## 2 Materials and Methods
### The 465 nm Stereolithographic Experimental Setup  
A handmade SLA experimental setup was built with the use of an industrial 465 nm laser LDM450-3-12 (Purelogic R&D, Voronezh, Russia). The laser was attached to a FANUC M-1 iA/0.5A (FANUC, Oshino, Japan) industrial robotic 6-axis manipulator to enable laser beam's mechanical XY-motion. A vat and a printing platform were designed and 3D-printed from ABS plastic, using an FDM 3D printer. The printing platform's ascending and descending functions were implemented with the vertical mechanical drive on the basis of Nema17 Stepper motor KS42 STH48-1684A (HANPOSE 3D Technology Co., Guangzhou, China). The laser had a wide elliptical beam shape (approximately 3 \(\times\) 2 mm) from the factory. A stainless-steel plate (a mask) with a 1 mm diameter pinhole was manufactured and inserted into the laser path to limit the exposed area. For some experiments, the mask was attached to the laser and aligned to the laser beam's center--this allowed us to crop the beam to a smaller diameter, trading off the intensity. For other experiments, the setup was used without the mask. When the mask was on, the laser light intensity was reduced 15-fold, but dimensional accuracy of contouring and shading was improved.  
The printing operations with the experimental SLA setup were similar to those of commercial SLA machines, except that the paste portions were delivered to the printing platform by hands. The delivered paste was automatically spread over the printing platform by the robot, keeping the layer thickness of 100 \(\upmu\)m. The check of layer thickness consistency was made at multiple locations of the printing platform with an Elcometer wet film comb (Eclometer, Manchester, United Kingdom).  
The laser power was measured with the Ophir Laser Power meter (Ophir Optronics, Jerusalem, Israel). The intensity of the laser beam was not adjustable. Hence, the amount of energy transferred to the material was regulated via the exposure time. For stationary testing, the exposure time was directly controlled by hardware. For the tests with laser  
Figure 1: XRD pattern of a commercial BaTiO\({}_{3}\) powder, before milling.  
motion, laser marking speed and hatching spacing determined the local dosage of the light energy irradiated to the photopolymerizable material. There were three tests conducted with the experimental setup.  
1. Test of the powder loading effect. There were six variants of ceramic paste prepared featuring powder loading of 10, 20, 30, 40, 50, and 55 vol %. The mask was attached to the laser for these testing series to mimic the realistic 3D-printing operations with this setup. The laser speed was set at 5 mm/s, and the hatching space was 200 \(\upmu\)m--these parameters correspond to the energy intensity of 14.8 J/cm\({}^{2}\).
2. Test of the laser speed and hatching space variation. There were 20 vol % and 55 vol % ceramic pastes used in this test. The tested laser speeds were 1, 2, 3, 5, and 10 mm/s. The tested hatching spacings were 0.1, 0.2, 0.3, 0.4, 0.5, and 1 mm. The energy intensities investigated in this test, with the help of varying laser speed or hatching spacing, were in the range of 2.97-67.36 J/cm\({}^{2}\) for the masked laser and 45.76-1152.44 J/cm\({}^{2}\) for the unmasked laser. The optimal parameters for 3D printing operations were determined in this test.
3. Test of multi-layered objects 3D printing. The optimal process parameters selected for 3D printing were hatching spacing of 0.2 mm, laser speed of 3 mm/s, and paste powder concentration of 55 vol %. One 50 \(\times\) 2 mm stripe and one 10 \(\times\) 10 mm square sample were 3D-printed to demonstrate the technical possibility of BT's 3D printing using 100 \(\upmu\)m thick layers. The stripe consisted of 20 layers and was printed using the unmasked laser. The square sample consisted of 50 layers (the total thickness was 5 mm) and was 3D-printed using the masked laser.