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MZr4P6O24 (M=Mg, Ca, Sr, Ba), which belongs to a new, low‐thermal‐expansion family of materials known as [NZP] or [CTP], were synthesized by solid‐state reaction (oxide mixing) and sol‐gel methods, and their sinterability in two cases was investigated and compared. Thermal‐expansion measurements were made on sintered samples by dilatometry, high‐temperature X‐ray diffractometry, and the laser speckle technique. An anisotropy in axial thermal‐expansion coefficients was observed in these materials. CaZr4P6O24 and SrZ4P6O24 showed reverse anisotropy as well as opposite bulk thermal expansion; i.e., CaZr4P6O24 had negative bulk thermal expansion and SrZr4P6O24 positive bulk thermal expansion in the temperature range 25° to 500°C. The microstructure of the sintered samples was also examined by scanning electron microscopy.

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We report on a scaleable synthesis route for highly luminescent silicon nanocrystal assemblies and demonstrate that their emission properties are identical to those known for other systems containing silicon nanocrystals. Structural investigations confirmed that chemically porosified metallurgical grade silicon powder consists of silicon nanocrystal assemblies having nanometer sizes characterized by very high total internal surface area. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Interfacial shear strength and interfacial sliding friction stress were assessed in unidirectional Sic-filament-reinforced reaction-bonded silicon nitride (RBSN) and borosilicate glass composites and 0/90 cross-ply reinforced borosilicate glass composite using a fiber pushout test technique. The interface debonding load and the maximum sliding friction load were measured for varying lengths of the embedded fibers by continuously monitoring the load during debonding and pushout of single fibers in finite-thickness specimens. The dependences of the debonding load and the maximum sliding friction load on the initial embedded lengths of the fibers were in agreement with nonlinear shear-lag models. An iterative regression procedure was used to evaluate the interfacial properties, shear debond strength ( T~) , and sliding friction stress (T,), from the embedded fiber length dependences of the debonding load and the maximum frictional sliding load, respectively. The shear-lag model and the analysis of sliding friction permit explicit evaluation of a coefficient of sliding friction ( p ) and a residual compressive stress on the interface (a,,). The cross-ply composite showed a significantly higher cwffcient of interfacial friction as compared to the unidirectional composites. [