TiO2 SiO2 Research Articles

The novel incorporation of lignin-based systems for the preparation of antimicrobial cement composites

This paper, for the first time, presents a potential application of titanium(IV) oxide and silicon(IV) oxide combined with lignin through a solvent-free mechanical process as admixtures for cement composites. The designed TiO2–SiO2 (1:1 wt./wt.) hybrid materials mixed with lignin were extensively characterized using Fourier transform infrared spectroscopy (FTIR), electrokinetic potential analysis, thermal analysis (TGA/DTG), and porous structure properties. In addition, particle size distributions and scanning electron microscopy (SEM) were conducted to evaluate morphological and microstructural properties. In the next step, the effect of the TiO2–SiO2/lignin hybrid admixture on the workability, hydration process, microstructure, porosity, mechanical, and antimicrobial properties of the cement composites was evaluated. It was observed that appropriately designed hybrid systems based on lignin contributed to better workability, with an improvement of 25 mm, and reduced porosity of cement composites, decreasing from 14.4 % to 13.3 % in the most favorable sample. Additionally, a higher microstructure density was observed, and with increasing amounts of hybrid material admixture, the mechanical parameters also improved. In addition, the TiO2–SiO2/lignin hybrid systems had significant potential due to their high microbial purity, suggesting their effectiveness in minimizing microbial accumulation on surfaces. The final stage of analysis involved employing response surface methodology (RSM) to ascertain the optimum composition of cement composites. The results obtained indicate that the TiO2–SiO2/lignin admixtures are a promising approach for the valorization of lignin waste flows in the design of cement composites.

Facile and efficient superhydrophobic film for radiative daytime cooling

Abstract Facile and efficient radiative daytime cooling technology is still a huge challenge. In this paper, we proposed an eco-friendly, facile, efficient superhydrophobic radiative daytime cooling film composed of polydimethylsiloxane, nano TiO2, and nano SiO2. This radiative daytime cooling film could have about 15°C cooling of Al sheet, 9°C cooling for the building model on a sunny summer day, and 8°C cooling for the building model on a cloudy summer day, respectively. This method is promising to be used in building cooling fields.

New Thermodynamic Models for Anhydrous Alkaline-Silicate Magmatic Systems

Abstract A new thermodynamic model for silicate melt in the Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–TiO2–Fe2O3–Cr2O3 model system is presented, building on the tholeiitic through to granitic melt model of Holland et al. (2018) [Journal of Petrology, 59, 881–900] but extending for the first time into anhydrous alkaline systems. The new melt model is accompanied by new thermodynamic models for nepheline, kalsilite, leucite, melilite and ilmenite. Collectively these models enable pseudosection modelling of alkaline-silicate magmatic systems, providing a new tool for investigating this geologically- and economically-important compositional space. The models are calibrated with respect to experimental data on phase relations among minerals and melt, and the fit is benchmarked here via detailed comparison with seven experimental datasets, which encompass a range of pressure (0–22 kbar), temperature (680–1350°C), oxygen fugacity (log fO2 ΔFMQ-3 to +1), total alkali (3–16 wt %) and silica (37–70 wt %) conditions. The calculated pseudosections successfully reproduce experimental crystallisation sequences and phase compositions, indicating that the thermodynamic models are well calibrated across this spectrum of conditions. Redox buffered experimental conditions are simulated using oxygen buffered pseudosections. Contouring of oxygen buffered pseudosections with XFe3+ (mol. Fe3+/Fetotal), or pseudosections of varying XFe3+ with ΔFMQ, reveals (i) often complex and non-intuitive relationships between these two representations of oxidation state, and (ii) substantial variation in ferric iron over narrow temperature intervals in some oxygen buffered sets of experiments. An implication is that simulating oxygen buffering is vital when benchmarking thermodynamic models using experimental results. Furthermore, because natural igneous systems likely feature a near-constant XFe3+, it is important to assess experimental results in this framework when making inferences about natural systems, recognising that oxygen fugacity is a consequence not a control of phase equilibria in nature. Overall, our new models provide a novel tool to explore the role of variables, such as pressure, fractional crystallisation and crustal assimilation in the petrogenesis of alkaline-silicate magmatic systems and their associated mineralisation.

A green UV-resistant Natural rubber-Polydopamine-TiO2@SiO2 composite with high mechanical properties based on an electrostatic adsorption effect

Abstract Antioxidants are usually added into the natural rubber (NR) to resist the oxidation caused by the ultraviolet (UV) irradiation, while commonly used antioxidans are usually organic and prone to decomposition and migration. The inorganic UV absorbers like titanium dioxide nanoparticles (TiO2) and silicon dioxide (SiO2) can maintain chemical stability under UV radiation, while the hydroxyl radicals from electron-hole pairs in TiO2 would damage NR matrix and the poor compatibility of TiO2 with NR limited the process. Therefore, inert SiO2 is coated on TiO2 (TiO2@SiO2) to reduce its photocatalytic activity, and polydopamine (PDA) is coated on rubber to improve stability. The strong light-absorbing properties of PDA could also improve the UV-resistant ability of NR. Besides, poly (sodium-p-styrenesulfonate) (PSS) coating NR-PDA provides the matrix negative charge, and polydiallyl dimethyl ammonium chloride (PDDA) wrapped around TiO2@SiO2 can give a positive charge, thus moderating the compatibility between the filler and the matrix through electrostatic adsorption. The green UV-resistant natural composite NR-PDA TiO2@SiO2 was fabricated. The composites exhibited strong tensile strength and excellent UV-resistant properties, which particularly extend the service life of rubber products as UV-shielding materials, thus showing significant potential in extreme environments.

Phase equilibria in the low-TiO2 part of the CaO–MgO–SiO2–Al2O3–TiO2 system at a fixed MgO/CaO mass ratio of 0.2 and Al2O3/SiO2 mass ratio of 0.4

Adding titanium oxide has become a common practice in modern blast furnace operating procedures. The blast furnace slag is based on the CaO–MgO–Al2O3–SiO2–TiO2 low titanium slag system rather than CaO–MgO–Al2O3–SiO2 system. Phase equilibria in the CaO–SiO2–Al2O3–MgO–TiO2 system in the low-TiO2 part have been experimentally determined by means of high temperature equilibration and quenching technique followed by electron probe X-ray microanalysis. Introducing a small quantity of titanium-bearing materials can lower the liquidus temperature. The TiO2 content in the slag should be controlled below 4.6 wt%, otherwise it will enter the perovskite phase region where the liquidus temperatures increases rapidly. The compositions of the solid solutions corresponding to the liquidus have been precisely measured and should be utilized for developing the thermodynamic database.

Magnetron Sputter Deposition of Amorphous Silicon–SiO2 Quantized Nanolaminates

Quantization effects in nanolaminate structures of oxide materials are proposed and experimentally demonstrated only recently. Herein, the material combination of amorphous silicon and SiO2 deposited by magnetron sputtering is investigated and it is shown that the quantization effect can be observed indeed. Transmission electron microscopy characterization gives evidence of continuous layers of amorphous silicon and SiO2 with well‐defined interfaces. The deposition process is described and the tunability of the refractive index and the bandgap energy is demonstrated. By doing so, the advantages of this novel material over classical optical materials are shown and feasibility is proved. As an example, a longpass optical interference filter with edge at 720 nm is deposited using quantized nanolaminates as the high and SiO2 as the low refractive index material. This filter can be deposited successfully with close match to the design. It shows a blocking range throughout the visible spectrum whereas a comparable filter based on SiO2–TiO2 only blocks 500–700 nm.

Effect of ferrotitanium slag particle size on properties of Al2O3–SiC–C castables

Ferrotitanium slag can be used to replace bauxite to fabricate refractories owing to its high refractoriness (>1790 °C) and Al2O3 content (≥70 wt%). However, impurities in the ferrotitanium slag is harmful to the materials. In this paper, the mechanical properties and molten slag resistance of Al2O3–SiC–C castables were improved by replacing part of bauxite with large size ferrotitanium slag (8-5 mm). The large size ferrotitanium slag contained a small amount of impurities, which reacted with SiO2 at high temperature to form CaO–Al2O3–SiO2–TiO2 liquid layer on the surface of particles. Under the action of the liquid phase, the ferrotitanium slag particles and the matrix were combined more closely. With the decrease of the particle size of ferrotitanium slag, the slag resistance of the castables began to decrease. This was because the specific surface area of the particles with smaller particle size was relatively larger, large contact area with molten slag resulted in worse slag resistance. Meanwhile, decreasing ferrotitanium slag particle size brought the increase of apparent porosity of Al2O3–SiC–C castables, resulting in weak mechanical properties.

Investigation of scale formation and degeneration of silicide coating on Nb–Si based alloy in the temperature range from 1250 °C to 1560 °C

Nb silicide coatings modified with active elements have good oxidation resistance, but there is a lack of systematic research on their oxidation behavior at high temperatures above 1250 °C. The aim of this work is to investigate the oxidation behavior of an Al–Y modified silicide coating on Nb–Si based alloy in the temperature range from 1250 °C to 1560 °C. After oxidation at 1250 °C, the scale displays a typical layered structure consisting mainly of a TiO2 outer layer, an amorphous SiO2 matrix layer embedded with TiO2 and ZrSiO4, and an inner layer consisting of SiO2 and Cr2O3. Above 1350 °C, the evaporation reaction of Cr2O3 into CrO3 (g) is significantly accelerated and Cr2O3 disappeared gradually with temperature or time. The TiO2 layers covering on the scales formed at 1250–1500 °C grow along the crystallographic orientation of [100]. The micropores formed on the surface of TiO2 should be attributed to the further oxidation of Cr2O3 into volatile oxide CrO3 (g). The scales exhibit a similar structure consisting mainly of a SiO2 glass matrix embedded with ZrSiO4 and a surface TiO2 layer until 1500 °C. Above the eutectic temperature of SiO2–TiO2 system, the scale is mainly composed of a matrix layer of SiO2–TiO2 eutectic embedded with block TiO2 particles, and a thin SiO2 interface layer at 1560 °C. The degeneration path of the (Nb,X)Si2 coating is (Nb,X)Si2 → (Ti,Nb)5Si4 → γ-(Nb,X)5Si3.

Efficient synthesis and lithium storage performance of SiO2/TiO2 composite film anode by plasma electrolytic oxidation

SiO2/TiO2 composite films with different phase ratios have been successfully fabricated via the one-step plasma electrolytic oxidation (PEO) method in an alkaline electrolyte on Ti foil to obtain a binder-free anode for Li-ion batteries. The formed composite films present porous morphology of TiO2 with a uniform distribution of SiO2. The specific capacity can stabilize above 400 mAh/g at the current density of 100 μA cm−2 for 500 cycles, together with the apparent improved initial coulombic efficiency of 88.7 % and excellent rate capability, which arises from the peculiar structure and the synergic enhancement effect of SiO2 active materials and TiO2 matrix. This work provides an efficient and low-cost route for the preparation of Li-ion battery binder-free anodes and enriches the application of plasma electrolysis technology in energy field.

Phase equilibria of TiO2–SiO2–CaO–10%Al2O3-7.5%MgO at 1773 K and effects of MgO on the distribution of phase fields

The 1773 K phase diagram of the TiO2–SiO2–CaO-10 wt%Al2O3-7.5 wt%MgO system was constructed experimentally using the quenching method, focusing on the composition range of high TiO2 content. The obtained isothermal section contains four phase fields: the liquid phase field, the primary phase field of pseudo-brookite, the primary phase field of perovskite, and the liquid + perovskite + pseudo-brookite phase field. The pseudo-brookite particle precipitated in its primary phase field is more suitable for the efficient selective enrichment and separation of titanium resources. The increase of MgO from 5 % to 7.5 % in the TiO2–CaO–SiO2-10 wt%Al2O3–MgO system leads to a decrease of the liquidus temperature and an expansion of the liquid + pseudo-brookite + perovskite phase field. The increase of MgO promotes the enrichment of TiO2 into the pseudo-brookite phase and reduces the TiO2 level in the glass phase.

Structural and Spectroscopic properties of Eu3+ doped SiO2–TiO2 nanoparticles for photonic applications

The Eu3+-doped TiO2 nanoparticles in sol gel silicate glasses of composition (80-x)SiO2 + 20TiO2 + 0.5xEu2O3, (SiTiEu) where x = 0.0 0.5, 1.5, 2.5 and 3.5 mol%, have been prepared by sol-gel technique. The glass samples were investigated by thermos-gravimetric analysis (TGA/DTA), ATR-FTIR, XRD, SEM, TEM, EDX, optical absorption and photoluminescence emission spectroscopy at room temperature (RT). The absorption wavelength of TiO2 doped sol-gel silicate glass were red shifted due to a reduction in band gap energy with increasing annealing temperatures. According to the TEM images, all of the particles were spherical and had an average diameter is around 10 nm. The visible spectra of the Eu3+ doped TiO2 nanoparticles in sol-gel silicate glasses displayed characteristic PL emission 5D0→7FJ (J = 0, 1, 2, 3, 4, 5) transitions of Eu3+ ions at 370 nm excitation. The anatase TiO2:1.5Eu3+ nanocomposite showed high photoluminescence emission at 370 nm excitation, which was attributed to the f-f transitions of Eu3+. The hypersensitive 5D0→7F2 transition was responsible for the major red emission. From the recorded spectra, radiative parameters and Judd-Ofelt (JO) intensity parameters were computed. The Eu3+ co-doped TiO2 nanoparticles in sol-gel silicate glasses displayed emissions mostly in the red regions realized from a CIE chromaticity diagram. The results suggested that materials may be used as an optical material of technological importance such as display devices and also for optical amplifier.

A Highly Efficient, Selective, and Thermally Stable Dielectric Multilayer Emitter for Solar Thermophotovoltaics

Herein, the design, optimization, fabrication, and characterization of a highly efficient selective emitter (SE) for solar thermophotovoltaic systems is presented. An SE consisting of three layers (SiNx–SiO2–TiO2) deposited on a tungsten substrate is optimized for use with photovoltaic (PV) cells based on III–V semiconductors, such as GaSb, InGaAs, and InGaAsSb. The fabricated SE shows an emitter efficiency (ηSE) of 50% when coupled with a PV cell having an energy bandgap of 0.63 eV. After thermal treatment carried out at 1000 °C for 8 h in a vacuum environment, ηSE of 46% is recorded, demonstrating the thermal stability of the proposed SE. Its behavior at high temperatures has also been studied using simulations based on the transfer matrix method and on refractive indices experimentally measured at different temperatures (up to 1000 °C). The results show ηSE of 44% in the energy bandgap range of 0.55–0.63 eV, proving that the proposed structure is promising and can operate at high temperatures. In addition, the behavior of a real PV cell is simulated, and calculations show a maximum PV cell efficiency of 15% at 1000 °C and 25% at 1600 °C, exceeding the Shockley–Queisser limit.

The Properties and Activity of TiO2-based Nanorods as an Anti-Fouling Agent and a Photocatalyst

The properties and activity of TiO2-based nanorods as an antifouling agent and a photocatalyst for the catalytic degradation of methylene blue (MB) have been investigated. A modification of TiO2 with SiO2 was first carried out to enlarge the surface area. In order to enhance the TiO­2 photo response to the visible light region, a further modification of TiO2-SiO2 (TS) composites with polyaniline (PANI) was also conducted. The nanorod TiO2 exhibited an anatase structure based on the diffraction patterns. The TEM images showed that some TiO2 molecules were attached around SiO2 with a random orientation. The TiO2-SiO2-PANI (TS-PANI) exhibited the largest specific surface area (SBET) of about 256.85 m2/g. The profile on the AFM images of the composites showed that the nano-roughness of the coatings was confirmed. The photocatalytic activity was evaluated through the decomposition of MB both on the powder and the coated composites. The photocatalytic activity on the coatings was verified due to further application as anti-fouling coatings involving photocatalytic mechanism. The decomposition of MB using TS-PANI powder and TS-PANI coating composites was 89.5% and 90.2 %, respectively, with the irradiation time on the coatings was 20 min longer. The anti-fouling activity through the photocatalytic mechanism and nano-roughness surface was confirmed by the inhibition of barnacle growth on the teakwood surface immersed for two months in the sea.

Synthesis and characterization of TiO2 foam and SiO2@TiO2 core‐shell nanostructure for gnetin dye degradation from industrial effluent

AbstractThe current study intends to create TiO2 foam, SiO2 nanoparticles (NPs), and SiO2@TiO2 core‐shell nanostructure (CSN) with improved photocatalytic durability for the quick degradation of the textile industrial water pollutant in the presence of sunlight. The sol‐gel, Stöber, and chemical co‐precipitation methods have been used to synthesize TiO2 foam, SiO2 NPs, and SiO2@TiO2 CSN. X‐ray diffraction results have revealed the anatase phase of TiO2 foam, the amorphous nature of SiO2 NPs, and the amorphous nature of SiO2@TiO2 CSN due to equal wt.% of SiO2 NPs and TiO2 foam at 300 K. Field emission scanning electron microscope images show that the TiO2 foam, SiO2 NPs, and SiO2@TiO2 CSN exhibit cluster sheets, spherical, and spherical raspberry‐like homogeneous morphology. The ultraviolet spectrum confirmed that the TiO2 foam and SiO2@TiO2 CSN have a band gap of 2.9 eV and 3.4 eV. SiO2@TiO2 CSN has been shown an excellent decomposition rate of water pollutants (gentian dye) in comparison to TiO2 foam due to their better‐absorbing nature. Both NPs and CSN employed in the breakdown of gentian dye have been recycled and their original characteristics are preserved. The proposed SiO2@TiO2 CSN has a higher potential for application in developing self‐cleaning, long‐lasting, and air‐purifying materials.

Coating of expanded polystyrene spheres by TiO2 and SiO2–TiO2 thin films

Expanded polystyrene spheres (EPS) were coated by SiO2–TiO2 or TiO2 for application as a fluidized bed in the photocatalytic reactor. Silica coating was realized by the sol–gel process carried out in a vacuum evaporator at 60–70 °C. The most uniform and thin layer of silica coating was obtained by the Stöber method based on the hydrolysis of tetraethyl orthosilicate (TEOS) catalysed by an ammonia solution. Effective TiO2 coating was obtained by the immersion of EPS in the titania aqueous suspension and evaporation of water in a vacuum evaporator. Heating of EPS spheres coated by SiO2, TiO2 or SiO2–TiO2 at the temperatures of 120–140 °C resulted in a shrinkage of their volume. For the thick layer coating, a strong corrugation of EPS surface was observed. The photocatalytic tests showed, that highly corrugated surface of coated EPS slowed down ethylene decomposition, whereas a thin layer coating of both, SiO2 and TiO2 was advantageous.Graphical abstract

TiO2–SiO2 nanocomposite via a novel sol-gel method with the addition of an energy monitoring device: Synthesized, characterization and anti-bacterial applications

The present paper successfully employs a modified sol-gel method to synthesize TiO2–SiO2 nanocomposites. By incorporating a hygrometer and energy monitoring devices, we achieved real-time monitoring of the drying process and optimized temperature control. Energy consumption during the drying process was observed, revealing that higher temperatures result in shorter drying times. The lowest energy consumption was recorded at 80 °C, while the optimal temperature, obtained from the conversion of the optimization diagram, occurred at 77 °C. Characterization was performed using different tools such as XRD, FT-IR analysis, XPS, FE-SEM-EDS, and HRTEM to determine the size and distribution of elements, crystal structure, and chemical bonds. Furthermore, an anti-bacterial test was conducted, revealing that the nanocomposite exhibited superior antibacterial properties against Staphylococcus aureus and Escherichia coli. Meeting the required standards, the TiO2–SiO2 nanocomposite produced by this method shows the potential to create a cleaner and more efficient environment in medical and industrial applications.

Preparation of TiO2–SiO2–CaCO3 composite opacifier by hydrophobic agglomeration and mechanism of inhibiting glaze yellowing

This study investigates the preparation of TiO2–SiO2–CaCO3 composite opacifier (Ti–Si–Ca) and its application in sanitary ceramic glazes. This approach involved hydrophobic agglomeration through surface-induced hydrophobic modification of TiO2, SiO2 and CaCO3 particles, along with the interactions between the hydrophobic carbon chains of modifiers. The Ti–Si–Ca formed a uniform coating with well-dispersed TiO2 and SiO2 particles on the CaCO3 surface and strong bonds formed among TiO2, SiO2 and CaCO3 through interpenetration of the organic carbon chains on the surface. The Ti–Si–Ca was added to the basic glazes of sanitary ceramics at a proportion of 15.5 % and fired at 1125 °C for 4 h. The resulting white ceramic glazes had chromaticity values of L*, a*, and b* at 93.76, −0.73, and 3.89, respectively, demonstrating superior glaze opacity and whiteness compared to glazes made with a ZrSiO4 opacifier (L* 90.30, b* 4.50). Glass and titanite phase make up the majority of the Ti–Si–Ca ceramic glazing layer of, with titanite serving as the opacified phase. Elimination of organic groups in Ti–Si–Ca during glaze firing formed interfacial chemical bonds among TiO2, SiO2 and CaCO3, which facilitated the synthesis of titanite from the three components at high temperatures. The Ti–Si–Ca was a highly opaque glaze without yellowing because the organic groups of Ti–Si–Ca were removed and interfacial chemical bonds formed among the TiO2, SiO2 and CaCO3 in the low-temperature stage of glaze firing. This transformed the three phases into titanite at high temperature and eliminated free TiO2. The formation of rutile TiO2, which has a yellow hue, at high temperatures was inhibited. This study provides a novel approach for low-energy preparation of TiO2–SiO2–CaCO3 composite opacifiers and addresses the challenge of replacing ZrSiO4 with TiO2 in ceramic opacifiers.

Synthesis and Characterization of Silica-Titanium Oxide Nano-Coating on NiTi Alloy

To functionalize the surface of the NiTi alloy, hybrid layers comprising nanometric silica and titanium oxides were synthesized. The TiO2–SiO2 nanosystem was chemically prepared and utilized for electrophoretic deposition (EPD) to create multifunctional layers on the alloy surface. The impact of pH on Zeta potential and ceramic particle size was explored to ensure a stable colloidal suspension for EPD, with optimal parameters established at a pH of approximately 6. A uniform layer was formed by applying a voltage of 40 V for 3 min, appearing as a thin film interspersed with regularly spaced larger agglomerates. The thin film primarily consisted of a minor fraction of defective rutile nanoparticles, accompanied by silica and carbon agglomerates from the nanosystem synthesis process. Heat treatment at 800 °C for 2 h induced significant structural changes, developing a novel-generation material with a different structure. An interlayer with strong Si–O–Ti connections was formed. Moreover, the mechanism of layer formation was extensively discussed.

Production of biodiesel from waste culinary oil catalyzed by S2O82−/TiO2–SiO2 solid super-acid catalyst prepared with recovered TiO2 from spent SCR

Recovery and valorization of natural resources from waste materials are crucial for promoting sustainable development. In light of this, the present study explores the transesterification of waste culinary oil into biodiesel production using a silica-supported solid super-acid catalyst (S2O82−/TiO2–SiO2) prepared with recovered TiO2 from spent SCR. The synthesized materials were characterized through XRD, SEM-DES, XPS, FT-IR, NH3-TPD, and N2-BET analysis. Notably, the crystal structure of recovered TiO2 was not destroyed during the whole process. N2-BET analysis showed that the silica-supported catalyst significantly increased the specific surface area from 47.89 to 101.16 g/m2. The presence of superacid sites (Brønsted and Lewis acid sites) on the surface of the catalyst was confirmed by NH3-TPD and FT-IR analysis. The silica-supported catalyst (S2O82−/TiO2–SiO2) exhibited high catalytic activity for free fatty acid (FFA) about a conversion rate of 90.7 % under optimal reaction conditions: a reaction time of 4 h, at 180 °C with a 5 wt% catalyst loading, and a methanol-to-oil molar ratio of 12:1. The biodiesel production was confirmed by using FT-IR and 1HNMR techniques. Furthermore, the catalytic performance of the prepared catalyst was compared with other catalysts prepared from pure TiO2 reported in the literature. This approach showed a potential for sustainable biodiesel production by using low-cost solid acid catalyst synthesized from recovered materials.

Bimodal volcanism in the Hegau region (SW Germany): Differentiation of primitive melilititic to nephelinitic rocks produces evolved nosean phonolites

Peculiar bimodal volcanism in the Hegau region (SW Germany) comprises two contrasting SiO2-undersaturated rock suites.(I)Primitive olivine melilitites and melilite-bearing olivine nephelinites (12–9 Ma) are characterized by high MgO, CaO, Fe2O3, TiO2, Ni, V, F, moderate alkalis, Al2O3, P2O5, Ba, Nb, Zr, and low SiO2, Rb, Pb, and U concentrations. The rocks are composed of forsteritic olivine, diopsidic clinopyroxene, melilite, perovskite, Cr-bearing oxyspinel, F- and Ba-rich mica, and fluorapatite. In rare cases, they contain coeval coarse-grained ijolite patches generated by rapid in-situ fractionation in small melt pockets.(II)Evolved nosean phonolites (14–11 Ma) comprise high alkalis, Al2O3, SiO2, Rb, Nb, Zr, U, Pb, S, and low MgO, CaO, Fe2O3, TiO2, P2O5, Ba, Ni, and V concentrations, and contain abundant Ba-bearing alkali feldspar and nosean-haüyne-sodalitess macrocrysts, aegirine-augitic clinopyroxene, as well as accessory apatite, titanite, zircon, and pyrochlore.The melilititic–nephelinitic rocks formed by low degrees of partial melting of a carbonated amphibole ± phlogopite-bearing garnet wehrlite in the uppermost asthenosphere or in the thermal boundary layer and occur also in neighbouring regions. However, their coexistence with evolved nosean phonolites is a unique and so far, unexplained feature in the southern Central European Volcanic Province.Thermodynamic modelling implies that removal of 11–19% oxyspinel, 4–10% olivine, 42–57% clinopyroxene, <3% mica, <9% feldspathoids, <8% feldspar from melilititic–nephelinitic parental melts at upper crustal conditions (∼200 MPa) results in significant amounts of phonolitic residues that are compositionally similar to the exposed nosean phonolites. Strongly negative P and Ti anomalies and a trough of MREE in primitive mantle-normalized trace element patterns of phonolites indicate additional fractionation of titanite and apatite, consistent with the mineralogy of coarse-grained (nepheline) syenitic cumulates, which are present as enclaves in both rock suites. The modelling results suggest crystallization of the (nepheline) syenite cumulates between 1050 and 800 °C and ascent and eruption of the phonolite residues at no less than ∼900 °C with complete solidification of the observed assemblage at >750 °C. Significant crustal assimilation during fractionation appears unnecessary to explain the mineralogical, mineral chemical, and geochemical characteristics of the phonolites. Prolonged upper crustal differentiation of the magmas in one case (nosean phonolites) and fast ascent of primitive melts in the other (olivine melilitites and melilite-bearing olivine nephelinites) can be explained by stress field changes from an extensional to a more compressive regime, the magma ascent becoming thereby increasingly structurally controlled and supported by brittle deformation.