Structure and properties of La–Ca–Mn–O composites prepared by the glass-ceramic method

A composite mixture of the colossal magnetoresistive oxide, La0.67Ca0.33MnO3 and non-magnetic, insulating silicate/borate has been prepared, using the glass route with different nucleating agents. It is found that Sb2O3 is very effective in preferentially nucleating the LCMO phase compared to Cr2O3. The LCMO phase present in the as-quenched state in the three cases is found to grow as a result of annealing at 900 °C only when nucleated with Sb2O3. In the other two cases, simultaneous growth of other crystalline phases, such as LaBO3 and CaB2O4 is found to be accompanied with the growth of LCMO. The magnetic studies show that the LCMO phase nucleated by Sb2O3 has the highest value of magnetization. The magnetization, however, was found to be lower than the bulk value, indicative of the presence of magnetic disorder and non-magnetic phases, which was observed in the electrical transport behavior also. The LCMO phase nucleated with either of the nucleants, Sb2O3 or Cr2O3, has a high resistivity compared to the LCMO phase formed without any nucleants.