TY - JOUR
T1 - Polymorphic structures and properties of lead chromium phosphate Pb 3Cr2(PO4)4
AU - Mao, Shaoyu
AU - Mao, Yanping
AU - Batchelor, Raymond J.
AU - Guo, Haiyan
AU - Ye, Zuo Guang
AU - Xie, Zhaoxiong
AU - Zheng, Lansun
PY - 2009
Y1 - 2009
N2 - Single crystals of lead chromium phosphate Pb3Cr 2(PO4)4 were grown by a flux technique and characterized by X-ray powder and single crystal diffraction, differential thermal analysis, polarized light microscopy and magnetic measurements. Two polymorphic structures have been identified: a monoclinic Pb3Cr 2(PO4)4 of space group P21/c (14) and a tetragonal Pb3Cr2(PO4)4 of space group P41212 (94), and their phase correlation is described. Both structures consist of a three-dimensional framework which is composed of PO4 tetrahedra and CrO6 octahedra connected via vertices. Lead ions are situated at the cavities of the framework, but the positions of lead ions in the monoclinic Pb3Cr2(PO 4)4 are different from those in the tetragonal Pb 3Cr2(PO4)4. The Pb 3Cr2(PO4)4 crystals are found to exhibit interesting physical properties. The ferroelastic domain structures reveal characteristic patterns of the tetragonal and the monoclinic symmetry of the crystals. The birefringence of the tetragonal crystals decreases with increasing temperature. The monoclinic crystal is found to undergo a series of magnetic phase transitions upon cooling, from a paramagnetic phase (from room temperature down), to an antiferromagnetic phase below TN = 6 K, and then to a weakly ferromagnetic phase below the Curie temperature TC = 4 K, with a magnetic hysteresis loop displayed at 2 K.
AB - Single crystals of lead chromium phosphate Pb3Cr 2(PO4)4 were grown by a flux technique and characterized by X-ray powder and single crystal diffraction, differential thermal analysis, polarized light microscopy and magnetic measurements. Two polymorphic structures have been identified: a monoclinic Pb3Cr 2(PO4)4 of space group P21/c (14) and a tetragonal Pb3Cr2(PO4)4 of space group P41212 (94), and their phase correlation is described. Both structures consist of a three-dimensional framework which is composed of PO4 tetrahedra and CrO6 octahedra connected via vertices. Lead ions are situated at the cavities of the framework, but the positions of lead ions in the monoclinic Pb3Cr2(PO 4)4 are different from those in the tetragonal Pb 3Cr2(PO4)4. The Pb 3Cr2(PO4)4 crystals are found to exhibit interesting physical properties. The ferroelastic domain structures reveal characteristic patterns of the tetragonal and the monoclinic symmetry of the crystals. The birefringence of the tetragonal crystals decreases with increasing temperature. The monoclinic crystal is found to undergo a series of magnetic phase transitions upon cooling, from a paramagnetic phase (from room temperature down), to an antiferromagnetic phase below TN = 6 K, and then to a weakly ferromagnetic phase below the Curie temperature TC = 4 K, with a magnetic hysteresis loop displayed at 2 K.
UR - https://www.scopus.com/pages/publications/68749116486
U2 - 10.1039/b904277f
DO - 10.1039/b904277f
M3 - 文章
AN - SCOPUS:68749116486
SN - 0959-9428
VL - 19
SP - 6034
EP - 6041
JO - Journal of Materials Chemistry
JF - Journal of Materials Chemistry
IS - 33
ER -