Microwave synthesis of calcium bismuth niobate thin films obtained by the polymeric precursor method

Strain Engineered CaBi2Nb2O9 Thin Films with Enhanced Electrical Properties

“…In addition, it is easy to notice the shrinking and tilting of the P – E loops. This type of P – E loops are commonly observed in CBNO materials ,− and can be attributed to the effect of a space charge layer. − Figure shows a good fitting of the leakage current density-electric voltage curve ( J – V curve) of the CBNO film to a modified Schottky contact model. , The space-charge density ( N eff ) of the film can be estimated from the fitted J – V curve using the formula ln ( J ) = b ( V + V bi * ) 1/4 , where b is the fitted slope and , Here V bi * is the built-in interface potential related to the height of the interface energy barrier between the CBNO film and the electrode layer, and the value of V bi * is about 0.5 V. q is the electron charge, k is the Boltzmann constant, and T the temperature in Kelvin ( T = 298 K is used for room temperature). ε 0 , ε dy , and ε r are the vacuum permittivity, dynamic, and static dielectric constants of the CBNO film, respectively.…”

“…Furthermore, the dielectric loss tangent tgδ is <∼1.6% at E max , resulting in a superior figure of merit (FOM) for the dielectric tunability, FOM = tunability/loss tangent ∼30, significantly higher than those of the CBNO films reported in the literature (FOM ∼ 10−15). 26,27 The greatly enhanced dielectric properties can be understood by the combination of the two effects from strain engineering. First, the strained growth of the film on the chosen substrate of MgO results in reduction of c-grains, which were replaced by a-grains and grains tilting away from the a/b axis, leading to a better average polarization and a larger dielectric constant, as evidenced by the pioneering work on textured CBNO ceramics.…”

“…Growth of oriented films, while meeting the ever-increasing demand of device miniaturization and integration, provides a solution for the enhancement of electrical properties of ferroelectrics. , Cho and Desu , and A. Z. Simǒes et al − are the two major groups who reported preparations of CBNO thin films and investigated their electrical properties. The former fabricated highly c -axis oriented CBNO films with a remnant polarization ∼3.6 μC/cm 2 using a pulsed laser deposition method, , while the latter prepared highly a - and c -axis oriented thin films with a remnant polarization ∼4.2 μC/cm 2 via a polymer precursor method. − Their results confirmed that with an increasing amount of a -axis oriented grains ( a -grains), that is, the (200)/(020) crystallites, ferroelectric and piezoelectric properties of a CBNO film showed a clear trend of improvement.…”

“…Z. Simǒes et al − are the two major groups who reported preparations of CBNO thin films and investigated their electrical properties. The former fabricated highly c -axis oriented CBNO films with a remnant polarization ∼3.6 μC/cm 2 using a pulsed laser deposition method, , while the latter prepared highly a - and c -axis oriented thin films with a remnant polarization ∼4.2 μC/cm 2 via a polymer precursor method. − Their results confirmed that with an increasing amount of a -axis oriented grains ( a -grains), that is, the (200)/(020) crystallites, ferroelectric and piezoelectric properties of a CBNO film showed a clear trend of improvement. Recently, Y. Ahn et al prepared epitaxial c -axis oriented ( c -grain) and highly a -axis oriented CBNO thin films via pulsed laser deposition. , The remnant polarizations of their films were improved to ∼10 μC/cm 2 .…”

Piezoelectric behavior of SrRuO3 buffered lanthanum modified bismuth ferrite thin films grown by chemical method

“…The microwave furnace used to crystallize the SRO electrode was a simple domestic model similar to that described in literature. 18 Phase analyses of the films were performed at room temperature by x-ray diffraction ͑XRD͒ using a Bragg-Brentano diffractometer ͑Rigaku 2000͒ and Cu K␣ radiation. A PHI-5702 multifunction x-ray photoelectron spectrometer ͑XPS͒ was used, working with an Al K␣ x-ray source of 29.35 eV passing energy.…”