Half-metallic ferromagnetism,mechanical as well as thermoelectric properties for rare earth-based spinels MgHo_(2)Z_(4)(Z=S,Se)were investigated using density functional theory(DFT).Structural optimization was done wi...Half-metallic ferromagnetism,mechanical as well as thermoelectric properties for rare earth-based spinels MgHo_(2)Z_(4)(Z=S,Se)were investigated using density functional theory(DFT).Structural optimization was done with Perdew-Burke-Ehrenzorf(PBE)sol-generalized gradient approximation(GGA)to calculate the lattice constant of both spinels comparable to experimental data.In addition,Born stability criteria and negative formation energy show that our studied spinels are also structurally and dynamically stable in the cubic phase.For ferromagnetic(FM)state stability,we also calculated the energy differences among FM,antiferromagnetic(AFM),and non-magnetic(NM)states.Additionally,Curie temperatures of ferromagnetic phases were also estimated.We used Trans-Blaha improved BeckeJohnson(TB-mBJ)potential functional for electronics as well as magnetic characteristics,which lead to the consistent explanation of half-metallic ferromagnetism,representing the whole band-occupancy in material with exact detail of density of states(DOS).The stable FM state was examined in spinels due to the exchange splitting of Ho cation consisting of p-d hybridizations compatible with the result achieved for electronics band structure and DOS.Further,spin magnetic moment was explained in terms of anion,cation,and sharing charge on studied spinels.In addition,the calculated thermoelectric properties clearly show that operation range of these systems may be utilized by future experimental works for identifying the potential applications of these systems.展开更多
This paper reports on the spectral results of Nd3＋/yb3＋ ions codoped 50P2Os-30ZnO-20SrO （PZS, in mol.%） glasses which were prepared by a melting technique. The glass transition temperature and spectroscopic proper...This paper reports on the spectral results of Nd3＋/yb3＋ ions codoped 50P2Os-30ZnO-20SrO （PZS, in mol.%） glasses which were prepared by a melting technique. The glass transition temperature and spectroscopic properties of these glasses were estimated. From the absorption spectra, Judd-Ofelt （J-O） intensity parameters （Ωk）, were calculated. Using J-O intensity parameters, several radiative properties such as spontaneous transition probabilities （AR）, radiative branching ratios （fiR） and radiative lifetimes （rR） were determined for the exciting levels of the Nd3＋ ions. The large value of the stimulated integrated cross-section and the lifetimes of Nd3~ level revealed the potential of the present glasses as a candidate for generating laser emission at 1.06/am as continuous wave laser action and exploited for optical device fabrication. A broad emission band from 950 to 1100 nm was detected when the Nd3＋/yb3＋ was co-doped in PZS glasses excited by 805 nm lighting diode （LD）. The energy transfer process from Nd3＋--→Yb3＋ in co-doped phos- phate glasses was described in this paper.展开更多
基金the Deanship of Scientific Research at King Khalid University for funding this work through the small Groups Project under grant number(R.G.P.1/153/43)。
文摘Half-metallic ferromagnetism,mechanical as well as thermoelectric properties for rare earth-based spinels MgHo_(2)Z_(4)(Z=S,Se)were investigated using density functional theory(DFT).Structural optimization was done with Perdew-Burke-Ehrenzorf(PBE)sol-generalized gradient approximation(GGA)to calculate the lattice constant of both spinels comparable to experimental data.In addition,Born stability criteria and negative formation energy show that our studied spinels are also structurally and dynamically stable in the cubic phase.For ferromagnetic(FM)state stability,we also calculated the energy differences among FM,antiferromagnetic(AFM),and non-magnetic(NM)states.Additionally,Curie temperatures of ferromagnetic phases were also estimated.We used Trans-Blaha improved BeckeJohnson(TB-mBJ)potential functional for electronics as well as magnetic characteristics,which lead to the consistent explanation of half-metallic ferromagnetism,representing the whole band-occupancy in material with exact detail of density of states(DOS).The stable FM state was examined in spinels due to the exchange splitting of Ho cation consisting of p-d hybridizations compatible with the result achieved for electronics band structure and DOS.Further,spin magnetic moment was explained in terms of anion,cation,and sharing charge on studied spinels.In addition,the calculated thermoelectric properties clearly show that operation range of these systems may be utilized by future experimental works for identifying the potential applications of these systems.
文摘This paper reports on the spectral results of Nd3＋/yb3＋ ions codoped 50P2Os-30ZnO-20SrO （PZS, in mol.%） glasses which were prepared by a melting technique. The glass transition temperature and spectroscopic properties of these glasses were estimated. From the absorption spectra, Judd-Ofelt （J-O） intensity parameters （Ωk）, were calculated. Using J-O intensity parameters, several radiative properties such as spontaneous transition probabilities （AR）, radiative branching ratios （fiR） and radiative lifetimes （rR） were determined for the exciting levels of the Nd3＋ ions. The large value of the stimulated integrated cross-section and the lifetimes of Nd3~ level revealed the potential of the present glasses as a candidate for generating laser emission at 1.06/am as continuous wave laser action and exploited for optical device fabrication. A broad emission band from 950 to 1100 nm was detected when the Nd3＋/yb3＋ was co-doped in PZS glasses excited by 805 nm lighting diode （LD）. The energy transfer process from Nd3＋--→Yb3＋ in co-doped phos- phate glasses was described in this paper.
