comprises the compounds of thorium with the 4th main group elements silicon and germanium and all 5th main group elements except nitrogen. On the subject of ternary and polynary compounds containing oxygen, only those compounds with phosphorus are included (e.g., phosphates, hypophosphates, or phosphinates). Similar compounds of the other ele ments like silicates, arsenates, etc. were already treated in "Thorium" Suppl. Vol. C 2, 1976. Most of the compounds in the different systems treated in this volume are of scientific interest because of their special physical and chemical properties. On the other hand, there are also many compounds wh ich are of specific technological interest, mainly in the nuclear field. Refractory compounds like ThSi or ThP have potential interest as nuclear fuel for special reactors due to their physical properties like good heat conductivity and their chemical stability, e.g., against the corrosion of cladding alloys for nuclear fuel elements. Due to the present situation in the further development of the thorium nuclear fuel cycle, their large potential has not yet been fully investigated. For most of the binary and ternary phases in these systems, we presently have good knowledge about the preparation of the compounds and their physical and chemical properties. But nevertheless, there are still a lot of open questions concerning phase equilibria, solid solutions, and homogeneity of some of the phases described in this volume.

Horst Wedemeyer

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