Processing and properties of ferroelectric relaxor lead scandium tantalate Pb(Sc_1/2Ta_1/2)O₃ thin films

Abstract

Thin films of Pb(Sc 1/2 Ta 1/2 )O 3 (PST) were fabricated using an optimized chemical solution deposition procedure involving the de-hydration of scandium acetate and the addition of up to 30% excess lead in solution. The choice of substrate was found to impact the thermal induced stress in the films as confirmed by wafer bending and in-plane grazing angle x-ray diffraction measurements. The presence of either a compressive or a tensile in-plane stress led to a reduction in the temperature of the dielectric maximum, whereas the value of the dielectric maximum remained relatively unchanged; its value reduced by an order of magnitude compared with ceramic samples. It is concluded that mechanical stress alone is not the sole factor in the reduction of PST thin film permittivity. Microstructural features resulting from processing induced defects or an incomplete transformation to the relaxor state may be responsible for this commonly observed phenomenon.

Structural Evolution in Hollandite Solid Solutions Across the A‐Site Compositional Range from Ba1.33Ga2.66Ti5.34O16 to Cs1.33Ga1.33Ti6.67O16

“…The advantage of substituting Ti with Ga. This process is similar to processing routes used to fabricate lead (Pb)‐rich ceramics that exhibit similar volatility issues . Compositional analysis by inductively coupled plasma mass spectroscopy confirmed all compositions are close to the targeted compositions .…”

“…E ARLY reports on the development of crystalline ceramic waste forms pointed to a hollandite structure as a potential candidate for the immobilization of alkaline-earth elements such as rubidium (Rb) and cesium (Cs) found in waste streams from nuclear material reprocessing and treatment. 1,2 The hollandite structure was reported to incorporate Cs by insertion into tunnels in the solid resulting in compositions of the form Ba x Cs y (Al,Ti) 8 O 16 . 3 In the absence of Ti 3+ , Cs substitution for Ba on the A-site of the hollandite structure was limited to 0.3 Cs per unit cell when processed under ambient air.…”

“…3 In the absence of Ti 3+ , Cs substitution for Ba on the A-site of the hollandite structure was limited to 0.3 Cs per unit cell when processed under ambient air. This limitation was believed to be the result of the large size of the Cs ion (R = 1.75 A), which imposes an unacceptable level of deformation on the Ba x Cs y (Al,Ti) 8 O 16 hollandite structure. More recently, a number of publications have focused on the compositional ranges of various B-site dopants (i.e., Al, Ga, Fe, Cr, Mg) and their impact on Cs incorporation.…”

Phase transformation and growth mechanism of RF sputtered ferroelectric lead scandium tantalate (PbSc0.5Ta0.5O3) films

“…The value of S = 1 represents complete order, while S = 0 indicates a disordered material, using the definition from Setter and Cross 26 . The microstructure of ferroelectric films is reported to depend strongly upon deposition method (magnetron sputtering, pulsed laser deposition or chemical solution/sol‐gel) and a range of growth parameters 29,30 . The EC response is dependent on the degree of ordering and microstructure in films.…”

Fabrication and orientation control of highly cation-ordered epitaxial PbSc0.5Ta0.5O3 thin films on Si (100)

“…12,13 Thus, the epitaxial integration of PST films on Si substrates opens broad opportunities for scientific and technological development. Polycrystalline growth of PST films is well reported in the literature, [14][15][16][17][18][19][20][21] however, epitaxial growth of PST films is very limited. 6,11 In this paper, we report on fabrication and orientation control of PST films on Si (100) substrates using pulsed laser deposition (PLD).…”