Effect of BiScO3 Concentration On Structural, Vibrational and Electrical Properties of K0.5Na0.5NbO3-BiScO3 Ferroelectric Solid Solutions

Abstract

Ferroelectric and piezoelectric materials have drawn a lot of interest from the scientific community due to their numerous device applications in electronic and optoelectronic industries. Lead-based ferroelectric materials are widely used for various device applications. The toxic nature of lead is known to cause hazardous and irreversible damages to kidney, brain and nervous systems. Thus lead-free ferroelectric perovskite materials are being actively researched upon to replace lead based ones. The mostly studied lead-free systems are BaTiO3 (BT), (K0.5Bi0.5)TiO3 (KBT), and (Na0.5Bi0.5)TiO3 (NBT) etc. Because of notable dielectric and ferroelectric properties and high Curie (~420°C) temperature, potassium sodium niobate K0.5Na0.5NbO3 (KNN) is a prospective lead-free option among the many possible lead-free systems.1 Nevertheless, it has some disadvantages, including a modest piezoelectric coefficient (d33~60 pC/N), a tendency for aberrant grain development, low thermal stability, and extremely hygroscopic constituent alkali components.2 To overcome the above problems, few ways have been discerned e.g. i) Addition of sintering aid, ii) Microwave sintering, iii) Hot-plasma sintering, iv) Spark plasma sintering, v) Chemical substitution and vi) Fabrication of solid solutions. In this study, we have fabricated the solid solutions of KNN with the perovskite system BiScO3, as Bi3+ is isoelectronic with Pb 2+, can hybridize with O2- to produce a lone pair leading to enhancement piezoelectricity and other functional properties.3 The ferroelectric solid solutions with chemical formula: (1-x) K0.5Na0.5NbO3-xBiScO3, where x = 0.000, 0.005, 0.010, 0.015, 0.020, 0.030, 0.040, 0.050 are synthesized via conventional solid-state reaction method. X-ray diffraction, SEM micrographs, Raman scattering studies, temperature dependent dielectric, and piezoelectric properties measurement techniques have been used to collect the data over wide ranging experimental conditions. The XRD patterns confirmed the crystallization of the ceramic solid solution in a perovskite phase. Raman scattering spectra and Rietveld refinement analysis of the XRD data provides insights into the phase transitions driven by composition. Temperature dependent dielectric properties dielectric constant (r) and dielectric loss (tan ) at various frequencies provide insights into the ferroelectric phase transition behaviour. The piezoelectric coefficient (d33) for KNN has be Ferroelectric and piezoelectric materials have drawn a lot of interest from the scientific community due to their numerous device applications in electronic and optoelectronic industries. Lead-based ferroelectric materials are widely used for various device applications. The toxic nature of lead is known to cause hazardous and irreversible damages to kidney, brain and nervous systems. Thus lead-free ferroelectric perovskite materials are being actively researched upon to replace lead based ones. The mostly studied lead-free systems are BaTiO3 (BT), (K0.5Bi0.5)TiO3 (KBT), and (Na0.5Bi0.5)TiO3 (NBT) etc. Because of notable dielectric and ferroelectric properties and high Curie (~420°C) temperature, potassium sodium niobate K0.5Na0.5NbO3 (KNN) is a prospective lead-free option among the many possible lead-free systems.1 Nevertheless, it has some disadvantages, including a modest piezoelectric coefficient (d33~60 pC/N), a tendency for aberrant grain development, low thermal stability, and extremely hygroscopic constituent alkali components.2 To overcome the above problems, few ways have been discerned e.g. i) Addition of sintering aid, ii) Microwave sintering, iii) Hot-plasma sintering, iv) Spark plasma sintering, v) Chemical substitution and vi) Fabrication of solid solutions. In this study, we have fabricated the solid solutions of KNN with the perovskite system BiScO3, as Bi3+ is isoelectronic with Pb 2+, can hybridize with O2- to produce a lone pair leading to enhancement piezoelectricity and other functional properties.3 The ferroelectric solid solutions with chemical formula: (1-x) K0.5Na0.5NbO3-xBiScO3, where x = 0.000, 0.005, 0.010, 0.015, 0.020, 0.030, 0.040, 0.050 are synthesized via conventional solid-state reaction method. X-ray diffraction, SEM micrographs, Raman scattering studies, temperature dependent dielectric, and piezoelectric properties measurement techniques have been used to collect the data over wide ranging experimental conditions. The XRD patterns confirmed the crystallization of the ceramic solid solution in a perovskite phase. Raman scattering spectra and Rietveld refinement analysis of the XRD data provides insights into the phase transitions driven by composition. Temperature dependent dielectric properties dielectric constant (r) and dielectric loss (tan ) at various frequencies provide insights into the ferroelectric phase transition behaviour. The piezoelectric coefficient (d33) for KNN has been significantly enhanced, with a maximum value of 154 pC/N at x = 0.015, highlighting the effectiveness of BiScO3 in enhancing piezoelectric properties. en significantly enhanced, with a maximum value of 154 pC/N at x = 0.015, highlighting the effectiveness of BiScO3 in enhancing piezoelectric properties.