Growth of KNbO3 thin films on MgO by pulsed laser deposition

Abstract

Crystalline and stoichiometric KNbO3 thin films have been grown on (100) oriented MgO substrates by pulsed laser deposition technique. Electron microprobe analysis and Rutherford backscattering spectroscopy of the films show a progressive loss of K with increasing substrate-target distance. To compensate for this K loss the ceramic KNbO3 targets were enriched with K2CO3 powder, pressed at room temperature, and sintered at 650 °C. For a substrate-target distance of 6 cm, targets with [K]/[Nb] molar ratio=2.85 yield stoichiometric KNbO3 films. A partial oxygen pressure of 2×10−2 mbar was optimum for growing transparent films. Films grown between 650 and 700 °C show the KNbO3 crystalline phase with its (110) axis preferentially oriented perpendicular to the surface of the substrate. At these temperatures KNbO3 diffusion into the MgO substrate is observed. Films grown from KNbO3 single crystal targets only contain a Mg4Nb2O9 crystalline layer.

Structural and electronic properties of cubic KNbO3 (001) surfaces: A first-principles study

“…KNbO 3 is one of the most important ferroelectric perovskite oxides. Since the discovery of ferroelectric nature in 1951 [14], KNbO 3 has shown potential for piezoelectric and ferroelectric applications due to its large electromechanical coupling factor, high Curie temperature, the promising nonlinear optical property, and lead-free and environmentally friendly nature [15][16][17]. Taking into account this high technological importance, it is surprising that there are few experimental and theoretical studies reported dealing with KNbO 3 (0 0 1) surfaces.…”

Aging of magnetic properties in MgO films

“…expected to promote the development of cation vacancies in the deposited film. 9,10 Under these circumstances, by keeping all the other parameters constant, increasing the sputtering power density would increase the growth rate which would, in turn, reduce the number of cation vacancies. This allows for control on the final number of cation vacancies in the films.…”

Growth and field dependent dielectric properties of epitaxial Na0.5K0.5NbO3 thin films

“…The simpler KNbO 3 crystal has shown good performance in nonlinear optical applications and it has recently also been studied in thin film form. [18][19][20] The addition of Na provides the opportunity to adjust the lattice parameter of the growing film since the lattice parameters of (Na x ,K 1Ϫx )NbO 3 are smaller than those of KNbO 3 . 12 Na addition can also modify the dielectric and piezoelectric properties of KNbO 3 .…”