Laser ablation characteristics of yttria-doped zirconia in the nanosecond and femtosecond regimes

Abstract

The laser ablation characteristics of yttria-stabilized zirconia ͑YSZ͒ have been investigated as a function of the target microstructure and dopant level for different nanosecond-͓ArF, KrF, and XeCl excimers; Nd:YAG ͑yttrium aluminum garnet͒ ͑fourth harmonic͔͒ and femtosecond-laser sources ͓Ti:sapphire ͑fundamental and third harmonic͔͒. Particle ejection, which compromises the quality of coatings prepared by pulsed laser deposition ͑PLD͒, was analyzed in detail. Nanosecond-laser pulses cause a severe thermomechanical surface cracking and exfoliation of micron-sized fragments on a microsecond to millisecond time scale in the case of 8 -9.5 mol % Y 2 O 3 -doped, fully stabilized zirconia ͑8YSZ and 9.5YSZ͒ targets. As a consequence of the intrinsic material brittleness, fully stabilized YSZ coatings deposited by PLD contained particles for all tested conditions. Lower doped partially stabilized zirconia ͑3YSZ͒ exhibits a superior fracture toughness attributed to a laser-induced partial transition to the monoclinic phase, detected by Raman spectroscopy, which enables the deposition of particle-free dense thin films by conventional PLD using nanosecond-UV laser radiation at moderate fluences of 1.2-1.5 J / cm 2 . The ablation dynamics of ultrashort laser pulses differ fundamentally from the nanosecond regime as evidenced, e.g., by time-resolved shadowgraphy and light scattering experiments. Femtosecond pulses prevent the exfoliation of micron-sized fragments but result invariably in a pronounced ejection of submicron particles. The resulting PLD coatings are porous and reveal a large surface roughness as they consist of an agglomeration of nanoparticles. Femtosecond-NIR pulses provide a factor of 2.5-10 higher material removal rates compared to nanosecond-and femtosecond-UV pulses. The ablation metrics, i.e., threshold fluence and effective absorptivity, mainly depend on the laser wavelength while the pulse duration, target microstructure, and dopant level are of minor importance. Evidence is presented that incubation effects play a significant role in nanosecond-and femtosecond-laser ablations of YSZ enabling material removal at comparatively low fluences for sub-bandgap photon energies.

355, 532, and 1064 nm picosecond laser interaction with grass tissues

“…[5][6][7][8][9][10] Plant leaves, especially green leaves, are common landscaping and agricultural materials and lasers could be creatively used for many possible innovative applications. Plant leaves exhibit very complicated optical properties because they have complex multilayer structures and are basically a composite of many dissimilar optical elements, including photosynthesizing pigments.…”

Fe3O4 stabilized zirconia: structural, mechanical and optical properties

“…Figure 10a, b shows an increasing trend of refractive index (n) with increase up to 6 wt% for basic and 8 wt% for acidic Fe 3 O 4 dopant concentrations. However, decrease in refractive index with further increase in dopant concentration might be because of the incorporation of more oxygen vacancies in zirconia lattice which produce stabilization in zirconia [21]. This stabilization was observed in the XRD data (Fig.…”

“…Thin films of metal oxide doped zirconia have been prepared by laser ablation [21], RF sputtering [22,23] and sol-gel [24] etc.…”

A Comparative Study of CaO-MUZ Composites Elaboration by Plasma Melting and Sintering Techniques

“…However, the presence of zirconia phase in the microstructure of zirconia mullites affects the quality of the product. It is observed that stable monoclinic zirconia phase is present below 1,170 C, whereas the transformation temperature of monoclinic zirconia to pure tetragonal zirconia is 1,170 C, which remains stable up to the temperature of 2,370 C [5]. The transformation temperature from tetragonal zirconia to cubic zirconia is 2,370 C [5].…”