。732· 北京科技大学学报 2006年第8期 solidification interfaces.Comput Mater Sci.1996.7:221 face in the directional gmwth of ice crystals.J Crystal [9 Kauerauf B.Zimmermann G.Murmann L et al.Planar to Growth.2000.209:167 celllar transition in the system succinonitrile-acctone during [II]Davis S H.Theory of Solidification.Cambridge University directional solidification of a bulk sample.J Crystal Growth. Press,2001 1998.193:701 【1胡汉起.金属凝固原理.2版北京：机械工业出版社， [10 Nagashima K,Furukawa Y.Time development of a solute 2000 diffusion field and morphological instability on a planar inter Stability analysis of a planar liquid/solid interface of directional solidification in pure melt under perturbation of a far-field flow CHEN Mingwen2),WANG Zidong?,Y ANG Wei,SUN Renji,WU Xianming) 1)Applied Science School,University of Science and Technology Beijing.Beijing 100083.China 2)Materiak Science and Engincering School University of Science and Technology Beijing.Beijing 100083,China 3)Beihai Grain and Vegetable Oil (Tianjin)Co.Ltd,Tianjn 300454.China ABSTRACT The stability of a planar liquid/solid interface of solidification in pure melt under perturbation of a small far-field flow was studied by using asymptotic analysis.A dispersion relation betw een the wave number and perturbation am plification rate w as derived,and the morphological stability of planar liquid-sol- id interface of solidification w as determined.The results reveal the mechanism of the transition from planar interface to cellular interface in directio nal solidification. KEY WORDS melt;crystal growth;liquid/solid interface;planar interface;asymptotic analysis Minimizing chemical interference errors for the determination of lithium in brines by flame atomic absorption spectroscopy analysis WEN Xianming2),MA Peihua,ZHU Geqin,WU Zhim ing2) 1)Qinghai Institute of Salt Lakes.Chinese Academy of Sciences,Xining 810008,Chima 2)Graduate School of Chinese Academy ofSciences,Beijing 100039.China ABSTRACT Chemical interferences(ionization and oxide/hydroxide fomation)on the atomic absorbance signal of lithium in FAAS analy sis of brine samples are elaborated in this article.It is suggested that inade- quate or overaddition of deionization buffers can lead to loss of sensitivities under particular operating condi- tions.In the analy sis of brine samples signal enhancing and oxide/hydroxide formation inducing signal re- duction resulting from overaddition of deionizat ion buffers can be seen with varying amounts of chemical buffers.Based on experimental results,the authors have arrived at the optimized operating conditions for the detection of lithium,under which both ionization and stable compound formation can be suppressed. This is a simplified and quick method with adequate accuracy and precision for the detemmination of lithium in routine brine samples from chemical plants or R &D laboratories,which contain comparable amounts of lithium with some other components. KEY WORDS analy tical chemistry;simplified method;FAAS;lithium;brine;deionization;oxide/hy- droxide fommation 【摘自Rare Metals,2006.25(4:309solidification int erfaces.Comput Mater Sci, 1996, 7:221 [ 9] Kauerauf B, Zimmermann G, Murmann L, et al.Planar t o cellular transition in the system succinonitrile-acet one during directional solidification of a bulk sample.J Crystal Growth, 1998, 193:701 [ 10] Nagashima K, Furukawa Y .Time development of a solute diffusion field and morphologi cal instability on a planar inter￾f ace in the directional grow th of ice cryst als.J Crystal Growth, 2000, 209:167 [ 11] Davis S H .T heory of Solidification.Cambridge Universit y Press, 2001 [ 12] 胡汉起.金属凝固原理.2 版.北京:机械工业出版社, 2000 S tability analysis of a planar liquid/ solid interface of directional solidification in pure melt under perturbation of a far-field flow CHEN Mingwen 1, 2) , WANG Zidong 2) , Y ANG Wei 1) , SUN Renji 1) , WU X ianming 3) 1) Applied Science S chool, University of S cience and Technology Beijing, Beijing 100083, China 2) Materials Science and Engineering School, University of Science and Technology Beijing, Beijing 100083, China 3) Beihai Grain and Veget able Oil ( Tianjin) Co.Ltd., Tianjin 300454, China ABSTRACT The stability of a planar liquid/ solid interface of solidification in pure melt under perturbation of a small far-field flow w as studied by using asymptotic analysis .A dispersion relation betw een the w ave number and perturbation amplification rate w as derived, and the morphological stability of planar liquid-sol￾id interface of solidification w as determined .The results reveal the mechanism of the transition from planar interface to cellular interface in directio nal solidification . KEY WORDS melt ;crystal g row th ;liquid/solid interface ;planar interface ;asymptotic analysis Minimizing chemical interference errors for the determination of lithium in brines by flame atomic abso rption spectroscopy analysis WEN X ianming 1, 2) , MA Peihua 1) , ZHU Geqin 1) , WU Zhiming 1, 2) 1) Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China 2) Graduate S chool of Chinese Academy of S ciences, Beijing 100039, China ABSTRACT Chemical interferences ( ionization and o xide/hydroxide fo rmation) on the atomic absorbance signal of lithium in FAAS analy sis of brine samples are elaborated in this article .It is suggested that inade￾quate or overaddition of deionization buffers can lead to loss of sensitivities under particular operating condi￾tions .In the analy sis of brine samples, sig nal enhancing and oxide/hydroxide formation inducing sig nal re￾duction resulting from overaddition of deionization buffers can be seen with varying amounts of chemical buffers .Based on experimental results, the authors have arrived at the optimized operating conditions for the detection of lithium, under w hich both ionization and stable compound formation can be suppressed . This is a simplified and quick method w ith adequate accuracy and precision for the determination of lithium in routine brine samples from chemical plants or R &D laboratories, w hich contain comparable amounts of lithium with some other components . KEY WORDS analy tical chemistry ;simplified method ;FAAS ;lithium ;brine;deionization ;oxide/hy￾droxide formation [ 摘自 Rare Metals, 2006, 25( 4) :309] · 732 · 北 京 科 技 大 学 学 报 2006 年第 8 期