Facile Growth of Functional Perovskite Oxide Nanowire Arrays by Hybrid Physical-Chemical Techniques
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Facile Growth of Functional Perovskite Oxide Nanowire Arrays by Hybrid PhysicalChemical Techniques Corisa Kons and Anuja Datta Florida Cluster for Advanced Smart Sensor Technologies & Department of Physics, University of South Florida, Tampa, Florida 33620, USA ABSTRACT A generalized route encompassing a facile hybrid physical/chemical approach is reported for fabricating size and shape selective nanowires of technologically important ferroelectric perovskite oxides (Pb(Zr0.52Ti0.48)O3 (PZT) and Pb-free ZnSnO3) on industrially feasible largearea substrates. The approaches involve depositing nano-seed layers (50 - 100 nm in thickness) of the desired materials (Ti for PZT and ZnO for ZnSnO3) by pulsed laser deposition and RF sputtering techniques followed by oriented growth of nanowire arrays of these materials by solvothermal processes by varying solvent compositions and ratios. Similar crystal symmetry between the seed-layers facilitated the growth of well-aligned nanowire arrays of the targeted materials homogeneously on the substrates with a high packing density. Measurements of the electronic (field-emission), and ferroelectric properties of the materials are performed and discussed in terms of understanding their potential for future technological applications. The facile, low-cost method for fabricating high quality nanowires may expand the outreach of probes for understanding the structure-property relations in other perovskite materials. INTRODUCTION Perovskite oxides are important class of materials possessing high dielectric and piezoelectric coefficients, switchable ferroelectric polarization, large nonlinear optical coefficients and interesting electrical properties. These properties may be exploited in applications such as nonvolatile memory devices, thermistors, multilayer capacitors, dynamic random access memories and as cathode electron sources. The family of Pb-based perovskites such as Pb(Zr,Ti)O3 (PZT) has been extensively deliberated as feasible ferroelectric (FE) media owing to their high polarization and piezoelectric (PE) coefficients (remanent polarization, Pr ≈ 35 µC/cm2 at coercive field, Ec ≈ 1 kV/mm) [1,2]. However the use of toxic Pb in FE devices and the consequential environmental concerns have resulted in efforts to find environment-friendly materials with high FE properties. Advances have been made in the last few years to develop Pbfree FE materials and devices in the quest to replace Pb-based materials for electromechanical devices such as actuators, sensors, and transducers [3,4]. As alternative materials, LiNbO3-type (LN-type) ZnSnO3, a perovskite derivative show potential because of their symmetry-dependent FE and PE properties [4,5]. The cooperative cation shift along the c-axis direction against closepacked anions, results in high spontaneous polarization (theoretical Pr = 59 µC/cm2) in these types of oxide compounds, and makes them desirable candidates for exploring structure and morphology dependent properties. Nanostructuring results in an enhancement of the surface area of
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