Crystal structures of Dy₂(WO₄)₃ and GdY(WO₄)₃

Two compounds, Dy₂(WO₄)₃ and GdY(WO₄)₃, were synthesized by using the standard solid state reaction technique. The crystal structure was determined by powder X-ray diffraction and Rietveld refinement method. It is found that both compounds have Eu₂(WO₄)₃-type monoclinic structure, with space group C 2/c, Z=4. The unit cell parameters of Dy₂(WO₄)₃ are a=0.75981(1) nm, b=1.13220(1) nm, c=1.13254(1) nm, and β=109.8001(3)°, and those of GdY(WO₄)₃ are a=0.76175(1) nm, b=1.13543(1) nm, c=1.13496(2) nm, and β=109.8015(13)°. Each W atom has four oxygen nearest neighbors, while each rare-earth atom is surrounded by eight oxygen atoms. WO₄ tetrahedra share their four vertices with REO₈ (RE=Dy,Gd or Y) share an edge with each other. The phase transition and the magnetic properties were investigated by differential thermal analysis (DTA) and dc superconducting quantum interference device (SQUID) magnetometer.