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The presence of a temperature gradient (if any) within the ceramic sample is casually ignored during the sintering of ceramic shapes. The present work exposes some serious repercussions of such a thought process and provides simple solutions to mitigate the same; 3 mol.% yttria‐doped zirconia ceramic was used for this study. With the help of the combinatorial finite element analysis (FEA) model and real‐life experiments, our work illustrates the complex interplay of heat transfer mechanisms and reveals the dynamic nature of temperature distribution during the heating and cooling cycles of ceramics. Although the rate of heating is usually assigned as the most important factor during sintering, the present study shows that variations in heat transfer mechanism and sample geometry contribute very strongly to overall temperature distribution during the heating, holding, and cooling cycles. Along with of vertical positioning of the samples (inside the furnace), a bottom supporting ceramic plate with a high thermal conductivity can also help in reducing the temperature gradient between the top and bottom of the ceramic samples. Overall, exposing the sample most for the radiative heat transfer holds the key to successful sintering in order to avoid any phase, compositional, or microstructural heterogeneity across the thickness of the specimen. [ABSTRACT FROM AUTHOR]

A vacuum environment is usually preferred for reducing the dwell time and sintering temperature for doped zirconia ceramics. However, for the present work with 10 mol.% CaO‐doped ZrO2 (10CaSZ) ceramics, both hot‐pressing and vacuum sintering techniques yielded ceramics with open pores (ρ ∼ 93%) and significant amounts of the deleterious monoclinic phase (>$ > $50%). This is in stark contrast with the conventionally sintered highly dense (>99%) 10CaSZ ceramics, where only tetragonal and cubic phases were noted. Probing via electron paramagnetic resonance (EPR) depicted the trapping of oxygen vacancies by vacancies generated in vacuum at high temperature. A possible change in the local coordination (of ions) and the subsequent chemical environment was confirmed by the observed asymmetric signal shape and broader linewidth of the EPR signals. Potential loss of oxygen and deviation from stoichiometry (for dopant) was confirmed via EPR analysis along with the support of energy dispersive spectra analysis. Despite no noticeable shift in the XRD pattern for Ca2+ depletion, the observed compositional gradient differences in the calcium elemental mapping suggested dopant segregation at the grain boundaries. The conclusions from the present work point toward specificity of a given materials system for its beneficial densification under hot pressing or vacuum sintering. [ABSTRACT FROM AUTHOR]

Translucent, monoclinic-free, novel calcia-stabilised zirconia ceramics were developed utilising conventional (pressureless) sintering. The 10 mol% CaO-doped zirconia (10CaSZ) ceramic depicted a maximum transmittance of 81% at 600 nm for a 0.6 mm thick pellet while for 3 mol% CaO-doped zirconia (3CaSZ) phase-pure tetragonal system, the value was recorded as 59% at the same wavelength and thickness. The ultrafine (~ 3 nm) nanoparticles sintered via two-step sintering process yielded full densification (> 99%) at temperatures as low as 1150 °C. The average grain size of sintered 3CaSZ ceramic was 85 nm. For 10CaSZ ceramic, it increased from 170 nm to 0.76 μm with elevated sintering temperatures. The increase of sintering temperature ensured different microstructure from ultrafine grains, a bimodal grain size distribution, and ultimately leading to a grain-locking morphology. The influence of microstructure and constituent phases (tetragonal and cubic) on total forward transmittance in the visible range was analysed and explained. [ABSTRACT FROM AUTHOR]

Various magnetic materials (for example, ferro, ferri, antiferromagnetic) are characterized by their respective transition temperatures (for example, Curie and Néel transitions). Knowledge of these transition temperatures is vital from an application standpoint. Accurate measurements by suitable characterization techniques are needed for identifying these transitions. Several techniques have been used to identify Curie and Néel transition temperatures, with thermal methods being one of the preferred choice. These thermal methods include differential scanning calorimetry (DSC), differential thermal analysis, and thermogravimetric analysis. Although thermal analysis tools have been popularly used for examining magnetic phase transitions, still much confusion exists on their efficacy and might. This review article highlights the strength and limitations of measuring Curie and Néel transitions by thermal techniques; measurements by DSC were the most common choice in previous works. Considering the intrinsic/fundamental nature of these Curie/Néel transitions, such confusion on their measurements (by thermal techniques) and their subsequent analysis (for the order of transition) suggests that a more comprehensive understanding of the events should be an immediate future goal for the research community, at large. [ABSTRACT FROM AUTHOR]

We have fabricated VO 2 nano-columns (NCs) on the aluminized quartz glass substrates using glancing angle deposition (GLAD) technique inside the electron beam (e-beam) evaporator chamber. An e-beam deposited TiO 2 thin cap-layer has been introduced on the top of the VO 2 NCs to protect VO 2 phase which is usually unstable and turns to stable higher oxidation state, i.e., V 2 O 5. The X-ray diffraction (XRD) analysis of TiO 2 thin film (TF) coated VO 2 NCs shows the presence of VO 2 phases along with the other oxidation states. The Fourier-Transform-Infrared-Spectroscopy (FTIR) confirms the presence of Ti–O–V, V–O vibrations bands in VO 2 NCs/TiO 2 TF samples. The VO 2 NCs/TiO 2 TF sample possesses a sharp drop (~103 order) in resistance at the transition temperature (T c) ~66 °C. This sample also shows a stable semiconducting to metallic phase (vice versa as well) transition temperature (PTT) hysteresis even after one month which ensures the stable performance in terms of phase transition characteristic. Small-radius polaron model (SRPM) is used to calculate the sheet resistance of the VO 2 NCs, where we consider the effect of thermal lattice vibrations on the overlap integral of the crystal atoms. The temperature dependency of constants A and ε have been observed uniquely. The Fermi-Dirac (F-D), Migdal distribution (MD) model have been taken into account for the first time to calculate the conduction band carrier density of VO 2 NCs and ratio of the resistance in the semiconducting (R S), metallic phase (R M) is also calculated. The calculated electron concentration (n c) is 3.1 × 1019 cm-3 at the point of PTT (66 °C). [ABSTRACT FROM AUTHOR]

Recently, CaO‐doped (≤4 mol.%) tetragonal zirconia (CaSZ) ceramic was recommended as a potential alternative to yttria‐stabilized ZrO2 (YSZ). Here, we investigate the limits of starting particle sizes on the stability of tetragonal (t) phase and other associated benefits on measured properties. Synthesized CaSZ powders calcined with different temperatures were used as a mono‐sized or mixed (i.e., two different calcination temperatures) batch fraction for making dense CaSZ ceramic. The mixed‐batch powders were found to be far more efficient in stabilizing the t‐phase in ceramic. Compared to YSZ, CaSZ recorded remarkable enhancement in toughness (up to 8.3 MPa m$\sqrt {\mathrm{m}} $). Contrary to YSZ, CaSZ ceramic demonstrated outstanding thermal stability. [ABSTRACT FROM AUTHOR]

Yttria‐stabilized zirconia (YSZ), although well known for a lot of excellent engineering applications, has limited footprints in the field of adsorption/dye removal. Through this work, we demonstrate the remarkable efficacy (adsorption capacity ∼550 mg/g) of 8 mol.% YSZ nano‐adsorbents for toxic azo‐dye (e.g., Congo red) removal. The consistency of our adsorption experiments was validated with the help of a series of tests, such as regeneration (via thermal and chemical routes), in real‐life river water, with mixed ion solution, and under varied pH (3–11). Noteworthy is also that the commercial trademark composition (with the same dopant concentration) showed little/no adsorption. Our success of the adsorption experiments is credited to the multitude of factors, namely, size refinement ∼6 nm, retainment of phase‐pure cubicity, and enhanced surface area (155 m2/g), which eventually led to the generation of massive oxygen vacancies on our synthesized doped‐zirconia surfaces. [ABSTRACT FROM AUTHOR]

• Thermophysical properties measured for textured and un-textured La 2 Ce 2 O 7 ceramics. • Texturing took place along the closed packed 〈111〉 as well as measurement direction. • Thermal conductivity (1.68 W/mK), expansion (15.2 × 10−6/ °C) noted within 600–1200 °C. • Thermal expansion and conductivity follows a texture-insensitive trend, in general. Cubic crystals are generally known to be isotropic with respect to second rank property tensor and hence expected to show no change in relation to the measurements involving such properties. In a stark contrast, fluorite (F m 3 ¯ m) cubic textured La 2 Ce 2 O 7 ceramic depicted a strong dependence with electrical resistivity in our recent study. This motivated us to examine the effect of texture on other second rank tensor properties, namely, thermal conductivity (TC) and thermal expansion coefficient (TEC). The texturing in La 2 Ce 2 O 7 ceramic took place along the closest packed 〈111〉 direction. The thermophysical properties (TC and TEC), measured for both textured and un-textured ceramics, depicted no special relevance of texture; reveling a fundamental difference between electron conduction and thermal conduction via phonons. The dependence of thermophysical properties on the cubic systems seems to extend beyond symmetry; a number of such factors are highlighted. [Display omitted] [ABSTRACT FROM AUTHOR]

Sintering of ceramics is known to suffer from homogeneity issues (of phase, microstructure, etc.). The present work aims to provide a simple solution for the same via positioning the sample vertically during conventional sintering. Via vertical sintering, we present two different case studies (with doped-ZrO 2 and La 2 Ce 2 O 7 systems) and illustrate two distinct benefits; e.g., restricting the formation of an otherwise deleterious monoclinic phase in zirconia bodies, and ensuring uniform in-plane texture development on both sides of the ceramic. In each case, the issues observed in the horizontally placed ceramic have been explained in connection to the heat transfer in the ceramic body. Discrepancies in heat transfer resulted in variations in grain orientation and size (mean, median, and cumulative size distribution), eventually leading to different phase developments and texture. This small adjustment (of the positioning of ceramic bodies) may be beneficial at an industrial scale; especially with samples having a large length/diameter ratio. [Display omitted] • Crucial dependence of positioning of ceramic samples during conventional sintering. • Doped-ZrO 2 and La 2 Ce 2 O 7 ceramic was chosen for the case studies. • Vertical sintering resulting in uniform texture and control phase-purity. • Horizontal sintering depicted abundant monoclinic-ZrO 2 phases. • Discrepancies noted for in-plane texture of horizontally sintered La 2 Ce 2 O 7 ceramic. [ABSTRACT FROM AUTHOR]

In this work, we show the influence of strain in two different forms (plate and foil) of nickel for hydrogen evolution reaction (HER) in alkaline solution and 3.5% NaCl aqueous solution. The presence of tensile strain in nickel foil lowers the overpotential by about 10 mV to reach a current density of 10 mA cm−2 and improves the reaction kinetics of HER in alkaline solution. The Tafel slope showed a significant change in the strained nickel (i.e., in Ni foil) which gave a value of 111 mV dec−1 compared to unstrained nickel (Ni plate) which was found to be 151 mV dec−1, thus indicating a change in reaction mechanism. Compared to alkaline solution, the effect of strain becomes less pronounced in NaCl solution which can be attributed to Cl− adsorption on the electrode, thereby reducing its catalytic activity. [Display omitted] [ABSTRACT FROM AUTHOR]

• Pivotal dependence of mundane processing factors on texture, resistivity of ceramic. • Flow rate of alkali addition leading to massive changes in the texture of ceramic. • Crushing of nanopowders resulting in major changes in resistivity values. • More than 200% changes in Lotgering factor for La 2 Ce 2 O 7 ceramic. • Minor processing alterations increased electrical resistivity up to 40 times higher. In this work, we illustrate the crucial influence of two very common processing operations that lead to remarkable changes in the texture-electrical resistivity relationship of La 2 Ce 2 O 7 ceramics. The process of adding alkali (during synthesis) and crushing of the obtained ceramic powder depicted more than 200% changes in Lotgering factor (i.e. degree of texture) and up to 40 times variation in electrical resistivity values. The reason for the enhanced texture was correlated to the oriented type of growth in nanoparticles, which eventually led to a massive increase in electrical resistivity values. [ABSTRACT FROM AUTHOR]

Enhanced dye adsorption ability of ZrO 2 with progressive CaO-doping [Display omitted] • Remarkable adsorption (760 mg/g) behaviour of phase pure cubic zirconia (16CaSZ) • Rapid adsorption (∼99 %) via small size (∼4 nm) and high surface area (∼200 m2/g) • Role of zirconia polymorphs (mono, tetra, cubic) for dye adsorption explained. • Promising adsorption ability in simulated industrial effluent. • Dye adsorption via oxygen vacancies with an ion-exchange mechanism. The realm of dye adsorption involving zirconia systems remains an untapped frontier, awaiting the unveiling of its complete prowess. The present work investigates the adsorption potentials of CaO-doped ZrO 2 nanoparticles with varying doping of CaO (0, 7, 10, and 16 mol.%). With the highest adsorption capacity (of 760 mg/g) reported ever for any zirconia system, the 16 mol.% CaO-doped ZrO 2 (16CaSZ) ultrafine nanoparticles portrayed fastest kinetics of dye (Congo red) removal. Along with effect of different pHs (in the presence of different anions such as Cl-, NO 3 –, SO 4 2- and the mixture of them), a simulated wastewater (comprising urea, different salts, dye, sand, grass, engine oil etc.) was made to examine the efficacy of our nano-adsorbent. The 16CaSZ nanoparticles depicted excellent adsorption (∼99 %) in simulated industrial effluent and duplicated the same performance for pHs ranging from 2 to 10. Multitude of factors (e.g., phase-pure cubicity, highest oxygen vacancy content, pronounced surface area etc.) were credited for this chemisorption-based (R-SO 3 - interactions, as revealed by the structural and spectroscopic investigations on the post-adsorption products) remarkable adsorption process. [ABSTRACT FROM AUTHOR]