Among the wide variety of routes reported for the chemical synthesis of zirconia, the development of simple, aqueous sol−gel technology is of considerable interest for industrial-scale applications. In this study, zirconium hydroxide nanoparticles were produced by the controlled hydrolysis of zirconium carbonate in nitric acid, followed by gentle heating at 70 °C. Transparent, colorless gels were subsequently produced from the concentrated sols (500 g/L, oxide basis) by drying at ambient temperature. The nanoparticle sols and gels were characterized using a range of techniques, including EXAFS, Raman spectroscopy, dynamic light scattering, and SAXS, which revealed the presence of platelike particles of width 2.8 ± 0.4 nm and thickness 0.5 ± 0.1 nm. The platelets exhibit a surprisingly high degree of short-range ordering, and it is demonstrated that they are composed of stacked layers of two-dimensional “[Zr(OH)4]n” sheets, as proposed (but not established) in earlier studies. The speciation of the nitrate...