Growth and characterization of Titanium Niobium Oxide (TiNb 2 O 7 ) thin films
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Growth and characterization of Titanium Niobium Oxide (TiNb2O7) thin films Venkateswarlu Daramalla1 and S.B.Krupanidhi1* 1 Materials Research Centre, Indian Institute of Science, Bangalore-560012, India. ABSTRACT Comprehensive studies were done on the growth and characterization of TiNb2O7 (TNO) complex oxide thin films by pulsed laser deposition for the first time. The TNO thin films were successfully grown on Pt(200)/TiO2/SiO2/Si(100) substrates. The structure, surface morphology and chemical properties of as-grown thin films were studied as function of deposition temperature, pressure and laser fluence. The GIXRD and HRTEM analyses revealed that the asgrown TNO films were in the monoclinic crystal structure and independent of laser fluence. The HAADF STEM elemental mapping confirms the uniform composition of Ti, Nb and O in TNO thin films. The atomic force microscopy and field emission scanning microscopy shows that, the surface morphology and microstructure of TNO films varied significantly with respect to experimental conditions. The X-ray photoelectron spectroscopy quantitative results indicated that the binding energies of Ti and Nb elements shifted towards right with increasing oxygen partial pressure. The effects of oxygen partial pressure and laser fluence on as-grown TNO films were studied.
INTRODUCTION Complex metal oxides have been considered to play a vital role in near future technologies such as oxide electronics, energy storages [1-2]. Titanium Niobium Oxides (TiNb2O7 (TNO)) is an oxide material which exists in monoclinic crystal structure. Due to their layered structure, they possess a variety of properties which make them to be useful candidates for many applications such as anode materials in Li-ion batteries, protecting layers or transmitting layers in compact disks (CDs), and as dielectric materials in capacitors [3-4]. Some of these properties are good, for example, optical band gap (2.9 eV), low thermal expansion coefficient (~ 4.5 x10-7/ o C), and high dielectric constant (~130). But due to their complex structure and difficulty in synthesis, researchers have not paid much interest to study this material until recently. So far, the TNO material has been synthesized by different methods such as solid state reaction, sol gel method and hydrothermal method. These methods have their own advantages and limitations to understand its structure, property relation [5-6]. Recently, much attention is growing towards developing new complex oxides by novel techniques such as pulsed laser deposition (PLD), molecular beam epitaxy (MBE) as they offer powerful ways to synthesis new materials including meta-stable materials which cannot be possible by other synthesis methods. PLD is one of the physical vapor deposition techniques widely used particularly for investigating new materials, especially to control stochiometry and optimizing oxide materials. It offers new ways to develop and understand complex structures which are not possible by other methods [7]. In this present work, we report the successful gr
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