GOST 23862.17-79
GOST 23862.17−79 Praseodymium and its oxide. Method of determination of impurities of oxides of rare earth elements (with Amendments No. 1, 2)
GOST 23862.17−79
Group B59
INTERSTATE STANDARD
PRASEODYMIUM AND ITS OXIDE
Method of determination of impurities of oxides of rare earth elements
Praseodymium and its oxide. Method of determination of rare-earth element oxides
ISS 77.120.99
AXTU 1709
Date of introduction 1981−01−01
The decision of the State Committee USSR on standards on October 19, 1979 N 3989 date of introduction is established 01.01.81
Limitation of actions taken by Protocol No. 7−95 Interstate Council for standardization, Metrology and certification (ICS 11−95)
EDITION with Amendments No. 1, 2 approved in April 1985, may 1990 (IUS 7−85, 8−90).
This standard specifies neutron activation method for the determination of impurities of oxides of rare earth elements praseodymium and its oxide.
The method is based on irradiation of the analyte samples and comparison with thermal neutron flux of 3·10on natural hair./cm·s with subsequent measurement of activity of radioactive isotopes of the elements.
Intervals determined by a mass fraction of impurities of oxides:
Lantana | from 1·10% 1·10% |
cerium | from 1·10% 1·10% |
neodymium | from 1·10% 1·10% |
Samaria | from 3·10% to 5·10% |
(Changed edition, Rev. N 1).
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 23862.0−79.
2. APPARATUS, REAGENTS AND SOLUTIONS
The research reactor of the pressurized water with a stream of neutrons ·10on natural hair./cm·s and the ratio of thermal neutrons to fast 10:1.
Gamma-ray spectrometer with a semiconductor, consisting of a multichannel analyzer AI-4096, blocks amplification of the signals, the semiconductor germanium-lithium detector with a volume of 60 cmwith photoaffinity γ-lines of cobalt-57 is not less than 0,8−1,0%. The resolution of the spectrometer in the gamma line of cesium-137 (0,682 MeV) to (3−4) Kev.
Gamma-spectrometric sources exemplary (OSGI) according to GOST 8.315−97.
Personal protective equipment against radiation and contamination by radionuclides according to the requirements of OSP-72*.
_______________
* Act SP 2.6.1.799−99, here and hereafter. — Note the manufacturer’s database.
Radiometer «TISS» or similar.
Container lead transport stamps KL-7.
The container table of the brand CT.
995 aluminum foil-A thickness of 0.2−0.3 mm.
Graphite powder of high purity according to GOST 23463−79.
Drying oven with thermostat providing temperatures up to 110 °C.
Mortar and pestle made of organic glass.
The polyethylene film.
Boxy glass type СВ24/10.
Pipette 0.1 cm.
Oxide of lanthanum, cerium, neodymium and samarium with a purity not less than 99.99%.
Hydrochloric acid by the GOST 3118−77, concentrated, 6 mol/DM.
The technical rectified ethyl alcohol GOST 18300−87.
3. PREPARATION FOR ASSAY
3.1. Sample preparation comparison
References (OS) is prepared by mixing powder of graphite oxides determined REE. Prepare two series OS: first (OLS) contain additives of lanthanum and samarium, the second (OSCN) — additives cerium and neodymium.
For the preparation of ACLS 1 containing 10% oxides of lanthanum and samarium, or OSCN 1 containing 10% of oxides of cerium and neodymium in a mortar made of organic glass were placed 800 mg of graphite powder and 100 mg svezhepoymannyh oxides of lanthanum and samarium (OLS 1) or 100 mg svezhepoymannyh oxides of cerium and neodymium (OCN 1). The content was stirred for 60 min, adding alcohol until mushy state mass. After mixing the mixture is dried in a drying Cabinet at a temperature of 100−110 °C for 60 min and mashed to a grinding of the formed lumps.
Samples comparison of OLS 2 OLS 7 or OSCN 2-OSCN 6 prepare a serial dilution, respectively, OLS 1 or OCN 1, and then each subsequent sample graphite powder, repeating each time the mixing procedure and drying, as described for the preparation of samples, OLS 1 and OSTN 1.
The content of each of the designated impurities in the samples comparison, OLS 2 OLS 7 and OCCN 2-OSCN 6 and added to the mixture of graphite powder sample and the previous sample comparisons are shown in table.1.
Table 1
The mass of charge, g | |||
Marking sample | The mass fraction of each impurity determined based on the content of oxides of in the mixture of oxides and graphite powder, % |
powder graphite |
the previous sample (in parentheses symbol) |
OSLS 1 |
10 |
- | - |
OLS 2 |
1,0 |
1,004 |
0,112 (OLS 1) |
OSLS 3 |
1·10 |
1,046 |
0,116 (OLS 2) |
OSLS 4 |
1·10 |
1,458 |
0,162 (OLS 3) |
OSLS 5 |
5·10 |
0,620 |
0,620 (OLS 4) |
OSLS 6 |
1·10 |
Oil 0.960 |
0,240 (OLS 5) |
OSLS 7 |
2·10 |
0,800 |
0,200 (OLS 6) |
OSCN 1 |
10 |
- |
- |
OSCN 2 |
1,0 |
1,004 |
0,112 (OCN 1) |
OSCN 3 |
1·10 |
1,046 |
0,116 (OCN 2) |
OSCN 4 |
1·10 |
1,440 |
0,160 (OCN 3) |
OSCN 5 |
5·10 |
0,600 |
0,600 (OSCN 4) |
OSCN 6 |
1·10 |
0,800 |
0,200 (OCN 5) |
4. ANALYSIS
4.1. A portion of the analyzed oxides of praseodymium with a mass of 10 mg was mixed with 90 mg of graphite powder, Packed in aluminum foil, pre-wiped with alcohol and marked.
A portion of the analyzed metal praseodymium weight of 8.3 mg are Packed in aluminium foil, pre-wiped with alcohol and marked.
Samples comparison of OLS 4 OLS 7 and ASCN 4-OSCN 6 weighing 100 mg each packaged in aluminum foil (each OS separately) and labeled.
The sample and the comparison samples are irradiated in a nuclear reactor for 10 h in a thermal neutron flux of 3·10on natural hair./cm·C. the Transportation of the irradiated samples comparison, in accordance with the requirements of OSP-72, is in lead transport containers stamps KL-7 in a special vehicle. Irradiated the sample and the comparison sample is kept for 11 days.
In the case of the analysis of praseodymium oxide irradiated the sample and the comparison samples after aging are transferred into plastic bags and measured by semiconductor gamma spectrometer (see section 4.2).
In the analysis of praseodymium metal sample and the comparison samples are transferred to glass buxy (for each reference sample a separate buxu), pour in 1 cm of6 mol/lhydrochloric acid and measured by semiconductor gamma spectrometer (see section 4.2).
4.2. Measurement of radioactivity
Before the measurements, gamma-ray spectrometer will graduate in energy using standards of gamma-ray emitters set OSGI. When the graduation is chosen such amplification of signals from the detector to one channel of the analyzer had of 0.8−1 Kev.
The sample is measured consistently with the comparison samples in the same geometric conditions.
The determination carried out in the main botopical in the spectrum: lanthanum — lanthanum-140 (487 Kev), cerium — cerium-141 (144 Kev), neodymium — neodymium-147 (91 Kev), samarium at samarium-153 (103 Kev).
The definition of the area of the main fotopic in the spectrum , pulse/min carried out using a unit of mathematical operations analyzer or graphical way after the recording of the spectrum on paper and calculated by the formula
,
where is the radiation intensity in channel, pulse/min;
, the intensity of the radiation (minimal) right and left of the peak, imp/min.
Time measuring the area of the main fotopic samples and samples of comparison is determined by the actual content of impurities in the measured samples and the samples of comparison and is 5−10 min.
5. PROCESSING OF THE RESULTS
5.1. Mass fraction determined by the oxide impurities of REE () in percent is calculated by the formula
,
where — mass fraction determined by impurities in the reference sample, %;
— mass of the reference sample, mg;
— the weight of the portion of the sample based on the oxide, mg;
— the area of the main fotopic impurities in the spectrum of the sample pulse;
— the area of the main fotopic impurities in the spectrum of the reference sample, imp.
The result of the analysis taking the arithmetic mean of the results of two parallel measurements.
(Changed edition, Rev. N 2).
5.2. Discrepancies in the results of two parallel determinations or the results of the two tests should not exceed values of allowable differences specified in table.2.
Table 2
Mass fraction of oxides of lanthanum, cerium, neodymium, % |
Allowable difference, % |
Mass fraction of oxide of samarium, % |
Allowable difference, % |
1·10 |
4·10 |
3·10 |
1,5·10 |
1·10 |
2·10 |
1·10 |
4·10 |
5·10 |
2·10 |