Stiffening of nanoscale anatase Ti0.9Zr0.1O2 upon multiple compression cycles

Abstract

The compression behavior of nanoscale Zr-doped anatase was studied by means of a diamond anvil cell experiment with alternating cycles of compression and decompression in the stability field of anatase (up to 13 GPa). We found that multiple cycles of compression lead to stiffening of the material: Precompressed samples of nanoanatase Ti 0.9 Zr 0.1 O 2 have a higher bulk modulus (K 0 = 249(9) and 266(6) GPa) compared to the sample when compressed for the first time (K 0 = 211(7) GPa). Upon compression, the crystallite size remains the same and the crystalline areas are free of defects. After the experiment, the crystallites are surrounded by amorphous rims, confirming the theoretical prediction by Pischedda et al.[1] for nanoscale anatase, but yielding much lower pressures (12 GPa) for the onset of partial amorphization.

The structural origin of the unusual compression behaviors in nanostructured TiO2: insights from first-principles calculations

“…5c at P 4 8 GPa as belonging to a disordered nc anatase Ti 0.9 Zr 0.1 O 2 . 21,23 The hysteretic compression-decompression paths (Fig. 5c) and smaller V o of the decompressed 12 AE 3 nm Ti 0.9 Zr 0.1 O 2 anatase (Table 3) suggest partial structural disorder and densification acquired within the non-elastic regime.…”

“…It is suggested that the inclusion of P-V data belonging to both ordered and disordered Ti 0.9 Zr 0.1 O 2 anatase in the Birch-Murnaghan equation fit potentially led to the anomalous EoS parameters in the earlier work. 22,23 The larger K o value obtained for the precompressed 15 nm Ti 0.9 Zr 0.1 O 2 anatase (Table 3) indicates contributions from both nanocrystallinity and ''frozen-in'' (not fully reversible) disorder.…”

“…5 Pressure dependencies of relative lattice parameters for single crystal, 45 microcrystalline, 45,46 and nc 16 anatase TiO 2 (a) and nc anatase Ti 0.9 Zr 0.1 O 2 (b, c). 22,23 In (b) red squares and curves represent the pre-compressed 15 nm sample, 22 black circles represent the 12 nm sample, and green curves represent B3LYP results. In (c) the P-V data of first compression and decompression of originally uncompressed material 23…”

“…A large stiffness increase following multiple compressions was also reported for a 12 AE 3 nm Ti 0.9 Zr 0.1 O 2 anatase. 23 Nanoribbon-structured single crystalline TiO 2 -B was also reported to undergo pressure-induced amorphization (PIA) to an HDA TiO 2 at around 16 GPa and further HDA -LDA polyamorphic transition upon decompression from highpressures to about 8.1 GPa, 24 in a very similar fashion to nc anatase. 20 It is noteworthy that PIA has not been observed in nc rutile 15 and not reported for nc brookite.…”

The Behavior of a TiO2 Nanoparticle under Extreme Conditions

“…The has also been much interest in the properties of nano structures of TiO 2 and notably when such structures are subject to extreme conditions of temperature or pressure [1, [3][4][5][6][7][8][9]. There is particle size behavior under pressure as compared to the bulk counterpart and often changes in compressibility as measured by a bulk modulus [8,9] are reported.…”