Slow evaporation method was used to grow single crystals of lithium rubidium sulphate with high transparency.Single crystal X-ray diffraction analysis shows that at room temperature,the crystal belongs to a monoclinic...Slow evaporation method was used to grow single crystals of lithium rubidium sulphate with high transparency.Single crystal X-ray diffraction analysis shows that at room temperature,the crystal belongs to a monoclinic system with the space group P21/n.Some physical parameters like plasma energy,Penn gap,Fermi energy and electronic polarizability have been evaluated for the grown crystal.The relation between electronic polarizability and diamagnetic susceptibility for the crystal has been established on the basis of Kirkwood’s semiempirical equation.The ac conductivity and dielectric behavior of the grown crystal were systemically investigated as a function of frequency and temperature.The title compound obeys Jonscher’s power law relations:ð(ω)=σo+Aω^(s),with exponent s<1.From the conduction study,it is observed that both small and large polarons take part in conduction process,and at low temperature,both the band and hopping mechanisms are responsible for conduction.From impedance and modulus studies,it is observed that only one conduction relaxation is observed in the crystal at low frequency.The activation energy of the dielectric relaxation(0.41 eV)and that of the conduction(Econd¼0:43 eV)are in agreement,as a result,there is no difference among the conduction and relaxation species at high temperature.Differential scanning calorimetric analysis of the crystal shows three endothermic peaks at 166℃,185℃,and 202℃,from which various thermodynamic parameters such asΔH,ΔS andΔC_(p) have been calculated.From Vickers hardness test,we have determined the mechanical strength,and other parameters which include fracture toughness,brittleness index,yield strength,and stiffness constant for the crystal.展开更多
Gadolinium-terbium fumarate heptahydrate crystals were grown in silica gel by using single gel diffusion technique.The crystals were characterized by different physico-chemical techniques of characterization.Powder X-...Gadolinium-terbium fumarate heptahydrate crystals were grown in silica gel by using single gel diffusion technique.The crystals were characterized by different physico-chemical techniques of characterization.Powder X-ray diffraction results showed that the grown material is purely crystalline in nature.Elemental analyses suggested the chemical formula of the compound to be Gd Tb(C_(4)H_(2)O_(4)_(3)·7H_(2)O.Energy dispersive X-ray analysis confirmed the presence of Gd and Tb in the title compound.The dielectric and conductivity studies of the grown compound were carried as function offrequency of applied field and the temperature.The grown material showed a dielectric anomaly which was correlated with its thermal behavior.The ac conductivity of the material showed Jonscher's power law behavior:σ(ω)=σ_(0)+Aω^(s),with a temperature-dependent power exponent s(<1).The conductivity was found to be a function of temperature and frequency.展开更多
基金One of the authors,FAN,is highly thankful to the UGC,New Delhi and Department of Higher Education,Government of Jammu and Kashmir for providing teacher fellowship under FIP scheme F.No.27-71/2014(TF/NRCB)from S.P.College Srinagar.
文摘Slow evaporation method was used to grow single crystals of lithium rubidium sulphate with high transparency.Single crystal X-ray diffraction analysis shows that at room temperature,the crystal belongs to a monoclinic system with the space group P21/n.Some physical parameters like plasma energy,Penn gap,Fermi energy and electronic polarizability have been evaluated for the grown crystal.The relation between electronic polarizability and diamagnetic susceptibility for the crystal has been established on the basis of Kirkwood’s semiempirical equation.The ac conductivity and dielectric behavior of the grown crystal were systemically investigated as a function of frequency and temperature.The title compound obeys Jonscher’s power law relations:ð(ω)=σo+Aω^(s),with exponent s<1.From the conduction study,it is observed that both small and large polarons take part in conduction process,and at low temperature,both the band and hopping mechanisms are responsible for conduction.From impedance and modulus studies,it is observed that only one conduction relaxation is observed in the crystal at low frequency.The activation energy of the dielectric relaxation(0.41 eV)and that of the conduction(Econd¼0:43 eV)are in agreement,as a result,there is no difference among the conduction and relaxation species at high temperature.Differential scanning calorimetric analysis of the crystal shows three endothermic peaks at 166℃,185℃,and 202℃,from which various thermodynamic parameters such asΔH,ΔS andΔC_(p) have been calculated.From Vickers hardness test,we have determined the mechanical strength,and other parameters which include fracture toughness,brittleness index,yield strength,and stiffness constant for the crystal.
基金The corresponding author B.Want is highly thankful to DST(SERB),Govt.of India for providing financial assis-tance under the major research project No.SR/S2/CMP-102/2012.
文摘Gadolinium-terbium fumarate heptahydrate crystals were grown in silica gel by using single gel diffusion technique.The crystals were characterized by different physico-chemical techniques of characterization.Powder X-ray diffraction results showed that the grown material is purely crystalline in nature.Elemental analyses suggested the chemical formula of the compound to be Gd Tb(C_(4)H_(2)O_(4)_(3)·7H_(2)O.Energy dispersive X-ray analysis confirmed the presence of Gd and Tb in the title compound.The dielectric and conductivity studies of the grown compound were carried as function offrequency of applied field and the temperature.The grown material showed a dielectric anomaly which was correlated with its thermal behavior.The ac conductivity of the material showed Jonscher's power law behavior:σ(ω)=σ_(0)+Aω^(s),with a temperature-dependent power exponent s(<1).The conductivity was found to be a function of temperature and frequency.
