Aurivillius BaBi4Ti4O15 based compounds: Structure, synthesis and properties

The discovery of some Aurivillius materials with high Curie temperature or fatigue-free character suggests possible applications in high temperature piezoelectric devices or non-volatile ferroelectric random access memories. Furthermore, increasing concerns for environmental issues have promoted the study of new lead-free piezoelectric materials. Barium bismuth titanate (BaBi4Ti4O15), an Aurivillius compound, is promising candidate to replace lead-based materials, both as lead-free ferroelectric and high temperature piezoelectric. In this review paper, we report a detailed overview of crystal structure, different synthesis methods and characteristic properties of barium bismuth titanate ferroelectric materials

Barium titanate thick films prepared by screen printing technique

The barium titanate (BaTiO3) thick films were prepared by screen printing technique using powders obtained by soft chemical route, modified Pechini process. Three different barium titanate powders were prepared: i) pure, ii) doped with lanthanum and iii) doped with antimony. Pastes for screen printing were prepared using previously obtained powders. The thick films were deposited onto Al2O3 substrates and fired at 850°C together with electrode material (silver/palladium) in the moving belt furnace in the air atmosphere. Measurements of thickness and roughness of barium titanate thick films were performed. The electrical properties of thick films such as dielectric constant, dielectric losses, Curie temperature, hysteresis loop were reported. The influence of different factors on electrical properties values was analyzed

La-doped and La/Mn-co-doped Barium Titanate Ceramics

Barium titanate ceramics doped with 0.3 mol.% lanthanum and co-doped with 0.3 mol.% lanthanum and 0.05 mol.% manganese were investigated. The powders were prepared by a modified polymeric precursor method based on the Pechini process. The ceramics were obtained by sintering at 1300 degrees C for 8 h. The influence of dopants on structural changes and grain size reduction was analyzed. The presence of dopants influenced the tetragonality of the barium titanate crystal structure. Reduction of polygonal grain size with dopant addition was noticed. In the doped ceramics, characteristic phase transitions were shifted to lower temperatures in comparison with pure barium titanate. The dielectric permittivity value showed the tendency of a slight increase with lanthanum addition and further increase with adding of manganese. La as a single dopant increased the diffuseness of phase transitions indicating the formation of a diffuse ferroelectric material but in the co-doped ceramics the phase transition diffuseness decreased. The resistivity of the co-doped ceramics was higher than for lanthanum doped ceramics, indicating possible segregation of manganese at grain boundaries that influenced the total resistivity of the material

Study of Barium Bismuth Titanate Prepared by Mechanochemical Synthesis

Barium-bismuth titanate, BaBi4Ti4O15 (BBT), a member of Aurivillius bismuth-based layer-structure perovskites, was prepared from stoichiometric amounts of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Mechanochemical synthesis was performed in air atmosphere in a planetary ball mill. The reaction mechanism of BaBi4Ti4O15 and the preparation and characteristics of BBT ceramic powders were studied using XRD, Raman spectroscopy, particle analysis and SEM. The Bi-layered perovskite structure Of BaBi4Ti4O15 ceramic forms at 1100 degrees C for 4 h without a pre-calcination step. The microstructure of BaBi4Ti4O15 exhibits plate-like grains typical for the Bi-layered structured material and spherical and polygonal grains. The Ba2+ addition leads to changes in the microstructure development, particularly in the change of the average grain size

Karakterizacija Morus vrsta u odnosu na mikro, makro i toksične elemente

This study examines the mineral composition of the extracts of the fruits, leaves and roots of white mulberry (Morus alba L.) and black mulberry (Morus nigra L.) grown in Serbia. All extract samples of white and black mulberry were analyzed for the content of micro (B, Co, Cr, Cu, Fe, Li, Mn, Ni, Se, Sr, Zn), macro (Ca, Mg, Na), and toxic metals (Al, As, Cd, Hg, Pb) by inductively coupled plasma optical emission spectrometry (ICP-OES). The study revealed that parts of the plant had statistically significant impact on the levels of the examined elements among the two Morus species. All extracts contained high amounts of Ca, Mg, Na, B, Cu, Fe, Mn and Zn. The studies showed that in the most of extracts dominant macro element was Mg (591- 1942 μg/g of dry extract), while dominant microelements were Zn, B, Cu in all extracts, except for the black mulberry leaves, whose extract was most abundant in Fe (143 μg/g of dry extract). The highest content of micro and macro elements was detected in the extract of black mulberry leaves. This work contributes to the knowledge of the nutritional properties of Morus species. The obtained results may be useful in the evaluation of new dietary and food products.Ispitivanje je bazirano na određivanju mineralnog sastava ekstrakata Morus alba L. (beli dud) i Morus nigra L . (crni dud) uključujući plod, list i koren sa teritorije Srbije. U svim analiziranim ekstraktima određen je sadržaj mikro (B, Co, Cr, Cu, Fe, Li, Mn, Ni, Se, Sr, Zn), makro (Ca, Mg, Na) i toksičnih elemenata (Al, As, Cd, Hg, Pb) primenom optičke emisione spektroskopije sa induktivno kuplovanom plazmom (ICP-OES). Ispitivanje je pokazalo da postoji statistički značajna korelacija između delova biljke Morus vrste i sadržaja ispitivanih elemenata. U svim ekstraktima je dokazan visok sadržaj elemenata: Ca, Mg, Na, B, Cu, Fe, Mn i Zn, respektivno. Dominantan makro element u većem broju ekstrakata je Mg (591 - 1942 μg/g suvog ekstrakta). Što se tiče mikroelemenata, u svim ispitivanim ekstraktima u većem sadržaju su zastupljeni Zn, B i Cu. U uzorku M. nigra posebno se izdvaja Fe po svom sadržaju (143 μg/g suvog ekstrakta) u odnosu na ostale prisutne elemente. Od svih ispitivanih uzoraka najviši sadržaj mikro i makro elemenata je detektovan u ekstraktima lista M. Nigra. Ovaj rad doprinosi poznavanju nutritivnih svojstava Morus vrsta. Dobijeni rezultati mogu biti korisni u kreiranju novih dijetetskih i prehrambenih proizvoda

PZT-NZF/CF ferrite flexible thick films: Structural, dielectric, ferroelectric, and magnetic characterization

The preparation and properties of thick flexible three-phase composite films based on lead zirconium titanate (PZT) and various ferrites (nickel zinc ferrite (NZF) and cobalt ferrite (CF)) were reported in this study. Properties of three-phase composite films were compared with pure polyvinylidene fluoride (PVDF) and PZT-PVDF films. X-ray diffraction data indicated the formation of well crystallized structure of PZT and NZF/CF phases, without the presence of undesirable phases. Scanning electron micrographs showed that the ceramic particles were dispersed homogeneously in the PVDF matrix and atomic force microscopy confirmed that the size of the particles is around 30 nm. Non-saturated hysteresis loops were evident in all samples due to the presence of highly conductive ferrite phases. Under magnetic field of 10 kOe, composite films exhibited a typical ferromagnetic response. Dielectric properties were investigated in the temperature range from -128 to 250 degrees C and frequency range of 400 Hz-1 MHz. The results showed that the value of dielectric constant of the PVDF/PZT/ferrite composites increased about 25% above the one obtained for pure PVDF

Multiferroic BaTaO3–NaFe2 O4 composites: from bulk to multilayer thin films

Over the past decade, magnetoelectric multiferroic materials have been one of the highest priority research topics as they represent new generation of novel multifunctional materials. Multiferroics are characterized by the coexistence of at least two ferroic orders and the presence of ferroelectricity and ferromagnetism, as well as a strong coupling interaction between them (defined as magnetoelectric effect). These properties are essential for new applications in multifunctional devices. This article focuses on various fabrication techniques used for preparation of multiferroic composite ceramics and thin films. The main goals are comparing obtained composite and thin film structures and their properties and acquiring a better understanding of the coupling between magnetic and ferroelectric orders that could surely be very helpful in the design of novel multiferroic materials and hence elucidating their new applications

Ishrana bolesnika sa novodijagnostikovanim rakom pluća

Introduction/Objective Although smoking is the main risk factor for lung cancer (LC), studies have shown that diet could also play an important role. The objective of this study was to analyze dietary intake of newly diagnosed LC patients and to compare with sex- and age-matched healthy controls. Methods Sixty-nine non-treated LC patients (50 male, 19 female, aged 46-80 years), and 70 healthy controls (50 male, 20 female, aged 47-76 years) filled out a validated food frequency questionnaire in the presence of a trained nutritionist. Nutrient intake was calculated using the Serbian Food Composition Database. Results Similar energy intake was reported by both groups. However, the controls had significantly higher intake of total fats, saturated, monounsaturated, and n-3 polyunsaturated fatty acids (PUFAs) and lower intake of carbohydrates and n-6 PUFAs. Patients with LC reported markedly lower intake of milk and dairy products, eggs, seafood, vegetables, and fruits, and higher intake of grains and grain products. Conclusion Patients with LC had significantly different dietary intake of most nutrients compared to healthy participants, suggesting that changes in dietary patterns could contribute to prevention of LC development.Uvod/Cilj Iako je pušenje vodeći faktor rizika za rak pluća (RP), studije pokazuju da i način ishrane igra važnu ulogu. Cilj ove studije je da se analiza ishrana kod bolesnika sa novodijagnostikovanim RP i da se uporedi sa zdravom populacijom istog pola i godina starosti. Metode Šezdeset devet bolesnika sa novootkrivenim RP (50 muškaraca, 19 žena, starosti 46-80 godina) i 70 zdravih ispitanika (50 muškaraca, 20 žena, starosti 47-76 godina) popunilo je u prisustvu lekara upitnik o učestalosti kon- zumiranja namirnica. Nutritivni unos je računat pomoću Srpske baze podataka o sastavu namirnica. Rezultati Obe grupe su imale sličan unos energije, ali je u kontrolnoj grupi zabeležen veći unos masti, zasićenih, mononezasićenih i n-3 polinezasićenih masnih kiselina (PNMK), a niži unos ugljenih hidrata i n-6 PNMK. Grupa bolesnika je imala značajno niži unos mleka i mlečnih proizvoda, jaja, morskih plodova, voća i povrća, a veći unos žitarica i proizvoda od brašna. Zaključak Bolesnici sa RP imali su značajno drugačiji način ishrane od zdravih ispitanika, što sugeriše da promene u načinu ishrane mogu da doprinesu prevenciji nastanka kancera pluća

Magneto-dielectric properties of ferrites and ferrite/ferroelectric multiferroic composites

Ni-Zn ferrites, with the general formula Ni1-xZnxFe2O4 (x = 0.0, 0.3, 0.5, 0.7, 1.0), CoFe2O4, BaTiO3 and PbZr0.52Ti0.48O3 powders were synthesized by auto-combustion method. The composites were prepared by mixing the appropriate amounts of individual phases, pressing and conventional sintering. X-ray analysis, for individual phase and composites, indicated the formation of crystallized structure of NiZnFe2O4, BaTiO3 and PbZr0.52Ti0.48O3 without the presence of secondary phases or any impurities. SEM analyses indicated a formation of uniform grain distribution for ferromagnetic and ferroelectric phases and formation of two types of grains, polygonal and rounded, respectively. Magneto-dielectric effect was exhibited in all samples because of the applied stress occurring due to the piezomagnetic effect and the magnetic field induced the variation of the dielectric constant. For all samples the dielectric constant was higher in applied magnetic field. At the low frequency, the dispersion of dielectric losses appeared, while at the higher frequency the value of tan δ become constant (Maxwell-Wagner relaxation). Investigation of J-E relation between leakage and electric field revealed that both nickel zinc ferrite and composites have three different regions of conduction: region with ohmic conduction mechanism, region with the trap-controlled space charge limited current mechanism and region with space charge limited current mechanism