Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effects of calcium substitution on the superconducting properties of
  R(1-x)CaxBa2Cu3Oz (R=Eu, Gd, Er; 0=<x<=0.3)polycrystalline samples   The influence of Ca substitution on the superconducting properties of
polycrystalline R1-xCaxBa2Cu3Oz (R = Eu, Gd, Er; x=0; 0.2; 0.25 and 0.3)
samples has been studied by X-ray powder diffraction, ac susceptibility and dc
magnetization measurements. The superconducting parameters such as critical
temperature, inter- and intra-granular critical current and flux pinning are
found to be strongly dependent both on Ca content and type of R element. The
best combination of these parameters is found for the system Gd1-xCaxBa2Cu3Oz
forming R1+yBa2-yCu3Oz clusters. The level of overdoping and the type of
intergrain connection, were found to be influenced by the R element and the Ca
concentration. Flux pinning in Gd1-xCaxBa2Cu3Oz is connected with the presence
of R1+yBa2-yCu3Oz clusters.

24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs