  In this research, we report on the synthesis and characterization of
$La_{0.67}Ca_{0.33}MnO_3$ (LCMO), $La_{0.67}Ba_{0.33}MnO_3$ (LBMO), and
$La_{0.67}Sr_{0.33}MnO_3$ (LSMO) perovskites. Precursor powders for the
perovskite samples were prepared using ball mailing technique. The resulting
powder was pressed into disks which were subsequently sintered at 1000 C for
2h. The structural characteristics of the prepared samples were investigated
using X-ray diffraction (XRD) and scanning electron microscope (SEM), and the
magnetic properties were investigated using vibrating sample magnetometry
(VSM). XRD pattern of LCMO sample revealed a pure perovskite phase with Pnma
space group, while the pattern of LSMO sample revealed a pure perovskite with
R3c$^-$ space group. XRD pattern of LBMO sample, however, demonstrated the
presence of a major perovskite phase with R3c$^-$ symmetry, together with a
secondary $BaMnO_3$ phase. This secondary phase disappeared upon sintering LBMO
at a higher temperature of 1100 C. Isothermal magnetic measurements and
thermomagnetic curves revealed that LCMO was paramagnetic at room temperature.
However, LSMO exhibited soft ferromagnetic behavior at room temperature, with
Tc = 380 K and Ms = 50.9 emu/g. Also, LBMO sample sintered at 1000 C exhibited
soft ferromagnetic behavior at room temperature, with Curie temperature Tc =
343 K and a rather low saturation magnetization of Ms = 30.7 emu/g. The higher
sintering temperature of LBMO compound resulted in a significant increase of
the saturation magnetization to 50.8 emu/g for the sample sintered at 1100 C.
