Zinc oxide

Nanomaterial surface chemistry

Administrative data

Endpoint:

nanomaterial surface chemistry

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was not conducted in compliance with GLP. The results are scientifically acceptable. Thus, the study was regarded as reliable with restrictions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

XPS measurements were obtained in ultra high vacuum using a Kratos AXIS Ultra DLD (Kratos Analytical, UK) instrument fitted with a monochromated Al Ksource, which was operated at 15kV and 5mA emission. Photoelectrons from the top few nanometres of the surface were detected in the normal emission direction over an analysis area of approximately 700 x 300 micrometres. Spectra in the range 1400 to –10 eV binding energy and a step size of 1 eV, using a pass energy of 160 eV were acquired from selected areas of each sample. The peak areas were measured after removal of a Tougaard background. The manufacturer’s intensity calibration and commonly employed sensitivity factors were used to determine the concentration of the elements present. High resolution narrow scans of some of the peaks of interest were acquired with a step size of 0.1 eV and 20 eV pass energy. (The manufacturer calibrated the intensity calibration over the energy range). The energy scale was calibrated according to ISO 15472 Surface chemical analysis – X-ray photoelectron spectrometers – Calibration of energy scales. However, the charge neutraliser was used when acquiring the spectra, which shifted the peaks by several eV. The C 1s hydrocarbon peak (285 eV binding energy) was used to determine the shift for identifying the peaks.


The pellets of the sample powders were produced using the KBr Quick Press pellet presser. The powder was loaded from half to ¾ filled and gently pressed before the 3 pieces were inserted into the socket of the pellet maker. The handle was carefully pressed until some resistance was felt, and when pressed downwards there was ~ 1. 5 cm gap between the stop-screw on the handle to the central body. After a few minutes the handle was released, and pressure re-applied twice more until the presser clicked three times in total. The 3 piece assembly was taken out and the pellet removed.

GLP compliance:

no

Type of method:

XPS

Test material

Test material information

Constituent 1

Reference substance name:

Zinc oxide

EC Number:

215-222-5

EC Name:

Zinc oxide

Cas Number:

1314-13-2

Molecular formula:

ZnO

IUPAC Name:

oxozinc

Test material form:

solid: nanoform

Results and discussion

Any other information on results incl. tables

Showing the elemental compositions from the NM111 ZnO HP1 sample as determined by XPS.

Stub name	replicate number	C 1s %	O 1s %	Si 2s %	Zn 2p3/2 %
0803	rep1	21.5	44.0	1.8	32.6
		21.9	43.8	1.9	32.4
	rep2	24.8	41.5	2.0	31.8
		25.5	41.3	1.5	31.7
	rep3	25.5	41.3	1.5	31.6
		25.9	40.7	1.9	31.5
1951	rep1	31.2	37.1	1.4	30.3
	rep2	29.2	39.0	1.7	30.1
	rep3	29.9	38.5	2.0	29.7
1455	rep1	31.5	37.2	1.6	29.7
	rep2	30.5	38.1	1.1	30.3
	rep3	32.0	36.9	1.4	29.6
2017	rep1	29.6	38.6	1.8	30.0
	rep2	30.1	38.0	1.6	30.3
	rep3	30.4	37.8	2.2	29.6
2100	rep1	30.3	37.6	1.6	30.5
	rep2	31.8	36.6	1.8	29.7
	rep3	31.5	37.0	1.2	30.3
		30.0	37.9	1.6	30.5
4414	rep1	31.1	37.6	1.2	30.1
		31.7	36.9	1.6	29.8
	rep2	28.2	39.4	2.0	30.5
		29.0	38.9	1.9	30.1
	rep3	29.2	38.4	2.2	30.2

 

Showing the elemental compositions from the NM110 ZnO sample as determined by XPS.

Stub name	replicate number	C 1s %	O 1s %	Si 2s %	Zn 2p3/2 %
0979	rep1	24.2	39.3	0.0	36.5
	rep2	24.8	39.6	0.0	35.6
	rep3	25.9	39.2	0.0	34.8
0599	rep1	24.1	40.2	0.0	35.7
	rep2	26.2	39.1	0.0	34.7
	rep3	26.6	39.0	0.0	34.4
0945	rep1	23.7	40.3	0.0	36.0
	rep2	25.0	39.6	0.0	35.5
	rep3	25.9	39.4	0.0	34.7
4779	rep1	23.2	36.0	0.0	36.2
	rep2	26.0	39.3	0.0	34.7
	rep3	25.6	39.6	0.0	34.7
4410	rep1	19.6	41.2	0.0	39.2
	rep2	22.2	40.2	0.0	37.6
	rep3	22.0	40.7	0.0	37.3
3911	rep1	20.3	40.8	0.0	38.9
	rep2	21.5	40.3	0.0	38.2
	rep3	22.8	40.2	0.0	36.9

 

 

Applicant's summary and conclusion

Conclusions:

For the NM 111 - ZnO HP1 sample Zinc, Oxygen and Silicon (the latter from the silane layer) were all detected. All samples showed a large amount of carbon probably adsorbed from the atmosphere. The percentage concentration of carbon is consistent in the region 30-32% except from 0803 sample, which is in the region 22-26%. The percentage levels of the other sub-samples are remarkable consistent varying only between 37 – 40 % for Oxygen, 39-31% for Zinc and 1.2 – 2.2 % for Silicon. More Oxygen that Zinc was detected due to the oxygen in the silane layer.
For the NM110 - ZnO sample Zinc and Oxygen were detected but no Silicon. In addition, Carbon was detected. More Oxygen was detected than expected considering the amount of Zinc (assume a 1:1 ratio from Zinc Oxide). The amount of Oxygen varied between 39-41% and Zinc from 35-39%.Carbon shows the greatest variability from 20 – 26%.

Executive summary:

NPL, 2010 determined the elemental composition of the different nanomaterials as measured by XPS. XPS measurements were obtained in ultra high vacuum using a Kratos AXIS Ultra DLD (Kratos Analytical, UK) instrument fitted with a monochromated Al K alpha source, which was operated at 15kV and 5mA emission. Photoelectrons from the top few nanometres of the surface were detected in the normal emission direction over an analysis area of approximately 700 x 300 micrometres. Spectra in the range 1400 to –10 eV binding energy and a step size of 1 eV, using a pass energy of 160 eV were acquired from selected areas of each sample. The peak areas were measured after removal of a Tougaard background. The manufacturer’s intensity calibration and commonly employed sensitivity factors were used to determine the concentration of the elements present. High resolution narrow scans of some of the peaks of interest were acquired with a step size of 0.1 eV and 20 eV pass energy. (The manufacturer calibrated the intensity calibration over the energy range). The energy scale was calibrated according to ISO 15472 Surface chemical analysis – X-ray photoelectron spectrometers – Calibration of energy scales. However, the charge neutraliser was used when acquiring the spectra, which shifted the peaks by several eV. The C 1s hydrocarbon peak (285 eV binding energy) was used to determine the shift for identifying the peaks. The pellets of the sample powders were produced using the KBr Quick Press pellet presser. The powder was loaded from half to ¾ filled and gently pressed before the 3 pieces were inserted into the socket of the pellet maker. The handle was carefully pressed until some resistance was felt, and when pressed downwards there was ~ 1. 5 cm gap between the stop-screw on the handle to the central body. After a few minutes the handle was released, and pressure re-applied twice more until the presser clicked three times in total. The 3 piece assembly was taken out and the pellet removed.

 

The experimentally determined elemental compositions for all materials For the NM 111 - ZnO HP1 sample Zinc, Oxygen and Silicon (the latter from the silane layer) were all detected. All samples showed a large amount of carbon probably adsorbed from the atmosphere. The percentage concentration of carbon is consistent in the region 30-32% except from 0803 sample, which is in the region 22-26%. The percentage levels of the other sub-samples are remarkable consistent varying only between 37 – 40 % for Oxygen, 39-31% for Zinc and 1.2 – 2.2 % for Silicon. More Oxygen that Zinc was detected due to the oxygen in the silane layer.

 

For the NM110 - ZnO sample Zinc and Oxygen were detected but no Silicon. In addition, Carbon was detected. More Oxygen was detected than expected considering the amount of Zinc (assume a 1:1 ratio from Zinc Oxide). The amount of Oxygen varied between 39-41% and Zinc from 35-39%.Carbon shows the greatest variability from 20 – 26%.