  This work reports on magnetic, dielectric, thermodynamic and magnetoelectric
properties of Gd$_{1-x}$Y$_{x}$MnO$_{3}$, with 0 \leq x \leq 0.4, with emphasis
on the (x, T) phase diagram, towards unraveling the role of the driving
mechanisms in stabilizing both magnetic and ferroelectric orderings. The (x, T)
phase diagram reflects the effect of lattice distortions induced by the
substitution of $Gd^{3+}$ ion by smaller $Y^{3+}$ ion, which gradually
unbalances the antiferromagnetic against the ferromagnetic exchange
interactions, enabling the emergence of ferroelectricity for higher
concentrations of yttrium. For $x \leq 0.1$, the paramagnetic phase is followed
by a presumably incommensurate collinear antiferromagnetic phase, then a weak
ferromagnetic canted A-type antiferromagnetic ordering is established at lower
temperatures.For $0.2 \leq x \leq 0.4$, a different phase sequence is obtained.
The canted A-type antiferromagnetic arrangement is no more stable, and instead
a pure antiferromagnetic ordering is stabilized below T$_{lock}$ $\approx$ 14 -
17 K, with an improper ferroelectric character. From these results, a cycloid
modulated spin arrangement at low temperatures is proposed, accordingly to the
inverse Dzyaloshinskii Moriya model. Anomalous temperature dependence of the
dipolar relaxation energy and magnetization evidence for structural and
magnetic changes occurring at $T* \approx 22 - 28 K$, for $0.1 \leq x \leq
0.4$.
