  We studied the correlation between magnetic, electrical, structural, and
magnetostriction properties of the electron doped manganites
Ca$_x$Sm$_{1-x}$MnO$_3$ (x = 0.85, 0.8). The paramagnetic to antiferromagnetic
transition in both the compounds while cooling is accompanied by an abrupt
increase of the spontaneous volume thermal expansion ($\Delta $V/V = 0.07 % for
x = 0.85 and 0.25 % for x = 0.2). The x = 0.15 exhibits multiple phase
separation at 5 K: G-type, and C-type antiferromagnetic phases in orthorhombic
(\QTR{it}{Pnma}) and monoclinic (\QTR{it}{P2}$_1$\QTR{it}{/m}) structures
respectively. Magnetic study on x = 0.85 also suggest ferromagnetic regions
possibly in $Pnma$ structure coexist with the antiferromagnetic phases. The
magnetization (M = 1.2 $\mu_B$) of x = 0.85 does not reach the value expected
for the complete alignment of Mn spins even at 12 T and at 12 K. Metamagnetic
transitions (C-type to Ferromagnetic) in both compounds are accompanied by
contraction of volumes under high magnetic fields. We suggest that a high
magnetic field induces \QTR{it}{P2}$_1$\QTR{it}{/m} (high volume) to
\QTR{it}{Pnma} (low volume) structural transition. This is also supported by
the neutron diffraction study.
