摘要
基于GGA近似使用第一性原理方法对3C-SiC的ZB至NaCl相的高压相变过程进行了研究,得出中间过渡相的最高对称性为Imm2(而此前有研究认为是Cmm2和Pmm2),激活焓计算值为0.647eV,与Catti等人的结果很接近.尽管如此,计算的相变压力为69GPa仍然比实验值100GPa小很多,可能是由于实验中的相转变具有较大的滞后性.对相变压力时两相的能带结构也作了计算和分析,可以得出相变过程除几何结构的重构之外还伴随着半导体—金属的电子转变,这对于实验上准确判断相变点有一定的指导意义.
Based on the generalized gradient approximation, we have investigated the phase transition of 3C-SiC from ZB to NaCl structure using first-principles method, and obtained the accurate symmetry Imm2 （previously regarded as lower symmetry Cram2 and Prom2） of the intermediate phase. The relative activation enthalpy 0.647eV is close to the result of Catti. The obtained transition pressure 69GPa is lower than the experimental value of 100GPa which may be attributed to the hysteresis of the phase transition. Meanwhile, the energy bands for ZB- and NaC1-SiC were also calculated and discussed, the results suggest that the phase transition of 3C-SiC is accompanied by an electronic transition from semiconducting to metallic character besides the structure reconstruction, which may be useful for the accurate determination of the transition pressure.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第7期3576-3580,共5页
Acta Physica Sinica
基金
国家自然科学基金重点项目(批准号:50325103
50271062)资助的课题.~~
关键词
高压相变
第一性原理
3C-SIC
激活焓
high pressure transformation, first-principles method, 3C-SiC, activation enthalpy
