Tetragonal ZrO2 Phase Research Articles

Formation of metastable zirconium oxides using pulsed laser deposition of ZrO based target

There is a growing interest about the possibilities for preparation of various zirconium oxides from scientific as well as application point of view. Laser ablation of solid target consisting of sintered grains of metallic hexagonal Zr3O and monoclinic ZrO2 results in evaporation of Zr, O species (ions, atoms) and subsequent deposition of Zr-O film. Ta and Cu have been used as substrates. The films were analyzed by SEM-EDX, Raman and FTIR spectroscopy and X-ray diffraction. SEM analysis revealed µm/sub-µm sized roundshape and ring-like objects on continuous coat. Using Raman spectroscopy broad peaks which can suggest partial laser induced amorphization of Zr-O deposits were detected. FTIR spectroscopy shows bands which are assignable to Zr-O vibration of nanostructured zirconia. X-ray diffraction analysis provides more explicit assignment of deposited phases where the deposit on Ta exhibits presence of monoclinic ZrO2, oxygen deficient rhombohedric Zr3O and interestingly indicates presence of high-pressure orthorhombic ZrO2 phase. The coat on Cu consists of monoclinic ZrO2, rhombohedric Zr3O, and metastable tetragonal ZrO2 phase.

Preparation and fine thermal insulation performance of Gd2Zr2O7/ZrO2 composite fibers

Gd2Zr2O7/ZrO2 (GZC) composite fibers were prepared by electro-spinning method. The XRD, XPS and Raman results showed that there were three crystalline phases, tetragonal phase ZrO2, cubic phase ZrO2 and defect fluorite phase Gd2Zr2O7 in GZC composite fibers. GZC fibers remained an intact fiber texture up to 1400 °C according to SEM photographs. The thermal conductivity of GZC fibers was between 0.173 W/(m·K) at 400 °C and 0.309 W/(m·K) at 800 °C, which was lower than that of 7YSZ under the same experimental conditions. The fiber sheet with density about 3.5 g/cm3 has thermal shrinkage less than 3% at 1400 °C. Hence, GZC fibers could be used as refractories for heat protection.

Crystal Phase Distribution and Ferroelectricity in Ultrathin HfO2–ZrO2 Bilayers

(Hf,Zr)O2 ultrathin films are used as ferroelectric layers in emerging digital logic and nonvolatile memory devices. The ferroelectric properties of (Hf,Zr)O2 can be improved by interface engineering, such as the formation of nanolaminates with distinct HfO2 and ZrO2 layers. Herein, the ferroelectric performance of HfO2–ZrO2 ultrathin bilayer devices is shown to depend on the stacking order of HfO2 and ZrO2, which affects the quantity of the noncentrosymmetric orthorhombic Pca21 crystal phase. By combining X‐ray diffraction with a novel extended X‐ray absorption fine structure (EXAFS) analysis procedure, the orthorhombic, tetragonal, and monoclinic phase fractions are quantified for bilayers composed of 3 nm HfO2 and 3 nm ZrO2. A significantly larger orthorhombic ZrO2 phase fraction is found when ZrO2 has an unconstrained surface during annealing, whereas the presence of a ZrO2 interface with the substrate results in a substantial tetragonal ZrO2 phase fraction and a 2.4× smaller remanent polarization. HfO2 is found to be less susceptible than ZrO2 to crystal phase templating. The methods presented herein enable mechanistic studies of ferroelectric wake‐up, fatigue, and processing effects in (Hf,Zr)O2 films, accelerating the development of electronic devices that rely on ferroelectric oxides.

The Effect of Ceria Content on the Acid–Base and Catalytic Characteristics of ZrO2–CeO2 Oxide Compositions in the Process of Ethanol to n-Butanol Condensation

Ethanol conversion into n-butanol was performed over ZrO2–CeO2 mixed oxide catalysts. The effect of ceria content on the acid–base and catalytic properties of ZrO2–CeO2 compositions has been studied. The introduction of CeO2 additives into zirconia stabilizes the tetragonal phase of ZrO2 leading to an increase in basicity of the samples and, as a result, increases the activity of catalysts towards n-butanol. The highest ethanol conversion, selectivity and the rate of n-butanol formation were obtained over the ZrO2–CeO2 sample with 10% of ceria, which exhibited the highest concentration and strength of base sites. This sample consists of a solid solution of ZrO2–CeO2, whereas at higher concentrations of additive, CeO2 forms an individual phase.

Porous Fe2O3-ZrO2 and NiO-ZrO2 nanocomposites for catalytic N2O decomposition

Mesoporous Fe2O3-ZrO2 and NiO-ZrO2 nanocomposites with 10 and 20 wt% of Fe2O3 and NiO composition were prepared by modified sol-gel method. The physico-chemical characteristics of calcined nanocomposites were evaluated utilizing different techniques such as X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron spectroscopy, N2-physisorption, H2-temperature programed reduction, Fourier transformed infrared spectroscopy after pyridine adsorption and X-ray photoelectron spectroscopy. The N2O decomposition activity of calcined nanocomposite catalysts was evaluated using fixed bed reactor at different reaction temperatures. Bare mesoporous ZrO2 without any reducible oxide exhibited 30% N2O conversion at reaction temperature of 550 °C. Fe2O3-ZrO2 nanocomposites with 10 wt% Fe2O3 offered enhanced N2O conversion (≈95%) and stability for N2O decomposition at 550 °C. Interestingly, NiO-ZrO2 nanocomposite with 20 wt% NiO exhibited lowest N2O conversion among the synthesized nanocomposites. The variations in N2O decomposition activity of Fe2O3-ZrO2 and NiO-ZrO2 nanocomposites could be expounded on the basis of catalyst characterization results. It was observed that presence of reducible M-O-Zr (M = metal) species along with crystalline tetragonal ZrO2 phase is essential to obtain better N2O decomposition. A complete ZrO2 phase transformation to cubic and large NiO particle size were responsible for the poor catalytic activity for NiO-ZrO2 nanocomposite with 20 wt% NiO. The durability of Fe2O3-ZrO2 and NiO-ZrO2 nanocomposites was tested for about 120 h and the results revealed that the synthesized nanocomposites were robust without losing any catalytic activity.

Synthesis, characterization and luminescence properties of ZrBDC:Eu3+,Tb3+ nanoscaled metal organic frameworks

AbstractZirconium nanoscaled metal–organic frameworks doped and co‐doped with Eu3+ and/or Tb3+ (ZrBDC:Eu3+,Tb3+) have been synthesized by hydrothermal method using 1,4‐dicarboxylic acid as linkers. The luminescence spectra obtained indicated that under 254 nm excitation, the as‐synthesized ZrBDC:Eu3+,Tb3+ and ZrO2:Eu3+,Tb3+ nanoparticles have multicolour visible emissions at 473, 591, 612 and 701 nm assigned to the 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3 and 5D0 → 7F4 transition of Eu3+ ions and at 488, 582 and 621 nm assigned to 5D4 → 7F, 5D4 → 7F5; 5D4 → 7F4 and 5D4 → 7F3 transitions of Tb3+ ions, respectively. The X‐ray diffraction and field emission scanning electron microscopy results suggest that the ZrBDC:Eu3+,Tb3+ nanoscaled metal–organic frameworks can be used as precursors to design the tetragonal phase of ZrO2:Eu3+,Tb3+ nanoparticles with high purity and a narrow size distribution via heat treatment process. The as‐prepared ZrO2:Eu3+,Tb3+ nanoparticles have size of about 10‐15 nm with BET multipoint surface area of 162 m2/g.

Coral reef-like Pt/TiO2-ZrO2 porous composites for enhanced photocatalytic hydrogen production performance

Polystyrene (PS) colloidal microspheres synthesized by the self-assembly technology were used as templates, a series of Pt/TiO2-ZrO2 composites with TiO2 anatase phase and ZrO2 tetragonal phase were synthesized by sol–gel, vacuum impregnation and photoreduction based on the colloidal crystal template. The composites treated with PS microspheres as templates exhibited an overall shape similar to the natural formation of uneven grooves. Meanwhile, there were three-dimensional ordered macroporous structures on the surface of composites, showing a coral reef-like porous structure. In addition, the loading of the precious metal Pt significantly enhanced the absorption of the composite in the visible region. The plasma resonance effect and the larger work function of Pt prolonged the carrier lifetime, thus enhancing photocatalytic properties of coral reef-like porous composite Pt/TiO2-ZrO2. The photocatalytic activity of coral reef-like porous composite Pt/TiO2-ZrO2 was higher in the experiment of multi-mode photocatalytic degradation of Rhodamine B, which had certain degradation of various dyes and organic pollutants. In the meanwhile, the experimental results of photocatalytic hydrogen production from water showed that the hydrogen production of coral reef-like Pt/TiO2-ZrO2 porous composites (7082.8 μmol g−1) was more 600 times than that of TiO2 (11.3 μmol g−1) during 8 h, indicating that the loading of noble metal Pt, the synergistic effect of TiO2 and ZrO2, and the coral reef-like porous structure of the composite enhanced the photocatalytic activity.

Photoluminescence studies of ZrO2:Tm3+/Yb3+ coatings formed by plasma electrolytic oxidation

Zirconia coatings doped with various contents of Tm3+ and Yb3+ were formed by the plasma electrolytic oxidation process of zirconium foils for 15 min in alkaline electrolyte containing Tm2O3 and Yb2O3 powders in different concentrations. The coatings were composed of monoclinic and tetragonal ZrO2 phases, but Tm and Yb incorporated into ZrO2 coatings induces phase transformation from monoclinic phase to tetragonal phase. The excitation photoluminescence (PL) spectra of ZrO2:Tm3+/Yb3+ coatings were featured by a broad band at around 280 nm related to zirconia host, and a peak at around 359 nm corresponding to the 3H6→1D2 transition of Tm3+. The coatings were excited by the 280 nm and 359 nm incident light, resulting in a strong zirconia PL band, and 1D2→3F4 down-conversion luminescence of Tm3+, respectively. With 980 nm excitation and subsequent absorption by Yb3+, an up-conversion PL was observed. Emission at 799 nm is attributed to the 3H4→3H6 transition of Tm3+. PL spectra of samples doped with 8 different combinations of Tm3+ and Yb3+, allow the analysis of the responsible mechanisms and their presentation in the Jablonski diagram. CIE chromaticity coordinates were calculated, revealing dependence of the PL color upon the Tm3+/Yb3+ doping concentration and excitation light wavelength. By 280 nm and 359 nm excitation, the samples emit cyan and purple light, respectively.

Three-dimensional ordered hollow sphere composite Pt/TiO2-ZrO2: enhanced performance of photocatalytic degradation and photocatalytic hydrogen evolution

In this paper, a three-dimensional ordered hollow sphere (3DOH) structure composite Pt/TiO2-ZrO2 was prepared by using polystyrene (PS) colloidal spheres as the template and combining with two-step vacuum impregnation method, of which the composition, crystalline structure, morphology, and surface physicochemical properties were characterized by X-ray diffraction (XRD), UV-vis diffuse reflectance (UV-vis/DRS), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and nitrogen adsorption-desorption measurements. The results illustrate the crystal type of 3DOH Pt/TiO2-ZrO2 is mainly anatase TiO2 and tetragonal ZrO2 phase, which exhibits a three-dimensional ordered hollow sphere structure. Hollow spheres are arranged orderly; moreover, the composite shows a strong absorption in the visible region due to the effect of surface plasmon absorption (SPA) after doping Pt nanoparticles. Meanwhile, the photocatalytic activity of 3DOH Pt/TiO2-ZrO2 was investigated by using Congo red as the model molecule. The results show that 3DOH Pt/TiO2-ZrO2 has good photocatalytic activity under multi-modes photocatalytic experiments, and its activity is higher than that of P25, ZrO2, and other Pt/TiO2-ZrO2 not treated by PS colloidal spheres. In addition, the total amount of hydrogen production of 3DOH Pt/TiO2-ZrO2 is 100 times as much as the commercial P25 in the photocatalytic hydrogen evolution experiment (8 h), which shows an excellent photolysis of water hydrogen production activity.

Synthesis of Ni Catalyst Supported on SiO2-ZrO2 Binary Oxide for Hydrodeoxygenation of Phenol

Hydrodeoxygenation is a one-step reaction that involve the hydrogenation of unsaturated carbon followed with the deoxygenation of the carbon-oxygen bond. This reaction is effective for converting biomass-derived chemicals from bio-oils, fats, woods, and lignocellulosic materials into biofuels using metal-based oxide catalysts. A Ni based-metal oxide catalyst is reported for hydrodeoxygenation reaction of phenol. The catalyst was prepared by a wet-impregnation method using Ni(NO3)2.6H2O dissolved in deionized water and mixed with the previously prepared SiO2-ZrO2 binary oxide as support. After calcination and reduction at 500 °C, Ni/SiO2-ZrO2 catalyst was obtained. The XRD results showed 2θ peaks for metallic Ni at 30°, 44° and 76°. Additional peaks were detected at 2θ = 35°, 50°, 51°, and 60° for ZrO2 tetragonal phase. However, peaks were not detected for SiO2 suggesting amorphous SiO2-ZrO2 composite formation. The XRF analysis of Ni loading was detected at 16.45%. The catalyst activity test for hydrodeoxygenation of phenol was performed using a batch reactor at 200 °C for 2 h and 8 h. The GC-MS analysis gave product conversion for 2 h at 16.84% with the selectivity formation of cyclohexanol and cyclohexanone at 48.10% and 45.78% yield, respectively. After a prolonged reaction time of 8 h, 100% selectivity for cyclohexanol was achieved. Product distribution showed that the catalyst is active for hydrogenation of benzene better than -OH or C=O deoxygenation. The results suggest Ni/SiO2-ZrO2 could be a potential catalyst for biofuel production via hydrogenation reaction.

Ni/Y2O3–ZrO2 catalyst for hydrogen production through the glycerol steam reforming reaction

In the study presented herein, the catalytic activity and stability of a Ni catalyst supported on Y2O3–ZrO2 was examined for the first time in the glycerol steam reforming reaction and compared with a Ni/ZrO2. The addition of Y2O3 stabilized the ZrO2 tetragonal phase, increased the O2 storage capacity of the support and the medium strength acid sites of the catalyst, and although the Ni/Zr catalyst had a higher concentration of basic sites, the Ni/YZr presented more stable monodentate carbonates. Moreover, the Ni/YZr had substantially higher Ni surface concentration and smaller Ni particles. These properties influence the gaseous products’ distribution by increasing the H2 yield and selectivity and preventing the transformation of CO2 to CO, by inhibiting the reverse water gas shift (RWGS) reaction from taking place. For both catalysts the main liquid products identified were allyl alcohol, acetaldehyde, acetone, acrolein, acetic acid and acetol; these were subsequently quantified. The time-on-stream experiments showed that the Ni/YZr was more stable during reaction and had a higher H2 yield after 20 h (2.17 in comparison to 1.50 mol H2/mol C3H8O3, for the Ni/Zr). Extensive investigation of the carbon deposits showed that although lower amounts of coke were deposited on the Ni/Zr catalyst, these structures were more graphitic in nature and had fewer defects, which means they were harder to oxidize. Moreover, transmission electron microscopy (TEM) analysis showed that sintering of Ni nanoparticles during the reaction was significant for the Ni/Zr catalyst, as the mean particle diameter increased from an initial value of 48.2 to 67.9 nm, while it was almost absent on the Ni/YZr catalyst (the mean particle diameter increased from 42.1 to 47.4 nm).

Fission recoil-induced microstructural evolution of the fuel-cladding interface [FCI] in high burnup BWR fuel

Understanding the structural evolution and reduction-oxidation behavior of nuclear fuel and cladding during operation is essential for predicting performance during and after service in light water reactors. Using TEM/STEM imaging of cross-sections of the fuel-cladding oxide interface region of high burnup BWR fuel, fission recoil radiation was demonstrated to not only stabilize the tetragonal phase of ZrO2 at temperatures well below the equilibrium temperature, but also to cause grain growth proportional to the fission recoil radiation damage. The tetragonal phase ZrO2 was exclusively present (no monoclinic phase) only in the region where fission product metal particles were found (∼6 μm depth).

TaZr2.75O8 ceramics as a potential thermal barrier coating material for high-temperature applications

A series of TaO2.5-doped ZrO2 (1-x)ZrO2-xTaO2.5 (x = 0.08, 0.15, 0.2 and 0.28) ceramics were synthesized by solid state reaction at 1600 °C for 20 h. XRD results reveal that no tetragonal ZrO2 phase forms in the TaO2.5–ZrO2 system. Instead, a mixture of monoclinic ZrO2 (m-ZrO2) and orthorhombic TaZr2.75O8 can be detected for (1-x)ZrO2-xTaO2.5 ceramic within compositions x ≤ 0.2. As the doping content increases, the content of m-ZrO2 decreases and the final product in the composition of 0.72ZrO2-0.28TaO2.5 is primarily composed of TaZr2.75O8. Microstructure together with the thermophysical and mechanical properties of TaZr2.75O8 ceramic were investigated for possible applications as thermal barrier coatings (TBCs). The thermal conductivity with a minimum value of 1.65 W/m·K at 800 °C for TaZr2.75O8 ceramic is ∼30% lower than that of dense YSZ and the dense ceramic also has a moderate average thermal expansion coefficient (TEC), about 9.14 × 10−6 K−1 from room temperature (RT) to 1300 °C. Besides, TaZr2.75O8 exhibits a high microhardness (11.85 ± 0.42 GPa) and fracture toughness (3.15 MPa·m1/2). These preliminary results indicate that TaZr2.75O8 can be used as an alternative material for the ceramic layer in TBCs system with respect to its superior thermal and mechanical properties.

Stabilization of ZrO2 Concentrate by Rare Earth Elements (La, Nd, Pr, Ce)

The effect of annealing and sintering temperature on phase transformation of ZrO2 is studied in relation to REE concentrate content using differential thermal analysis, Raman spectroscopy and x-ray diffraction. It is shown that introduction of REE concentrate in an amount of more than 15 wt.% stabilizes ZrO2 tetragonal phase solely at below 1200 °C. A further increase in temperature leads to destabilization of the tetragonal phase with formation of the monoclinic and cubic phases of the Ln2Zr2O7 type isostructural compounds (n = La, Nd, ...) with a pyrochlore structure.

Effect of Modifying Additives on the Catalytic Properties of Zirconium Dioxide in the Conversion of Ethanol Into 1-Butanol

It was established that modifying additives CeO2, SiO2, and H3PO4 change the catalytic properties of compositions based on ZrO2 in the conversion of ethanol into 1-butanol due to a change in the phase composition of ZrO2, which determines its acid–base properties. As a result of stabilization of the tetragonal ZrO2 phase with additions of CeO2 and H3PO4 an increase in basicity occurs, leading to an increase in the selectivity and productivity of the catalysts in 1-butanol.

Iron modified /ZrO2 in application of removing trace olefins from aromatics

A solid super-acid catalyst /Fe2O3-ZrO2 (FeSZ) was prepared by coprecipitation method to remove olefins from aromatics. Effects of iron sources and Fe2O3 content were studied. FeSZ and /ZrO2 (SZ) were characterized by XRD, FT-IR and NH3-TPD. The characterization of the catalysts revealed that the addition of iron purified the tetragonal phase of ZrO2, increased the strength of the acid sites. Catalytic activity test showed that FeSZ with 5 wt% Fe2O3, using Fe2 (SO4)3 as iron source, exhibited the highest activity for removal of olefins. Compared with SZ, the catalytic activity of FeSZ increased 6.1%.

Performance enhancement of all-solid CO2 absorbent based on Na2CO3-promoted MgO by using ZrO2 dispersant

MgO is a promising base material for CO2 absorbents to be used at elevated temperatures of 200–500 °C. To develop a CO2 capture process utilizing the fluidized bed technology, in which the absorbents are required to be mechanically robust, alkali carbonates are considered as the promoter for MgO. However, alkali carbonate-promoted MgO absorbents have the problems of low capacity and poor cycling characteristics. In the present study, we sought the solutions of these problems of alkali carbonate-promoted MgO absorbents by using a solid dispersing medium. We investigated the effect of using a large surface area tetragonal ZrO2 derived from ZrO(OH)2⋅xH2O as the dispersing medium of Na2CO3-promoted MgO absorbent on its CO2 absorption properties. The tetragonal phase of ZrO2 was formed through doping Mg and/or Na in the course of sample preparation. The presence of ZrO2 increases MgO conversion by 50%, conversion rates by 350%, and durability in repeated absorption and desorption cycles by 20%. The analysis data on the samples in various stages of CO2 absorption and desorption show that the ZrO2 dispersant induces a more homogeneous distribution of the active components and keep them from segregating from each other. The same principles work well with other promoters such as K2CO3.

A DFT study of dimethyl carbonate synthesis from methanol and CO2 on zirconia: Effect of crystalline phases

The reaction mechanism of dimethyl carbonate (DMC) synthesis from methanol and CO2 over cubic (c), tetragonal (t), and monoclinic (m) ZrO2 phases have been investigated by density functional theory (DFT) calculations. The two possible reaction routes have been examined on the three most stable surfaces of zirconia, namely the dry perfect c-ZrO2(1 1 1), t-ZrO2(1 0 1), and m-ZrO2(1¯ 1 1). The Mulliken charge analysis suggested that methanol and CO2 were activated by the Lewis basic sites. Our DFT results showed that the reaction took place through the same route on all three surfaces: 2CH3OH + CO2 → 2CH3O + 2H + CO2 → CH3OCOO + 2H + CH3O → CH3OCO + O + CH3O + 2H → DMC + H2O. In the process, CH3OCOO → CH3OCO + O was the rate-controlling step on the c-ZrO2(1 1 1) and m-ZrO2(1¯ 1 1) surfaces, while CH3OCO + CH3O → DMC was rate-controlling step on the t-ZrO2(1 0 1) surface. The activation free barriers were evaluated on the basis of the rate-controlling steps. The lowerst value was found for the reaction on the t-ZrO2(1 0 1) surface and was equal to 196.4 kJ/mol, while the highest activation free barrier was 274.1 kJ/mol, relative to the reaction on c-ZrO2(1 1 1). Therefore, the results showed that the order of catalytic activity of the dry catalysts was as follows: t-ZrO2 > m-ZrO2 > c-ZrO2. In addition, the catalytic activity of ZrO2 could be determined by the acid-baisic properties of surface and electronic structures. The present work therefore provides a theoretical guidance for designing the hydrated and composite catalysts for DMC synthesis from methanol and CO2.

Mesoporous V‐Zr Catalysts for Selective Formation of 1,4‐Naphthoquinone by Degradation of Naphthalene with Hydrogen Peroxide

AbstractIn order to control the deep oxidation of naphthalene with hydrogen peroxide for increasing the 1,4‐naphthoquinone selectivity, the mesoporous V−Zr samples were prepared by evaporation induced self‐assembly (EISA) method, and their physical chemical properties were characterized by X‐ray diffraction, X‐ray fluorescence spectrometer, N2 sorption, Raman, temperature programmed oxidation, scanning electron microscope‐energy dispersive X‐ray spectroscopy and transmission electron microscope techniques. The characterization results showed that the vanadium species can be successfully homogeneously incorporated into the ordered framework of mesoporous ZrO2, and it would stabilize the tetragonal ZrO2 phase and increase the temperature of phase transformation from tetragonal to monoclinic phase. The highest surface areas and appropriate pore volumes derived from more oxygen vacancies owing to the valence unbalance between the vanadium and zirconium species for the 12V−Zr‐773 sample with the Xm value of 1.1% has a better catalytic performance than other catalysts, whose selectivity of 1,4‐naphthoquinone can reach 67.7%. The catalytic performance would be promoted and the catalytic stability can be kept well even after reaction for five times using ascorbic acid as reducer. This method can provide a valuable reference for the degradation of naphthalene to the protection of the environment.

Full Tetragonal Phase Stabilization in ZrO₂ Nanoparticles Using Wet Impregnation: Interplay of Host Structure, Dopant Concentration and Sensitivity of Characterization Technique.

Here, we show that wet impregnation of ZrO2 nanoparticles with 10% and 20% Eu oxide followed by thermal anneal in air above 500 °C produces full stabilization of the tetragonal phase of ZrO2 without evidencing any phase separation. The bare ZrO2 nanoparticles were obtained using three synthetic methods: oil in water microemulsion, rapid hydrothermal, and citrate complexation methods. The homogeneity of the solid solutions was assessed using X-ray diffraction, Raman spectroscopy, high resolution transmission electron microscopy, and advanced luminescence spectroscopy. Our findings show that wet impregnation, which is a recognized method for obtaining surface doped oxides, can be successfully used for obtaining doped oxides in the bulk with good homogeneity at the atomic scale. The limits of characterization technique in detecting minor phases and the roles of dopant concentration and host structure in formation of phase stabilized solid solutions are also analyzed and discussed.