Mn-doped Niobate Perovskite Ceramics and Thin Films for High Field Applications

Silver and sodium niobate perovskites are promising lead-free antiferroelectric (AFE) materials for capacitors with large discharge power density. Challenges to developing these materials include increasing stored energy density by increasing the maximum polarization and breakdown field and improving recoverable energy efficiency by decreasing hysteretic and losses and high-field conductivity. In bulk ceramics, solid solutions of silver niobate - silver tantalate and sodium niobate – bismuth ferrite, have previously been shown to have narrow hysteresis loops and high breakdown strength ideal for these applications. Preparing these materials as thin films would allow investigation of energy storage properties at higher fields than bulk ceramics, however high-field leakage current remains an issue. Introduction of 0-2 mol% Mn<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4+</sup> can be an effective way to reduce leakage in perovskite dielectrics. In this work, Ag(Nb<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.45</inf>Ta<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.55</inf>)O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> and (Na<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.9</inf>Bi<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.1</inf>)(Nb<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.9</inf>Fe<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.1</inf>)O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>, with and without Mn-doping, were prepared first as bulk ceramics and then as thin films by pulsed laser deposition (PLD). Dielectric properties of bulk ceramics as a function of temperature and field strength, and Mn doping concentration are reported. Optimization of PLD deposition parameters to produce epitaxial growth, with smooth surface morphology is discussed and effect of processing parameters on film composition is presented.