GOST 23862.16-79

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  ГОСТ 23862.16-79

GOST 23862.16−79 Rare-earth metals and their oxides. Method of determination of cerium and terbium (with Amendments No. 1, 2)

GOST 23862.16−79

Group B59

INTERSTATE STANDARD

RARE EARTH METALS AND THEIR OXIDES

Method of determination of cerium and terbium

Rare-earth metals and their oxides. Method of determination of cerium and terbium

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 3988 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 establishes a fluorescent method for the determination of cerium and terbium in rare earth metals and their oxides.

The method is based on excitation of a mercury or xenon lamp in the luminescence spectra of the CE ion, or ion Тbin the sample solution and record the received radiation. Mass fraction of impurities find by the method of additions.

Intervals determined by a mass fraction of impurities of oxides:

(Changed edition, Rev. N 2).

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 23862.0−79.

2. APPARATUS, MATERIALS AND REAGENTS

The spectrofluorimeter MPF-4 of Hitachi, with a xenon lamp or similar device.

Measuring cylinders with ground stoppers with a capacity of 10 cm.

Volumetric flasks with a capacity of 100 cm.

Glasses with a capacity of 100 cm.

Glass pipettes with a capacity of 1 and 10 cm.

The micropipette ПЛО1−20, with a capacity of 0.02 cm.

Tile electric.

Hydrochloric acid of high purity according to GOST 14261−77 or hydrochloric acid by the GOST 3118−77, H. h., diluted 1:1.

Sulfuric acid GOST 4204−77, H. h

Ammonia water according to GOST 3760−79.

Hydrogen peroxide according to GOST 10929−76.

Tin dichloride.

Terbium oxide brand Тв0-I.

Cerium dioxide brand of OSS-SS.

A solution of cerium spare, containing 0.3 mg/cm(dioxide of cerium): 150 mg of cerium dioxide is placed in a beaker with a capacity of 100 cm, flow 10 cmof concentrated sulfuric acid, dissolved by heating on a hot plate with the addition of 20 cmof hydrogen peroxide. The solution is neutralized with ammonia, and adding excess of ammonia to the precipitation of cerium hydroxide. The precipitate was filtered off, washed twice with hot water, dissolve in hydrochloric acid, diluted 1:1. The solution was transferred to a volumetric flask with a capacity of 500 cmand was adjusted to the mark with water.

Solutions of cerium 1−5 workers (see table.1) is prepared by dilution of a backup solution of cerium water in 1000, 500, 200, 100 and 20 times.

Mass fraction of dioxide of cerium in the samples and recommended as additives for these samples the working solutions with different concentrations of cerium dioxide are given in table 1.

Table 1

Solutions recommended for the two supplements (lesser and greater) to the sample in the sample sample 1 g.

A solution of terbium spare, containing 1 mg/cmof terbium (terbium oxide): 0.1 g of terbium oxide were placed in a glass with a capacity of 100 cm, poured 5cmof hydrochloric acid and dissolved by heating. The solution was transferred to a volumetric flask with a capacity of 100 cmand adjusted to the mark with water.

Solutions of terbium workers with a concentration of 10 micrograms/CCand 100 micrograms/cm.of terbium (calculated as its oxide) is prepared by dilution of a backup solution of terbium respectively 100 and 10 times.

Mass fraction of oxide of terbium in the samples and recommended as additives for these sample solutions with different concentration of terbium are listed in table.1A.

Table 1A

Sec. 2. (Changed edition, Rev. N 1, 2).

3. DEFINITION OF CERIUM

3.1. A portion of the sample mass of 0.1−1 g (depending on the content of the cerium) is placed in a beaker with a capacity of 100 cm, flow 10 cmof hydrochloric acid (1:1), dissolve by heating on the tile, adding a few drops of hydrogen peroxide. In the presence of the yellow colour of the solution add a few crystals (2−5 pieces) tin dichloride to the total disappearance of color. The solution is evaporated to wet salts, dissolve in a minimum amount of water, poured 1 cmof a solution of hydrochloric acid (1:1), transferred to a measuring cylinder and adjusted with water to 10 cm.

In three test tubes with a capacity of 15−20 cmwas injected by pipette at 3 cmof the analyzed solution.

The first tube is introduced 2 cmof water, during the second and third at 1 and 2 cm, respectively, of working solutions of cerium so that the amount of cerium was approximately equal to and exceeding twice the expected number of cerium in the sample.

Simultaneously with the analysis of the sample carried out control experience in chemical

s.

3.2. Excitation and registration of luminescence spectra

Prepared solutions pour alternately in a quartz cuvette, starting with most supplements. Quartz cuvette placed in the spectrofluorimeter kuvamateriaalia of MCI-4 (spectrophotometer SF-4 in the analysis of praseodymium and its oxide).

The spectrum of luminescence excited by radiation of the xenon lamp, in the analysis of praseodymium and mercury oxide. Wavelength line excitation (255±3) nm. Band excitation of trivalent cerium is recorded in the range 300−400 nm. The band maximum of 355 nm. The sensitivity of the amplifier and the output gap is adjusted depending on the magnitude of the signal.

The entrance slit fully open.

The voltage at the photomultiplier is 800 V.

3.1, 3.2. (Changed edition, Rev. N 1).

3A. THE DEFINITION OF TERBIUM

3A.1. A portion of the sample weighing 1−4 g (depending on the content of terbium) were placed in a glass with a capacity of 100 cm, poured 10−40 cmof hydrochloric acid (1:1) and dissolved by heating. The solution was boiled down to 4−8 cm, transferred into a measuring cylinder with a capacity of 10 cmand adjusted with water to 10 cm. The solution is poured into a quartz cuvette and record the luminescence spectra of terbium in the region of wavelengths 520−570 nm when excited by radiation of 220 nm. Slit of a monochromator excitation 20 nm, the slit of the emission monochromator 10 nm, scan rate 60 nm/min.

In each registrarme measure the peak height of the band of terbium luminescence at 544 nm.

The measured solution is transferred to the same measuring cylinder and an additive injected working solution of terbium () at the level of the intended content in the sample (see table.1A).

The solution is thoroughly mixed, re-poured in a quartz cuvette and record the luminescence spectra of terbium, measure the peak height ().

Solution with first additive being transferred to the same measuring cylinder, and inject the second additive is equal to the first. Thus the second (cumulative) Supplement exceed approximately two times the expected content of terbium in the sample (see table.1A). The solution is thoroughly mixed and recorded the luminescence spectra of the terbium by measuring the peak height ().

Sec. 3A. (Added, Rev. N 2).

4. PROCESSING OF THE RESULTS

4.1. In each registrarme measure the height () of the peak of the analytical band of cerium.

Mass fraction of cerium dioxide () in percent is calculated by the formula

,

where is the peak height of the band of cerium to the sample solution, scale;

 — the height of the peak bands of cerium in the sample with the additive scale;

 — the height of the peak of the band control of the experience scale;

 — the concentration of a working solution of cerium, introduced as additives, mg/cm;

 — the quantity of working solution of cerium, cm;

 — the volume of the solution taken for measurement, cm;

 — the total volume of solution, cm;

 — the weight of the portion of the sample,

The result of the analysis take the average of two results of determinations obtained by calculating the two doba

VCAM.

4.2. Discrepancies in the results of parallel measurements, and the results of the two tests should not exceed the values of permissible differences given in table.2 and 2A.

Table 2

Table 2A

(Changed edition, Rev. N 1, 2).

4.3. Mass fraction of oxide of terbium () in percent is calculated by the formula

,

where is the mass of terbium is in the first or second (cumulative) Supplement ág;

 — the height of the peak of luminescence band of the terbium for the sample solution, mm;

 — the height of the peak of luminescence band of the terbium for the sample solution with the addition of the first or second (overall), mm;

 — the weight of the portion of the sample,

The result of the analysis take the average of two results of determinations obtained by calculating the two additives.

(Added, Rev. N 2).