坩埚下降法生长近化学计量比Cr∶LiNbO_3晶体及光谱研究  

Preparation and Spectra Properties of Near-stoichiometric Cr∶LiNbO_3 Single Crystals Grown by Bridgman Method

作　　者：王金浩[1] 张约品[1] 夏海平[1] 陈红兵[2] 

机构地区：[1]宁波大学光电子功能材料研究所,宁波315211 [2]宁波大学材料科学与化学工程学院,宁波315211

出　　处：《人工晶体学报》2010年第B06期18-22,共5页Journal of Synthetic Crystals

基　　金：宁波市自然科学基金(2010A610165)

摘　　要：以K2O为助熔剂,在较大的温度梯度(60～80℃/cm)条件下进行引种和晶体生长,应用坩埚下降法技术生长了Cr3+掺杂的近化学计量比的LiNbO3晶体。采用电感耦合等离子体原子发射光谱法(ICP-AES)分析了晶体的主要成分,其中Cr3+、Li2O、Nb2O3的含量分别为0.62mol%、49.23mol%和50.15mol%,并在FT-IR谱中观察到了因组分变化引起的OH-伸缩振动的变化。测定了晶体的吸收与发射光谱,观测到Cr3+在晶体中有两个宽且强的吸收带及两个微弱的吸收线,两宽带中心波长分别为480nm与658nm,对应于Cr3+的4A2→4T1与4A2→4T2两个具有相同的总自旋能级之间的跃迁,并观测到了微弱的684nm和728nm的R线吸收。同时测定了Cr3+∶LiNbO3晶体在670nm激发下的荧光光谱,是由4T2→4A2跃起所产生的850～1150nm的宽带荧光发射发光带,此发光带是由于取代Li+与Nb5+格位的Cr3+的4T2→4A2能级跃起的复合发光所致,并计算了该晶体的晶场强度以及Racah参数等。The near-stoichiometric LiNbO3 single crystals doped Cr^3＋ in the raw compositions were grown by Bridgman method using K2O as flux, and taking high temperature gradient of about 60 - 80 ℃/cm of the interface as seeding and growing of the crystal. The composition of as-grown crystal were analyzed by Inductively Coupled Plasma Atomic Emission Spectrometry （ICP-AES）, the content of Cr^3＋ , Li2O and Nb2O3 were 0. 62 mol% ,49. 23 mol% and 50. 15 mol%, respectively. The FT-IR indicated that stretching vibration of OH- changes as the composition changing. The absorption and fluorescence were also measured, two wide absorption band centered at 480 nm and 658 nm which corresponded to the ^4A2 →4Tt and ^4A2→^4T2 level transition, and two weak absorption of R-lines were at 684 nm and 728 nm were observed. The fluorescence spectrrum showed a emission wideband ranging from 850 nm to 1150 nm excited by 670 nm pulse laser in room temperature. It was to note that the wide emission assigned to the CrNi^3＋ and CrNb^3＋ transition of ^4 T2→^4A2 level. The crystal field and Racah parameters were also calculated.

关 键 词：坩埚下降法 近化学计量比 CR^3+ LINBO3 

分 类 号：O78[理学—晶体学]