Low pore sedimentary rocks(from Guangxi, China) were subjected to uniaxial compression loading experiment under different initial stresses. The rock samples were investigated by nuclear magnetic resonance before and a...Low pore sedimentary rocks(from Guangxi, China) were subjected to uniaxial compression loading experiment under different initial stresses. The rock samples were investigated by nuclear magnetic resonance before and after the loading. The relationships between the mesoscopic rock damage and macroscopic mechanical parameters were established, and the initial damage stress of the low-porosity sedimentary rock was determined. The results showed that this type of rock has the initial stress of damage. When the initial loading stress is lower than the initial stress of damage, the T2 spectrum area of the rock sample gradually decreases, and the primary pores of the rock are further closed under the stress. The range of the initial stress of damage for this type of rock is 8-16 MPa. When the loading stress exceeds the initial stress of damage, the T2 spectrum area gradually increases, indicating that the porosity of the rock increases and microscopic damage of the rock appears. The rock damage degree is defined, and the nonlinear function between the rock damage degree and the initial loading stress is established.展开更多
With the strong-field scheme and trigonal bases, the complete d<SUP>3</SUP> energy matrix in a trigonally distorted cubic-field has been constructed. By diagonalizing this matrix, the normal-pressure energ...With the strong-field scheme and trigonal bases, the complete d<SUP>3</SUP> energy matrix in a trigonally distorted cubic-field has been constructed. By diagonalizing this matrix, the normal-pressure energy spectra and wavefunctions of GSGG:Cr<SUP>3+</SUP> at 70 K and 300 K have been calculated without the electron-phonon interaction (EPI), respectively. Further, the contributions to energy spectra from EPI at two temperatures have also been calculated, where temperature-independent terms of EPI are found to be dominant. The sum of aforementioned two parts gives rise to the total energy spectrum. The calculated results are in good agreement with all the optical-spectral experimental data and the experimental results of and . It is found that the contribution from EPI to R<SUB>1</SUB> line of GSGG:Cr<SUP>3+</SUP> with taking into account spin-orbit interaction (H<SUB>so</SUB>) and trigonal field (V<SUB>trig</SUB>) is much larger than the one with neglecting H<SUB>so</SUB> and V<SUB>trig</SUB>, and accordingly it is essential for the calculation of the EPI effect to take first into account H<SUB>so</SUB> and V<SUB>trig</SUB>. The admixture of base-wavefunctions,and , the average energy separation and their variations with temperature have been calculated and discussed.展开更多
基金Project(41672298)supported by the National Natural Science Foundation of China。
文摘Low pore sedimentary rocks(from Guangxi, China) were subjected to uniaxial compression loading experiment under different initial stresses. The rock samples were investigated by nuclear magnetic resonance before and after the loading. The relationships between the mesoscopic rock damage and macroscopic mechanical parameters were established, and the initial damage stress of the low-porosity sedimentary rock was determined. The results showed that this type of rock has the initial stress of damage. When the initial loading stress is lower than the initial stress of damage, the T2 spectrum area of the rock sample gradually decreases, and the primary pores of the rock are further closed under the stress. The range of the initial stress of damage for this type of rock is 8-16 MPa. When the loading stress exceeds the initial stress of damage, the T2 spectrum area gradually increases, indicating that the porosity of the rock increases and microscopic damage of the rock appears. The rock damage degree is defined, and the nonlinear function between the rock damage degree and the initial loading stress is established.
文摘With the strong-field scheme and trigonal bases, the complete d<SUP>3</SUP> energy matrix in a trigonally distorted cubic-field has been constructed. By diagonalizing this matrix, the normal-pressure energy spectra and wavefunctions of GSGG:Cr<SUP>3+</SUP> at 70 K and 300 K have been calculated without the electron-phonon interaction (EPI), respectively. Further, the contributions to energy spectra from EPI at two temperatures have also been calculated, where temperature-independent terms of EPI are found to be dominant. The sum of aforementioned two parts gives rise to the total energy spectrum. The calculated results are in good agreement with all the optical-spectral experimental data and the experimental results of and . It is found that the contribution from EPI to R<SUB>1</SUB> line of GSGG:Cr<SUP>3+</SUP> with taking into account spin-orbit interaction (H<SUB>so</SUB>) and trigonal field (V<SUB>trig</SUB>) is much larger than the one with neglecting H<SUB>so</SUB> and V<SUB>trig</SUB>, and accordingly it is essential for the calculation of the EPI effect to take first into account H<SUB>so</SUB> and V<SUB>trig</SUB>. The admixture of base-wavefunctions,and , the average energy separation and their variations with temperature have been calculated and discussed.
