First papers on AC-TEM report on results obtained with 200 kV TEMs, redeemed by papers obtained with 300 kV TEMs. Since 2006, papers with 20-80 kV are published. In all voltage ranges, the number of publications using aberration-corrected electron microscopy is strongly increasing. Today, the ratio of publications that use 20-80 kV; 100-200 kV; 300 kV is 20%; 38%; 42%.
We evaluated the journal impact factor in which publications using aberration-corrected TEM appeared. We distinguish between higher (>10) and lower (<10) impact factor publications. Since the beginning of aberration-corrected TEM, the ratio of higher to lower impact factor publications for the voltage range 100 - 300 kV is 0.16.
Since the beginning of aberration-corrected low-voltage TEM, the ratio of higher (>10) to lower (<10) impact factor publications is 0.67. This extraordinarily high value shows the novelty of discoveries obtained by 20 - 80 kV AC-TEM, above all low-dimensional materials, which since 2004 continue to deliver groundbreaking new discoveries.
Since the beginning of aberration-corrected low-voltage TEM, the ratio of higher (>10) to lower (<10) impact factor publications is 0.46. This extraordinarily high value shows the novelty of discoveries obtained by 20 - 80 kV AC-TEM, above all low-dimensional materials, which since 2004 continue to deliver groundbreaking new discoveries.
The application of AC-TEM (20-80 kV) at low voltages started in 2005. In the first years TEM configuration was used primarily. Since then, the use of STEM increased strongly, and today the ratio of publications that use TEM; STEM; TEM/STEM is 44%; 42%; 14%.
For AC-TEM/STEM with acceleration voltages between 100 kV and 300 kV, the application fields are dominated by classical materials (nanocrystals oxides and semiconductors). Low-D materials and biological objects only investigated in very exceptional cases like cross section views at 100-300 kV because these materials are quickly destroyed by medium voltage electron irradiation.
For AC-TEM/STEM with acceleration voltages between 20 kV and 80 kV, the application fields are dominated by low-D materials. Some researchers perform STEM at 80 kV for classical materials to increase the scattering cross section. A breakthrough for direct imaging of biological materials has still not been reached.
From the low-D material class, the number of publications on pure low-d carbon is almost stable, the number of publications on low-D carbon with other molecules is slightly increasing. 2D chalcogenides show strong exponential increase. The continuing discovery of new low-D materials contributes to the extraordinarily high percentage of high impact publications in LV-AC-TEM.
The manufacturer ranking for aberration-corrected transmission electron microscopes based on the number of publications for the 100 to 300 kV acceleration voltage range is headed by Thermo Fisher Scientific and JEOL Ltd. followed by Nion Corp., Hitachi and Zeiss.
The manufacturer ranking for aberration-corrected (scanning-) transmission electron microscopes in the voltage range 20 to 80 kV now shows the same placement as for the medium voltage range, since Zeiss has exited the high-resolution transmission electron microscopy market.
The proportion of the two commercial manufacturers for aberration correctors, CEOS company and NION Corp. is corresponding to the manufacturer ranking since most manufacturers use CEOS correctors, except Nion, who produce their own correctors for their microscopes. Recently, also JEOL Ltd. started equipping some of their microscopes with their own correctors.
Aberration correctors in the 20 - 80 kV AC-TEM/STEM range are dominated by CEOS company. All microscopes from JEOL and Thermo Fisher use CEOS correctors beside the 30 and 60 kV JEOL TEM/STEMs which use the low-voltage Cs/Cc corrector “DELTA” developed by JEOL in the frame of the Triple-C project and the Cs corrector “Eta”, which can be operated at 80 kV. As also for the medium-voltage range, Nion company is producing their own correctors.
Since 2009 the number of publications using Cs/Cc-correction is increasing and reaches today 9% in the lower voltage range and 5% in the medium voltage range, respectively. This reflects the importance of chromatic aberration correction to achieve atomic resolution at lower voltages. At present CEOS GmbH is the only commercial provider of Cs/Cc-correctors.