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Title: Synthesis and optical properties of pure CdTiO<sub>3</sub> and Ni<sup>2+</sup> and Zn<sup>2+</sup> ion substituted CdTiO<sub>3</sub> obtained by a novel precursor route
Authors: Kharkwal, Mamta
Uma, S
Nagarajan, R
Keywords: Ilmenites
Issue Date: Nov-2012
Publisher: CSIR
Abstract: Monophasic CdTiO<sub>3</sub> 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 CdTiO<sub>3</sub> (space group <i style="mso-bidi-font-style:normal">R</i><i style="mso-bidi-font-style: normal"><span style="font-family:Symbol;mso-ascii-font-family:" times="" new="" roman";="" mso-hansi-font-family:"times="" roman";mso-char-type:symbol;mso-symbol-font-family:="" symbol"="" lang="EN-GB"> </span></i>) with the lattice parameters<i style="mso-bidi-font-style:normal"> a</i> = 5.237(1) and <i style="mso-bidi-font-style: normal">c</i> = 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<sup>-1</sup> due to <i style="mso-bidi-font-style:normal">E</i><sub>g</sub> and <i style="mso-bidi-font-style: normal">A</i><sub>g</sub> modes in the Raman spectroscopy. Phase transition from ilmenite to perovskite structure (space group <i style="mso-bidi-font-style: normal">Pbnm</i>) occurs at 1000 °C. PXRD pattern of the transformed CdTiO<sub>3</sub> is indexed in the orthorhombic symmetry with <i style="mso-bidi-font-style:normal">a</i> = 5.305 (3); <i style="mso-bidi-font-style: normal">b</i> = 5.421 (1); <i style="mso-bidi-font-style:normal">c</i> = 7.617 (3) Å. The broadness and the shift of the Raman band position to 279, 326, 400, 444 and 578 cm<sup>-1</sup> 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 CdTiO<sub>3</sub>. An additional emission band at 3.21 eV is observed in the photoluminescence spectrum of ilmenite CdTiO<sub>3</sub>. Synthesis and optical properties of Ni<sup>2+</sup> and Zn<sup>2+</sup> substituted CdTiO<sub>3</sub> are also reported.
Description: 1538-1544
ISSN: 0975-0975(Online); 0376-4710(Print)
Appears in Collections:IJC-A Vol.51A(11) [November 2012]

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