Figure 1: Morphology of stripe-type-λ-Ti₃O₅ and pressure-and-heat-induced phase transition between λ-Ti₃O₅ and β-Ti₃O₅.

(a) TEM image of stripe-type-λ-Ti₃O₅. The scale bar below the TEM image indicates 50 nm. (b) HRTEM image of the surface of stripe-type-λ-Ti₃O₅ showing the atomic arrangement on the bc plane. The scale bar below the TEM image indicates 1 nm. (c) Visualized electron density maps on the bc plane of stripe-type-λ-Ti₃O₅ obtained by the MEM (isosurface 0.8e Å⁻³). The scale bar below the electron density map (left) indicates 1 nm. (d) Pressure (P) and temperature (T) dependence of the XRPD patterns (λ=1.5418 Å). The ambient-temperature XRPD pattern of the as-prepared sample at atmospheric pressure (P=0.1 MPa) is shown in the front, followed by XRPD patterns of the pellet samples pressurized by P=15−530 MPa, measured after pressure release. These are followed by the XRPD patterns of pressure-produced β-Ti₃O₅ with increasing temperature from 300 K to 510 K. (e) Pressure evolution of the phase fractions of λ-Ti₃O₅ (blue) and β-Ti₃O₅ (red). The pressure where the fraction of λ-Ti₃O₅ becomes 50% (P_1/2) is an extremely small value of ∼60 MPa. (f) Temperature evolution of the phase fractions of λ-Ti₃O₅ (blue) and β-Ti₃O₅ (red) in the heating process.