助熔剂法和浮区法生长Nd_(2-x)Ce_xCuO_4单晶及其热传导研究北大核心CSCD

本文研究了用助熔剂法和浮区法两种方法生长Nd2-x Cex CuO4(NCCO)单晶的生长条件和NCCO单晶的热传导性质.用助熔剂法方法可以生长出组份为x=0至x=0.18的一系列单晶样品.用X射线衍射表征了单晶的结构和品质,并观测了不同的退火过程对样品的超导转变的影响.在浮区法方面,生长NCCO(x=0.15)单晶也取得了很好的结果.另外,本文还测量了不同组份的单晶样品的低温热导率,发现Nd3+离子磁性对热导率的影响以及掺杂Ce后热导率的变化情况.     

Synthesis,Structure and Properties of a New Molybdate-tellurite Compound with 2D Triangular Lattice

A new 3 d transition-metal molybdate-tellurite(NH4)2 Co(TeMo2O9)2 was obtained through a conventional hydrothermal method.This compound was confirmed to crystallize in the monoclinic system of space group P2₁/c with a=10.5133(5),b=10.6456(5),c=7.6078(5)?,β=108.879(6)o,V=805.66(8)?³,Z=2,M_r=1021.97,Dc=4.213 g/cm³,μ=7.685 mm^–1,F(000)=930,the final R=0.0399 and w R=0.1025 for 1580 observed reflections with I>2σ(I),showing a tunnel structure with spin triangle-lattice composed by CoO₆ octahedra.Magnetic and heat capacity measurements confirmed a paramagnetic behavior down to 2 K with a negative Weiss temperature of–20 K,suggesting remarkable spin frustration in the system.