Influence of Thermal Treatment on Relaxor Properties of BaBi2Nb2O9 Ceramics

In the hereby paper the implications of thermal modification of BaBi2Nb2O9 ceramics in high vacuum (5×10-11 bar) at a temperature equal of 1173K are widely discussed. The mentioned modification caused changes in the ions concentration (confirmed by EDS and XPS analysis) and as a consequence an influence on the value of the unit cell parameters as well as on the dielectric and relaxor properties of described ceramics. The obtained results of EDS and XPS analysis of the sample before and after thermal treatment revealed bismuth ions diffusion to the surface of the sample (which was expected) and an almost complete the lack of barium ions on the modified surface. The comparison of EDS and XPS analysis results, suggested that they penetrated the interior of the sample and embedded into the crystal structure in place of bismuth. The hypothesis is in good agreement with the results of X-ray diffraction-the volume of the unit cell had an insignificant increase. The changes in the ions concentration influenced, also in a distinct manner, the dielectric and relaxor properties as well as on the shape of temperature characteristic of thermal stimulated depolarization current observed in BBN ceramics

Własności mechaniczne ceramiki BBN domieszkowanej wanadem

The BBN ceramics doped by vanadium have been broadly recognized by using nano indentation techniques and ultrasound velocity and measurements. The results affirm that the vanadium admixture significantly improved the mechanical quality of ceramics. Such a small dopant doesn’t change the dielectric properties, but we obtain visible increasing of the dielectric permittivity value and shifts the temperature of the "max to higer values. The vanadium admixture decreased the diffusion degree as well as influenced on the parameters characteristic for the relaxor behaviour. Our suggestion is that partial substitution of the smaller vanadium ions into the niobium sites renders for example ordering of the dipoles

Structural, dielectric specroscopy and internal friction correlation in BaBi2NB2O9 ceramics

The research presented in this paper concerns BaBi2Nb 2O9 (BBN) which is the member of the Aurivillius family and seems to be interesting from the point of view of its potential applications in storage media. Our investigations focused on temperature dependence crystal structure and mechanical properties of this ceramics as well as on the dielectric properties of samples. Correlation between positions of the maximum of the real part of electric permittivity and the behavior integral width of diffraction lines XRD versus temperature had been discussed based of the presence of polar nano-regions with orthorhombic distortion in macroscopic tetragonal matrix

Piezoelectric and elastic properties of relaxor-like PZT:Ba ceramics

The solid solutions of PbZr1-xTixO3 (PZT) are the most known and widely applicable piezoelectric ceramic materials. The influence of different dopants on PZT properties has been studied for many years. Some of such compositions have revealed a behavior typical for ferroelectric relaxors. In the case of Pb0.75Ba0.25Zr0.70Ti0.30O3 ceramics (abbreviation PBZT 25/70/30), prepared by mixed-oxide processing technique elastic, it was found that macroscopic piezoelectric activity is present far above the temperature at which structural changes and maximum of permittivity occur in unpoled samples (~ 200 °C). Anomalies of the elastic and piezoelectric properties have been observed very clearly near the temperature of 152 °C. Within the temperature range of 152–220 °C, unstable piezoelectric properties have been detected due to the existence of polar micro/nano-clusters and non-trivial elastic-electric interactions between them, through the non-polar paraelectric matrix. The origin of such interactions could be lattice instabilities, dynamic change in polar cluster sizes, and fluctuations in chemical composition. Based on the results of the research, it can be said that PZT ceramics of such composition is a relaxor-like material and it is not a ferroelectric relaxor

Periostin in exhaled breath condensate and in serum of asthmatic patients : relationship to upper and lower airway disease

PURPOSE: Periostin is considered a biomarker for eosinophilic airway inflammation and have been associated with NSAID-Exacerbated Respiratory Disease (NERD) and chronic rhinosinusitis (CRS). In this study, we aimed to evaluate periostin in exhaled breath condensate (EBC) and in serum of patients with various asthma phenotypes. METHODS: The study included 40 asthmatic patients (22 with NERD) and 17 healthy controls. All the procedures (questionnaire, spirometry, FeNO, nasal swabs, EBC collecting, and blood sampling) were performed on the same day. Periostin concentrations were measured using an ELISA kit. RESULTS: Periostin was detected in EBC from 37 of 40 asthmatics and in 16 from 17 of controls. The concentration of periostin in EBC did not differ between the study groups and was not associated with NERD or asthma severity. However, the EBC periostin was significantly higher in asthmatics with CRS as compared to those without (3.1 vs 2 ng/mL, P=0.046). Patients with positive bacterial culture from nasal swabs had higher EBC periostin concentrations than those without (3.2 vs 2.1 ng/mL; P=0.046). The mean serum periostin level was higher in asthmatics with a 1-year history of exacerbation than in those without (3.2 vs 2.3 ng/mL, P=0.045). Asthmatics with skin manifestation of NSAIDs hypersensitivity had higher serum periostin levels as compared to those without (3.5 vs 2.3 ng/mL; P=0.03). CONCLUSIONS: EBC periostin levels seem to reflect intensity of upper airway disease in asthmatics, while serum levels of periostin are associated with asthma activity (exacerbations or FeNO) or NERD subphenotypes

Investigation of La3+ doping effect on piezoelectric coefficients of BLT ceramics

Effects of La3+ admixture in barium lanthanum titanate (BLT) ceramics system with colossal permittivity on performance of prospective piezoelectric cold plasma application were studied. Usage of cold atmospheric pressure plasma appears promising in terms of industrial and healthcare applications. Performed investigation provide consistent evaluation of doping lanthanum amount on piezoelectric coefficients values with simultaneous capability of charge accumulation for effective plasma generation. Modification of ferroelectric materials with heterovalent ions, however with the lower radii than the original atoms, significantly affects their domain mobility and consequently electromechanical properties. To determine the piezoelectric coefficients, the resonance-antiresonance method was implemented, and values of piezoelectric and dielectric parameters were recorded. Finally the results indicated that addition of 0.4 mol.% of La3+ ions to the ceramic structure maximally increased the values of piezoelectric coefficient to d33 = 20 pC/N and to huge dielectric constant to ϵ33 T = 29277

Magnetoelectric properties of multiferroic Aurivillius type Bi7Fe3Ti3O21 ceramics

Multiferroic Bi7Fe3Ti3O21ceramic materials having six perovskite-like layers were prepared by solid statereaction from simple oxides and sintered at 1263 K. The microstructure and magnetoelectric properties wereinvestigated. Based on dielectric measurements, the valueof magnetoelectric coupling coefficient was figured.The magnetization as a function of temperature and magneticfield at selected temperatures was examined.Additionally, the hysteresis loop at 2 K was measured. The molar concentration of magnetic ions Fe3+in themultiferroic Bi7Fe3Ti3O21compound was also determined