Rare-earth cuprates

Figure 2 Stability fields of the T and T structures in rare-earth cuprates as a function of average rare-earth ionic radius. Filled circles represent T phases, open circles represent T phases. Asterisk represents T phase.

B. Raveau, C. Michel and M. Hervieu, Crystal chemistry of superconducting rare-earth cuprates 31... 

Chapter 200, by Peter M. Allenspach and M. Brian Maple, reviews some aspects of the low-temperature heat capacity of the ceramic oxide superconductors. These measurements yield valuable information about the electronic, lattice, magnetic, crystalline electric field and hyperfine nature of the various rare-earth cuprate materials, and in that respect compliment other physical property studies, such as neutron diffraction, inelastic neutron scattering, and various spectroscopic measurements. The authors review the heat-capacity properties of the stoichiometric RBaCu307 compoimds and oxygen-deficient materials, and show that there are significant differences. The heat capacities of other lanthanide cuprates, such as RBa2Cu40g and R2B4CU7O14+X, are also discussed. 

Raghuveer V, Thampi KR, Xanthopoulos N, Mathieu HI, Viswanathan B (2001) Rare earth cuprates as electrocatalysts for methanol oxidation. Solid State Ionics 140(3-4) 263-274... 

B. Raveau, C. Michel, and M. Hervieu, Crystal Chemistry of Superconducting Rare Earth Cuprates- Handbook on the Physics and Chemistry of Rare Earths High Temperature Rare Earths Superconductors -1 , eds. K. A. Gschneider, L. Eyring, and M. B. Maple, 2000, Vol. 30, Chap. 188, Elsevier, North Holland. 

CRYSTAL CHEMISTRY OF SUPERCONDUCTING RARE-EARTH CUPRATES... 

The crystal chemistry of the rare-earth cuprates is discussed in chapter 188 by B. Raveau, C. Michel and H. Hervieu. These authors noted that all of the hiTc superconductors are derived from the perovskite structure. This is done by disconnecting the CuOe octahedra of the perovskite structure along one direction so then an infinite number of CUO2 layers are formed. These layers are responsible for the superconductivity. Raveau et al. note that the rare-earth cations are not directly responsible for the appearance of superconductivity, but by virtue of their large size and trivalent character they help stabilize these layered structures. 

The complex oxides of transition metals belonging to perovskite and spinel families have also been investigated for electrocatalysis of AOR. Raghuveer et al. [113] have tested a series of rare earth cuprates with compositional formulae Ln2 xM Cui yMy 04 ii (where Ln=La and Nd M=Sr, Ca, and Ba M =Ru and Sb 0.0 < x < 0.4 and 1/=0.1) as anode electrocatalysts for MOR... 

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