哈工大-sem實(shí)驗(yàn)報(bào)告

1、先進(jìn)材料表征技術(shù)課程學(xué)生實(shí)驗(yàn)報(bào)告實(shí)驗(yàn)名稱(chēng)：掃描電鏡與能譜儀的原理及應(yīng)用實(shí)驗(yàn)時(shí)間：2015 年 11 月6 日哈爾濱工業(yè)大學(xué)深圳研究生院I. Purpose1. Be familiar with the structure and principle of seanning electron microscope .2. Be familiar with the requirement of sample preparation.3. Know about the operation specification of SEM, be familiar with the differences b

2、etwee n image of sec on dary electro n and backscatter electro n.4. Know about the operation specification of EDS, be familiar with the point analysis, line an alysis and mapp ing.II. Prin ciples2. IResolution and contrastFor imaging, resolution means the minimum distance between two distinct points

3、.For composition analysis, resolution means the minimum region can be analyzed. In SEM system, resolutio n depe nds on the diameter of the in cide nt electr on beam and sig nal type.Contrast means the difference of brightness , and it can be caused by morphology or atomic number. The morphology cont

4、rast is always observed in SE image, and the atomic con trast is always observed in BSE image.2.2 Electron microscopy imagingThe beam emitted from the electron gun is focused at the surface of the sample through a series of electromagnetic lens (Fig 1.). The last lens equipped with a scanning coil c

5、an drive electron beam scan on the surface. The interaction between high energy electr on beam and sample gen erate various sig nals, and the sig nals can be received by the detector. Do this point by point and we can get a image (Fig 2.).電于檜昭一崔丸冬証Fig 1.Electron gunFig 2. the seanning process to for

6、m a image2.3 SE image and BSE imageSecon dary eleetr on sig nal are gen erated from the very surface (Fig 3.), so the intensity of the signal sensitive to the orientation of the incident beam. Along angle formed by surface and in cide nt beam in creases, the sec on dary electr on yield in crease. Th

7、erefore, the SE image is suitable for display the morphology con trast.From Fig 2. we can see that backscatter electr on is gen erated from a relative big volume near to the surface, so the image has poorer resolution .The BSE yield is sensitive to the atomic nu mber (40), as a result, the regi ons

8、where the heavier atomic exists are brighter tha n other regi ons.MmaFig 3. the region of SE (left) and BSE (right)2.4 EDS-Primary X-raysX-ray is a result of inelastic collision between the incident beam and sample. When high en ergy electro n in teract with atomic, it can stimulate inner electro n.

9、 The inner en ergy level has a hole, and the outer electron will move to the hole and the atom emits the primary X-ray at the same time (Fig 4.). The primary X-ray is associated with the atomic number, so we can identify the elements by primary and roughly measure the relative qua ntity of differe n

10、t eleme nts by calculate the area betwee n the peak on spectrum.Fig . the gen eratio n of X-rayIII. Equipme nt3.1掃描電鏡電鏡主體主要是由電子光學(xué)系統(tǒng)、樣品室、檢測(cè)器以及真空抽氣系統(tǒng)組成。電 子光學(xué)系統(tǒng)包括電子槍、電磁透鏡、掃描線圈等。電源電路系統(tǒng)由控制鏡體部分的 各種電源、信號(hào)處理、圖象顯示和記錄系統(tǒng)以及用于全部電氣部分的操作面板構(gòu) 成。真空系統(tǒng)由用于低真空抽氣的旋轉(zhuǎn)機(jī)械泵 (RP)和高真空抽氣的油擴(kuò)散泵(DP) 或離子泵構(gòu)成。圖1所示為我院實(shí)驗(yàn)室使用的掃面電子顯微鏡，該掃描電鏡主

11、要技術(shù)參數(shù)如下：圖1實(shí)驗(yàn)室所用的掃描電子顯微鏡a) 電子槍?zhuān)豪鋱?chǎng)發(fā)射型b) 分辨率：15KV : 1.5nm( WD : 12mm), 1kV : iro 00 軋n,(oEnergy - hcVElementWt%At%ok19.4946.04 :MnK49.6434.16CoK30.8719.80MatrixCorrectio nZAFI found the Primary X-ray of the 3 elements online, as chart 1. Shown. We found that a peak with energy about 2.1keV is not belon

12、g to the 3 elements. It may be the Kb of eleme nt P, but I dodtwhy this peak is not marked.ElementKaK aKbiL aLaLbO0.523Mn5.8985.887；6.4900.6360.647 1Co6.9306.9157.6490.7750.790So, the sample is main ly composed by eleme nt O, Mn, and Co, maybe eleme nt P also exist in the sample.The atomic ratio O:M

13、 n:Co is about 9:7:4.What is this sample used for? From the Internet, I got that Co-Mn-O composite oxides were also prepared and studied in details as the catalyst for CO selective oxidation.We know that the property of catalyst is sen sitive to its specific surface. From the SEM image with 20.0k magnification(Fig .), we can see that the particle is balls consist of numerous sma