  In this work, we study the effect of the magnetic dilution of Cr$^{3+}$ on
the LaCrO$_3$ half doped with Al. Pure and half-doped samples were prepared by
combustion method using urea as fuel. The crystal structure was investigated by
X-ray diffraction. Rietveld analysis reveal a structural phase transition
caused by the increase of the chemical pressure due difference of Al$^{3+}$ and
Cr$^{3+}$ ionic radii. SEM images shows that the samples exhibit a spherical
formation and irregular morphologies. Magnetization measurements as a function
of temperature reveal an antiferromagnetic order in both samples with a large
decrease of T$_N$ (N\'eel temperature) with Al doping. The reduction of
frustration factor and the increase of the magnetic moment of the doped sample
could be attributed to the breaking of the long-range antiferromagnetic order.
The magnetic hysteresis loops show a typical antiferromagnetic behavior with a
slightly spin canting for the doped sample.
