## 1 Introduction  
Additive manufacturing (AM) technology removes many restrictions in piezoceramics manufacturing related to the shape, size, and internal structure of the produced items. The AM implementation reduces the production cost of single items and small batches due to the exclusion from the manufacturing workflow of the expensive tools and molds, typical for traditional approaches [1]. Multiple tryouts of different AM technologies for piezoceramics manufacturing were demonstrated in the literature in the last decade [2]. Of the different AM approaches, the SLA/DLP-based methods (SLA--stereolithography apparatus; DLP--digital light processing) demonstrated the most promising results in terms of piezoceramics shaping, due to the high accuracy, reasonable dimensional control, and the usage of pastes and suspensions with high powder loadings (over 50 vol %) in the feedstock. Conventional piezo-materials based on lead zirconate titanate (PZT) have been used in industrial applications for decades. They demonstrate the best piezoelectric properties among piezoceramics when manufactured in a traditional or additive way [2]. However, due to the emerging ecological risks of PZT usage, a gradual replacement of these materials with lead-free contenders is ongoing. One of the most intensively studied lead-free ferroelectric materials is BaTiO3 [3] (BT).  
Since the beginning, the applications of SLA/DLP technology to BT was problematic [4]. This material was acknowledged as challenging to work with due to mediocore photopolymerization response of BT-based pastes and suspensions to UV laser light (for SLA) or UV masked light (for DLP). The photopolymerization depth of BT pastes was reaching no greater than 30-50 \(\upmu\)m. The layer thickness in SLA/DLP had to be set to 10-20 \(\upmu\)m in order to produce mechanically sound items. Some researchers even designed a particular subsystem to accurately prepare very thin layers of BT suspension for DLP-based processing [5].  
The poor photopolymerization of materials in stereolithography-based 3D printing is traditionally attributed to the large difference in the refractive indices between powder and an organic binder [6; 7]. In the spectral region of 350-410 nm, typical for conventional SLA/DLP technology, BT-based piezoceramic materials have a greater refractive index (2.65-2.81) than other technical ceramics, such as Al\({}_{2}\)O\({}_{3}\) (1.79-1.8), ZrO\({}_{2}\) (2.22-2.26), or yttrium-stabilized zirconia (2.22-2.26), which are successfully used in SLA and DLP technologies.  
In this work, we demonstrate that besides the refractive index differences, the significant factor affecting the performance of the SLA technology is the light absorption of BT ceramic powder in the selected spectral range. To demonstrate the effect of light absorption, we selected a wavelength of 465 nm, where BT piezoceramics absorbs little light, and conducted a photopolymerization study. We developed an SLA-based experimental setup featuring a 465 nm industrial laser connected to an industrial robot to assist with testing and 3D printing of simple BT greenbody items.  
This work aimed to demonstrate that photopolymerization problems with BT-based pastes/suspensions may have a simple technological solution. The thermal processing of the samples and study of their properties and microstructure, concerning different 3D printing and thermal processing regimes, are out of the scope of this preliminary work--they are the subjects of the future research.