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Melting point / freezing point

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Endpoint:
melting point/freezing point
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 02 NOV 2005 to 19 APR 2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 102 (Melting point / Melting Range)
Version / remarks:
and EU method A1 (Melting / Freezing temperature)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
thermal analysis
Key result
Melting / freezing pt.:
> 400 °C
Decomposition:
no

- Deduction of melting point: During the preliminary and main tests, no endothermic heat effect was observed; thus, preventing to deduce a melting point.

- Appearance and weight of the test item: After both tests, the sample was still a white powder, loosing about 0.4 and 0.3% of its mass in preliminary and main tests respectively.

Conclusions:
Yttrium oxide does not melt under the conditions of the test.
Executive summary:

The melting point of yttrium oxide was assessed using a thermal analysis, according to OECD Guideline 102. A test item amount of 16.82 mg was heated up from 25°C to 400°C at a rate of 20°C/min during a preliminary test. The quantities of heat absorbed or released were measured by Differential Scanning Calorimeter and recorded. In this test, no peak was observed, and the melting point of the sample could not be deduced. The thermal analysis was thus repeated in a main test, using 22.5 mg of test item in the same temperature range, but with the rise adjusted to 10°C/min. No endothermic reaction could be observed. In conclusion, yttrium oxide does not melt under the conditions of the test.

Endpoint:
melting point/freezing point
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
no data
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
Data in this peer-reviewed publication were taken from many sources, including both compilations and primary literature. Where conflicts were found, the value deemed most reliable was chosen for inclusion in the handbook. Reference sources were not provided for this parameter, nor were the experimental methods.
Melting / freezing pt.:
ca. 2 710 °C
Conclusions:
The melting point under the study conditions was reported to be 2710 degrees C.
Endpoint:
melting point/freezing point
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
no data
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
Data in this peer-reviewed publication were taken from many sources, including both compilations and primary literature. Where conflicts were found, the value deemed most reliable was chosen for inclusion in the handbook. Reference sources were not provided for this parameter, nor were the experimental methods.
GLP compliance:
no
Melting / freezing pt.:
2 680 °C
Conclusions:
The melting point under the study conditions was reported to be 2680 degrees C.
Endpoint:
melting point/freezing point
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
Based on a weight of evidence approach using melting point data for the individual substances zirconium dioxide (around 2700°C, Lide, 2001; O'Neil, 2006) and yttrium oxide (> 400°C, Weissenfeld, 2006), the melting point of yttrium zirconium oxide can be expected to be at least > 400°C, being environmentally irrelevant.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Melting / freezing pt.:
> 400 °C

Description of key information

No key information is available on the melting point of yttrium zirconium oxide, however, based on a weight of evidence approach using melting point data for the individual substances zirconium dioxide (around 2700°C, Lide, 2001; O'Neil, 2006) and yttrium oxide (> 400°C, Weissenfeld, 2006), the melting point of yttrium zirconium oxide can be expected to be at least > 400°C, being environmentally irrelevant.

Key value for chemical safety assessment

Additional information

1. Information on zirconium dioxide (CAS# 1314-23-4)

Two values (Lide, 2001; O'Neil, 2006) are available, i.e., 2710 and 2680°C. It can be safely concluded that the melting point of zirconium dioxide is approximately 2700°C, making it environmentally irrelevant.

2. Information on yttrium oxide (CAS# 1314-36-9)

A value for the melting point of the substance was obtained from an OECD 102 study. Yttrium oxide did not melt under the conditions of the test. The melting point of the substance is reported to be > 400°C (Weissenfeld, 2006).

3. Conclusion on yttrium zirconium oxide (CAS# 64417-98-7)

It is expected that the substance has a similarly high melting point as the read across substances zirconium dioxide and yttrium oxide (i.e., at least > 400°C). No exact value can be derived, however, this is not necessary as the high melting point is environmentally irrelevant.