Spin-Reorientation, Ferroelectricity, and Magnetodielectric Effect in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>YFe</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Mn</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>0.1</mml:mn><mml:mo mathvariant="bold">≤</mml:mo><mml:mi>x</…

We report the observation of magnetoelectric and magnetodielectric effects at different temperatures in Mn-substituted yttrium orthoferrite, ${\mathrm{YFe}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}{\mathrm{O}}_{3}(0.1\ensuremath{\le}x\ensuremath{\le}0.40)$. Substitution of Mn in antiferromagnetic ${\mathrm{YFeO}}_{3}({T}_{N}=640\text{ }\text{ }\mathrm{K})$ induces a first-order spin-reorientation transition at a temperature, ${T}_{\mathrm{SR}}$, which increases with $x$ whereas the N\'eel temperature (${T}_{N}$) decreases. While the magnetodielectric effect occurs at ${T}_{\mathrm{SR}}$ and ${T}_{N}$, the ferroelectricity appears rather at low temperatures. The origin of magnetodielectric effect is attributed to spin-phonon coupling as evidenced from the temperature dependence of Raman phonon modes. The large magnetocapacitance (18% at 50 kOe) near ${T}_{\mathrm{SR}}=320\text{ }\text{ }\mathrm{K}$ and high ferroelectric transition temperature ($\ensuremath{\sim}115\text{ }\text{ }\mathrm{K}$) observed for $x=0.4$ suggest routes to enhance magnetoelectric effect near room temperature for practical applications.