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As the utilization of nuclear energy continues to expand, there is a growing focus on the development of lightweight and efficient nuclear shielding composites. In this paper, novel WB X /Al (x = 1, 2, 4) composites were designed based on shielding performance. The effects of reinforcement type, volume fraction, and material thickness on the 60Co and 137Cs γ-rays, fast and thermal neutron shielding performances were simulated. The results show that WB/Al composites offer better development potential compared to WB 2 /Al or WB 4 /Al composites. Additionally, a predictive model for the γ-ray shielding effectiveness of WB/Al composites, based on the areal density of tungsten, was proposed. The fabrication process involved mechanical ball milling and spark plasma sintering to fabricate 30 vol% WB/Al composites, with optimization of ball milling time, sintering temperature, and holding time. As a result, a novel nuclear radiation protection composite with uniform composition, a relative density of 97 %, and flexural strength of 527 MPa was acquired. [ABSTRACT FROM AUTHOR]

Zirconia nanorods and polyhedral particles were prepared using the molten-salt method. The effects of the LiF dosage on the ZrO 2 crystal morphology were studied using XRD combined with Rietveld refinement, FE-SEM combined with EDS, FTIR, Raman spectroscopy, and high-temperature microscopy. The results show that the ZrO 2 obtained with LiF is in the monoclinic phase. ZrO 2 nanorods were synthesized at low LiF dosages. Polyhedral ZrO 2 particles were synthesized, and the ZrO 2 crystal planes (100) and (200) were exposed to a high LiF dosage. LiF promoted the dissolution of ZrO 2 and was adsorbed onto the ZrO 2 crystal surface. This work provides a new strategy for controlling morphology and crystal surface exposure. [ABSTRACT FROM AUTHOR]

In this paper, a novel nuclear shielding material capable of shielding neutrons and gamma rays, WB-reinforced Al (WB/Al) composites, was prepared by spark plasma sintering (SPS) process. The microstructure of the composites was characterized, and the effects of WB content, heat treatment and matrix type on the properties of the composites were discussed. The results demonstrate that the WB particles are uniformly dispersed in the aluminum matrix and formed a good binding interface with the matrix. WAl 12 as an interfacial reaction product is identified, and segregation of Si and Mg elements at the reinforcement/matrix interface occurs. The mechanical properties of the WB/Al composites are sensitive to the WB content. The hardness, elastic modulus and bending strength of the composites increase monotonously as the WB volume fraction increasing, up to 234%, 107% and 91.6% higher respectively than those of the monolithic 6061Al. However, the tensile strength reaches a peak point when the volume fraction is 20%. The effects of T6 treatment and matrix type are not pronounced, especially for the composites with high WB content. The thermal neutron and gamma ray shielding properties of the composites both increase with the increase of material thickness and WB content. The WB/Al composites developed in this work show good application prospects in the field of nuclear radiation protection, due to their good mechanical properties and well neutron and gamma-ray shielding performance. [ABSTRACT FROM AUTHOR]

A fluorine-free route has been developed to fabricate V/Pr co-doped zircon (ZrSiO 4) ceramic pigments with Na 3 VO 4 and Pr(NO 3) 3 ·6H 2 O as colourants. The as-prepared pigments were characterized by XRD, Raman, XPS, UV–vis, FE-SEM, TEM and automatic colourimeters. The results show that Na 3 VO 4 can not only act as colourant to produce blue hue, but as mineralizer to accelerate the formation of V/Pr co-doped ZrSiO 4 pigment. A colour tuning between blue, green and yellow can be achieved by increasing the mole ratio of Pr/V, and the most intense yellow hue (L* = 74.55, a* = −0.38, b* = 46.82) is obtained at a mole ratio of Pr/V = 0.5. Both Pr4+ and Pr3+ cations are co-existed in the pigments, where Pr4+ contributes to the generation of yellow hue while Pr3+ undermines the yellow hue. The good chromatic ability in glaze at high temperature suggest its potential application in ceramic decoration. [ABSTRACT FROM AUTHOR]

Effects of cores types on non-solvent displacement nonaqueous precipitation synthesis of core-shell structured materials were investigated via taking case study on effects of carbon sources on C@ZrSiO 4 preparation. The influencing mechanism of carbon sources was investigated via XRD, FE-SEM, TEM and the CIELAB colorimeter. The results show that the optimized carbon source for non-solvent displacement nonaqueous precipitation synthesis of C@ZrSiO 4 is amorphous and isolated spheroid-like carbon source. Neither layer-structured particle nor sheet-like particle can be effectively encapsulated through non-solvent displacement nonaqueous precipitation method. The shell layer is difficult to be effectively encapsulated on the edges of the around of corresponding particle. In comparison with the higher crystallinity core, the amorphous core is more favorable for encapsulation. The core materials selection principles discovered in this work are expected to be widely referred in the preparation of other core-shell structural materials. [ABSTRACT FROM AUTHOR]

A novel (Li,Cr)–ZrSiO 4 jade green ceramic pigment was prepared using LiF as the mineralizer and synergistically enhanced charge-compensator. The effects of Cr/Si mole ratio on the synthesis and coloration of the pigment and the coloring mechanism were investigated via XRD, SEM, TEM, XPS, EPR, NMR, UV–Vis–NIR and CIELAB colorimetry. The results demonstrate that the charge-compensator promotes the synthesis of ZrSiO 4 , and more Cr enters into the zircon lattice. When the n(Cr)/n(Si) is 0.2, the pigments exhibit a jade green hue (L* = 75.74, a* = -7.37, b* = 5.18). The band of the (Li,Cr)–ZrSiO 4 pigments in the visible light region shifts towards positive wavelength (535 nm), which is closer to the center of the green light region. The novel pigments have excellent coloring performance stability while in a base glaze synthesized at 1200 °C and near-infrared reflectance in the range of 700–2500 nm. The co-doping of lithium balances bonding, thereby improving near-infrared performance, which shows broad development prospects in the field of ceramic applications and energy saving. [ABSTRACT FROM AUTHOR]

Novel pressure field assisted non-hydrolytic sol-gel method is developed for the in-situ synthesis of novel seed-pulp-structured C@ZrSiO 4 pigments. The obtained pigments, which are composed of in-situ carbon derived from leaving organic groups as core and zircon as shell, were characterized via DSC-TG, XRD, FT-IR, Raman, XPS, SEM, TEM, UV–Vis, and automatic colorimeters. It was found that the pressure field promotes the non-hydrolytic sol-gel heterogeneous polycondensation reaction and the direct transformation of reaction groups into in-situ spherical carbon. Meanwhile, the in-situ spherical carbon was enclosed by heterogeneous condensation bonds wrap and formed a dense structure. The as-prepared pigments exhibited excellent color rendering performance (L* = 21.07, a* = 0.48, b* = 0.75) and thermal stability. [ABSTRACT FROM AUTHOR]

Novel (Cr,V)–ZrSiO 4 jewel green pigments with good near-infrared reflection performance were prepared by in-situ mineralization at a low temperature of 900 °C. The synthesized pigments were characterized through XRD, FE-SEM, TEM, UV–Vis–NIR, XPS, and CIE L*a*b* colorimetry. The results show that Cr–V co-doping into the zircon lattice can effectively promotes the synthesis of zircon, and significantly produce a coloring effect from blue to jewel green and then to dark green with the increase of Cr/Si mole ratio from 0.025 to 0.4. The optimized Cr/Si is 0.2, showing excellent color rendering performance (L * = 56.69, a * = -18.52, b * = -9.28). The electron transitions of the (Cr,V)–ZrSiO 4 pigments exhibits broadband emission and shifts to longer wavelength (530 nm) relative to V–ZrSiO 4 with Cr/Si mole ratio of 0, corresponding to the jewel green region. And the pigments possess good near-infrared reflectance in the range of 700–2500 nm. The properties especially excellent near-infrared reflection performance make it promising functional pigment for energy-saving and health. [ABSTRACT FROM AUTHOR]

A novel non-solvent displacement-nonaqueous precipitation method was developed for the preparation of core-shell materials by considering C@ZrSiO 4 black pigments synthesis as the case. The effects of the impregnation time, precursor concentration, and carbon content on the synthesis and coloration of the C@ZrSiO 4 pigment and the mechanism of this method were investigated via X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and CIELAB colorimetry. The results showed that the optimal impregnation time, precursor concentration, and carbon content were 24 h, 1.5 mol/L, and 9 wt%, respectively. C@ZrSiO 4 -encapsulated pigments prepared by a non-solvent displacement-nonaqueous precipitation method have a uniform and dense shell-encapsulated zircon layer with a thickness of 10–20 nm. The size of C@ZrSiO 4 encapsulated pigments was 50–210 nm, without particle agglomeration. This uniform and dense encapsulation facilitated an excellent color-rendering effect in the high-temperature glaze, and the chromaticity values of the glaze were L* = 35.05, a* = 0.34, and b* = 1.08. The alkyl halide elimination non-hydrolytic heterocondensation reaction ensured the formation of a uniform precipitate along the surface of the carbon particles with Si–O–Zr bonds as the skeleton. The introduction of the non-solvent kerosene ensured the complete, uniform, and dense progress of the precipitation process to form a C@ZrSiO 4 pigment with a high-quality core-shell structure. The non-solvent displacement-nonaqueous precipitation method might be an extremely promising method for preparing core-shell structural materials. [ABSTRACT FROM AUTHOR]

The effects of raw materials on the nonhydrolytic sol-gel synthesis of Ba 0.6 Sr 0.4 TiO 3 were systematically studied in this work. The samples were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM). Ba(CH 3 COO) 2 , Sr(CH 3 COO) 2 , BaCO 3 and SrCO 3 can undergo deesterification substitution reaction with Ti(OC 4 H 9) 4 to synthesize Ba 0.6 Sr 0.4 TiO 3 phase. Sample taking Ba(CH 3 COO) 2 and Sr(CH 3 COO) 2 as barium and strontium source has better Ba 0.6 Sr 0.4 TiO 3 synthesis results than that of samples using BaCO 3 or SrCO 3. Ba 0.6 Sr 0.4 TiO 3 phase can not be synthesized at low temperature taking BaCl 2 , SrCl 2 and TiOSO 4 as barium, strontium or titanium source due to their strong ionic bonding. TiCl 4 undergoes an alcoholysis reaction with (oxygen donor) alcohol to form a multimolecular association structure and solvated complex chlorotitanium alkoxide, which reduces the possibility of a deesterification polycondensation reaction. The Ba 0.6 Sr 0.4 TiO 3 phase cannot be synthesized at low temperatures when CH 3 CH 2 OH or C 3 H 7 OH is used as the solvent. The synthesis of Ba 0.6 Sr 0.4 TiO 3 is insufficient because of the coordination ability and solvation effect when CH 3 COOH is used as the solvent. The synthesis of Ba 0.6 Sr 0.4 TiO 3 is the best when Ba(CH 3 COO) 2 , Sr(CH 3 COO) 2 , Ti(OC 4 H 9) 4 and glycerol (C 3 H 8 O 3) are used as the barium source, strontium source, titanium source and solvent, respectively. Pure Ba 0.6 Sr 0.4 TiO 3 phase with a particle size of 17–43 nm and high dispersion is synthesized when the molar ratio of barium-strontium-titanium is 0.6:0.4:1.2. [ABSTRACT FROM AUTHOR]

A fluorine-free and low temperature synthetic route derived from in-situ formed mineralizer has been developed to fabricate V–ZrSiO 4 turquoise ceramic pigment. When the calcination temperature is 750 °C and mole ratio of Na 3 VO 4 to ZrOCl 2 ·8H 2 O (NV/Zr) is 0.3, the as-prepared pigment exhibits a cluster-like structure and deep blue hue (L* = 69.28, a* = −12.15, b* = −20.04). The solid state reaction taking place during the mechanical grinding process lead to the in-situ formation of mineralizer NaCl and certain Si–O–Zr bond. The XRD refinement results and hyperfine structure in EPR spectra indicate that vanadium is located at the zircon interstitial site 16g with an isolated V4+ cluster state. The enameled samples exhibit excellent coloring ability, high chemical and thermal stability, suggesting its potential application in ceramic decoration. [ABSTRACT FROM AUTHOR]

Ba 0.7 Sr 0.3 TiO 3 ceramics have excellent electrical performance and wide applications in sensors, capacitors, dynamic random access memory, and so on. High-quality Ba 0.7 Sr 0.3 TiO 3 powders preparation is the premise and basis for obtaining Ba 0.7 Sr 0.3 TiO 3 ceramics with excellent properties. Monodispersed Ba 0.7 Sr 0.3 TiO 3 powders were synthesized using a novel ultrasonic-driven polycondensation nonaqueous precipitation method with tetrabutyl titanate, anhydrous barium acetate, and anhydrous strontium acetate as precursor materials and glycol as the solvent. Ultrasonic irradiation promotes the polycondensation of raw materials; Ba–O–Ti and Sr–O–Ti bonds form in the precipitate, facilitating low-temperature synthesis of Ba 0.7 Sr 0.3 TiO 3 at 550 °C. Ultrasonic irradiation also assists in the monodispersing of precipitates and BST powders and low-temperature sintering, and considerable properties of Ba 0.7 Sr 0.3 TiO 3 ceramics. The Ba 0.7 Sr 0.3 TiO 3 powder and ceramic particle sizes are approximately 30–50 nm and 100–150 nm, respectively. The proposed ultrasonic-driven polycondensation nonaqueous precipitation method is expected to be widely used for preparation of ceramic powders. [ABSTRACT FROM AUTHOR]

Stabilized aluminum titanate fibers were prepared via nonhydrolytic sol-gel (NHSG) method through linear self-assembly of precursors. The results show that NHSG method generates the heterogeneous condensation with the formation of Al–O–Ti, Mg–O–Ti, Fe–O–Ti, Mg–O–Al, Fe–O–Ti bonds, which ensures that magnesium ions and iron ions can enter aluminium titanate lattice and stabilize it at 750 °C. Bimolecular associated structure of chlorotitanium ethoxide titanium precursor promotes the self-linear-assemble of all precursors, which enables the excellent spinnability of sol. Stabilized aluminum titanate fibers have excellent corrosion resistance. The thermal expansion coefficient of stabilized aluminum titanate ceramic is −0.142 × 10−6°C−1. [ABSTRACT FROM AUTHOR]

Abstract AlCrSiN coatings with splendid mechanical and thermal properties have attracted wide attention as excellent alternatives for advanced machining applications. Here, Ni-alloyed AlCrSiN coatings were deposited by cathodic arc evaporation and elaborated with respect to mechanical, tribological and anti-oxidation properties. With the increase of Ni content, multiphase composite structured AlCrSiN-Ni coatings show a sustained decline in hardness, elastic modulus and the ratio of hardness to modulus, which causes the decrease of wear resistance at room temperature and 600 °C. Nevertheless, the addition of Ni effectively enhances the toughness and reduces the friction, especially, at 600 °C, where AlCrSiN, AlCrSiN_Ni5, and AlCrSiN_Ni20 obtained a average friction coefficient of ~0.93, 0.86 and 0.66, respectively. Oxidation kinetics studies at 800 – 1000 °C indicate that Ni-containing coatings have relatively lower activation energies, 173.8 kJ/mol of AlCrSiN_Ni5 and 156.6 kJ/mol of AlCrSiN_Ni20, than 176.5 kJ/mol of AlCrSiN. The faster outward diffusion of Cr in Ni-containing coatings forms a Cr 2 O 3 /NiAl 2 O 4 two-layer oxide scale with less protection effect and poor adhesion, leading to inferior oxidation resistance. [ABSTRACT FROM AUTHOR]

Abstract Monodispersed alumina powders were prepared via nonaqueous precipitation process using aluminum powders as aluminum source, acetic acid as precipitant. Effect of oxygen donor and solvent alcohol such as methanol, ethanol, isopropanol on the preparation of ultrafine alumina powders and the precursor reaction mechanism have been investigated by XRD, FT-IR, TEM, FE-SEM and performance tests of sintered bodies. The intermolecular condensation of methanol with the catalysis of Lewis acid aluminum methoxide leads to hydrolysis of aluminum methoxide, forming amorphous precipitates, dehydration polycondensation of aluminum hydroxide and resulting in serious agglomeration of precipitates and alumina powders, the worst morphology and properties of sintered body. The pulling electron effect and steric hindrance of isopropyl group make the structure of aluminum isopropoxide overwhelmingly stable and relatively arduous to be replaced by precipitant acetic acid, which results in underdeveloped crystallinity and agglomeration of both precipitates and alumina powders, poor morphology and properties of sintered body. The optimized oxygen donor and solvent alcohol is ethanol. Monodispersed, high crystallinity C 4 H 7 AlO 7 precipitates and alumina powders can be obtained when ethanol is used as oxygen donor and solvent, and the highest relative density, mechanical properties and the most homogeneous microstructure was obtained. The density, flexural strength, volume resistivity, breakdown voltage and thermal expansion coefficient are 99.1% of TD, 128.0 ± 2.2 MPa, 9.8 × 1016 Ω∙cm, 45.2 kV/mm and 7.6 × 10−6 °C−1, respectively. Precursor reaction mechanism is deduced that aluminum powders react with oxygen donor alcohol to form aluminum alkoxide with the catalyst iodine, and then react with acetic acid to form crystal C 4 H 7 AlO 7 precipitates. Nonaqueous precipitation method is expected to become a promising candidate for mass production of alumina powders. [ABSTRACT FROM AUTHOR]

Abstract High strength, lightweight mullite whisker skeleton porous materials were prepared via novel facile nonaqueous precipitation method. The phase transition process of precipitate, microstructures and phase compositions of samples, and effects of aluminum fluoride amount on morphologies and properties of mullite whisker skeleton porous materials were investigated by DTA-TG, FE-SEM, XRD, the acid solubility and compressive strength tests. The growth direction of the whisker was determined. The growth mechanism of mullite whisker and formation mechanism of skeleton porous material were also investigated. The results show that the mullite phase forms at a low temperature of 900 °C via nonaqueous precipitation method, due to the formation of Al-O-Si bonds in the precipitate. The formation of mullite whiskers is controlled by gas-solid reaction and the whiskers grow along [001] direction. Well-developed mullite whiskers interlacedly grow into skeleton porous material at 1100 °C. The optimum mullite whisker skeleton porous material with the optimized aluminum fluoride amount of 1.3 of theoretical amount exhibits attractive properties of low density (1.21 g cm−3), high strength (158.6 MPa), low acid solubility (1.58 wt%), low thermal expansion coefficient (1.6 × 10−6 °C−1) and low thermal conductivity (0.28 W/(m K)). This material has the mean pore size of 542 nm and pore size distribution of 32–865 nm. It shows attractive application prospects in filtering and biomedical applications. [ABSTRACT FROM AUTHOR]

A monodispersed Al 2 O 3 @YAG: Ce core-shell phosphor has been synthesized by coating Y 2 O 3 : Ce film on Al 2 O 3 particle. The phosphor has particles size of 60–120 nm and shows high dispersity due to the high dispersed Al 2 O 3 particles prepared by nonaqueous precipitation method. The core-shell structured phosphor consists of a corundum core and a YAG shell. The Al 2 O 3 @YAG: Ce core-shell yellow phosphor presents high yellow emission. The light-emitting diode (WLED) based on this yellow phosphor and InGaN blue chip displays high white purity. This Al 2 O 3 @YAG: Ce core–shell phosphor can be viewed as a promising candidate yellow phosphor for white LEDs. [ABSTRACT FROM AUTHOR]

Alumina powders were prepared via a novel nonaqueous precipitation method with aluminum powders as aluminum source and anhydrous acetic acid as precipitant. The thermal decomposition and phase transformation of crystal precipitate and the influence of precipitate aging were investigated via TG-DTA-MS, XRD, TEM, BET, FE-SEM and performance tests of sintered bodies. The results show crystal precipitate C 4 H 7 AlO 7 transforms to amorphous Al 2 O 3 at 300 °C, and then to γ -Al 2 O 3 at 950 °C, and finally to α -Al 2 O 3 at 1050 °C. The particle size of α -Al 2 O 3 prepared at 1100 °C is 50–100 nm with BET surface area of 25.98 m 2 ∙g −1 . FE-SEM morphology of sintered sample at 1400 °C shows excellent sinterability of the α -Al 2 O 3 powders. Aging eliminates aggregation, and leads to highly homogenized and densified particles. It also affects the densification behaviour during sintering and further influences density, thermal expansion coefficient, flexural strength, volume resistivity and electric breakdown strength of sintered bodies [ABSTRACT FROM AUTHOR]