Humidity sensing ceria thin-films

Lowering the constitutive domains of semiconducting oxides to the nano-range has recently opened up the possibility of added benefit in the research area of sensing materials, in terms both of greater specific surface area and pore volume. Among such nanomaterials, ceria has attracted much attention ; therefore, we chemically derived homogeneous ceria nanoparticle slurries. One set of samples was tape-casted onto a conducting glass substrate to form thin-films of various thicknesses, thereby avoiding demanding reaction conditions typical of physical depositions, while the other was pressed into pellets. Structural and microstructural features, along with electrical properties and derivative humidity-sensing performance of ceria thin-films and powders pressed into pellets, were studied in detail. Particular attention was given to solid- state impedance spectroscopy (SS-IS), under controlled relative humidity (RH) from 30%– 85%, in a wide temperature and frequency range. Moreover, for the thin-film setup, measurements were performed in surface-mode and cross-section- mode. From the results, we extrapolated the influence of composition on relative humidity, the role of configuration and thin-film thickness on electrical properties, and derivative humidity- sensing performance. The structural analysis and depth profiling both point to monophasic crystalline ceria. Microstructure analysis reveals slightly agglomerated spherical particles and thin-films with low surface roughness. Under controlled humidity, the shape of the conductivity spectrum stays the same along with an increase in RH, and a notable shift to higher conductivity values. The relaxation is slow, as the thickness of the pellet slows the return of conductivity values. The increase in humidity has a positive effect on the overall DC conductivity, similar to the temperature effect for semiconducting behavior. As for the surface measurement setup, the thin-film thickness impacts the shape of the spectra and electrical processes. The surface measurement setup turns out to be more sensitive to relative humidity changes, emphasized with higher RH, along with an increase in thin-film thickness. The moisture directly affects the conductivity spectra in the dispersion part, i.e., on the localized short-range charge carriers. Moisture sensitivity is a reversible process for thin-film samples, in contrast to pellet form samples

Synthesis of mesoporous Zr-doped CeO2 via hard template method

S porastom potrebe za djelotvornim i oporabljivim rješenjima za uspješno vođenje različitih kemijskih reakcija znanstveno-istraživački radovi usmjereni su ka pronalasku djelotvornih i ekološki prihvatljivih katalizatora, nosača djelatnih tvari, adsorbensa za vlagu i stakleničke plinove. U ovome je radu opisana sinteza i karakterizacija jednog takvog potencijalnog katalizatora: cerijeva(IV) oksida dopiranog cirkonijem. Uzorci su pripremljeni metodom nanolijevanja pomoću krutog predloška na mezoporoznoj siliki, čija je sinteza također sastavni dio ovoga rada. Nanostrukturirani materijali, naročito porozni keramički materijali, pokazuju se kao izvrsni adsorbensi, katalizatori te nosači djelatnih tvari u farmaceuticima zbog svoje iznimno velike specifične površine, što utječe na visok broj aktivnih mjesta na površini tih materijala. Pripravljeni su uzorci okarakterizirani raznim karakterizacijskim tehnikama te su u ovome radu izneseni rezultati ispitivanja i prokomentirana svojstva mezoporoznih nanostrukturiranih keramičkih materijala.Following the rising need for efficient and recyclable solutions for the successful management of a variety of chemical reactions scientific efforts are directed towards finding efficient and ecologically acceptable catalysts, carriers of active substances, humidity and greenhouse gas adsorbents. The synthesis and characterization of one such potential catalyst is described in this paper: zirconium doped cerium(IV) oxide. The samples have been prepared using the method of nanocasting with formerly synthesised mesoporous silica serving as a hard template. Nanostructured materials, especially porous ceramics, have shown themselves to be excellent adsorbents, catalysts and active substance carriers in pharmaceutics because of their significantly large specific surface area, which results in a vast number of active points on the surface of these materials. Synthesised samples have been characterized by various characterization techniques and the results of them, as well as the properties of mesoporous nanostructured ceramics are described in this paper

Electrochemical methods for investigation of biomedical metallic implant materials

Po ugradnji biomedicinskih metalnih implantnih materijala u agresivni biookoliš ljudskog tijela može doći do degradacije (korozije) materijala, stoga je od izuzetne važnosti ispitati njihovu korozijsku otpornost. U istraživanju metalnih implantnih materijala primjenjuju se elektrokemijske metode budući da su procesi korozije implantata u agresivnom biookolišu tkivnih tekućina elektrokemijske prirode. U radu je ispitivan implantni materijal titanij kao jedan od najčešće korištenih metalnih implantnih materijala, posebice za primjenu u dentalnoj medicini i ortopediji zbog njegove stabilnosti, dobrih fizikalnih i kemijskih svojstava. No uz dobru korozijsku otpornost prema agresivnim tekućinama u ljudskom tijelu i dobru biokompatibilnost temeljenu na formiranju oksidnog sloja, titanij pokazuje slaba svojstva bioaktivnosti. Stoga je u ovome radu ispitana modifikacija površine titanija slojem kalcijeva fosfata, CaP, koji je pripremljen elektrodepozicijom. Nemodificirani i modificirani uzorci titanija karakterizirani su koristeći elektrokemijske tehnike (ciklička voltametrija (CV), linearna polarizacija (LP) i elektrokemijska impedancijska spektroskopija (EIS)) i mikroskopsku analizu. Ispitivanja korozijskog ponašanja titanija provedena su u simuliranoj fiziološkoj otopini, Hanksovoj otopini, pH = 7,15.After the implantation of biomedical metallic implant materials into the aggressive bio-environment of the human body, degradation (corrosion) of the material can occur, so it is extremely important to examine their corrosion resistance. Electrochemical methods are used in the research of metal implant materials, since the processes of implant corrosion in the aggressive bio-environment of tissue fluids are of electrochemical nature. This work examines the implant material titanium as one of the most commonly used metal implant materials, especially for use in dentistry and orthopaedics due to its stability, good physical and chemical properties. Although possessing good corrosion resistance to aggressive liquids in the human body and good biocompatibility based on the spontanious formation of the oxide film, titanium shows poor bioactivity properties. Therefore, the modification of the titanium surface by a layer of calcium phosphate, CaP, prepaired by electrodeposition, was investigated in this work. Unmodified and modified titanium samples were characterized using electrochemical techniques (cyclic voltammetry (CV), linear polarization (LP) and electrochemical impedance spectroscopy (EIS)) and microscopic analysis. Corrosion behavior tests of titanium were preformed in simulated body fluid, Hanks' solution, pH = 7,15

Synthesis of mesoporous Zr-doped CeO2 via hard template method

S porastom potrebe za djelotvornim i oporabljivim rješenjima za uspješno vođenje različitih kemijskih reakcija znanstveno-istraživački radovi usmjereni su ka pronalasku djelotvornih i ekološki prihvatljivih katalizatora, nosača djelatnih tvari, adsorbensa za vlagu i stakleničke plinove. U ovome je radu opisana sinteza i karakterizacija jednog takvog potencijalnog katalizatora: cerijeva(IV) oksida dopiranog cirkonijem. Uzorci su pripremljeni metodom nanolijevanja pomoću krutog predloška na mezoporoznoj siliki, čija je sinteza također sastavni dio ovoga rada. Nanostrukturirani materijali, naročito porozni keramički materijali, pokazuju se kao izvrsni adsorbensi, katalizatori te nosači djelatnih tvari u farmaceuticima zbog svoje iznimno velike specifične površine, što utječe na visok broj aktivnih mjesta na površini tih materijala. Pripravljeni su uzorci okarakterizirani raznim karakterizacijskim tehnikama te su u ovome radu izneseni rezultati ispitivanja i prokomentirana svojstva mezoporoznih nanostrukturiranih keramičkih materijala.Following the rising need for efficient and recyclable solutions for the successful management of a variety of chemical reactions scientific efforts are directed towards finding efficient and ecologically acceptable catalysts, carriers of active substances, humidity and greenhouse gas adsorbents. The synthesis and characterization of one such potential catalyst is described in this paper: zirconium doped cerium(IV) oxide. The samples have been prepared using the method of nanocasting with formerly synthesised mesoporous silica serving as a hard template. Nanostructured materials, especially porous ceramics, have shown themselves to be excellent adsorbents, catalysts and active substance carriers in pharmaceutics because of their significantly large specific surface area, which results in a vast number of active points on the surface of these materials. Synthesised samples have been characterized by various characterization techniques and the results of them, as well as the properties of mesoporous nanostructured ceramics are described in this paper

Synthesis of mesoporous Zr-doped CeO2 via hard template method

S porastom potrebe za djelotvornim i oporabljivim rješenjima za uspješno vođenje različitih kemijskih reakcija znanstveno-istraživački radovi usmjereni su ka pronalasku djelotvornih i ekološki prihvatljivih katalizatora, nosača djelatnih tvari, adsorbensa za vlagu i stakleničke plinove. U ovome je radu opisana sinteza i karakterizacija jednog takvog potencijalnog katalizatora: cerijeva(IV) oksida dopiranog cirkonijem. Uzorci su pripremljeni metodom nanolijevanja pomoću krutog predloška na mezoporoznoj siliki, čija je sinteza također sastavni dio ovoga rada. Nanostrukturirani materijali, naročito porozni keramički materijali, pokazuju se kao izvrsni adsorbensi, katalizatori te nosači djelatnih tvari u farmaceuticima zbog svoje iznimno velike specifične površine, što utječe na visok broj aktivnih mjesta na površini tih materijala. Pripravljeni su uzorci okarakterizirani raznim karakterizacijskim tehnikama te su u ovome radu izneseni rezultati ispitivanja i prokomentirana svojstva mezoporoznih nanostrukturiranih keramičkih materijala.Following the rising need for efficient and recyclable solutions for the successful management of a variety of chemical reactions scientific efforts are directed towards finding efficient and ecologically acceptable catalysts, carriers of active substances, humidity and greenhouse gas adsorbents. The synthesis and characterization of one such potential catalyst is described in this paper: zirconium doped cerium(IV) oxide. The samples have been prepared using the method of nanocasting with formerly synthesised mesoporous silica serving as a hard template. Nanostructured materials, especially porous ceramics, have shown themselves to be excellent adsorbents, catalysts and active substance carriers in pharmaceutics because of their significantly large specific surface area, which results in a vast number of active points on the surface of these materials. Synthesised samples have been characterized by various characterization techniques and the results of them, as well as the properties of mesoporous nanostructured ceramics are described in this paper

Electrochemical methods for investigation of biomedical metallic implant materials

Po ugradnji biomedicinskih metalnih implantnih materijala u agresivni biookoliš ljudskog tijela može doći do degradacije (korozije) materijala, stoga je od izuzetne važnosti ispitati njihovu korozijsku otpornost. U istraživanju metalnih implantnih materijala primjenjuju se elektrokemijske metode budući da su procesi korozije implantata u agresivnom biookolišu tkivnih tekućina elektrokemijske prirode. U radu je ispitivan implantni materijal titanij kao jedan od najčešće korištenih metalnih implantnih materijala, posebice za primjenu u dentalnoj medicini i ortopediji zbog njegove stabilnosti, dobrih fizikalnih i kemijskih svojstava. No uz dobru korozijsku otpornost prema agresivnim tekućinama u ljudskom tijelu i dobru biokompatibilnost temeljenu na formiranju oksidnog sloja, titanij pokazuje slaba svojstva bioaktivnosti. Stoga je u ovome radu ispitana modifikacija površine titanija slojem kalcijeva fosfata, CaP, koji je pripremljen elektrodepozicijom. Nemodificirani i modificirani uzorci titanija karakterizirani su koristeći elektrokemijske tehnike (ciklička voltametrija (CV), linearna polarizacija (LP) i elektrokemijska impedancijska spektroskopija (EIS)) i mikroskopsku analizu. Ispitivanja korozijskog ponašanja titanija provedena su u simuliranoj fiziološkoj otopini, Hanksovoj otopini, pH = 7,15.After the implantation of biomedical metallic implant materials into the aggressive bio-environment of the human body, degradation (corrosion) of the material can occur, so it is extremely important to examine their corrosion resistance. Electrochemical methods are used in the research of metal implant materials, since the processes of implant corrosion in the aggressive bio-environment of tissue fluids are of electrochemical nature. This work examines the implant material titanium as one of the most commonly used metal implant materials, especially for use in dentistry and orthopaedics due to its stability, good physical and chemical properties. Although possessing good corrosion resistance to aggressive liquids in the human body and good biocompatibility based on the spontanious formation of the oxide film, titanium shows poor bioactivity properties. Therefore, the modification of the titanium surface by a layer of calcium phosphate, CaP, prepaired by electrodeposition, was investigated in this work. Unmodified and modified titanium samples were characterized using electrochemical techniques (cyclic voltammetry (CV), linear polarization (LP) and electrochemical impedance spectroscopy (EIS)) and microscopic analysis. Corrosion behavior tests of titanium were preformed in simulated body fluid, Hanks' solution, pH = 7,15

Electrochemical methods for investigation of biomedical metallic implant materials

Po ugradnji biomedicinskih metalnih implantnih materijala u agresivni biookoliš ljudskog tijela može doći do degradacije (korozije) materijala, stoga je od izuzetne važnosti ispitati njihovu korozijsku otpornost. U istraživanju metalnih implantnih materijala primjenjuju se elektrokemijske metode budući da su procesi korozije implantata u agresivnom biookolišu tkivnih tekućina elektrokemijske prirode. U radu je ispitivan implantni materijal titanij kao jedan od najčešće korištenih metalnih implantnih materijala, posebice za primjenu u dentalnoj medicini i ortopediji zbog njegove stabilnosti, dobrih fizikalnih i kemijskih svojstava. No uz dobru korozijsku otpornost prema agresivnim tekućinama u ljudskom tijelu i dobru biokompatibilnost temeljenu na formiranju oksidnog sloja, titanij pokazuje slaba svojstva bioaktivnosti. Stoga je u ovome radu ispitana modifikacija površine titanija slojem kalcijeva fosfata, CaP, koji je pripremljen elektrodepozicijom. Nemodificirani i modificirani uzorci titanija karakterizirani su koristeći elektrokemijske tehnike (ciklička voltametrija (CV), linearna polarizacija (LP) i elektrokemijska impedancijska spektroskopija (EIS)) i mikroskopsku analizu. Ispitivanja korozijskog ponašanja titanija provedena su u simuliranoj fiziološkoj otopini, Hanksovoj otopini, pH = 7,15.After the implantation of biomedical metallic implant materials into the aggressive bio-environment of the human body, degradation (corrosion) of the material can occur, so it is extremely important to examine their corrosion resistance. Electrochemical methods are used in the research of metal implant materials, since the processes of implant corrosion in the aggressive bio-environment of tissue fluids are of electrochemical nature. This work examines the implant material titanium as one of the most commonly used metal implant materials, especially for use in dentistry and orthopaedics due to its stability, good physical and chemical properties. Although possessing good corrosion resistance to aggressive liquids in the human body and good biocompatibility based on the spontanious formation of the oxide film, titanium shows poor bioactivity properties. Therefore, the modification of the titanium surface by a layer of calcium phosphate, CaP, prepaired by electrodeposition, was investigated in this work. Unmodified and modified titanium samples were characterized using electrochemical techniques (cyclic voltammetry (CV), linear polarization (LP) and electrochemical impedance spectroscopy (EIS)) and microscopic analysis. Corrosion behavior tests of titanium were preformed in simulated body fluid, Hanks' solution, pH = 7,15