Calcium phosphates (CPs) were fabricated with using a continuous flow-type tube reactor under pH 6.4 and 9, within the temperature range from 0 to 100°C. The sample fabricated at the temperature range from 0 to 60°C involved not only dicalcium hydrogenphosphate dihydrate (DCPD) as the primary phase but also octacalcium phosphate (OCP). As the relative X-ray diffraction intensity of OCP increased with increase in the synthesis temperature, particles of a sheet-like shape appeared. The samples fabricated at 80 and 100°C have a crystalline phase of hydroxyapatite (HAp) and morphology of rod-like shape. Under pH 9, in contrast, the reactor fabricated HAp crystalline, irrespective of the synthesis temperature. In particular, at 80 and 100°C, only oval or spindle-shaped HAp was yielded. It was therefore confirmed that the present tube reactor system was versatile to control the size, shape, and crystalline phase of CPs. The morphology, particle size, and specific surface area dependent on the pH and temperature of synthesis were discussed the relative stability of the relevant calcium phosphate phases and equilibrium relations among the orthophosphate ions.

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Metal–organic precursor for aluminum nitride (AlN) ceramics was synthesized by reacting aluminum tri-chloride (AlCl₃) with bis(trimethylsilyl)carbodiimide (BTSC). Fourier transform infra-red (FT-IR) spectrum of the synthesized precursor exhibited characteristic absorption bands assigned to the carbodiimide (N=C=N) group at 2150–2250, and 851 cm⁻¹, while the solid state ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectrum of the precursor exhibited single signal at 103 ppm which was thought to correspond to Al(N=C=N)₄ unit. To examine the potential as a precursor for AlN ceramics, the intrinsic thermal conversion behavior up to 1800°C of the synthesized precursor was investigated under argon atmosphere. X-ray diffraction analysis revealed that the crystallization of AlN was found to start above 800°C, and fully crystallized AlN ceramics was synthesized by the additional heat treatment at 1800°C. In addition to the FT-IR and NMR spectroscopic analyses for studying the synthetic parameters such as reaction temperature and use of catalyst for the formation of polymeric precursors derived from AlCl₃ and BTSC, the effects of heat treatment condition on the polymer/ceramics conversion yield, impurity and crystallinity of the AlN ceramics have been studied by using a thermogravimetric analyzer coupled with a quadrupole mass spectrometer (TG-MS). The results were discussed from a viewpoint to develop a novel synthesis method for AlN ceramics through the polymer precursor route.

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The influence of crystalline grain orientation on nonlinear piezoelectricity in lead-free (K, Na)NbO₃ system ceramics was studied. The orientation control was accomplished using a rolling-extension method with plate-like NaNbO₃ single-crystal particle templates prepared by single-step molten salt synthesis. A negative correlation between the orientation factor and the nonlinear piezoelectricity was observed. The nonlinear coefficient ξ_D31 measured in textured samples with an orientation factor of 97% decreased to one-sixth that of randomly oriented samples.

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A relationship between local structure, electrical conductivity (σ) and thermal property of 10SnO₂·10P₂O₅·10Fe₂O₃·xAgI·(70 − x)V₂O₅, 10SnO₂·10P₂O₅·10Fe₂O₃·xAg₂O·(70 − x)V₂O₅ and 10SnO₂·10P₂O₅·10Fe₂O₃·x/2(AgI·Ag₂O)·(70 − x)V₂O₅ glasses, respectively abbreviated as xAIVSPF, xAOVSPF and xAIAOVSPF with ‘x’ between 0 and 40 mol % were investigated by ⁵⁷Fe-and ¹¹⁹Sn-Mössbauer spectroscopies, X-ray diffractometry (XRD), Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), differential thermal analysis (DTA) and DC two- and four-probe methods. Heat-treatment at 500°C for 100 min of xAIVSPF glass with ‘x’ of 10, 20, 30 and 40 resulted in a marked increase in σ from 2.2 × 10⁻⁵, 9.4 × 10⁻⁶, 3.2 × 10⁻⁶ and 2.6 × 10⁻⁶ S cm⁻¹ to 2.6 × 10⁻¹, 2.1 × 10⁻¹, 5.2 × 10⁻² and 1.3 × 10⁻² S cm⁻¹, respectively. Similar increase in σ caused by heat-treatment was also observed for xAOVSPF and xAIAOVSPF glasses with ‘x’ being equal to or less than 20 mol %. From DTA study, glass transition temperature (T_g) of 248–298°C and crystallization temperature (T_c) of 362–379°C were observed for xAIVSPF glass, whereas gradual decreases in T_g from 277_±5 to 216_±5°C and T_c from 356_±2 to 283_±2°C were confirmed for xAOVSPF glass, implying that substitution of AgI for V₂O₅ didn’t affect the 3D glass network but that of Ag₂O causes the cleavage of the 3D glass network. FT-IR study of the heat treated xAOVSPF glass showed the dissappearance of bridging oxygen of P–O–P and V–O–V with the Ag₂O content, indicating that cleavage of the 3D glass network caused the decrease of the electrical conductivity. It can be concluded that AgI-subsutituted iron tin phosphovanadate glass is better than Ag₂O-subsutituted iron tin phosphovanadate glass for achiving the higher electrical conductivity.

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Mordenite was artificially synthesized using various diatomites for radioactive Cs decontamination. A high CEC (Cation Exchange Capacity) value was obtained when the diatomite had a high Al/Si elemental ratio. The Cs⁺ adsorption rate from 100 ppm Cs solution for the synthesized mordenite (1.0 g) was ca. 100% and ca. 83% in 100 mL of water and seawater, respectively. The composite powder material consisting of mordenite and nano-sized magnetite was synthesized from a mixed slurry of the diatomite and nano-sized magnetite. Magnetic collection rate for the composite material using a neodymium magnet was larger than 90% for the 20 and 30 wt % magnetite-containing composite materials. The total Cs decontamination rates using magnetic collection after the Cs⁺ adsorption in water were 92.7% and 97.2% for the 20 and 30 wt % magnetite-containing composite material, respectively.

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The incorporation of SiC particles into α-β SiAlON matrix leads to an enhancement on the properties. The precise detection of SiC particles in the microstructure is therefore of major interest for understanding the nature of resulting material. Here, α-β SiAlON/SiC composite was analytically examined by using transmission electron microscopy (TEM). Considering the results, nano-sized spherical SiC grains were visualised to be encapsulated with α-β SiAlON matrix. A decisive contrast between the α-β SiAlON and SiC phases was not observed by conventional (C)TEM. However, the SiC grains, α-β SiAlON matrix and grain boundary/intergranular phases were easily able to distinguished to each other via C-K (284 eV), N-K (401 eV) and O-K (532 eV) edges in energy filtering (EF)TEM 3-window elemental mapping and scanning (S)TEM-spectrum imaging (SI)-electron energy loss spectroscopy (EELS) analyses. It is anticipated that analytical (A)TEM approach presented here helps the precise determination of different reinforcement particles and matrix phases in many kind of composite systems.

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The effects of starting particle size and Ba addition on the flexural strength of bulk SiOC ceramics were investigated in polymer-derived SiOC ceramics prepared by a conventional ceramic processing route. Crack-free, dense SiOC discs with 6–7 mm thickness and a 30 mm diameter were successfully fabricated from commercially-available polysiloxane without any fillers or 1 mol % barium isopropoxide-derived Ba as an additive. Agglomerates formed after pyrolysis of polysiloxane led to the formation of domain-like structures surrounded by pores after sintering. The flexural strength of bulk SiOC is strongly dependent on the domain size formed and Ba addition. Both minimization of the agglomerate size in the starting powders by milling after pyrolysis and judicious selection of additives which reinforce the SiOC structure are efficient ways to improve the flexural strength of bulk SiOC ceramics. The typical flexural strength of bulk Ba-doped SiOC ceramics fabricated from submicron-sized SiOC powders was 220 MPa.

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The crystallization kinetics and catalytic properties with amount of precipitated CePO₄ of a 60P₂O₅–9B₂O₃–24ZnO–7CeO₂ glass was investigated. The kinetic parameters, activation energy for crystallization (E_c), and Avrami constant (n) were evaluated under non-isothermal conditions using different thermal analysis (DTA) performed at different heating rates. The DTA curves exhibited two overlapping exothermic peaks associated with the crystallization of the glass. BPO₄ was the first crystalline phase to be formed, and it was followed by the formation of CePO₄, as identified by XRD. The calculated values of the local activation energies for the growth of BPO₄ were 663 kJ mol⁻¹, obtained using the Kissinger method, and 669 kJ mol⁻¹, obtained by the Marotta method. The calculated values of the local activation energies for the growth of CePO₄ were 452 kJ mol⁻¹, obtained by Kissinger method, and 464 kJ mol⁻¹, obtained by the Marotta method. The Avrami constants of BPO₄ and CePO₄ were 1.83–2.56 and 1.40–1.54, respectively. The catalytic properties with the amount of precipitated CePO₄ were studied by thermogravimetric analysis (TGA), which showed that the greater the amount of CePO₄ precipitated, the more the catalytic properties of the glass decreased.

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MSi₂O₂N₂:Eu (M = Ca, Sr, Ba) phosphors were fabricated by a solid state reaction using Si₂N₂O powder as starting material. For the Ca_xSr_0.99−xSi₂O₂N₂:Eu_0.01 phosphor, an increase in the value defined as x causes the peak position to increase from 530 to 548 nm and the peak intensity to decrease while the morphotropic phase boundary is observed for x-values of 0.5 to 0.6. For the Ba_xSr_0.99−xSi₂O₂N₂:Eu_0.01 phosphor, an increase in the x-value from 0 to 0.8 causes the peak position to increase from 530 to 557 nm, while increasing the value of x above 0.8 shifts the peak position back within the range of 557–490 nm.

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Stabilized Al₂TiO₅-based porous ceramics reinforced by in-situ formed mullite whiskers were fabricated by reaction sintering method. The thermal stability, microstructure, mechanical properties and pore size distribution of these porous ceramics were examined. Results show that with the substitution of Al₂O₃ by Fe₂O₃, the thermal decomposition of Al₂TiO₅ is well suppressed, and with the increasing amount of in-situ formed mullite, the mechanical properties are improved obviously under the similar apparent porosity. Finally, a stabilized Al₂TiO₅-mullite porous ceramic with compressive strength of 51.8 MPa, flexural strength of 14.6 MPa and apparent porosity of about 42% was obtained. It had a bimodal pore size distribution and the pore diameter was in the range of 0.1 to 20 µm.

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Although the research on laser ablation advances steadily, mainly on ultra-short pulses (in the order of pico- and femtoseconds), research on the low-cost and low-power-consuming nanosecond regime (>100 ns) is relatively scarce. This process is still difficult to predict, due to the many simultaneous and interacting physical processes that take place in a relatively short time. This study provides an experimental analysis for a ytterbium pulsed fibre-laser on Al₂O₃, by evaluating surface morphology and fracture strength for two sets of parameters. A very well-defined difference in removal rate and resulting surface topographies was observed, suggesting a threshold point between distinct ablation mechanisms. Laser machining also caused a clear increase on the Weibull modulus, while reducing the characteristic stress.

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Giant MFI-type zeolite crystals were synthesized by bulk material dissolution (BMD) method at 473 K employing tetrapropylammonium (TPAOH) as structure directing agent (SDA). The giant crystals were successfully grown up to 2.0 mm in the length direction. The SDA remaining in the crystals could be removed without serious damages to the crystals by a mild heat treatment. In this short paper, size change of giant crystal with process parameters and removal characteristics of SDA are reported.

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