The Mg₂Al₄[ ]Sn_x[ ] ([ ]) ceramics were successfully synthesized via the solid-state reaction method. The XRD results show that the main phase of the ceramics is Mg₂Al₄Si₅[ ]. When [ ], there is a second phase of Al₂SiO₅. With the increase of x, the content of [ ] gradually increased, the Al₂SiO₅ phase disappeared, and the SnO₂ and MgAl₂O₄ phases appeared. In addition, the cell volume of the ceramic changes with the increase of x, which indicates that partial [ ] successfully enters the lattice with ion substitution and lattice distortion. The relative density and [ ] are highly correlated. The quality factor (Qf) is not only affected by the relative density but also by the symmetry of the [Si₄Al₂] ring. The bond strength as an evaluation of the stability of the crystal structure determines the magnitude of [ ]. Good microwave dielectric properties were achieved for samples at [ ] with sintering at 1400^∘C: [ ], [ ][ ]GHz and [ ][ ]ppm/^∘C, demonstrating that Mg₂Al₄[ ][ ][ ] ceramics are an ideal candidate for microwave electronics.

Calcium phosphate glasses, in which part of calcium oxide was replaced by lanthanum oxide, were prepared by using the conventional melt quench method. The structures of xLa₂O₃ · (50-x)CaO · 50P₂O₅ (x = 0, 1, 3, 6, 12 mol%) samples were investigated by X-ray diffraction (XRD), Raman spectrum, Fourier transform infrared spectrum (FTIR), and differential scanning calorimetry (DSC). The results show that lanthanum oxide acts as network modifier in the network space of glass structure. The glass formation occurs at an O/P ratio of about 3.0–3.12. At larger values, the crystalline phases calcium pyrophosphate (Ca₂P₂O₇) and calcium lanthanum phosphate [Ca₉La(PO₄)₇] are detected in the samples. Raman and FTIR spectra indicate that the structure of lanthanum-free sample is chain P–O–P bond metaphosphate–based Q² units. Glass structure will change to Q² and Q¹ units when the lanthanum oxide content is less then 6 mol%. When lanthanum oxide content increases to 9 and 12 mol% more nonbridging oxygen in the glass, resulting in the depolymerization of the phosphate network, the network of glass transforms to Q², Q¹, and Q⁰ units mixture. Based upon DSC results, T_g slightly decreases because of the depolymerization of microstructure. Endothermal peak of DSC curves indicate that crystal phases separate out from vitreous body with the addition of lanthanum oxide content.