光谱学与光谱分析
光譜學與光譜分析
광보학여광보분석
SPECTROSCOPY AND SPECTRAL ANALYSIS
2010年
4期
1035-1038
,共4页
光致吸收%近化学计量比铌酸锂晶体%拉曼光谱
光緻吸收%近化學計量比鈮痠鋰晶體%拉曼光譜
광치흡수%근화학계량비니산리정체%랍만광보
Light induced absorption%Nearly stoichiometric LiNbO_3 crystal%Raman spectrum
研究了不同锂含量的双掺铁锰铌酸锂晶体的紫外光致吸收特性,结果表明,同成分晶体的紫外光致吸收系数较低,随着锂含量的增加,晶体的紫外光致吸收系数逐渐增大,当晶体中的锂含量达到49.57mol%附近时,紫外光致吸收系数达到最大值4.20 cm~(-1),进一步增加晶体中的锂含量,饱和光致吸收系数开始下降.在此基础上,提出了近化学计量比双掺铁锰铌酸锂晶体的双色非挥发全息存储的三中心模型,即随着晶体锂含量的增加,双掺铁锰晶体的光折变中心除了Fe~(2+)/Fe~(3+),Mn~(2+)/Mn~(3+)外,还将增加双极化子/小极化子中心.
研究瞭不同鋰含量的雙摻鐵錳鈮痠鋰晶體的紫外光緻吸收特性,結果錶明,同成分晶體的紫外光緻吸收繫數較低,隨著鋰含量的增加,晶體的紫外光緻吸收繫數逐漸增大,噹晶體中的鋰含量達到49.57mol%附近時,紫外光緻吸收繫數達到最大值4.20 cm~(-1),進一步增加晶體中的鋰含量,飽和光緻吸收繫數開始下降.在此基礎上,提齣瞭近化學計量比雙摻鐵錳鈮痠鋰晶體的雙色非揮髮全息存儲的三中心模型,即隨著晶體鋰含量的增加,雙摻鐵錳晶體的光摺變中心除瞭Fe~(2+)/Fe~(3+),Mn~(2+)/Mn~(3+)外,還將增加雙極化子/小極化子中心.
연구료불동리함량적쌍참철맹니산리정체적자외광치흡수특성,결과표명,동성분정체적자외광치흡수계수교저,수착리함량적증가,정체적자외광치흡수계수축점증대,당정체중적리함량체도49.57mol%부근시,자외광치흡수계수체도최대치4.20 cm~(-1),진일보증가정체중적리함량,포화광치흡수계수개시하강.재차기출상,제출료근화학계량비쌍참철맹니산리정체적쌍색비휘발전식존저적삼중심모형,즉수착정체리함량적증가,쌍참철맹정체적광절변중심제료Fe~(2+)/Fe~(3+),Mn~(2+)/Mn~(3+)외,환장증가쌍겁화자/소겁화자중심.
The ultraviolet light induced absorption change (LTV-LIA) of nearly stoichiometric LiNbO_3 : Fe : Mn crystals was investigated. The experimental results show that the UV-LIA coefficient change of LiNbO_3 : Fe: Mn crystal is not large for congruent sample, increases with increasing Li_2O concentration, reaches the maximum 4. 2 cm~(-1) at about 49. 57 mol% Li_2O,and then decreases with further increasing Li_2O content. Because the UV-LIA change has a direct relationship with the nonvola-tile holographic sensitivity, the experimental results indicate that the nearly stoichiometric LiNbO_3 : Fe : Mn crystal with 49. 57 mol% Li_2O is the appropriate candidate material for the nonvolatile holographic storage The visible light induced bleaching re-sults also prove that the suitable composition is 49. 57 mol%. With the increase in Li20 concentration in the LiNbO_3: Fe : Mn crystal, the amount of the bipolaron increases. Bipolarons may be dissociated either optically or thermally so that metastable small polarons are formed. The energy level for biopolaron and small polaron is at about 2. 5 and 1.6 eV respectively. When the Li_2O concentration continues to increase, the small polarons are dominating intrinsic defects. The bipolarons have stronger pho-torefractive capability than the small polarons. The amount of bipolaron is the most with 49. 57 mol% Li_2O concentration in the LiNbO_3 : Fe : Mn crystal. Based on these experimental results, a three-photorefraetive-centers model in nearly stoichimetric LiNbO_3: Fe : Mn crystal is suggested: besides Fe~(2+)/Fe~(3+) and Mn~(2+)/Mn~(3+) , bipolarons/small polarons are considered as the third photoactive center.
