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Ó Indian Academy of Sciences Sadhana(0123456789().,-volV)F T3](0123456789().,-volV)

Electrophoretic deposition of Bi1.5Zn1.0Nb1.5O7 thick films on metal foils for flexible electronic devices K SUDHEENDRAN1,*

and PAULA M VILARINHO2

1

Department of Physics, Sree Kerala Varma College, Thrissur 680011, India Department of Materials and Ceramics Engineering, Centre for Research in Ceramics and Composite Materials, CICECO, University of Aveiro, 3810-093 Aveiro, Portugal *Author for correspondence ([email protected]) 2

MS received 25 April 2020; accepted 24 August 2020 Abstract. Cubic bismuth zinc niobate (c-BZN) thick films were fabricated on flexible platinum foils by electrophoretic deposition technique. The X-ray diffraction studies reveal that the films are under tensile stress. The permittivity of the c-BZN thick film sintered at 850 and 950°C, measured at an applied frequency of 1 MHz were 114 and 125, respectively. The corresponding values of dissipation factors were 0.004 and 0.0038. The films were also exhibiting voltage-dependent dielectric properties. The biaxial tensile stress, which is developed as a result of substrate constraints during the sintering, leads to significant change in the relaxation and dielectric characteristics of the films compared to that of ceramics. From this study, it is expected that large tensile stress in c-BZN thick films can bring down the dielectric loss and the variation of the dielectric permittivity with temperature, which will make them attractive, low loss and temperature stable applications. Keywords.

1.

Electrophoretic deposition; thick films; tunability; low temperature co-fired ceramic; bismuth zinc niobate.

Introduction

The development of electronic circuits on flexible substrates has attracted significant attention for the flexible displays, and several other low-cost, and large area electronic circuits [1,2]. Most of the flexible substrates used nowadays are of polymer based and therefore they are chemically compatible with the photo resists and enchants the photolithographic patterning techniques that are being used by the microelectronic industry [3]. At present, insulator films deposited on flexible metallic foils are also being examined for the flexible electronic applications, as it can withstand the conventional vacuum deposition and photolithographic patterning techniques used in the microelectronics [4]. Apart from this, high dielectric oxide thick or thin films on metal foils are also being considered for integrated electronic packaging approach that is currently receiving much attention due to the cost and space advantageous. This method will reduce the circuit board area to a great extent by replacing the surface mount components like capacitors by embedded capacitor layers. Moreover, the devices with embedded capacitor layers exhibit more reliable performance due to their decreased number of interconnects, which minimizes the parasitic noise. Hence the preparation of different dielectric thick films on flexible metallic foils is becom