Formation of a new polymorph of ZrO2 with orthorhombic crystal structure contained in a mesoporous structure

A new polymorph of ZrO2 of an orthorhombic crystal structure (o-ZrO2) is derived in a mesoporous structure. It has average 15 nm crystallite size after 2 h of heating at 500 °C a mesoporous ZrO(OH)2 · xH2O precursor. X-ray diffractogram determines lattice parameters of a=0.3340 nm, b=0.5535 nm and c=0.6364 nm in ρ=6.96 g/cm3 density. A high-pressure phase of Pnma o-ZrO2 is known with a similar ρ=6.78 g/cm3. Mesoporous o-ZrO2 has a strong XPS bandgroup of 3d5/2 and 3d3/2 components (bandwidth ΔEb=4.6 eV) at 182.7 and 184.7 eV binding energy Eb, with an additional weak bandgroup at 170–179 eV. IR spectrum infers a severely puckered structure with a corrugated surface through pores.