Optical Dispersion Characteristics of Polyvinyl Alcohol Reinforced with a Nanoceramic Filler

Andreea Irina Barzic,Romeo Cristian Ciobanu,Marius Soroceanu,Valeria Harabagiu,Razvan Rotaru

doi:10.37358/mp.20.1.5305

Abstract

Polymer films with high refractive index are suitable for a wide range of applications, such as optical fibers, lens and other components for optoelectronic devices. In this work, polyvinyl alcohol films were prepared from aqueous solutions, which were homogenized by ultrasonication. In order to increase the refractive index, the polymer was reinforced with barium titanate nanoparticles, which are previously ultrasonicated for an adequate dispersion inside the host polymer. The dispersion of the refractive index in visible domain was analyzed as a function of filler percent introduced in polymer, showing that an increase in sample s polarizability determined an increase in the refractive index values. The reinforcement caused a decrease of Abbe number indicating a higher light dispersion in the samples. Optical dispersion parameters were extracted from dispersion curves, revealing a reduction of band gap from 3.448 eV for pure polymer to 2.605 eV for the sample containing 2% barium titanate. Doping with the ceramic nanofiller determined a increase in optical conductivity and real part of dielectric constant as a result of appearance of new level states in the band gap. The increase of third order nonlinear optical susceptibility and nonlinear refractive index indicates the suitability of the analyzed nanocomposites for nonlinear optics applications.

Highlights

Polymeric materials have known a growing evolution, in the past decades, as a result of the necessity to optimize their balance of properties for specific applications
3.1 Refractive index and optical dispersion parameters The refractive index values for the pure and filled polyvinyl alcohol (PVA) films were determined by means of refractometry at room temperature (23°C)
Embedding BaTiO3 nanoparticles in PVA matrix induces an increase of the refractive index, at all measuring wavelengths, via enhancing the reinforcement degree with respect to the pure PVA

Summary

Introduction

Polymeric materials have known a growing evolution, in the past decades, as a result of the necessity to optimize their balance of properties for specific applications. There are many types of high refractive index dopants, such as ZnS and ZrO2 [12, 13], TiO2 (rutile, anatase or brookit phase) [11] and BaTiO3 [14]. BaTiO3 (white powder), is a ferroelectric inorganic material from the perovskite class with a high permittivity, which is widely investigated for its photorefractive effects [15] and piezoelectric properties [16]. From this point of view, it can be used in passive and active electronics components, sensors, electro-optic devices, thermistors, electromagnetic shields or in biomedical application [17]

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