Electrical and magnetic properties of GdCr_xMn_1−xO₃ (x = 0.0, 0.1) multiferroic nanoparticles

Gadolinium manganate (GdMnO₃) and chromium doped gadolinium manganate (GdCr_0.1Mn_0.9O₃) nanoparticles have been prepared using co-precipitation method. The effects of chromium (10% Cr⁺³) doping on structural, vibrational, optical, electrical and room temperature magnetic properties of GdMnO₃ have been carried out. The structural characterization analysed through X-ray diffraction (XRD) shows the formation of orthorhombic structure with Pbnm space group. The morphology was examined by scanning electron microscopy (SEM). Raman and Fourier transform infrared spectroscopy has been employed for the vibrational investigations of GdMnO₃ and doped GdMnO₃. The Jahn–Teller modes observed at ~482 cm⁻¹ (A_g) and 610 cm⁻¹ (B_1g) in Raman spectrum of GdMnO₃ have not shifted with Cr³⁺ ions doping, which shows that the Cr³⁺ ions are not active to Jahn–Teller distortions. The UV–Vis absorption peak at 461 nm attributed to Mn (d-d) transition has shifted ~10 nm in GdCr_0.1Mn_0.9O₃. The weaker absorption band at 725 nm (1.7 eV) is attributed to the dipole forbidden 5E_g–5T_2g transition of the Mn³⁺ ion. The detailed investigation on the dielectric properties like dielectric constant, dissipation factor, ac conductivity has been carried out in the temperature range of 20–400 °C and in the frequency range of 1 kHz–1 MHz. The temperature dependent dielectric constant shows two dielectric anomalies which get shifted towards high temperature side with increase in frequency, thereby indicating relaxor type behaviour of the material. The dissipation curves also show the similar trend, suggesting the temperature dependent dielectric relaxation. The Cr doping enhances the dielectric properties of GdMnO₃. The room temperature magnetic behaviour analyzed from the magnetic field dependent magnetization curves suggests paramagnetic behavior for both the composition; however Cr doping does enhance the magnetization.