Unstable state in epitaxial films of sodium niobate

Abstract

Epitaxial perovskite-type films of sodium niobate were grown by pulsed laser deposition, and their crystal structure and dielectric properties were experimentally studied. The dielectric permittivity, inverse permittivity and its derivative, and dielectric hysteresis were analyzed and compared with those of antiferroelectric lead zirconate films. At temperatures in the interval of 80–600 K, the state of the sodium niobate films with relaxed misfit strain is interpreted as an unstable coexistence of antiferroelectric and ferroelectric phases. The origin of the ferroelectric phase is discussed.

Dielectric properties of NaNbO3:SrTiO3 interface nanolayer

“…7͑a͔͒ reveal a weak sign of ferroelectricity in some SLs on MgO, in agreement with Ref. 5. In SLs on LAO, the shape of ͑E dc ͒ is hysteresis-free and almost flat, evidencing the absence of ferroelectric phase.…”

“…4 More details on growth, crystal structure, and electrical characterization of the heterostructures can be found elsewhere. 2,5 …”

“…5 Presence of strain and spontaneous polarization in the NNO layers of SLs is unwanted for the interface analysis. Studies of under applied dc electric field ͓Fig.…”

Effects of doping and epitaxy on optical behavior of NaNbO3 films

“…Although the corresponding lattice distortions are difficult to detect here, the ferroelectric behavior has been experimentally confirmed in similar films. [15][16][17][18] In particular, ferroelectric transition has been evidenced in epitaxial NNO films on LSAT. 18 The optical constants in the NNO films were explored by variable-angle spectroscopic ellipsometry (VASE) using a VUV J.…”

“…26 We anticipate that the PL intensity can be further enhanced in the Pr-doped NNO films by selecting appropriate substrates, which can enable epitaxial growth of thin films with a larger ferroelectric polarization. 16 In conclusion, the optical constants and photoluminescence are experimentally studied in 130-nm-thick epitaxial NNO and Pr-doped NNO films. Cube-on-cube epitaxy of the perovskite NNO cell on top of LSAT (001) is evidenced by XRD and HRTEM.…”