Preparation,Structural Characterization And Physical Properties Of Rare-Earth Tritellurides

The cerium doped CuIn1-xCexTe2(CICT,x=0,0.1,0.2,0.3)compounds and the manganese doped RTe3-xMnx(R=Pr,Eu,Dy;x=0,0.1,0.2,0.3)compounds have been synthesized by using vacuum arc melting method and vacuum solid reaction method.Powder X-ray diffraction(PXRD),Rietveld structural refinement,X-ray photoelectron spectrometer(XPS),ultraviolet and visible spectrophotometer(UV-Vis),standard four-probe method and vibrating sample magnetometer(VSM)were used to investigate the crystal structures,optical,electric and magnetic properties of CICT.Results show that the main phase of CICT is CuInTe2 type with a space group of I-42d.The lattice parameters are a=6.190(6)-6.193(0)A and c=12.406(5)-12.409(5)A.The atomic occupations in one unit cell are corresponding to the 4a(0,0,0)crystal site for Cu atoms,the 4b(0,0,0.5)site for In/Ce atoms and the 8d(x,0.25,0.125)site for Te.Ce of CICT shows mixture of valences 4+ and 3+,and the band gap Eg values are 1.28 eV and 1.16 eV before and after 0.1 mole Ce doping into CuInTe2,respectively.Ce doping into CuInTe2 still shows the semiconductor characteristics.In R-Te-Mn(R=rare earth)ternary systems,the tetragonal phase with Pr4Te7 type structure is obtained in PrTe3-xMnx,its space group is P4/nmm.The lattice parameters are a=4.428(9)-4.431(6)A and c=9.069(1)-9.076(1)A.The atomic occupations in one unit cell are corresponding to the 2c(1/4,1/4,z1)site for Pr atoms,the 2c(1/4,1/4,z2)and 2a(3/4,1/4,0)sites for Te atoms.EuTe3-xMnx produced impurity phases and the main phase is Eu2TeO2 with a space group of I4/mmm.The lattice parameters are a=3.973(7)-3.974(7)A and c=12.569(9)-12.572(7)A.The atomic occupations in one unit cell are corresponding to the 4e(0,0,z)site for Eu atoms,the 4d(1/2,0,1/4)site for O atoms and the 2a(0,0,0)site for Te.The phase of DyTe3-xMnx is Dy2Te3 with a space group of Fddd.The lattice parameters are a=12.206(1)-12.216(4)A,b=8.628(9)-8.639(2)and c=25.885(7)-25.922(2)A.The atomic occupations in one unit cell are corresponding to the 16g(1/8,1/8,z1)site for Dy atoms,16f(1/8,y1,1/8)and 32h(x,y2,z2)sites for Te.PrTe3-xMnx compounds exhibit mixture of ferromagnetic and paramagnetic,and both EuTe3-xMnx and DyTe3-xMnx show paramagnetic.