International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

In view of the practical applications of the piezoelectric ceramics produced from barium titanate (BaTiO3) and barium stannate (BaSnO3), (the BT-BS system), the dielectric behavior of such materials was studied. The starting components (powder of both BaTiO3 and BaSnO3) were synthesizedand structurally characterized in аdvance. Bulk samples of BT-BS (formed as tablets with addition of PVA plasticizer) were prepared using the sol-gel method by varying the BT-BS composition percentage. The samples were characterized by complex electrical impedance spectroscopy and dielectric spectroscopy in the frequency range from 0.1 Hz to 1 MHz. As compared to BaTiO3, an increase with at least 50 % was measured for the value of the room-temperature dielectric constant (e′ – the real part of the dielectric permittivity) of the BT-BS samples containing 15 wt% BaSnO3. In contrast, the 50 wt% content of BaSnO3 led to a decrease of ′ value of BT-BS by a factor of 3.5, due to relatively low e′ value of BaSnO3. Analyses of the frequency spectra of complex electrical impedance and complex dielectric permittivity revealed the dielectric relaxational behavior of the BaTiO3+BaSnO3 system. The results obtained for ′ of BT-BS dielectrics as a function of the temperature were correlated with the data from structural studies. In particular, a specific enhancement of e′ was observed in temperature range around 120C for the BT-BS samples containing 15 wt% BaSnO3. Corresponding conclusions were done. The effects observed show that the synthesized BaTiO3-BaSnO3 ceramics are promising materials for piezoelectric and dielectric applications, e.g., in energy storage devices.

The aim of the present work is to study the characteristics and conditions of obtaining thin films in the BaTiO3–BaSnO3 system, deposited by the sol-gel method on monolithic multilayer samples. In laboratory conditions, the structure, phase composition, micromorphology, electrophysical parameters of the prepared experimental samples were studied. The existing possibilities for optimizing the applied technological regime for the synthesis and surface deposition of thin-layer coatings with set characteristics have been analyzed.

There has been growing interest in the use of the sol-gel approach to form high-quality dielectric materials. Their tailored properties allow for developing functional electronic devices in a scalable and rapid manner. According to physicochemical principles, the displacement and response behavior of charges under an applied external field can manifest in unique dielectric properties, providing useful information to improve the process, design, and quality of electronic devices. Therefore, a systematic and in-depth investigation of the fundamentals of sol-gel dielectrics is necessary. In this Research Update, we present recent advances in various sol-gel-processed dielectric materials and their applications to functional electronic devices. A brief introduction to sol-gel chemistry to form oxide dielectric films and the basis of physical mechanisms under electrical fields are discussed. Along with the dielectric properties, recent achievements of proofof-concept experiments and their various applications to functional electronic devices are introduced. It is expected that further innovations in solution-processed metal oxide dielectrics will achieve cost-effective high-performance functional electronics in the near future.

A system based on BaTiO3 – BaSnO3 (BT-BS) has been developed in search of highly efficient lead-free piezoelectric ceramics. The powder samples were mixed and homogenized in a ratio of 50%: 50% and 15%: 85%. From the compositions thus obtained, tablets with the presence of a PVA plasticizer were formed, which were further annealed in a furnace with a corundum backfill. The temperature regime is in two steps. Drying time up to 800oC with a delay of 1h 30min. and additional heating to 1150°C with one hour delay. The results were characterized by XRD analysis, the relative dielectric constant of the two samples was determined.

Barium titanate ceramics doped with samarium were synthesized by low temperature sol-gel method. The physicochemical characterization of the samples was carried out by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). A pure BaTiO3 cubic phase was obtained. A technological regulation has been developed for the preparation of test samples .Monitoring ofthe relative dielectric permittivity of Sm-doped BaTiO3 ceramics with temperature changes (at frequency of 10 kHz) was realized.The resulting curve is typical of ferromagnetic material. The synthesized barium titanate ceramics possesses a high dielectric constant – 17500 at a Curie temperature Tc (65oC). The obtained values for the relative dielectric permittivity and Curie temperature of Sm-doped barium titanate ceramics are much better in comparison to conventionally non-doped BaTiO3-εr = 2000 and Tc = 120°C.

The research is aimed at creating a target from Sn doped barium-titanate ceramics. A technological regulation for the preparation of test bodies from a material synthesized by a low-temperature sol-gel method has been developed. The physicochemical parameters of the samples were determined and the temperature dependence of the dielectric permittivity was monitored. Physicochemical characterization of the samples was performed by X-Ray diffraction (XRD). and scanning electron microscopy (SEM). The preparation of pure BaTiO3 cubic phase was established. The dielectric permittivity of Sn doped barium-titanate possesses a maximum value of 45000 at a Curie temperature- Tc 40oC.

In recent years, interest in the application and use of materials for supercapacitors for electric vehicles has grown significantly. The advantage of capacitor ceramics over other dielectric materials for producing supercapacitors is its environmental friendliness and high economic efficiency. This paper presents the results of a study of capacitor ceramics doped with Sn at different locations of the modifier (tin) in BaSnTiO3 and BaTiSnO3 crystal lattice. The influence of modifiers in low-temperature sol-gel synthesis was studied. The samples were annealed at 1000°C. The resulting phases were identified by X-ray phase analysis. Microscopic analysis was also performed.

The proposed review looks at some aspects concerning ferroelectrics that are characterized by high dielectric constant at/ or near Curie temperature. Particular attention haс been paid to the doping of BaTiO3 with rare earth elements because they prove to be very promising for the production of supercapacitors. It is pointed out that the preparation of ceramic materials with high dielectric permittivity by sol-gel method is of huge interest due to the numerous advantages inhered to this technology.