Crystal Growth And Magnetic Properties Of LnCo₂Al₈,LnRu₂Ga₈（Ln=La And Pr）,VA,VIA Group Metal Compounds

Rare earth intermetallic compounds have lots of exotic properties due to strong electron-electron correlations and interactions between conduction electrons and localized 4f electrons.In rare earth intermetallic compounds,correlated electronic behaviors have been discovered in some members of the RT₂X₈（R=La,Ce,Pr,Nd,Sm,Eu,Yb,Ca,Sr,ect;T=Fe,Co,Ni,Ru,Rh,Ir,ect;X=Al,Ga,and In）family compounds,including magnetic ordering behavior,heavy fermion behavior,crystal field effects,quantum criticality and so on.However,up to now,most studies in this series of compounds are conducted based on polycrystalline samples,while single crystals can better exhibit the intrinsic properties of the samples,and high quality single crystals can be prepared by the high-temperature flux method.Therefore,exploring and studying the RT₂X₈ family of single crystal materials are very important for understanding their electronic behavior.In this thesis,LnCo₂Al₈ and Ln Ru₂Ga₈（Ln=La,Pr）single crystals were successfully grown by the flux method,and their crystal structure,magnetic properties,and electrical transport properties were measured and analyzed in detail.And some metal compounds in the VA and VIA groups were also synthesized and characterized.The main results are included by the following three aspects:（1）LaCo₂Al₈ and PrCo₂Al₈ single crystals were successfully synthesized using Al-flux method.The results of single crystal characterization and powder XRD measurements confirmed that LaCo₂Al₈ and PrCo₂Al₈ single crystals both crystallized in orthorhombic CaCo₂Al₈ type structure with space group of Pbam（No.55）.Magnetism,specific heat and electrical resistivity measurements indicated that LaCo₂Al₈ single crystals exhibited Pauli paramagnetism,while PrCo₂Al₈ single crystals exhibited antiferromagnetic order at 5 K.Compared to the data of polycrystalline PrCo₂Al₈,single crystals exhibited strong magnetic anisotropy along and perpendicular to the c-axis direction of the crystal,and the magnetization in the H//c direction was56 times larger than that in the H⊥c direction.（2）By replacingCo atoms with Ru atoms and Al atoms with Ga atoms,La Ru₂Ga₈and Pr Ru₂Ga₈ single crystals were successfully synthesized with Ga-flux method.Physical property measurements displayed that La Ru₂Ga₈ single crystals exhibited Pauli paramagnetic behavior,and Pr Ru₂Ga₈ exhibited antiferromagnetic order at 2.5 K.Compared to the data of polycrystalline Pr Ru₂Ga₈,single crystals exhibited magnetic anisotropy along and perpendicular to the c-axis direction of the crystal.The Kondo like behavior of Pr Ru₂Ga₈ in electrical resistivity measurements indicated that this material may be a heavy fermion compound.And the specific heat measurements obtained the Sommerfeld coefficient ofγ=31.06 m J/mol K² for Pr Ru₂Ga₈ single crystals,indicating the improvement of electronic quality in Pr Ru₂Ga₈ single crystals.（3）VA and VIA group metal compounds were synthesized and characterized.Orthombic WTe₂ single crystals were successfully synthesized by chemical vapor transport method,and 1T-Mo Te₂,La Sb Te,Pt Bi₂,and Ba Fe₂As₂ were successfully grown by flux method.In addition,the rare earth tungstate material La₂W₃O₁₂ crystals were successfully synthesized by CZ method.And the structure mearsurements and characterization of these materials were also carried out.