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Synthesis and Characteristics of the Zinc Effects on Eu3+ Doped (Zn,Ca)TiO3 Phosphors B. Hemalatha Rudramadevi1, S. Buddhudu2, Piyush Bhatt3 1

School of Physics, Madurai Kamaraj University, Madurai, Tamil Nadu, India. Department of Physics, Sri Venkateswara University, Tirupati, Andhra Pradesh, India. 3 Department of Electrical Engineering, Indian Institute of Technology Bombay, Bombay, India. 2

ABSTRACT For the purpose of development of highly energy-efficient light sources, one needs to design highly efficient green, red and yellow phosphors, which are able to absorb excitation energy and generate emissions. In this contribution, we present our results on producing some efficient phosphors with improved luminescence properties. The effects of zinc on the zinc-doped CaTiO3:Eu3+ phosphors have been investigated by varying the zinc concentrations. X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM) characterizations were studies for their structural and morphological analysis. The variation of zinc concentration influences the crystallinity and morphology of the phosphors. The luminescence spectra of (Zn,Ca)TiO3: Eu3+ have been measured. Eu3+: (Zn,Ca)TiO3 have shown five emission transitions of 5D0→7F 0,1,2,3 & 4 located at 580 nm,593nm 615 nm,655 and 704 respectively with excitation at λexci=398nm (7F0→5L6). Moreover, the emitting phosphor developed in this study can be very effectively excited at the wavelengths of 398 nm. The (Zn, Ca)TiO3:Eu3+ can be used as a complementary phosphor in there red region for the white LEDs.

INTRODUCTION As a new solid-state light source, the white light-emitting diodes (LEDs) are considered to be the fourth generation general lighting devices that stands a real chance of replacing conventional lighting sources such as incandescent and fluorescent lamps due to its long life time, saving energy, reliability, safety and its environmental-friendly characteristics [1-4]. Recently, white light-emitting diodes (LEDs) have attracted more attention because they have advantages of low energy consumption, long lifetime, without pollutants and so on. It is well-known that there are basically two approaches to generate white light from LEDs [5–7].White light-emitting diodes (LEDs), with the advantages of long lifetime, saving of energy consumption, and environment friendly characteristics, are thought to be the most important solid-state light sources for substituting the widely used incandescent and fluorescent lamps [8]. Some oxide-based green phosphors, such as ortho silicates, have been developed to obtain a blue LED. However, so far, appropriate oxide based red phosphors have not been developed. Therefore, it is important to develop an oxide based red phosphor with high brightness and good colour purity to extend the area of white LED applications. Rare earth ions have become good candidates for luminescent centers due to their special intra-4f-shell transitions [9]. In the search for red-emitting phosphors with high efficiency and proper CIE chromaticity coordinates, t