1

Images of Minerals at the Atomic Scale

Z-contrast and TEM Images from

Prof. Huifang Xu’s Research Group

Department of Geoscience, University of Wisconsin - Madison

2

Olivine Minerals

Fayalite

3

Z-contrast image of a forsterite with a layer of Mg-laihunite (FeMg0.5(SiO4)) due to oxidation of Fe-bearing olivine in a basaltic rock (Konishi and Xu, 2013).

4

Laihunite

Figure10. Polyhedral models along the a-axis projection for laihunite-1M (a), laihunite-2M (b), laihunite-3Or (c), and a previously proposed “laihunite-3M” (d) structure for the 3-layer

laihunite. The “laihunite-3M” (d) is not a correct model, because it does not fit the observed Z-contrast images. The polyhedral for Fe atoms at M1 and M2 sites are colored in yellow and

orange, respectively.

5

Figure7. Z-contrast images of 1-layer laihunite ([100]-zone-axis) showing positions of high-density spots (corresponding to Fe, Si) and low-density sites of vacancies. Noise-filtered image (b) better shows the positions of the atoms and vacancy sites. A unit cell of 1-layer laihunite model with the o0.5Fe2+ 0.5Fe3+SiO4 stoichiometry is also overlaid on the image. The Fe atoms at M1 and M2 sites, and Si atoms are colored in yellow, orange, and blue, respectively.

6

Figure6. A [110]-zone-axis Z-contrast image showing intergrowth of 1-layer laihunite (1M), 2-layer (2M), and 3-layer (3Or) phases that are between laihunite and fayalite. Inserted in the upper left and lower right comers are FFT patterns from the 3-layer phase and 1-layer laihunite domains, respectively. An outline box area shows an interface between the1-layer laihunite (1M) and the 3-layer phase (3Or).

7

Pyroxene

8

9

Pyroxene: protoenstatite

10

11

12

Feldspars: Ca-rich plagioclase

Figure 2. ABF STEM image (a) image and Z-contrast image (b) along a-axis. Arrows indicate ordering of Ca atoms (bright spots) at the boundary positions between the lamellae domains. (Color online.)

13

Figure 3. Noise-filtered Z-contrast image clearly showing Ca-Na ordering in lamellae domains and at the inversion boundary positions. Neighboring lamellae domains with I1 symmetry are in inversion twin relationship. A unit-cell structure model showing polarity of Na-Ca atoms is also overlaid on the image. (Color online.)

14

Feldspars: Na-rich plagioclase

15

16

Feldspars: labradorite

17

18

19

20

21

Talc: graphite and graphene-like carbon layers within black talc

Bright-field (BF, a and c) and dark-field (DF, b and e) STEM images of black talc crystals. (American Mineralogist, 2016)

22

Metals: Pt

Morphology mapping of platinum catalysts over the entire nanoscale

23

Typical micrographs of platinum nanoparticles greater than ~5 nm, taken in STEM mode. Greater intensity indicates greater thickness (perpendicular to the beam), and facilitates shape analyses, though some particles do not show lattice fringes due to the off zone axis.

24

STEM images showing (a) amorphous, non-crystalline Pt clusters, and (b) round (larger) Pt crystals. Note that the surface Pt on round crystals are less ordered (regular).