Once the growth method for a given crystal has been decided,one should be able to adjust a number of growth parameters in order to achieve best results.These parameters include ambient growth atmosphere,temperature gr...Once the growth method for a given crystal has been decided,one should be able to adjust a number of growth parameters in order to achieve best results.These parameters include ambient growth atmosphere,temperature gradient of growth furnace,percentage of fill of crucible,rotation and pulling rates.Among them,the most delicate thing we face is to design and create suitable temperature gradient for a given material according to its thermal properties and growth behavior.For YVO 4 crystals,this is particularly important because of its poor conductivity and strong thermo mechanical anisotropy.Optimum temperature gradient for the growth of large YVO 4 crystals should be as large as possible during the growth process,while be as small as possible during the annealing stage to alleviate thermal stress and avoid cleavage.展开更多
Orthogonal design methocl,based on the formation of a yellow complex of lead(Ⅱ) with α、β、γ、δ Trtra(p sulfopheny 1) Porphine in the pH10.2 H 3BO 3 NaOH buffer selution,has been proposed.The maximum absorption w...Orthogonal design methocl,based on the formation of a yellow complex of lead(Ⅱ) with α、β、γ、δ Trtra(p sulfopheny 1) Porphine in the pH10.2 H 3BO 3 NaOH buffer selution,has been proposed.The maximum absorption wavelength (λ max ) is 464nm.The molar absorption coefficient(ε max ) is 2.5×10 5L·mol -1 ·cm -1 .The detection limit is 4μg·L -1 .Beer’s law is applicable in the rang of 0.1～10.4μg/25ml for lead.The method has been used for determination of trace lead in synthetic sample with satisfactory result.展开更多
文摘Once the growth method for a given crystal has been decided,one should be able to adjust a number of growth parameters in order to achieve best results.These parameters include ambient growth atmosphere,temperature gradient of growth furnace,percentage of fill of crucible,rotation and pulling rates.Among them,the most delicate thing we face is to design and create suitable temperature gradient for a given material according to its thermal properties and growth behavior.For YVO 4 crystals,this is particularly important because of its poor conductivity and strong thermo mechanical anisotropy.Optimum temperature gradient for the growth of large YVO 4 crystals should be as large as possible during the growth process,while be as small as possible during the annealing stage to alleviate thermal stress and avoid cleavage.
文摘Orthogonal design methocl,based on the formation of a yellow complex of lead(Ⅱ) with α、β、γ、δ Trtra(p sulfopheny 1) Porphine in the pH10.2 H 3BO 3 NaOH buffer selution,has been proposed.The maximum absorption wavelength (λ max ) is 464nm.The molar absorption coefficient(ε max ) is 2.5×10 5L·mol -1 ·cm -1 .The detection limit is 4μg·L -1 .Beer’s law is applicable in the rang of 0.1～10.4μg/25ml for lead.The method has been used for determination of trace lead in synthetic sample with satisfactory result.
