Effect of surface modification on Tb doped bismuth ferrite nanofiller in polyvinyl alcohol based composite films

Abstract

In this paper, we report the fabrication and the characterizations of surface modified Tb doped bismuth ferrite nanoparticle embedded polyvinyl alcohol (PVA) films. This work begins with the synthesis of Tb doped bismuth ferrite (BTFO) nanoparticles (NPs). BTFO NPs are then functionalized using silanes. Here, the functionalizing agents are tetraethyl orthosilicate (TEOS) and (3-amino propyl) triethoxysilane. Morphological studies confirm that silica coated BTFO NPs possess a distorted hexagonal structure and effectively show less agglomeration. Untreated and functionalized BTFO NPs are embedded in PVA to fabricate flexible polymer nanocomposite systems. After functionalization, BTFO shows uniform dispersion in a PVA matrix. Optical bandgap decreases in functionalized BTFO loaded PVA films due to the increase in charge transfer complexes. BTFO-PVA nanocomposites (treated/untreated) are more thermally stable than the pristine PVA film. The charge carriers of each polymer film follow a correlated barrier hopping conduction mechanism. The outer silica shell thickness of BTFO NPs effectively affects the magnetic property of the films. Enhancement of the magnetic properties is best achieved in the TEOS functionalized BTFO loaded PVA nanocomposite. All the films follow both Ohmic (at lower voltage) and trap controlled space charge limited current (at higher voltage) conduction mechanisms. Considering the effect of intrinsic properties of the polymeric system, the trap controlled current conduction is further well explained by a Poole–Frenkel model. Among the film samples we have examined in this work, TEOS functionalized BTFO–PVA nanocomposite exhibits the best quality in optical, electrical, and magnetic observations.