Rare earth chalcogenides

Rare earth sulfides, selenides, and tellurides show semiconducting properties and have potential for application in thermoelectric generation. Thin film chalcogenides of various rare earths have been prepared by multisource evaporator systems [233]. 

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Crystallographic Relationships of Ternary and Quaternary Rare Earth Chalcogenides of Si, Ge, ... 

Crystallographic peculiarities of rare earth chalcogenides of Si, Ge, Sn, Pb, and In are shortly discussed at the end of this chapter. 

CRYSTALLOGRAPHIC RELATIONSHIPS OF TERNARY AND QUATERNARY RARE EARTH CHALCOGENIDES OF SI, GE,... 

The author expresses his gratitude to the U. S. Atomic Energy Commission for partial support of his research endeavors at the University of Michigan on the cryogenic thermal and magnetic properties of the rare-earth chalcogenides and related substances. He also wishes to thank... 

PAU/NOG] Paukov, 1. E., Nogteva, V. V., Yarembash, E. 1., The true heat capacity of rare-earth chalcogenides at low temperatures. 1. The true low-temperature heat capacity, entropy, and enthalpy of lanthanum selenide, Russ. J. Rhys. Chem., 40, (1966), 1661-1662. Cited on page 383. 

The silver systems 69 8. Rare earth-chalcogenide systems 91... 

To our knowledge this compound has been the subject of only one paper, Chander et al. (1978). The crystalline structure is given as primitive cubic with a = 3.145 A. This result seems unusual in comparison with other rare earth chalcogenides which always exhibit a fee NaCl-type, structure. (By multiplying the parameter by 2, it becomes 6.29 A, which is comparable to that of SmTe and TmTe.)... 

There is currently much interest in rare-earth chalcogenides. These compounds have a great variety of properties. Some are semiconductors [1-3], others have metallic conduction [4, 5], and some become superconducting at low temperatures [6, 7]. The compounds represented by LnX and Ln2X3 (Ln is a rare-earth lanthanide and X is sulfur, selenium, or tellurium) have been investigated more thoroughly than the other compounds. 

Qualitative information on the nature of chemical bonds in rare-earth chalcogenides is given in [3, 11—14]. 

Rare earth chalcogenides 785 AVIV = relative volume change... 

From the history of thermal conductivity (ic) investigations in solids one can see that fc has always responded on the appearance of new effects. We will try to review the unusual character of k in RECs. Unfortunately, k of many interesting RECs has not yet been measured and many mysteries have no answer at this moment. This review is the first major review devoted to k of RECs. There is only one prior review devoted to k and other thermal properties of rare earth chalcogenides (Smirnov 1972), in which data are collected up to 1972. 

LA, Smirnov, 1973, Physical Properties of Rare Earth Chalcogenides (Nauka, Leningrad). In Russian. 

The binary compounds, for which almost all the crystal structures are known, are now well studied from different physical points of view. In the case of the ternary compounds, for which a complete knowledge is not yet obtained in spite of a lot of work, only the structural aspect will be considered here-except for some optic, magnetic and electrical studies. The present paper will be especially concerned with the structural aspect of the rare earth chalcogenides. 

In the following sections, we shall describe the main characteristics of the rare earths chalcogenides, with references to works after 1965. Older works are described, for instance, in Flahaut (1968, 1972) and Flahaut et al. (1968). Should it happen that some of these results are used, their references are not given. 

Fig. 31.2. Structural types and polymorphism of rare earth chalcogenides of R2X formula.

E. I. Yarembash, A. A. Eliseev, Khal kogenidy Redkozemel nykh Elementov Sintez i Kristallo-khimiya [Rare Earth Chalcogenides Synthesis and Crystal Chemistry], Nauka, Moscow 1975, pp. 1/258 C.A. 83 [1975] No. 125545. 

A.V. Golubkov, E.V. Goncharova, V. P. Zhuze, et al., Fizicheskie Svoistva Khal kogenidov Redkozemel nykh Elementov [Physical Properties of Rare Earth Chalcogenides], Nauka, Leningrad 1973, pp. 1/304 C.A. 80 [1974] No. 7332. 

I. A. Smirnov, Thermal Properties of Rare Earth Chalcogenides, Phys. Status Solidi A14 [1972]... 

For melting points and Debye temperatures of rare earth chalcogenides, estimated from crystal chemical literature data for the NaCl type, see Kuz micheva et al. [14]. 

G. Guntherodt, R. Merlin, Raman Scattering in Rare-Earth Chalcogenides, Top. Appl. Phys. 54 [1984] 243/87. 

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