Glass-ceramics containing pyroelectric Sr₂TiSi₂O₈ (STS) crystals are produced from parent glasses of compositions STS + 0.8 SiO₂ + (0.2 − x) Na₂O + x CaO, with x = 0; 0.05; 0.10; and 0.15. The aim of this work is to investigate the effect of the additions to the stoichiometric STS composition on the crystallization mechanisms and on the piezoelectric properties of the glass-ceramic. The DSC analyses evidence that the glass transition temperatures T_g, the onset temperature of the crystallization peak T_o and the temperature T_c of the maximum of this peak increase with the CaO/Na₂O ratio. On the basis of the DSC data, the crystallization of the parent glass samples was operated by thermal treatment. The observation of the cross-sections of the heat-treated samples highlights that the competition between the surface and volume crystallization mechanisms is influenced by the CaO/Na₂O ratio and the temperature. For all the samples, the XRD analyses performed on the surfaces as obtained after the crystallization treatment evidenced a preferential orientation of the STS crystals with the plans (00l) parallel to the surface. The XRD analyses performed after grinding the surface show that only the surface crystallized layers are preferentially oriented. Moreover, changes in preferential orientation to plans (202) or (201) are observed over the depth, depending on the composition and the temperature of the thermal treatment. These changes influence the polarization of the surface crystallized layer and, consequently, its piezoelectric charge coefficient d₃₃. The highest values of d₃₃ were measured on the glass-ceramic samples exhibiting mainly a (202) preferential orientation over their thickness.

Additive manufacturing (AM) techniques are continuously evolving to meet the increasing demand for high-performance ceramics with intricate geometries. This review covers four widely investigated ceramic AM methods: stereolithography (SLA), digital light processing (DLP), fused deposition modeling (FDM), and direct ink writing (DIW). Each technique is analyzed from a technical standpoint, with particular attention given to feedstock formulation, printing parameters, debinding, sintering, and final densification. Vat photopolymerization provides high resolution and good surface quality, but remains constrained by photocurable slurry behavior. FDM offers accessible equipment and material versatility, though high ceramic loading can lead to feeding and printing difficulties. DIW can process highly loaded ceramic inks and is suitable for porous and architectured structures, but requires precise control of ink rheology and shape retention. The main challenges associated with ceramic printing are also examined, together with proposed solutions, emerging trends, and research gaps. This review provides a comparative overview of the critical parameters governing ceramic AM and helps identify the most suitable technique according to the targeted application.