BiZr(PO), a negative thermal expansion material with a Nasicon-type structure.

A new negative thermal expansion ceramic material, BiZr(PO), with a sodium zirconium phosphate structure, has been investigated and the results are presented. A three-dimensional structural framework is formed by the interconnection of ZrO octahedra and PO tetrahedra through their vertices. The occupation of a Bi ion in a type I site, located between two ZrO octahedra along ZrO < PO > ZrO ribbons induced the structure to crystallize in a trigonal system with a 3̄1 space group.

Langbeinite Phosphates KPbM(PO) (M = Cr, Fe): Synthesis, Structure, Thermal Expansion, and Magnetic Properties Investigation.

New langbeinite-type phosphates KPbCr(PO) and KPbFe(PO) are synthesized by solution method and characterized by powder X-ray diffraction, infrared spectra, thermogravimetric and differential thermal analysis, scanning electron microscope, and energy dispersive X-ray analysis. Rietveld refinement reveals that both of the compounds crystallize in the cubic system with 23 space group, and the calculated lattice parameters for Cr and Fe phases are 9.7332(2) and 9.