Optical and Piezoelectric Study of KNN Solid Solutions Co-Doped with La-Mn and Eu-Fe

Abstract

The solid-state method was used to synthesize single phase potassium-sodium niobate (KNN) co-doped with the La3+–Mn4+ and Eu3+–Fe3+ ion pairs. Structural determination of all studied solid solutions was accomplished by XRD and Rietveld refinement method. Electron paramagnetic resonance (EPR) studies were performed to determine the oxidation state of paramagnetic centers. Optical spectroscopy measurements, excitation, emission and decay lifetime were carried out for each solid solution. The present study reveals that doping KNN with La3+–Mn4+ and Eu3+–Fe3+ at concentrations of 0.5 mol % and 1 mol %, respectively, improves the ferroelectric and piezoelectric behavior and induce the generation of optical properties in the material for potential applications.

Extraction of Electromechanical Coefficients from Capacitance–Voltage Measurements of Unannealed Solution‐Processed KNN Thin Films: Effects of Frequency and Electrostatic and Mechanical Deformation

“…where changes in area and thickness are in general functions of applied bias (V) and can take positive or negative values. Intrinsic specific capacitance (c π ≡ CðVÞ A 0 ) can be calculated after rearrangement of the terms and substituting the value of ν for KNN, [28][29][30] Àd 31 d 33 ¼ ν ¼ 0.4608. Thus, Equation ( 7) leads to…”

“…The third term can thus be neglected. where changes in area and thickness are in general functions of applied bias (V) and can take positive or negative values. Intrinsic specific capacitance () can be calculated after rearrangement of the terms and substituting the value of ν for KNN, [ 28–30 ] . Thus, Equation () leads to …”

(Bi0.5Na0.5)(Zr0.97W0.01Fe0.02)O3 doping effects on KNN‐based lead‐free ceramics prepared via two‐step sintering technique

“…replaced Na + and K + with La 3+ and Eu 3+ at the A‐site, and replaced Nb 5+ with Mn 4+ and Fe 3+ at the B‐site of the perovskite structure, and prepared the co‐doped ((K 0.5 Na 0.5 ) 1‐4x/5 La 4x/5 )(Nb 1−4.5x/5 Mn 4.5x/5 )O 3 (x = 0.005) and ((K 0.5 Na 0.5 ) 1‐x Eu x )(Nb 1‐x Fe x )O 3 (x = 0.01) solid solutions. The change of emission spectra intensity ratio I( 7 F 2 )/I( 7 F 1 ) of the Eu‐Fe co‐doped solid solution samples indicates that the addition of dopants causes a large distortion in the crystal structure, which directly affects dielectric, ferroelectric, and piezoelectric properties of the Eu‐Fe co‐doped solid solutions 28 …”

“…The change of emission spectra intensity ratio I( 7 F 2 )/I( 7 F 1 ) of the Eu-Fe co-doped solid solution samples indicates that the addition of dopants causes a large distortion in the crystal structure, which directly affects dielectric, ferroelectric, and piezoelectric properties of the Eu-Fe co-doped solid solutions. 28 For preparing the KNN-based ceramics, the high volatility of alkaline elements during sintering should be considered specially, which induces many pores and low density. 29 Lower sintering temperature leads to lower density since ceramics cannot obtain sufficient sintering energy, while higher sintering temperature should be avoided due to the high evaporation of alkali metals during sintering.…”