- Email: [email protected]
Preparation and structure of EuIINb4O11
Mat. Res. Bull. Vol. i0, pp. 989-99Z, 1975. in the United States.
P e r g a m o n Press, Inc. Printed
PREPARATION AND STRUCTURE OF EuIINb4011
K. Sato, K. Maeda, G. Adachi and J. Shiokawa Department of Applied Chemistry, Faculty of Engineering, Osaka UniVersity, Yamadakami, Suita-Shi, Osaka-Fu, Japan
( R e c e i v e d July Z5, 1975; C o m m u n i c a t e d by B. T. M a t t h i a s ) ABSTRACT The occurrence of compound in the system has been studied by means of X-ray powder diffraction. A compound, EuIINbJOll , ~
was found.
The X-ray powder diffraction data
for Eu±INb. O.. could be indexed on a tetragonal cell with o
~
11
o
a=52.52 A, C=7.69 A. The temperature dependence of the magnetic susceptibility for this compound is expressed by the equation, ×M=7.10/(T+0.20). This compound is oxidized at about 290°C or above in air. Introduction There are many examples of Eu 2+ compounds which are isosyructural with Sr 2+ compounds (i), and it is known that Nb 5+ behaves similarly to Ta 5+ (2). Desgardin and Fayolle (3) studied the system EuO-Nb205, and prepared the niobate, Eu~INb4015, which was isostructural wlth Sr5Ta4015. This study was made f~r the purpose of the preparation of the new europium(II) niobates except Eu~INb4015Experimental As raw materials were used high purity europium oxide (99.9 %, Shin-etsu Chemical Corp.), niobium pentoxide and niobium metal (99.9% and 99.7% purity respectively, Wako Pure Chemical Industries, Ltd.). Mixtures of varying compositions were ground together in an agate mortar and pressed at 70Kg/cm into pellets, and fired on a m o l y b d e n u m dish in a graphite crucible at i150°C or higher in argon atmosphere (99.99%) or vacuum (~10-~mmHg). After rapid cooling, the central part of each pellet was taken out as a sample. Chemical analysis for any sample was made by the method described in Ref. (4). The analytical results were as follows. Found:
989
990
EUROPIUM
NIOBATE
Vol. I0, No. 9
TABLE 1 Experimental Condition and Xg for Samples Sample No. 1 2 3 4 5
Starting Material Eu203:Nb:Nb205 5 : 2 : 19 5 : 3 : 18.5 " " 5 : 4 : 18
Atm.
Ar Ar vac. vac. Ar
Heating Temp. (°C) 1250 1250 1200 1150 1250
Heating Time (hrs.) 3 " " " "
X (20°c) ×.~-6 . ±u emu/g 24.1 29.1 34.7 36.2 29.1
calculated value; E u I I N b 4 O l l , 38.1x10 -6 emu/g.
Eu,21.7; Nb,53.1 wt%; Eu:Nb=4.03:l.00. 21.6; Nb,53.1 wt%; Eu:Nb=4.00:l.00.
Calc.
for EuIINb4011 : Eu,
Fluorescent X-ray analysis was made to determined
the ion
ratio. Other analyses were made by the same methods used in previous work (5). Results and Discussion The preparation of EuIINb40.. was tried under several conditions. The niobium metal was ~ s ~ as the reductant. Table 1 shows the results of measurements of magnetic susceptibility for the samples obtained. The magnetic susceptibility per gram, X_, for sample no.4 is close to a calculated value for EuIINb4Oll .~ In table 2 are summarized the X-ray powder diffractionodata for Eu~INb4011 (sample no.4) which is tetragonal with a=52.52A and c=7.69A. X-ray diffraction for EuIINb4Oll and SrTa4011(6) have developed essentially identical patterns. Therefore, sample no.4 must be the compound, EuIINb4Oll. The pycnometric density measured for EuIINb40~I (sample no. 4) of 5.25 g.cc-lis in agreement with the X-ray denslty of 5.43 g.cc-l. The occurrence of compound system EuO-Nb?O~ has been studied. the same as fSr'sample no.4. The given in table 3. The results of are designated in parentheses. A "unknown".
other than EuIINb4Oll in the Experimental conditions were results of these experiments are the fluorescent X-ray analysis and B in the table 3 denote
X-ray reflections for sample no.8 and 9 are the same with those for EuIINb4Oll (sample no.4). The cell constants of these amples are given in-table 4. There is no appreciable difference in cell constants among these samples. The magnetic
susceptibility
for EuIINb4011
(sample no.4)
Vol. I0, No. 9
EUROPIUM TABLE
NIOBATE
991
2
Powder Diffraction Dataofor EuIINb.O... Tetragonal a=52.52A, c=7.69A. ~ l± hkl 930 1260 002 1430 502 1500 1530 1550 9--02 12120 i-~i-O0 1590 I-~00 1222 1860 1502 i-~32 2100
do
dc
Io
5.51 3.919 3.795 3.669 3.570 3.501 3.433 3.322 3.182 3.093 3.051 3.001 2.920 2.849 2.766 2.576 2.548 2.500
5.54 3.915 3.798 3.668 3.571 3.501 3.433 3.322 3.183 3.095 3.053 3.002 2.918 2.852 2.768 2.575 2.548 2.501
2 48 2 2 4 3 44 2 41 16 6 i00 42 3 96 29 22 3
hkl 18120 14102 1832 18150 2460 18180 24120 2790 2-7100) ~8-2 ~180. ~-~0-~ ) 9--94 3060 27150 1504 i-~94 ) 1804
TABLE Phase Present Sample No.
do
dc
Io
2.425 2.379 2.294 2.245 2.121 2.061 1.958 1.846
9 4 4 6 18 5 44 18
1.822
2.428 2.380 2.294 2.242 2.123 2.063 1.957 1.845 1.824 1.822
1.751 1.726 1.714 1.702
1.751 1.725 1.717 1.700
59
1.671 1.594
1.669 1.591
12
6
6 5 12
45
3
in the System EuO-Nb02. 5.
Starting Material EuOi.5:Nb:NbO2.5
Ion Ratio Eu2+ :Nb5+
6
2:0.6:3.4
1:2.0(1:2.03)
64.5
62.6
A+"EuIINb4OII ''
7
2 :0.6:
6.8
1:3.8(1:3.83)
39.0
41.1
4
2 :0.6:
7.4
1:4.0(1:3.91)
36.2
38.8
"EuIINb. O.~"+A II ~ ii EU a Nb4Oll
8
2:0.6:8.4
1:4.5(1:4.48)
32.9
35.4
Eu{INb4011
9
2:0.6:9.4
1:5.0(1:4.83)
29.3
32.6
EuIINb4OII
10
2:0.6:10.4
1:5.5(1:5.51)
28.2
30.2
ii
2:0.6:11.4
1:6.0(1:6.11)
26.5
28.1
a=l.0,
b=0.89,
Xg(20°C)
Phases
Present
xl0-6emu/g obs. calc.
"EuIINb4OII"+B "EuIINb4OII"+B
c=0.80.
was measure d in the range from 1.5 to 288 °K, and a part of the results obtained are illustrated in fig.l. The temperature dependence of that for EuIINb4Oll is expressed by the equation, ×M = 7.10/(T+0.20), and from this, ~he effective magnetic moment forEu 2+ in this compound is calculated to be a value of 7.57 B.M., which is close to a theoretical one (7.94 B.M.). At a temperature below 2.1°K, however, the m a g n e t i c susceptibility is lower than a theoretical one. This fact suggests this compound may be antiferromagnetic below 2.1°K.
99Z
EUROPIUM
NIOBATE
Vol. I0, No. 9 TABLE
1.5
4
Cell Constants of Sample no.4, 8 and 9. Sample No.
o
4 8 9
1.0
0.5 / / / / / !
0
t
5 10 TEMPERATURE(°K)
Fig.
52.52 52.58 52.51
7.69 7.60 7.63
EuIINb4Oll.
This value
agrees wl£h the total weight gain of 1.1% which is calculated assuming that EuIINb4Oll is oxidized to EuIIINb4011.5.
1
Magnetic Susceptibility for EuIINb4011.
c (A)
The thermal behavior of the product in air was examined by means of DTA and TGA. The weight gain starts at about 290°C, and the m a x i m u m of the exothermic DTA peak is at about 350°C where a total gain of weirht amounts to 1.0% of the starting material,
IE
/.
o
a (A)
(I/XM vs. T)
Conclusions In the system EuO-Nb205, a compound, EuIINb4Oll, was found. The structure for this compound was studied by means of X-ray diffraction method. The results of the magnetic susceptibility measurements, DTA and TGA experiments confirmed that this compound was represented by the formula EuIINb4Oll. References i.
A. Brous,
Acta Cryst.
6, 67
(1953).
2.
F. Fairbrother, The Chemistry Elsevier, A m s t e r d a m (1967).
3.
J. P. Fayolle
4.
M. Kato,
Teiryo
5.
K. Sato, (1975).
G. Adachi
6.
M. Gasperin,
and B. Raveau, Bunsekiho,
Bull.
of Niobium C. R. Acad.
p.20.
Sci.
(1974).
p. 642. Maruzen,
and J. Shiokawa, Soc.
and Tantalum,
franc.
Mat.
Miner.
Tokyo
Res.
Cryst.
279,
521
(1938).
Bull. 86,
386
10, 113 (1963).
P e r g a m o n Press, Inc. Printed
PREPARATION AND STRUCTURE OF EuIINb4011
K. Sato, K. Maeda, G. Adachi and J. Shiokawa Department of Applied Chemistry, Faculty of Engineering, Osaka UniVersity, Yamadakami, Suita-Shi, Osaka-Fu, Japan
( R e c e i v e d July Z5, 1975; C o m m u n i c a t e d by B. T. M a t t h i a s ) ABSTRACT The occurrence of compound in the system has been studied by means of X-ray powder diffraction. A compound, EuIINbJOll , ~
was found.
The X-ray powder diffraction data
for Eu±INb. O.. could be indexed on a tetragonal cell with o
~
11
o
a=52.52 A, C=7.69 A. The temperature dependence of the magnetic susceptibility for this compound is expressed by the equation, ×M=7.10/(T+0.20). This compound is oxidized at about 290°C or above in air. Introduction There are many examples of Eu 2+ compounds which are isosyructural with Sr 2+ compounds (i), and it is known that Nb 5+ behaves similarly to Ta 5+ (2). Desgardin and Fayolle (3) studied the system EuO-Nb205, and prepared the niobate, Eu~INb4015, which was isostructural wlth Sr5Ta4015. This study was made f~r the purpose of the preparation of the new europium(II) niobates except Eu~INb4015Experimental As raw materials were used high purity europium oxide (99.9 %, Shin-etsu Chemical Corp.), niobium pentoxide and niobium metal (99.9% and 99.7% purity respectively, Wako Pure Chemical Industries, Ltd.). Mixtures of varying compositions were ground together in an agate mortar and pressed at 70Kg/cm into pellets, and fired on a m o l y b d e n u m dish in a graphite crucible at i150°C or higher in argon atmosphere (99.99%) or vacuum (~10-~mmHg). After rapid cooling, the central part of each pellet was taken out as a sample. Chemical analysis for any sample was made by the method described in Ref. (4). The analytical results were as follows. Found:
989
990
EUROPIUM
NIOBATE
Vol. I0, No. 9
TABLE 1 Experimental Condition and Xg for Samples Sample No. 1 2 3 4 5
Starting Material Eu203:Nb:Nb205 5 : 2 : 19 5 : 3 : 18.5 " " 5 : 4 : 18
Atm.
Ar Ar vac. vac. Ar
Heating Temp. (°C) 1250 1250 1200 1150 1250
Heating Time (hrs.) 3 " " " "
X (20°c) ×.~-6 . ±u emu/g 24.1 29.1 34.7 36.2 29.1
calculated value; E u I I N b 4 O l l , 38.1x10 -6 emu/g.
Eu,21.7; Nb,53.1 wt%; Eu:Nb=4.03:l.00. 21.6; Nb,53.1 wt%; Eu:Nb=4.00:l.00.
Calc.
for EuIINb4011 : Eu,
Fluorescent X-ray analysis was made to determined
the ion
ratio. Other analyses were made by the same methods used in previous work (5). Results and Discussion The preparation of EuIINb40.. was tried under several conditions. The niobium metal was ~ s ~ as the reductant. Table 1 shows the results of measurements of magnetic susceptibility for the samples obtained. The magnetic susceptibility per gram, X_, for sample no.4 is close to a calculated value for EuIINb4Oll .~ In table 2 are summarized the X-ray powder diffractionodata for Eu~INb4011 (sample no.4) which is tetragonal with a=52.52A and c=7.69A. X-ray diffraction for EuIINb4Oll and SrTa4011(6) have developed essentially identical patterns. Therefore, sample no.4 must be the compound, EuIINb4Oll. The pycnometric density measured for EuIINb40~I (sample no. 4) of 5.25 g.cc-lis in agreement with the X-ray denslty of 5.43 g.cc-l. The occurrence of compound system EuO-Nb?O~ has been studied. the same as fSr'sample no.4. The given in table 3. The results of are designated in parentheses. A "unknown".
other than EuIINb4Oll in the Experimental conditions were results of these experiments are the fluorescent X-ray analysis and B in the table 3 denote
X-ray reflections for sample no.8 and 9 are the same with those for EuIINb4Oll (sample no.4). The cell constants of these amples are given in-table 4. There is no appreciable difference in cell constants among these samples. The magnetic
susceptibility
for EuIINb4011
(sample no.4)
Vol. I0, No. 9
EUROPIUM TABLE
NIOBATE
991
2
Powder Diffraction Dataofor EuIINb.O... Tetragonal a=52.52A, c=7.69A. ~ l± hkl 930 1260 002 1430 502 1500 1530 1550 9--02 12120 i-~i-O0 1590 I-~00 1222 1860 1502 i-~32 2100
do
dc
Io
5.51 3.919 3.795 3.669 3.570 3.501 3.433 3.322 3.182 3.093 3.051 3.001 2.920 2.849 2.766 2.576 2.548 2.500
5.54 3.915 3.798 3.668 3.571 3.501 3.433 3.322 3.183 3.095 3.053 3.002 2.918 2.852 2.768 2.575 2.548 2.501
2 48 2 2 4 3 44 2 41 16 6 i00 42 3 96 29 22 3
hkl 18120 14102 1832 18150 2460 18180 24120 2790 2-7100) ~8-2 ~180. ~-~0-~ ) 9--94 3060 27150 1504 i-~94 ) 1804
TABLE Phase Present Sample No.
do
dc
Io
2.425 2.379 2.294 2.245 2.121 2.061 1.958 1.846
9 4 4 6 18 5 44 18
1.822
2.428 2.380 2.294 2.242 2.123 2.063 1.957 1.845 1.824 1.822
1.751 1.726 1.714 1.702
1.751 1.725 1.717 1.700
59
1.671 1.594
1.669 1.591
12
6
6 5 12
45
3
in the System EuO-Nb02. 5.
Starting Material EuOi.5:Nb:NbO2.5
Ion Ratio Eu2+ :Nb5+
6
2:0.6:3.4
1:2.0(1:2.03)
64.5
62.6
A+"EuIINb4OII ''
7
2 :0.6:
6.8
1:3.8(1:3.83)
39.0
41.1
4
2 :0.6:
7.4
1:4.0(1:3.91)
36.2
38.8
"EuIINb. O.~"+A II ~ ii EU a Nb4Oll
8
2:0.6:8.4
1:4.5(1:4.48)
32.9
35.4
Eu{INb4011
9
2:0.6:9.4
1:5.0(1:4.83)
29.3
32.6
EuIINb4OII
10
2:0.6:10.4
1:5.5(1:5.51)
28.2
30.2
ii
2:0.6:11.4
1:6.0(1:6.11)
26.5
28.1
a=l.0,
b=0.89,
Xg(20°C)
Phases
Present
xl0-6emu/g obs. calc.
"EuIINb4OII"+B "EuIINb4OII"+B
c=0.80.
was measure d in the range from 1.5 to 288 °K, and a part of the results obtained are illustrated in fig.l. The temperature dependence of that for EuIINb4Oll is expressed by the equation, ×M = 7.10/(T+0.20), and from this, ~he effective magnetic moment forEu 2+ in this compound is calculated to be a value of 7.57 B.M., which is close to a theoretical one (7.94 B.M.). At a temperature below 2.1°K, however, the m a g n e t i c susceptibility is lower than a theoretical one. This fact suggests this compound may be antiferromagnetic below 2.1°K.
99Z
EUROPIUM
NIOBATE
Vol. I0, No. 9 TABLE
1.5
4
Cell Constants of Sample no.4, 8 and 9. Sample No.
o
4 8 9
1.0
0.5 / / / / / !
0
t
5 10 TEMPERATURE(°K)
Fig.
52.52 52.58 52.51
7.69 7.60 7.63
EuIINb4Oll.
This value
agrees wl£h the total weight gain of 1.1% which is calculated assuming that EuIINb4Oll is oxidized to EuIIINb4011.5.
1
Magnetic Susceptibility for EuIINb4011.
c (A)
The thermal behavior of the product in air was examined by means of DTA and TGA. The weight gain starts at about 290°C, and the m a x i m u m of the exothermic DTA peak is at about 350°C where a total gain of weirht amounts to 1.0% of the starting material,
IE
/.
o
a (A)
(I/XM vs. T)
Conclusions In the system EuO-Nb205, a compound, EuIINb4Oll, was found. The structure for this compound was studied by means of X-ray diffraction method. The results of the magnetic susceptibility measurements, DTA and TGA experiments confirmed that this compound was represented by the formula EuIINb4Oll. References i.
A. Brous,
Acta Cryst.
6, 67
(1953).
2.
F. Fairbrother, The Chemistry Elsevier, A m s t e r d a m (1967).
3.
J. P. Fayolle
4.
M. Kato,
Teiryo
5.
K. Sato, (1975).
G. Adachi
6.
M. Gasperin,
and B. Raveau, Bunsekiho,
Bull.
of Niobium C. R. Acad.
p.20.
Sci.
(1974).
p. 642. Maruzen,
and J. Shiokawa, Soc.
and Tantalum,
franc.
Mat.
Miner.
Tokyo
Res.
Cryst.
279,
521
(1938).
Bull. 86,
386
10, 113 (1963).