Isostructural ZrW2O8 and HfW2O8 show strong negative thermal expansion from 0.3 K up to their decomposition temperatures of approximately 1050 K. This behavior is especially unusual because these compounds are apparently cubic over their entire existence range. Detailed structural studies of ZrW2O8 were conducted using high-resolution neutron powder diffraction data taken at 14 temperatures from 0.3 to 693 K. Below 428 K, ZrW2O8 adopts the acentric space group P213 and has a well-ordered structure containing corner-sharing ZrO6 octahedra and two crystallographically distinct WO4 tetrahedra. Above the phase transition at 428 K, which appears to be second order, the space group becomes centric Pa3. The structure is now disordered with one oxygen site 50% occupied, suggesting the possibility of high oxygen mobility. Oxygen motion above 428 K is also suggested by dielectric and ac impedance measurements. The negative thermal expansion of ZrW2O8 and HfW2O8 is related to transverse thermal vibrations of bridgi...

Negative Thermal Expansion in ZrW2O8 and HfW2O8

https://cyberleninka.org/article/n/1272461.pdf

Synthesis and characterization of conducting polyaniline nanocomposites containing ZnO nanorods

Inorganic lanthanide compounds with complex anions.

Epoxy/polyaniline–ZnO nanorods hybrid nanocomposite coatings: Synthesis, characterization and corrosion protection performance of conducting paints

Sergey V. Krivovichev,*,†,‡ Olivier Mentre,́ Oleg I. Siidra,† Marie Colmont, and Stanislav K. Filatov† †St. Petersburg State University, Department of Crystallography, University Emb. 7/9, 199034 St. Petersburg, Russia ‡Institute of Silicate Chemistry, Russian Academy of Sciences, Makarova Emb. 6, 199034 St. Petersburg, Russia UCCS, Equipe de Chimie du Solide, UMR CNRS 8181, ENSC LilleUST Lille, BP 90108, 59652 Villeneuve d’Ascq Cedex, France

N. Kumada

Papers

Crystal structure of BaCa2MgSi2O8 and the photoluminescent properties activated by Eu2

Preparation of alkaline earth bismuth pyrochlores containing Bi5+ by low temperature hydrothermal reaction

Ion-exchange reaction of Na+ in NaBiO3·nH2O with Sr2+ and Ba2+

Hybrid nanocomposite based on NbWO6 nanosheets and polyaniline

Vibrational spectra of the ilmenite modifications of LiNbO3 and NaNbO3