International Journal of Anesthesiology & Pain Medicine

Keywords

Solid state reaction; STO (strontium titanate); Ceramic-polymer composite; Perovskite; Impedance

Introduction

In recent years, Strontium titanate (STO) has gained a lot of attraction in the field of electronics because of its significant electro-chemical properties. It has high dielectric constant, high melting temperature, low coefficient of thermal expansion [1]. It is a ferroelectric perovskite material with face centered cubic structure [2]. Moreover, STO is an important band insulator because it has a band gap=3.2 eV [3].It plays a vital role in photo-catalysts in solar cells, and solid oxide electronic devices [4]. It has been used in various microwave application because of its dielectric nonlinearity nature (dielectric constant depends on applied electric field) [5]. It has a vast application in the fields of RF filters, hydrocarbon sensors and antennas [6]. Zn Doping can induce the dielectric response of Quality paraelectric STO. Also reveals the photocatalytic activity with improvement of double time than undoped STO. Hence due to the high dielectric constant and low dielectric loss at room temperature Zn doped STO can be applied in microwave devices, tunable capacitors, resonators, phase shifters and oscillators. Zn doped STO There are several methods to synthesize STO but in this work, we have followed solid state method to synthesize Zn doped STO ceramic powders and then made composite of these ceramic-polymers with the help of PMMA polymers by solution casting method and studied about how the Zn doping affects its electrical impedance which can give us an idea about the grain boundary, overall electrical properties, relaxation period, bulk properties and the various types of polarization occurring inside the material.

Experimental Technique

The sample Zn doped SrTiO ₃ was synthesized using solid state reaction technique between high-purity stoichiometry raw materials at high-temperature. The stoichiometrically weighed raw materials was first blended in an air atmosphere for 2 hours and then in alcohol for another 1 hour. Later the mixed powders were calcinated at a temperature of 950°C for 4hr in a high purity alumina crucible. The verification of compound formation was done using XRD technique. Calcined powders were then taken according to weight percent (10%, 0.5 gm) with PMMA (5 gm) to prepare the ceramic-polymer composite film. The process was carried out at room temperature by using solution casting method. After the polymerization, using high purity silver paste the two faces of polymer were coated and dried at 100°C. The structural properties of the samples were identified by XRD. Measurements of dielectric and impedance were studied using an LCR meter computed.

The variation of the real part of modulus with frequency are plotted It indicates that the value of M′ is almost zero at very low frequency region. Further it rises rapidly with increase in frequency because of the conduction process due to the shortrange mobility of charge carriers and also for the absence of therestorative force which dictate the mobility of charge carriers under the action of an induced electric field [8].

The fluctuation of Imaginary part of complex modulus (M") with frequency at room temperature. The value of M" also increases with rise in frequency. The existence of peak in the above plot confirms the relaxation of conductivity in the system i.e. the transition of mobility from long to short range distance. In the low frequency region, the Zinc ions can move quickly from one site to another at a longer distance. But, at higher frequency region, the ions are drifted only at a short distance within a potential.

Significance of study

The fluctuation of Imaginary part of complex modulus (M") with frequency at room temperature [9]. The value of M" also increases with rise in frequency. The existence of peak in the above plot confirms the relaxation of conductivity in the system i.e. the transition of mobility from long to short range distance. In the low frequency region, the Zinc ions can move quickly from one site to another at a longer distance. But, at higher frequency region, the ions are drifted only at a short distance within a potential well [10-15].

Conclusion

The perovskite material is prepared by solid state reaction method which is cubical in structure and the polymeric composite films were synthesized by solution casting method. From XRD, the average size of crystallite is found to be 28 nm. The SEM image verifies that the grains are nearly spherical. The average grain size is approximately in between 1-2 μm. The uniform distribution of grains can be seen. The impedance study indicates that AC conductivity increases with rise in frequency. From modulus study hoping mechanism is found in the material with relaxation process. Thus, the prepared material has a good future in the field of ferroelectric electronics.

Acknowledgement

No acknowledgement

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