Structural Properties of CaCu3Ti3RuO12

Due to a very large dielectric permittivity (≥ 105), thermal stability over a wide temperature range (from 100 to 400 K) and frequency independence in the frequency range of 1 kHz–1 MHz, calcium coper titanate (CaCu3Ti4O12, CCTO) ceramics have been recognized as promising materials for applications in microelectronics industry and microwave devices [1–5]. Although a high permittivity value of CCTO-based materials allows fabrication of capacitors with improved capacitive performance for portable electronics devices, the nature of ceramics-metal electrode interface can deteriorate dielectric properties. Actually, significant differences in the crystal structure and electrical properties of the CaCu3Ti4O12 as a dielectric material and a metallic electrode, can cause an energy barrier and the occurrence of stress on the ceramic-electrode interface which reduce the dielectric permittivity. Therefore, to avoid occurrence of an energy barrier and stress on the ceramic electrode interface it is necessary to use dielectric ceramic and electrode with similar both crystal structure and unit cell parameters. The reduction of the stress on the ceramic-electrode interface can be achieved by using commercially available materials as an interlayer having lattice parameters match with both dielectric and electrode. It was noticed that incorporation of Ru4+ ions into the CCTO crystal structure significantly increases conductivity of these materials. It has been shown that CaCu3Ru4O12 (CCRO) material is isostructural with CaCu3Ti4O12 material, it has cubic ������3 space group and shows metallic character [6]. Thus, since CCTO and CCRO have the same crystal structure and similar unit cell parameters, with CCRO layer as an interface between ceramic and electrode it can be possible to overcome problem of an energy barrier on the ceramic-electrode interface

CaCu3Ti4-xRuxO12: Crystal structure, electrical and magnetic properties

The CaCu3Ti4O12 belongs to the large ACu3B4O12 family of materials. Crystallographic A site is most often occupied by alkaline-earth metals or lanthanides, while B site is occupied by transition metals. The type of cations that build up the structure strongly affects the properties of these. The CaCu3Ti4O12 has been extensively studied due to its high dielectric permittivity stable over a wide temperature and frequency range (up to 105, for 100-600 K and 102–105 Hz). Because of such characteristics, it has promising application in microelectronics. However, it has been shown that differences in the crystal structure and electrical properties of dielectric ceramics and metallic electrodes, may cause an energy barrier and occurrence of stress on the ceramic-electrode contact which reduces dielectric permittivity. Such stress can be prevented by using dielectric and electrode materials with as much as possible similar crystal structure, especially unit cell parameters. This investigation dealt with detailed structural (XRPD, HRTEM, SAED), dielectric and magnetic study of CaCu3Ti4-xRuxO12 (CCTRO, x = 0, 1 and 4) materials. The results of structural refinement show that in cubic symmetry with space group Im3 , both titanium and ruthenium ions occupied crystallographic B site. Moreover, the variation in stoichiometry slightly affects the value of the unit cell parameters but changes electrical properties of studied material. Thus, substitution of even one atom of Ru in CaCu3Ti4-xRuxO12 unit cell is enough to change material properties from dielectric to conductor solving the problem of stress appearance on the contact layer of dielectric/electrode in capacitors

Simultaneous thermal analysis and dilatometric study of HAp-LiFePO4 system

Sintered hydroxyapatite bioceramics have been widely studied as a potential material for bone tissue reparation, however, concerning its microstructural and mechanical properties some limits were achieved at the moment. Addition of other materials that could improve functionalities, while preserving inherent advantages of this bioactive ceramics is desirable strategy. In this work, a new idea of addition of lithium iron phosphate as hydroxyapatite sintering aid, provoking liquid phase sintering in the intermediate sintering phase, has been evaluated from the point of view of thermal and dilatometric studies in inert atmosphere, with coupled mass spectroscopy monitoring. Detailed characterization of prepared materials and sintered products is given, confirming the proof of concept. Sintering ability was significantly enhanced and important microstructural features were obtained

Surface modification of titanium implants by adherent hydroxyapatite/titanium oxide composite coatings using novel in-situ synthesis

The medical devices based on titanium and its alloys are widely used in the repair and replacement of a degraded or inhibited func-tion of locomotor system [1]. Ti and its alloys exhibit high mechanical strength, good workability, resistant to corrosion and low cost. Although, they are widely used as orthopedic and dental implants their inability to interact with living tissue will inhibit their biological fixation and osseoin-tegration [2]. Therefore, to improve the hard-tissue compatibility of Ti various sur-face treatments have been developed for the inorganic coating formation [3]. The hyd-roxyapatite (HAp, Ca10(PO4)6(OH)2) with superior osteogenic activity is a competitive approach to make novel coatings for titanium implants applications. HAp is a calcium phosphate very similar to the inorganic part of the human bone and hard tissues both in morphology and compo-sition. Herein, in-situ synthesis of HAp/TiO2 coating on titanium was performed via ana-phoretic deposition of HAp and simulta-neous anodization of Ti to produce highly adherent and strengthened composite coating. It can be seen that morphology of Ti substrate of anHAP/TiO2 coating is of tubular shape, and tube formation occurs mainly due to competing processes of anodization and electrophoretic deposition of HAp. anHAp/TiO2 coating does not need sintering process, and simultaneous Ti anodization and HAp deposition occur, where HAp crystals incorporate in the anodized Ti surface. From the presented results it can be concluded that novel suggested process of in situ simultaneous anHAp/TiO2 deposition with Ti surface anodization gives much better results that cathaphoretic deposition regarding adhesion

Novel in-situ synthesis of hydroxyapatite/titanium oxide composite coatings on titanium by simultaneous anodization/anaphoretic electrodeposition

In-situ synthesis of HAp/TiO2 coating on titanium was performed via anaphoretic deposition of HAp and simultaneous anodization of Ti to produce highly adherent and strengthened composite coating. The prepared coatings were characterized by field emission scanning electron microscopy, X-ray diffraction and electron dispersive spectroscopy. HAp on anodized titanium was prepared at constant voltage of 60 V and deposition time of 45 s, which provided uniform and adherent HAp/TiO2 composite coating on Ti. Since smaller size of HAp crystals within highly porous coating structures is of improved binding ability to various biomolecules, our coating is expected to be of excellent coverage and compactness. The obtained coating can be good candidate for bone implants due to reduced brittleness and improved adhesion

Surface modification of titanium implants by adherent hydroxyapatite/titanium oxide composite coatings using novel in-situ synthesis

The medical devices based on titanium and its alloys are widely used in the repair and replacement of a degraded or inhibited func-tion of locomotor system [1]. Ti and its alloys exhibit high mechanical strength, good workability, resistant to corrosion and low cost. Although, they are widely used as orthopedic and dental implants their inability to interact with living tissue will inhibit their biological fixation and osseoin-tegration [2]. Therefore, to improve the hard-tissue compatibility of Ti various sur-face treatments have been developed for the inorganic coating formation [3]. The hyd-roxyapatite (HAp, Ca10(PO4)6(OH)2) with superior osteogenic activity is a competitive approach to make novel coatings for titanium implants applications. HAp is a calcium phosphate very similar to the inorganic part of the human bone and hard tissues both in morphology and compo-sition. Herein, in-situ synthesis of HAp/TiO2 coating on titanium was performed via ana-phoretic deposition of HAp and simulta-neous anodization of Ti to produce highly adherent and strengthened composite coating. It can be seen that morphology of Ti substrate of anHAP/TiO2 coating is of tubular shape, and tube formation occurs mainly due to competing processes of anodization and electrophoretic deposition of HAp. anHAp/TiO2 coating does not need sintering process, and simultaneous Ti anodization and HAp deposition occur, where HAp crystals incorporate in the anodized Ti surface. From the presented results it can be concluded that novel suggested process of in situ simultaneous anHAp/TiO2 deposition with Ti surface anodization gives much better results that cathaphoretic deposition regarding adhesion

Novel in-situ synthesis of hydroxyapatite/titanium oxide composite coatings on titanium by simultaneous anodization/anaphoretic electrodeposition

In-situ synthesis of HAp/TiO2 coating on titanium was performed via anaphoretic deposition of HAp and simultaneous anodization of Ti to produce highly adherent and strengthened composite coating. The prepared coatings were characterized by field emission scanning electron microscopy, X-ray diffraction and electron dispersive spectroscopy. HAp on anodized titanium was prepared at constant voltage of 60 V and deposition time of 45 s, which provided uniform and adherent HAp/TiO2 composite coating on Ti. Since smaller size of HAp crystals within highly porous coating structures is of improved binding ability to various biomolecules, our coating is expected to be of excellent coverage and compactness. The obtained coating can be good candidate for bone implants due to reduced brittleness and improved adhesion

Tailoring morphology and particle size of ZnO powders

U ovom tekstu objašnjeni su postupci sinteze prahova ZnO i mogućnosti da se tim sintezama morfologija i srednja veličina čestica kreiraju od mikrometarskih štapića do nanometarskih sfernih čestica. Primenjene su dve metode sinteze, niskotemperatursko hidrotermalno (HT) procesiranje i ultrazvučno (UZ) procesiranje. Morfologija i srednja veličina čestica su kreirane podešavanjem molskog odnosa [Zn2+]/[OH-] polaznog (prekurskorskog) rastvora. Aglomeracija čestica je sprečena upotrebom polivinil pirolidona (PVP). Sintetisani prahovi su karakterisani metodom rendgenske difrakcije na prahu (XRD), skanirajuće elektronske mikroskopije (FESEM) i UV-Vis difuzione refleksione spektroskopije (UV-Vis DRS). Na osnovu skanirajućih elektronskih mikrografija predložen je mehanizam rasta čestica ZnO u zavisnosti od molskog odnosa [Zn2+]/[OH-] polaznog rastvora. Takođe, ispitan je i uticaj veličine i morfologije čestica na optičke karakteristike prahova ZnO; uočeno je da veličina i morfologija čestica utiču kako na apsorpciju vidljive svetlosti (%) tako i na pomeraj energetskog procepa (eV).Different ZnO powders synthesis methods as well as possibilities to obtain particles with controlled morphology and average particle size from micro- to nano-level were discussed. Two synthesis methods were applied, low-temperature hydrothermal (HT) and ultrasound processing (UZ). Morphology and average particle size were tailored by adjusting of initial solution [Zn2+]/[OH-]molar ratio. Particles agglomeration is suppressed by polyvinylpyrrolidone (PVP). Synthesized powders were characterized by X-ray diffraction method (XRD), field emission scanning electron microscopy (FESEM) and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). Considering FESEM micrographs the ZnO particles growth mechanism depending on initial solution [Zn2+]/[OH-] molar ratio is proposed. Furthermore, influence of average particle size and morphology on ZnO optical properties is studied; it is observed that both average particle size and morphology affect visible light absorption (%) as well as shift of Ebg (eV)

Tailoring morphology and particle size of ZnO powders

U ovom tekstu objašnjeni su postupci sinteze prahova ZnO i mogućnosti da se tim sintezama morfologija i srednja veličina čestica kreiraju od mikrometarskih štapića do nanometarskih sfernih čestica. Primenjene su dve metode sinteze, niskotemperatursko hidrotermalno (HT) procesiranje i ultrazvučno (UZ) procesiranje. Morfologija i srednja veličina čestica su kreirane podešavanjem molskog odnosa [Zn2+]/[OH-] polaznog (prekurskorskog) rastvora. Aglomeracija čestica je sprečena upotrebom polivinil pirolidona (PVP). Sintetisani prahovi su karakterisani metodom rendgenske difrakcije na prahu (XRD), skanirajuće elektronske mikroskopije (FESEM) i UV-Vis difuzione refleksione spektroskopije (UV-Vis DRS). Na osnovu skanirajućih elektronskih mikrografija predložen je mehanizam rasta čestica ZnO u zavisnosti od molskog odnosa [Zn2+]/[OH-] polaznog rastvora. Takođe, ispitan je i uticaj veličine i morfologije čestica na optičke karakteristike prahova ZnO; uočeno je da veličina i morfologija čestica utiču kako na apsorpciju vidljive svetlosti (%) tako i na pomeraj energetskog procepa (eV).Different ZnO powders synthesis methods as well as possibilities to obtain particles with controlled morphology and average particle size from micro- to nano-level were discussed. Two synthesis methods were applied, low-temperature hydrothermal (HT) and ultrasound processing (UZ). Morphology and average particle size were tailored by adjusting of initial solution [Zn2+]/[OH-]molar ratio. Particles agglomeration is suppressed by polyvinylpyrrolidone (PVP). Synthesized powders were characterized by X-ray diffraction method (XRD), field emission scanning electron microscopy (FESEM) and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). Considering FESEM micrographs the ZnO particles growth mechanism depending on initial solution [Zn2+]/[OH-] molar ratio is proposed. Furthermore, influence of average particle size and morphology on ZnO optical properties is studied; it is observed that both average particle size and morphology affect visible light absorption (%) as well as shift of Ebg (eV)

Surface modification of titanium implants by adherent hydroxyapatite/titanium oxide composite coatings using novel in-situ synthesis

The medical devices based on titanium and its alloys are widely used in the repair and replacement of a degraded or inhibited func-tion of locomotor system [1]. Ti and its alloys exhibit high mechanical strength, good workability, resistant to corrosion and low cost. Although, they are widely used as orthopedic and dental implants their inability to interact with living tissue will inhibit their biological fixation and osseoin-tegration [2]. Therefore, to improve the hard-tissue compatibility of Ti various sur-face treatments have been developed for the inorganic coating formation [3]. The hyd-roxyapatite (HAp, Ca10(PO4)6(OH)2) with superior osteogenic activity is a competitive approach to make novel coatings for titanium implants applications. HAp is a calcium phosphate very similar to the inorganic part of the human bone and hard tissues both in morphology and compo-sition. Herein, in-situ synthesis of HAp/TiO2 coating on titanium was performed via ana-phoretic deposition of HAp and simulta-neous anodization of Ti to produce highly adherent and strengthened composite coating. It can be seen that morphology of Ti substrate of anHAP/TiO2 coating is of tubular shape, and tube formation occurs mainly due to competing processes of anodization and electrophoretic deposition of HAp. anHAp/TiO2 coating does not need sintering process, and simultaneous Ti anodization and HAp deposition occur, where HAp crystals incorporate in the anodized Ti surface. From the presented results it can be concluded that novel suggested process of in situ simultaneous anHAp/TiO2 deposition with Ti surface anodization gives much better results that cathaphoretic deposition regarding adhesion