Effects of strontium doping on microstructure and functional properties of solution-derived potassium sodium niobate thin films

Abstract

The effects of strontium doping (0-2 mol%) on structure, microstructure and functional properties of potassium sodium niobate (KNN) thin films deposited on Pt(111)/TiO y /SiO 2 /Si substrates were investigated. Incorporation of Sr up to 1 mol% into the KNN crystal lattice hindered the grain growth, vertical roughness and contributed to the fine-grained and dense thin film microstructure with monoclinic crystal syngony. This effectively reduced leakage current and improved ferroelectric characteristics. Higher doping content (2 mol%) led to the formation of secondary phases and complete deterioration of functional properties. Stabilization of 1 mol% Sr-doped KNN solution with diethanolamine resulted in the film with dielectric constant and losses of 394 and 0.018 at 100 kHz, respectively, leakage current of 3.8 • 10 −8 A/cm 2 at 100 kV/cm and well saturated ferroelectric hysteresis with P r of 6.8 µC/cm 2 and low E c of 85 kV/cm. Benefiting from improved leakage current characteristics at high electric fields and less defect structure, the film showed maximal local piezoelectric coefficient, d 33 ∼ 110 pm/V determined by piezo-response force microscopy (PFM), ability to reach fully saturated local hysteresis under low switching DC voltage of 15 V, and good ferroelectric domain mobility proven by successful in-situ poling of chosen area using PFM lithography.

Composition Regulation of Potassium Sodium Niobate Thin Films through Post-Annealing under Alkali Element Atmospheres

“…Both out-of-plane and in-plane images of amplitude (Figure 5b,d) and phase (Figure 5c,e) show that the film possesses a monograin-like domain structure rather than the strip-like domain typically observed in KNN ceramic bulk. Such a grain domain structure has also been observed in previous reports of KNN films [31,32], likely attributed to the insufficient size of the nanoscale grains, which are unable to accommodate larger strip domains. Furthermore, phase-field simulations indicated that within the nanoscale, smaller domains imply that less energy is needed to achieve ferroelectric inversion [33], and it has also been preliminarily noted in KNN-based materials [34].…”

Synthesis of Microcomponent Doped Strontium Titanate Single Crystal Special Raw Material Powder by Solid Phase Method

“…Solid phase chemical reaction refers to the reaction between solid reactants, in which the solid reactants undergo heat treatment to obtain solid products with new structures, compositions, or properties [2]. Compared to solution or gas phase methods, solid-state chemical reactions have higher reactivity and lower side reactivity, and can prepare high-quality and high-purity products that are suitable for mass production.…”

Research and Development of Preparation Technology of Strontium Niobate Titanate Single Crystal

“…The addition of up to 1mol% SR in KNN lattice hinders grain growth and vertical roughness, and helps to form fine-grained dense thin film microstructure with monoclinic system. This effectively reduces the leakage current and improves the ferroelectric characteristics; By successfully in-situ polarization of the selected region using PFM lithography, good ferroelectric domain mobility is proved [1]. Using alumina obtained from alum sludge, rmka prepared EU and Dy doped strontium aluminate persistent luminescent materials by solid-state reaction.…”