Hard Agglomerates Research Articles

Ferroelectromagnetic Properties of PbFe1/2Nb1/2O₃ (PFN) Material Synthesized by Chemical-Wet Technology.

In this work, PbFe1/2Nb1/2O3 (PFN) ceramic samples synthesized by chemically wet method (precipitation from the solution) were obtained. Due to the tendency to form powder agglomerates, the synthesized powder was subjected to ultrasound. The sintering was carried out under various technological conditions, mainly through controlling the sintering temperature. -X-ray powder-diffraction (XRD), scanning electron microscope (SEM) microstructure analysis, as well as the examinations of dielectric, ferroelectric, and magnetic properties of the PFN ceramics were carried out. Studies have shown that hard ceramic agglomerates can be partially minimized by ultrasound. Due to this treatment, closed porosity decreases, and the ceramic samples have a higher density. Optimization and improvement of the technological process of the PFN material extends the possibility of its use for the preparation of multiferroic composites or multicomponent solid solutions based on PFN. Such materials with functional properties find applications in microelectronic applications, e.g., in systems integrating ferroelectric and magnetic properties in one device. The optimal synthesis conditions of PFN ceramics were determined to be 1050 °C/2 h.

Ye’elimite synthesis by chemical routes

Ye’elimite is formed during the production of sulfoaluminate cement. This article presents the synthesis of ye’elimite by different chemical routes: Pechini method (Pech), Organic Steric Entrapment method (OSE) and Self-Propagating Combustion (SPC). 1250 °C for 1 h is the optimal sintering cycle to synthesize ye’elimite, which is lower than the sintering conditions (1300 °C, 3 h) to obtain pure ye’elimite from solid-state reaction using pure oxide raw materials. OSE and SPC methods produce the purest ye’elimite (> 98 wt%). After the heat treatment, the nanosized crystallites (51 to 57 nm) form particles about 3 times larger (136 to 175 nm) which could result from the sintering of the crystallites. The particles form hard agglomerates whose size ranges between 1 to 100 μm. This distribution, which is typical of a ground Portland clinker, is obtained in the present case directly after sintering and without the necessity of a grinding step.

Deactivation Behavior of a Refractory-Brick Supported CuO Material in Decomposition-Oxidation Cycles of Chemical Looping with Oxygen Uncoupling (CLOU)

Chemical Looping with Oxygen Uncoupling (CLOU) which uses solids oxygen carrier providing gaseous oxygen for combustion is an effective technology for CO2 capture with low-energy penalty. Oxygen carrier is a cornerstone for CLOU, because stable and high rate of oxygen release must be assured. In this work, a refractory brick was attempted as support for Cu-based oxygen carrier due to its high crushing strength and agglomeration resistance. Samples of Cu25RefBri, Cu30RefBri and Cu40RefBri with 25-40wt.% CuO loadings were prepared via successive impregnation and then calcined at 800oC for 6h in air atmosphere. Decomposition-oxidation cycles were performed in a TGA apparatus and a batch fluidized bed reactor at temperatures of T=900-950oC. The Cu25RefBri showed the highest rate of oxygen release among the stated oxygen carrier samples. This material, however, showed decrease of reactivity in either TGA or fluidized bed tests, mainly attributable to the formation of low-active CuAl2O4 spinel. The stable rate of oxygen release from Cu25RefBri could be as low as 0.2∙10-4 kgO2/(s∙kgOC), while the stable O2 concentration can be decreased to 0.8vol.% at 900oC, which is much lower that the equilibrium value at this temperature. In combination of hard agglomeration found at oxidation stage under 950oC, the attempted Cu25RefBri could not be considered as a suitable oxygen carrier for CLOU.

Modification of polypropylene with nanosized α-Al2O3 powders prepared by the mechanochemical method

Nanosized [Formula: see text]-Al2O3 powders were prepared by the mechanochemical method, with AlCl[Formula: see text]H2O and NH4HCO3 as raw materials, the environmentally friendly starch as an effective dispersant. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed to characterize the ammonium aluminum carbonate hydroxide (AACH) precursor and products. The results show that nanosized spherical [Formula: see text]-Al2O3 powders without hard agglomeration and with particle size in the range of 20–40 nm can be obtained by this novel and green method. Then, polypropylene (PP)/nano [Formula: see text]-Al2O3 nanocomposites were prepared by melt blending in a mixer apparatus. The crystallization behavior and mechanical properties of PP/[Formula: see text]-Al2O3 nanocomposites were further investigated in this study. Wide-angle X-ray diffraction (WAXD) results show that a small amount of [Formula: see text]-crystal of PP forms after adding [Formula: see text]-Al2O3 nanoparticles. According to differential scanning calorimetric (DSC) measurement, the [Formula: see text]-Al2O3 nanoparticles make crystallization temperature of PP enhanced by acting as effective nucleating agents. The tensile strength and impact strength were both improved significantly with the addition of [Formula: see text]-Al2O3 nanoparticles through tensile and impact tests. Scanning electron microscopy (SEM) observation showed that the fracture surface became rougher and further confirmed the above result.

Nonlinear Resonance Response of Porous Beam-Type Implants Corresponding to Various Morphology Shapes for Bone Tissue Engineering Applications

Having excellent biocompatibility and apatite mineralization as well as efficient mechanical properties makes bredigite as one of the most attractive bioceramics. A beam-type porous biological implant in a 3D-printed architecture is designed with micron pore size. The surface properties, morphology, and size of the composed powders are evaluated using Scherrer and Williamson-Hall equation. The effect of MNPs deposition into the bredigite bioceramics and correlation with temperature effect on roughness of the prepared bio-nanocomposite are also investigated for hyperthermia application potential. The composed powders are characterized by x-ray diffraction, and then scanning electron microscopy (SEM), differential scanning calorimetry, thermogravimetric analysis (weight change, TGA), and atomic force microscopy are utilized to evaluate the surface topography. The resonance response is the tendency of a bone scaffold to respond at prominent amplitude while the frequency of its oscillations is equal to the structure’s natural frequency of vibration. Therefore, based on the obtained mechanical properties via the experimental approach for the bio-nanocomposite material, an analytical solution based upon the multiple-timescale method is carried out to analyze the nonlinear primary resonance of a 3D-printed porous beam-type biological implant under uniform-distributed load. According to SEM observations, there are hard agglomerates in the bredigite-magnetite nanoparticles (Br-MNPs) bio-nanocomposite material with low weight fraction of MNPs. However, they are broken down by increasing the amount of MNPs. Also, it is displayed that for lower MNPs weight fraction, the height of jump phenomenon related to the nonlinear resonance response is maximum and minimum for, respectively, irregular and mesoporous shapes of morphology, but their associated forcing amplitudes related to the bifurcation points are minimum and maximum, respectively.

Honey mediated microwave assisted sol–gel synthesis of stabilized zirconia nanofibers

Aim of the present work is to prepare zirconia nanofibers using microwave assisted sol–gel method. Both honey and microwave powers are employed as structure directing agents to improve the stability and reduce the crystallite size. Honey, acting as capping agent, prevents the particles from hard agglomeration. Soft agglomeration or less agglomeration results in smaller crystallite size that prevents the transformation of tetragonal to monoclinic phase resulting in stabilized tetragonal zirconia (t-ZrO2). Zirconium oxychloride is used as precursor of zirconium and deionized water as solvent. Effect of microwave powers, in the range of 100–900 W with interval of 200 W, on zirconia stabilization is observed. X-ray diffraction analysis shows the presence of phase pure t-ZrO2 at low microwave power ~ 100 W with crystallite size ~ 26 nm. Formation of phase pure t-ZrO2 at low microwave power is due to the presence of sufficient amount of honey to coat the zirconia crystals. Relatively higher x-ray density has been observed in case of phase pure t-ZrO2 at 100 W of microwave power. This high density and phase purity reveals the high value of hardness (~ 1503 HV). Scanning electron microscopy analysis reveals the formation of well-separated nanofibers without agglomeration at 100 W. These nanofibers are purposed for bone implants and bone grafting. Structural transformation along with hard agglomeration is observed with increase in microwave powers from 500 W to 900 W. FTIR and Raman fundamental tetragonal bands, appearing at 490 cm−1 and 148 cm−1, respectively, confirm the formation of t-ZrO2 at low microwave power. Sample with phase purity exhibits high grain boundary resistance (1.95 MΩ) along with high dielectric constant (~ 74) and low tangent loss (at log f = 4.0). It is worth mentioning here that phase pure t-ZrO2 at very low microwave power (~100 W) with high density and well-separated nanofibers has been obtained without any post heat treatment.

Yttria nanopowders with low degree of aggregation by a spray precipitation method

Highly sinterable Y2O3 nano-powder with low degree of agglomeration was synthesized by using a spray precipitation technology, without the use of any additives and dispersants. Compared with the precursor made by using the dripping method (D-precursor), the precursor made by the spraying method (S-precursor) had much lower degree of hard agglomeration. So did the resultant calcined Y2O3 powder (S-Y2O3 powder) as compared with the D-Y2O3 powder. Sintering behaviors of the two powders were studied. Ceramics made from the S-Y2O3 powder (S-Y2O3 ceramics) showed much higher densification rate and final density. After vacuum sintered at 1650 °C for 5 h, relative density of the D-Y2O3 ceramics was merely 97.3%, while that of the S-Y2O3 ceramics reached 99.5%. In addition, the D-Y2O3 ceramics cannot be sintered to 98% relative density by using the vacuum sintering technique, due to the high degree of agglomeration of the D-Y2O3 powder. Moreover, the S-Y2O3 ceramic exhibited homogeneous microstructure and an in-line optical transmittance of 81.6% at 1200 nm after HIP treatment. The spray precipitation method should be applicable to synthesizing other oxide powders.

Improvement of Colloidal Stability in Colloidal Processing for Highly Translucent, Nanosized Zirconia

This study aimed to improve the colloidal stability of yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) suspension through colloidal processing to obtain highly translucent Y-TZP. Agglomeration is often the main complication in the processing of nanosized Y-TZP as it deteriorates mechanical and optical properties. Thus, colloidal processing is necessary to mitigate the agglomeration in Y-TZP. The colloidal stability of Y-TZP suspension plays a key role for the success of colloidal processing. In this study, colloidal processing was conducted at several stages, namely, dispersant addition, pH adjustment and sedimentation. Changes in particle size and zeta potential at various stages were recorded. The suspensions were then slip-casted to form green bodies. Green bodies were sintered and characterized for density and translucency. The results showed that dispersant addition followed by pH adjustment effectively dispersed soft agglomerates by introducing electrosteric stabilization, whereas sedimentation successfully segregated hard agglomerates and contributed excellent colloidal stability. With high colloidal stability, the translucency of Y-TZP was improved by approximately 30%. This study demonstrated different colloidal processing stages and proved that high colloidal stability and fine particle size are vital to produce highly translucent Y-TZP.

Praseodymium doped ceria as electrolyte material for IT-SOFC applications

Praseodymium-doped ceria (PDC, Ce0.9Pr0.1O2) electrolyte material for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been successfully synthesised by EDTA-citrate method. From X-Ray diffraction (XRD), fluorite structure along with a crystallite size of 5.4 nm is obtained for PDC nanopowder calcined at 350 °C/24 h. Raman spectroscopy confirmed the structure, presence of oxygen vacancies with the manifestation of the main peak at 457 cm−1 and with a secondary peak at 550 cm−1. From Transmission Electron Microscopy (TEM) analysis, the average particle size is around 7–10 nm and selected area electron diffraction (SAED) patterns further confirmed the fluorite structure of PDC nanopowder. The PDC nanopowder displayed a BET surface area of 65 m2/g with a primary particle size of ∼13 nm (calculated from BET surface area). Dilatometer studies revealed a multi-step shrinkage behaviour with the multiple peaks at 522, 1171 and 1461 °C which may be originated due to the presence of multiple size hard agglomerates. The PDC electrolyte pellet sintered at 1500 °C displayed an ionic conductivity of 1.213E-03 S cm−1 along with an activation energy of 1.28eV. Instead of a single fluorite structure, XRD of sintered PDC pellet showed multiple structures (Fluorite structure (CeO2) and cubic structure (PrO2).

Mechanistic Elucidation of Hard Agglomerate Formation from Drying Kinetics in the Integrated Sorption Chamber

The formation of hard agglomerates during drying has impacts on the product quality, particle size distribution, and downstream formulation. Hence, understanding the cause of hard agglomerates and determining a remedy for them or preventing their formation are necessary. The integrated sorption chamber (ISC) has been successfully applied to the study of hard agglomerate formation. The design and development of this ISC are briefly described. The vapor-phase profile of a binary mixture of acetone and water without active pharmaceutical ingredient (API) was predicted using an analytical solution of a batch distillation and verified via mass spectrometry (MS). The drying of the API wet cake, which is very soluble in water, using a starting point of 5 wt % water in acetone was conducted in the ISC. A significant delay in water removal was observed from both the weight measurement and the MS signal. The slow removal of water was attributed to diffusion of water from a thin crust layer induced by the solution o...

Effect of ionic liquid inclusion and amino–functionalized SAPO-34 on the performance of mixed matrix membranes for CO2/CH4 separation

Surface voids and filler agglomeration affect the membrane’s structure and gas separation which limits the use of mixed matrix membranes (MMM) for carbon dioxide (CO2) separation in industry. Therefore, synthesis of MMM with ionic liquid and modified inorganic fillers had improved performance and morphologies. In this regards the filler surface (SAPO-34) was modified by introducing organic amino cation, namely ethylenediamine (EDA) and hexylamine (HA). Four (04) mixed matrix membranes were synthesized by the incorporation of un-modified and modified filler along with ionic liquid (IL) in polyethersulfone (PES) matrix. The effects of IL addition and filler functionalization on morphology, thermal and mechanical stability were investigated; while pure gas permeation test using carbon dioxide (CO2) and methane (CH4) was carried out at 4 bar pressure to analyze the membrane gas transport properties. Characterization showed that surface voids and hard agglomerations disappeared by the addition of modified SAPO-34 and ionic liquid [emim][Tf2N]. Moreover, membranes were thermally and mechanically stable after the addition of IL and modified SAPO-34. Synergetic effect of IL and modified filler exhibited excellent CO2/CH4 selectivity (37.23) for PES + IL + modified SAPO-34 + HA MMM.

Green synthesis of nanocrystalline α-Al2O3powders by both wet-chemical and mechanochemical methods

Nanosized [Formula: see text]-Al2O3powders were prepared with AlCl[Formula: see text]6H2O and NH4HCO3as raw materials by both wet-chemical and mechanochemical methods, through the synthesis of the ammonium aluminum carbonate hydroxide (AACH) precursor followed by calcination. The environmentally benign starch was used as an effective dispersant during the preparation of nanocrystalline [Formula: see text]-Al2O3powders. X-ray diffraction (XRD), thermogravimetric differential thermal analysis (TG-DTA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to characterize the precursor AACH and products. The results show that nanosized spherical [Formula: see text]-Al2O3powders without hard agglomeration and with particle size in the range of 20–40 nm can be obtained by the two methods. Comparing the two “green” processes, the mechanochemical method has better prospects for commercial production.

Optimizing particle characteristics of nanocrystalline aluminum nitride

Aluminum nitride (AlN) nanopowders are synthesized in a chemical vapor synthesis (CVS) process using triethylaluminum (TEAl) and ammonia as precursors. A simple reaction-coagulation-sintering model is used to investigate the influence of process parameters, such as hot-wall reactor temperature and system pressure, on particle characteristics: size and agglomeration for example. The results of these simulations show good agreement with the experimental data and enable a better understanding of these effects of temperature and pressure on particle size and microstructure. Pure wurtzite phase AlN nanocrystals are obtained for all tested process parameters. The primary particle (crystallite) size ranges from 2.7nm to 11.5nm with (secondary) particle size in the range of 4.3nm to 12.4nm. As predicted by the simulations, the experiments show a low degree of (hard) agglomeration that even reaches the value of 1 for syntheses above 1400°C and 100mbar, implying the complete absence of hard agglomerates at those conditions.

Preparation of YAG nanopowder by different routes and evaluation of their characteristics including transparency after sintering

Yttrium aluminium garnet (YAG) nanopowder has been synthesized by five different routes: three of them are co-precipitation with different combinations of aluminium and yttrium sources as well as the precipitating agents, and the rest are by solid state synthesis with certain variation. They are designated as: process-1 (Al-nitrate, yttria, HNO3, NH4HCO3), process-2 (Al-nitrate, Y-nitrate, NH4HCO3), process-3 (Al-nitrate, Y-nitrate, NH4OH,), process-4 (Al-nitrate and Y-nitrate heated to 1000 °C), and process-5 (alpha-alumina and yttria heated to 1100 °C). Of them, process-2 develops the highest surface area (31 m2/g), soft agglomerated and near spherical crystalline YAG nanopowders through minimum mass loss, and excellent cation homogeneity. Pseudo solid state reaction between aluminium nitrate/yttrium nitrate (process-4) and solid state reaction of alumina/yttria (process-5) requires high-calcination temperature and results in hard agglomerates. In most cases, highly crystalline YAG is formed together with the formation of an intermediate metastable phase of YAP. Powder prepared by process-2 leads to 99.6% dense and 60% transparent YAG ceramics on hot isostatic pressing.

Morphological and crystalline evolution of Sm-(20 mol%)–doped ceria nanopowders prepared by a combined co-precipitation/hydrothermal synthesis for solid oxide fuel cell applications

Abstract Nanocrystalline Samarium (20 mol%)-doped ceria (SDC20) nanopowders were prepared using a combined co-precipitation/hydrothermal treatment synthesis route carried out at reduced temperature (120 °C). The amorphous precursor experiences some microstructural transformations during the hydrothermal treatment, and after 16 h a Samarium-Cerium hydroxide carbonate, characterized by a hexagonal crystalline lattice, spherical morphology and particles of about 100 nm in size, with a very low degree of agglomeration, is the only present phase in contrast to the initial amorphous state. After the calcination step, the powders which preserved this morphology are still characterized by the absence of hard agglomerates. As a consequence, these powders exhibited an excellent sintering behaviour with a microstructure characterized by regular, equiaxed and micrometric grain size. In fact, at 1500 °C a nearly perfect densified sample was obtained, but also at 1300 °C a very good sintering behaviour was observed. Finally, the electrochemical characterization carried out by EIS measurements showed a very good electrical behaviour with high ionic conductivity, i.e. at 800 °C 5.2·10−2 S cm−1 and 4.8·10−2 S cm−1 for pellets sintered at 1500 °C and 1300 °C respectively, making them suitable for IT-SOFCs.

Surface and grain‐boundary excess of ZnO‐doped SnO2 nanopowders by the selective lixiviation method

AbstractThe primary characteristic of nanopowders is the high surface area and consequently high fraction of atoms on the interfaces, which changes the energy of the system. The additive distribution in the nanopowder interfaces is a fundamental aspect to control the energy, particle size, and final properties of nanopowders. In this work, the surface excess was determined using a selective lixiviation method, where a low‐water‐soluble oxide, SnO2, was used as the matrix, and a high‐water‐soluble oxide, ZnO, was used as the additive. The X‐ray photoelectron spectroscopy (XPS) analysis confirmed that ZnO segregated on SnO2 surfaces. However, after acid lixiviation the same analysis showed an undetectable surface concentration of ZnO. The evaluation of the nanostructure change and surface composition enables us to calculate the heat of segregation for the grain boundary and surface and the interface energy reduction because of segregation. At low‐ZnO concentrations, the additive solubilizes in the bulk and promotes particle growth. However, the segregation to the grain boundary and surface determines the relative stability of each interface, which promotes hard agglomeration and particle size stabilization at intermediated ZnO amounts. At high‐ZnO concentrations, the surface segregation stabilizes the solid‐gas interface and decreases the agglomeration and final particle size.

Synthesis and Photoluminescence Properties of ZrO2:Eu3+ Nanoparticles Using Salt-Assisted Ultrasonic Pyrolysis Process

Inorganic phosphors based on ZrO2:Eu3+ nanoparticles were synthesized by a salt-assisted ultrasonic spray pyrolysis process that is suitable for industrially-scalable production because of its continuous nature and because it does not require expensive precursors, long reaction time, physical templates or surfactant. This facile process results in the formation of tiny, highly crystalline spherical nanoparticles without hard agglomeration. The powder X-ray diffraction patterns of the ZrO2:Eu3+ (1-20 mol%) confirmed the body centered tetragonal phase. The average particle size, estimated from the Scherrer equation and from TEM images, was found to be approximately 11 nm. Photoluminescence (PL) emission was recorded under 266 nm excitation and shows an intense emission peak at 607 nm, along with other emission peaks at 580, 592 and 632 nm which are indicated in red.

Composites of ionic liquid and amine-modified SAPO 34 improve CO2 separation of CO2-selective polymer membranes

Mixed matrix membranes with ionic liquids and molecular sieve particles had high CO2 permeabilities, but CO2 separation from small gas molecules such as H2 was dissatisfied because of bad interfacial interaction between ionic liquid and molecular sieve particles. To solve that, amine groups were introduced to modify surface of molecular sieve particles before loading with ionic liquid. SAPO 34 was adopted as the original filler, and four mixed matrix membranes with different fillers were prepared on the outer surface of ceramic hollow fibers. Both surface voids and hard agglomerations disappeared, and the surface became smooth after SAPO 34 was modified by amine groups and ionic liquid [P66614][2-Op]. Mixed matrix membranes with composites of amine-modified SAPO 34 and ionic liquid exhibited excellent CO2 permeability (408.9 Barrers) and CO2/H2 selectivity (22.1).

Modificação da superfície do ZnAl1,9Eu0,05O4 visando a obtenção do híbrido ZnAl1,9Eu0,05O4/SiO2 para aplicação como biossensor

Resumo Este trabalho teve como objetivo investigar a modificação de superfície do ZnAl1,9Eu0,05O4 visando a obtenção do híbrido ZnAl1,9Eu0,05O4/SiO2 para aplicação como biossensor. Inicialmente as nanopartículas de ZnAl1,9Eu0,05O4 foram sintetizadas por reação de combustão e, subsequentemente, as suas superfícies foram modificadas com o agente silano. As amostras foram caracterizadas por difração de raios X, microscopia eletrônica de varredura (MEV), espectroscopia de infravermelho com transformada de Fourier (FTIR) e espectroscopia de excitação e de emissão. Os resultados evidenciaram a formação da fase majoritária do ZnAl2O4. Através de MEV observou-se a presença de aglomerados de aspecto duro, com formato irregular na forma de placas, com presença de poucos poros irregulares e variáveis. A modificação da superfície foi confirmada por FTIR através dos grupos silanóis e siloxanos. Os espectros de excitação e de emissão revelaram a presença de uma banda larga da matriz ZnAl2O4 e transições finas e intensas do íon európio provenientes da dopagem do óxido não estequiométrico ZnAl2O4 com o európio. Pelos resultados de emissão e excitação constatou-se que a luminescência do híbrido ZnAl1,9Eu0,05O4/SiO2 apresentou uma pequena diminuição em relação às nanopartículas de ZnAl1,9Eu0,05O4, sendo esta diminuição praticamente insignificante diante dos benefícios da silanização ocasionada pela introdução de grupos funcionais que promovem a conjugação do híbrido ZnAl1,9Eu0,05O4/SiO2 com biomoléculas, sendo este promissor para aplicação como biossensor aplicado na área biomédica para o diagnóstico e tratamento de doenças.

Phase composition and morphology characteristics of ceria-stabilized zirconia powders obtained via sol-gel method with various pH conditions.

High purity, fine crystalline, degradation-free at low temperature powders have attracted special interest in CAD/CAM prosthetic dentistry full ceramic restorations. This study reports the preparation and characterisation of zirconia-ceria (0.9 ZrO2 0.1 CeO2) powders. Materials were obtained from zirconium-n-alkoxide and cerium nitrate hexahydrate in the pH 2-4 and 8-10. Zirconia- ceria powders were obtained with the sol-gel method in a humid-free environment. Thermal analysis (TGA/DTA) of the as-prepared materials was made for an assessment of its behaviour at elevated temperatures. Specimens were dried at 80 °C and calcinated in two stages: at 300 °C with soaking time 2.5 h and 850 °C with holding time 2.5 h, in order to evaluate the phase transformations. Thermal analyses of the as-dried powders were made for an assessment of its thermal behaviour during heat treatment up to 1000 °C. By X-ray diffraction (XRD), polymorphs of ZrO2 were identified. Additionally, scanning electron microscopy (SEM) and laser particle size distribution (PSD) were involved for characterisation of morphology of the powders. A correlation between the pH of the colloidal system and the morphology of the as-obtained powders were found. Based on analysis (SEM, PSD), structures were identified known as soft and hard agglomerates. It can be stated that differences found between powder morphology were dependent on the value pH used, which can be crucial for powder densification during sintering and compacting green bodies which, as a consequence, may be crucial for the lifetime of zirconia prostheses. Correlations between phase composition and pH are difficult to grasp, and require further, more sophisticated, studies.