The electronic heat capacity of Re03

Abstract

Signature was redacted for privacy.Signature was redacted for privacy.Signature was redacted for privacy. Table 2. Explanation of lettering, materials of 25a construction, and dimensions of items in Pig. 8 Table 3. Explanation of lettering, materials of 41 construction and dimensions of lettered items in Pig. 16 Table 4. Explanation of lettering in Pig, 20 49 This study was undertaken for several reasons. ilFirst, ReO^ is a simple prototype for the cubic perov skites (ABO-j), as shown by Karian (5). In general, the perovskites are of interest to solid state research because they display a wide range of properties (e.g. from diamagnetic to ferromagnetic, from dielectric to ferroelectric, from electrically insulating to conducting) (6), and further be cause they have shown promise as laser host materials, as laser modulators, and as infrared windows (6).Second, ReO^ has been treated theoretically in Group VI (5) and elsewhere (7) where C® is the molar "free" electron heat capacity at con stant volume (commonly referred to as the electronic heat capacity), y is a constant, and T is absolute temperature.Later in 193^ Bethe and Sommerfeld (31) C» HeO^As mentioned in the INTRODUCTION, ReO^ has served as a prototype for the Cubic perovskites. This similarity can be visually appreciated by comparing the known (37) crystal structure of ReO^ with that of a cubic perovskite (ABO^) (6), Figure 1 shows the cubic perovskite structure. The ReO^ structure is obtained by substituting rhenium for B, and removing the A atom from the body center.The electrical conductivity of ReO^ has been measured and found to be roughly one-tenth that of Cu at room temperature (38). Optical properties were measured (39) and discussed in terms of several band models that had been proposed earlier.The de Haas-van Alphen effect in ReO^ was measured by Marcus The main body of the apparatus used to carry out the above outlined procedure is shown schematically In Pig. 2. Table 1 explains the lettering. The cooling system consisted of an outer pyrex glass dewar (I), which was filled with liquid N2, another pyrex dewar (H), filled with liquid He-4, an "Inner" He-4 pot (0), Into which He-4 gas was condensed, and a He-3 pot (Q), Into which He-3 gas was condensed. The SPA (T) was brought Into contact with the outer baths by put ting exchange gas In the sample can (N), and Into contact with the Inner baths by spring loading It onto the cooling platform (U). The SPA was thermally isolated from the baths by evacu ating the sample can, and lifting the SPA off the cooling platform with a winch (A). The "lift off" is commonly re ferred to as "opening the heat switch". In an actual experi ment the sample can was evacuated after the SPA had reached 77°K, and the heat switch was opened at about .4°K.Heat was introduced into the SPA by passing a d-c current through a Pt-9# W wire heater wrapped non inductively around a heater post on the sample holder. The temperature of the SPA was followed by monitoring the resistance of germanium re sistors situated in the...

Structural, magnetic, and spectroscopic study of nickel squarate dihydrate

“…Such capability has recently been achieved in this group with the completion of a ^He calorimeter (Keller, 1970 Watanabe (1966) and Quantum Chemistry by Eyring, Walter and Kimball (1944).…”