Ba0.97La0.02Ti0.95Nb0.04O3 polycrystalline sample was produced through molten-salt technique. The morphological, structural, impedance and optical properties were investigated by scanning electron microscope, X-ray powder diffraction (XRD), and ultraviolet–visible diffuse reflectance spectrophotometer, respectively. XRD pattern illustrate a single-pure phase of tetragonal perovskite structure with P4/mmm group space. No impurity was noticed for present ceramic. The optical band gap (Eg) values were calculated from the absorption spectra. Notwithstanding, electrical and dielectric properties were used to analyze the dielectric constant and loss, the modulus as well as dissipation factors as functions of both frequencies and d.c bias voltage for obtained sample. The frequency (f) dependence dielectric study shows that the value of dielectric constant is high at lower frequencies and decreases with increase in frequency. It is obvious to comprehend how to overwhelm the formation of inter-grain and intra-grain, and how to restrain the propagation of Ti species is an important challenge for the realization of an alternative “high-k gate dielectric” applications. Thus, some kind of semicircular arc caused by a variety of electrically active regions can originate from grains, grain boundaries, and electrode polarization effects. The modulus mechanism indicates the non-Debye type of conduction relaxation in the material, which is supported by impedance data.
相似文献Polycrystalline sample of Ba0.97La0.02Ti0.98Nb0.016O3 (distinguished as BLTi0.98Nb0.016) has been prepared through Molten-Salt-Flux reaction route. The XRD, surface morphology, absorption spectra, impedance, and dielectric behaviors were employed to typify the prepared polycrystalline ceramic. The XRD analysis reflects that obtained perovskite having the pure-tetragonal structure with space group P4/mmm. As of the absorption spectra, the optical band gap (Eg), Urbach energy (Eu), and refractive index values have designed. The electrical properties of synthesized compound have been inspected via complex impedance spectroscopy vs. frequency (f) (102 Hz–106 Hz) within the d.c-bias voltage range [0.5 V–5 V]. The fitting of the Nyquist plot exposes that both intra- and intra grains contribute to relaxation and the grain limits are more resistive and capacitive than the grains. Modulus analysis confirms that relaxation in our sample is of non-Debye nature and d.c-bias voltages dependent. Depending on the frequency, the change of ε′ can be discussed founded on the principle of interfacial polarization of the Maxwell–Wagner category. BLTi0.98Nb0.016 shows notable frequency independent relative studied properties, it is a potential candidate for devices.
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