Aug 15 2013
Topics Covered
Description
Chemical Properties
Mechanical Properties
Recent Developments
Description
Since the evolution of high temperature superconductors in cuprate systems, lanthanum copper oxide and related compounds with a similar structure have been model materials for studying superconductivity phenomena, due to their simple structure and formulation. As such, a number of studies have been undertaken to understand their properties.
Chemical Properties
The chemical properties of lanthanum copper oxide are provided in the table below:
|
Chemical Properties |
|
Chemical Formula |
La2CuO4 |
|
Group |
Lanthanum – NA
Copper – 11
Oxygen - 16 |
|
Lattice Constant |
a = 13.86 Å
b = 3.74 Å
c = 27.94 Å |
Mechanical Properties
The mechanical properties of lanthanum copper oxide are provided in the table below:
|
Mechanical Properties |
|
Density |
6.93 g/cm3 |
|
Absorption Coefficient |
150.9 mm-1 |
Recent Developments
Ohwada K et al (1993) carried out normal coordinate analysis of the optically active vibrations of doped lanthanum copper oxide with the assumption of an infinite [(CuO2)O2]6 - layer model. With respect to the results of this analysis, some of the observed bands have been successfully assigned to the Cu-O lattice vibrations. In addition, the force constants concerning Cu-O bonds have also been obtained within the framework of a modified valence force field. It was found that this analysis based on the infinite layer model is useful for assigning the relatively high vibrational frequencies observed at the center of the first Brillouin zone in doped lanthanum copper oxide.
Golosovsky IV et al (1999) demonstrated a noncollinear anti-ferromagnetic structure with the transition temperature of approximately 130 K and propagation vector k = [0 ½ 0] in the monoclinic compound La2Cu2O5 by using single-crystal neutron diffraction method. They obtained the values and directions of the magnetic moments and crystal structure parameters by least-squares refinement. The results showed that La2Cu2O5 posses low-dimensional magnetic behavior with critical index beta = 0.228(8), like rare-earth cuprates R2CuO4.
Wang X et al (2001) synthesized lanthanum copper oxide precursors for superconductors by acetate/nitrate self-propagating combustion synthesis in the presence of urea. They studied the synthesis conditions, demonstrating the existence of a relationship between the calcination temperature and calcination time required for obtaining pure phase. The results revealed that the emission of H2O as well as CO2 was responsible for the formation structure during the calcination process.