摘要
用硝酸锌（Zn（NO3）2·4H2O）或醋酸锌（Zn（CH3COO）2·2H2O）分别与六亚甲基四胺（（CH2）6N4）以等浓度0．005mol／L配制成两种反应溶液，通过化学溶液法在玻璃衬底上生长出ZnO六角型亚微米棒（长5—8μm，直径300-700nm）。测量了样品的XRD和扫描电镜像。经XRD分析，所得样品均为纤锌矿的ZnO六角型晶体。扫描电镜（SEM）像表明，生长时间为3h或5h时，样品为细长条的棒状结构，长径比超过10：1；生长48h后的ZnO亚微米棒的一端被腐蚀成一定深度的ZnO亚微米管。用负离子配位四面体生长模型分析了ZnO亚微米棒的生长机理。ZnO亚微米棒退火前后的光致发光谱表明，退火处理后的发射谱中的紫外峰消失，而红色发光峰红移并且增强（峰值由630nm左右移到710nm），同时它的激发光谱中的室温激子激发峰也增强。
ZnO hexagonal sub-microrods have been synthesized onto glass substrates through aqueous growth method by using the thermal decomposition of an aqueous solution of equimolar zinc nitrate （ Zn （ NO3 ） 2 ·4H2O） or zinc acetate（ Zn（CH3COO） 2·2H2O） ） with methenamine （ （ CH2 ） 6N4 ） by controlling the experimental conditions. XRD patterns, SEM images have been measured, which reveals the shape of the most of the ZnO sub-microrods are hexagonal-rod with two flat faces on the two ends, but some are pair rods symmetrically grown from a center to both sides and some form radial clusters from one center. The length of the rods is from 5μm to 8μm, the diameter from 300 nm to 700 nm and the ratio of the length to the diameter is more than 10：1. When the growth time reaches 48 h, we found that the microrods turned into hollow microtubes with the tube-thickness in the tenth of diameter.
The growth mechanism is discussed by using the growth model of cathodion ligand tetrahedron. Zn-（NO3） 2 dissolves and forms growth units of tetrahedron Zn-（ OH）4 under the reaction of the surface activator （CH2 ）6N4. Then the incorporation of growth units leads to the formation of the ZnO crystal lattice at the interface through a dehydration reaction （OH^- ＋ OH^-=H2O＋ O^2- ）. The fastest of the growth speed along [ 0001 ] direction leads to the formation of the ZnO microrods. The reason of forming hollow microtubes is the face of （0001） and [0001] of ZnO rods as eroded by chemical dissolution because of its metastable state. The excitation spectra of ZnO sub-microrods show that except the intrinsic inter-band excitation shorter than 370 nm, there is a strong exciton excitation peak located at around 377 -385 nm at room temperature. The photoluminescent spectra show that there is a wide orange-red emission peaking at about 630 nm and FWHM 250 nm with the excitation wavelength 310 nm. When the excitation is a strong 325 nm He-Cd laser, the same sample will emit a strong excition emission peaking at about 385 nm, with FWHM 16 nm and a green emission peaking at about 552 nm with FWHM 120 nm. Compared with the calculated data of these intrinsic defects with the theory of FP-LMTO, the green, orange-red and red emission peaks can be attributed to the transition of oxygen vacancies to the valence band. The studies on PL of ZnO sub-microrods after annealing showed that the excitation peak at about 384 nm disappeared, and the orange-red defect emission （peak at -630 nm） shows red shift （peak at -710 nm）, and the emission intensity increases. The excitation spectra of samples after annealing showed an enhanced exciton peak at -377 nm. It indicates that after annealing, the energy transfer from the excition to the defect center occurred.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2006年第1期59-65,共7页
Chinese Journal of Luminescence
基金
国家自然科学基金(19874057)
安徽省自然科学基金(01044904)资助项目
关键词
氧化锌
光致发光
晶体生长
化学溶液法
纳米晶
ZnO
luminescence
photoluminescence
crystal growth
solution growth method
nanocrystal
