Transfer of High-Temperature-Sputtered BiFeO3 Thin Films onto Flexible Substrates Using α-MoO3 Layers.

Inducing external strains on highly oriented thin films transferred onto mechanically deformable substrates enables a drastic enhancement of their ferroelectric, magnetic, and electronic performances, which cannot be achieved in films on rigid single crystals. Herein, the growth and diffusion behaviors of BiFeO3 thin films grown at various temperatures is reported on α-MoO3 layers of different thicknesses using sputtering. When the BiFeO3 thin films are deposited at a high temperature, significant diffusion of Fe into α-MoO3 occurs, producing the Fe1.89Mo4.11O7 phase and suppressing the maintenance of the 2D structure of the α-MoO3 layers. Although lowering the deposition temperature alleviates the diffusion yielding the survival of the α-MoO3 layer, enabling exfoliation, the BiFeO3 is amorphous and the formation of the Fe1.89Mo4.11O7 phase cannot be suppressed at the crystallization temperature. High-temperature-grown BiFeO3 thin films are successfully transferred onto flexible substrates via mechanical exfoliation by introducing a blocking layer of Au and measured the ferroelectric properties of the transferred films.

Microstructure and piezoelectric properties of (Na0.5K0.5)NbO3 lead-free piezoelectric ceramics with V2O5 addition.

Various amounts of Nb(2)O(5) in the (Na(0.5)K(0.5)) NbO(3) (NKN) ceramic were replaced by V(2)O(5) to decrease its sintering temperature to below 950 degrees C. A small V(2)O(5) content resulted in a dense microstructure with an increased grain size for the specimen sintered at 900 degrees C due to the presence of a liquid phase. When V(2)O(5) was added to the NKN ceramics, their orthorhombic-to-tetragonal transition temperature increased from 178 degrees C to around 200 degrees C. However, their Curie temperature decreased from 402 degrees C to around 330 degrees C. The k(p), epsilon(3) (T)/epsilon(0), and Q(m) values increased with V(2)O(5) addition, probably due to the increased density and poling state, which was identified by the phase angle. The specimen with x = 0.05, sintered at 900 degrees C for 8 h, exhibited the following piezoelectric properties: k(p) = 0.32, epsilon(3) (T)/epsilon(0) = 245, d(33) = 120 (pC/N), and Q(m) = 232.