Direct Visualization of Trimerized States in 1T'-TaTe2

Ismail El Baggari, Nikhil Sivadas, Gregory M. Stiehl, Jacob Waelder, Daniel C. Ralph, Craig J. Fennie, and Lena F. Kourkoutis

Transition-metal dichalcogenides containing tellurium anions show remarkable charge-lattice modulated structures and prominent interlayer character. Using cryogenic scanning transmission electron microscopy (STEM), we map the atomic-scale structures of the high temperature (HT) and low temperature (LT) modulated phases in 1T'-TaTe2. At HT, we directly show in-plane metal distortions which form trimerized clusters and staggered, three-layer stacking. In the LT phase at 93 K, we visualize an additional trimerization of Ta sites and subtle distortions of Te sites by extracting structural information from contrast modulations in plan-view STEM data. Coupled with density functional theory calculations and image simulations, this approach opens the door for atomic-scale visualizations of low temperature phase transitions and complex displacements in a variety of layered systems.

Figure 1
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Plan view_room temperatureemi17_s40_7.2Mx_0.5us_1024_21.4mrad_CL130mm_0.93nA.emi
Plan view_room temperaturetif17_s40_7.2Mx_0.5us_1024_21.4mrad_CL130mm_0.93nA_1_REGISTERED.tif
Plan view_room temperaturetif17_s40_7.2Mx_0.5us_1024_21.4mrad_CL130mm_0.93nA_1_REGISTERED_ROTATED_CROP420.tif
Plan view_room temperatureser17_s40_7.2Mx_0.5us_1024_21.4mrad_CL130mm_0.93nA_2.ser
Cross section_room temperatureemi32_s35_10Mx_.8us_1024_-5deg.emi
Cross section_room temperatureser32_s35_10Mx_.8us_1024_-5deg_1.ser
Cross section_room temperaturetif32_s35_10Mx_.8us_1024_REGISTERED_ALIGNED_CROPPED.tif
Figures 2 and 3
ItemTypeFile
Plan view_cryotif25_s40_7.2Mx_0.5us_1024_21.4mrad_CL130mm_REGISTERED.tif
Plan view_cryotif25_s40_7.2Mx_0.5us_1024_21.4mrad_CL130mm_REGISTERED_ROTATED__CROP420.tif
Plan view_cryoemi25_s40_7.2Mx_0.5us_1024_21.4mrad_CL130mm_rot.emi
Plan view_cryoser25_s40_7.2Mx_0.5us_1024_21.4mrad_CL130mm_rot_1.ser
SI Figure 2
ItemTypeFile
Cross sectionemi23_1.8Mx_6us_1024_-5deg.emi
Cross sectionser23_1.8Mx_6us_1024_-5deg_1.ser
Cross Sectionpng23_1.8Mx_6us_1024_-5deg_1.ser.png
Cross Sectiontif23_1.8Mx_6us_1024_-5deg_1.ser.tif
Cross Sectionemi42_s35_7.2Mx_.8us_1024_-10deg.emi
Cross Sectionser42_s35_7.2Mx_.8us_1024_-10deg_1.ser
Cross Sectionpng42_s35_7.2Mx_.8us_1024_-10deg_1.ser.png
Cross Sectiontif42_s35_7.2Mx_.8us_1024_-10deg_1.ser.tif
SI Figure 5
ItemTypeFile
Cross-section_other zone low Temi40_s40_10Mx_512_2us_alpha-2.34.emi
Cross-section_other zone low Tser40_s40_10Mx_512_2us_alpha-2.34_1.ser
Cross-section_other zone low Ttif40_s40_10Mx_512_2us_alpha-2.34_1.ser.tif