Synthesis and optical properties of pure CdTiO₃ and Ni²⁺ and Zn²⁺ ion substituted CdTiO₃ obtained by a novel precursor route

Abstract

1538-1544Monophasic CdTiO3 in ilmenite and perovskite structures have been synthesized by a novel precursor route using oxine as the complexing agent and their optical and photoluminescence properties have been characterized. The co-precipitated oxinates of cadmium and titanium on one time heating at 600 °C for 6 h yields the ilmenite structured CdTiO3 (space group R<i style="mso-bidi-font-style: normal"> ) with the lattice parameters a = 5.237(1) and <i style="mso-bidi-font-style: normal">c = 14.84 (6) Å as revealed by its powder X-ray diffraction pattern. The presence of rhombohedral symmetry is further confirmed by the six bands observed at 216, 246, 325, 461, 598, and 694 cm-1 due to Eg and <i style="mso-bidi-font-style: normal">Ag modes in the Raman spectroscopy. Phase transition from ilmenite to perovskite structure (space group <i style="mso-bidi-font-style: normal">Pbnm) occurs at 1000 °C. PXRD pattern of the transformed CdTiO3 is indexed in the orthorhombic symmetry with a = 5.305 (3); <i style="mso-bidi-font-style: normal">b = 5.421 (1); c = 7.617 (3) Å. The broadness and the shift of the Raman band position to 279, 326, 400, 444 and 578 cm-1 endorses the orthorhombic symmetry. From the diffuse reflectance measurements, band gap values of 2.9 eV and 2.8 eV have been estimated for the ilmenite and perovskite forms of CdTiO3. An additional emission band at 3.21 eV is observed in the photoluminescence spectrum of ilmenite CdTiO3. Synthesis and optical properties of Ni2+ and Zn2+ substituted CdTiO3 are also reported